1,095 results on '"Image guided radiotherapy"'
Search Results
2. A body mass index-based method for "MR-only" abdominal MR-guided adaptive radiotherapy.
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Rippke, Carolin, Renkamp, C. Katharina, Stahl-Arnsberger, Christiane, Miltner, Annette, Buchele, Carolin, Hörner-Rieber, Juliane, Ristau, Jonas, Debus, Jürgen, Alber, Markus, and Klüter, Sebastian
- Abstract
Dose calculation for MR-guided radiotherapy (MRgRT) at the 0.35 T MR-Linac is currently based on deformation of planning CTs (defCT) acquired for each patient. We present a simple and robust bulk density overwrite synthetic CT (sCT) method for abdominal treatments in order to streamline clinical workflows. Fifty-six abdominal patient treatment plans were retrospectively evaluated. All patients had been treated at the MR-Linac using MR datasets for treatment planning and plan adaption and defCT for dose calculation. Bulk density CTs (4M-sCT) were generated from MR images with four material compartments (bone, lung, air, soft tissue). The relative electron densities (RED) for bone and lung were extracted from contoured CT structure average REDs. For soft tissue, a correlation between BMI and RED was evaluated. Dose was recalculated on 4M-sCT and compared to dose distributions on defCTs assessing dose differences in the PTV and organs at risk (OAR). Mean RED of bone was 1.17 ± 0.02, mean RED of lung 0.17 ± 0.05. The correlation between BMI and RED for soft tissue was statistically significant (p < 0.01). PTV dose differences between 4M-sCT and defCT were D mean : −0.4 ± 1.0%, D 1% : −0.3 ± 1.1% and D 95% : −0.5 ± 1.0%. OARs showed D 2% : −0.3 ± 1.9% and D mean : −0.1 ± 1.4% differences. Local 3D gamma index pass rates (2%/2mm) between dose calculated using 4M-sCT and defCT were 96.8 ± 2.6% (range 89.9–99.6%). The presented method for sCT generation enables precise dose calculation for MR-only abdominal MRgRT. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Virtual clinical trial-based study for clinical evaluation of projection-reduced low-dose cone-beam CT for image guided radiotherapy.
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Meijiao Wang, Kaining Yao, Yixin Zhao, Jianhao Geng, Xianggao Zhu, Zhiyan Liu, Yongheng Li, Hao Wu, and Yi Du
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CONE beam computed tomography ,IMAGE-guided radiation therapy ,WILCOXON signed-rank test ,COMPUTED tomography ,CLINICAL trials - Abstract
Purpose: Repeated cone-beam CT (CBCT) scans for image-guided radiotherapy (IGRT) increase the health risk of radiation-induced malignancies. Patientenrolled studies to optimize scan protocols are inadequate. We proposed a virtual clinical trial-based approach to evaluate projection-reduced low-dose CBCT for IGRT. Materials and Methods: A total of 71 patients were virtually enrolled with 26 head, 23 thorax and 22 pelvis scans. Projection numbers of full-dose CBCT scans were reduced to 1/2, 1/4, and 1/8 of the original to simulate low-dose scans. Contrast-to-noise ratio (CNR) values in fat and muscle were measured in the fulldose and low-dose images. CBCT images were registered to planning CT to derive 6-degree-of-freedom couch shifts. Registration errors were statistically analyzed with the Wilcoxon paired signed-rank test. Results: As projection numbers were reduced, CNR values descended and the magnitude of registration errors increased. The mean CNR values of full-dose and half-dose CBCT were >3.0. For full-dose and low-dose CBCT (i.e. 1/2, 1/4 and 1/8 full-dose), the mean registration errors were< ± 0.4 mm in translational directions (LAT, LNG, VRT) and ±0.2 degree in rotational directions (Pitch, Roll, Yaw); the mean magnitude of registration errors were< 1 mm in translation and< 0.5 degree in rotation. The couch shift differences between full-dose and lowdose CBCT were not statistically significant (p>0.05) in all the directions. Conclusion: The results indicate that while the impact of dose-reduction on CBCT couch shifts is not significant, the impact on CNR values is significant. Further validation on optimizing CBCT imaging dose is required. [ABSTRACT FROM AUTHOR]
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- 2024
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4. A body mass index-based method for 'MR-only' abdominal MR-guided adaptive radiotherapy
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Carolin Rippke, C. Katharina Renkamp, Christiane Stahl-Arnsberger, Annette Miltner, Carolin Buchele, Juliane Hörner-Rieber, Jonas Ristau, Jürgen Debus, Markus Alber, and Sebastian Klüter
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Adaptive radiotherapy ,Image guided radiotherapy ,Synthetic CT ,Bulk density ,MR-only ,MR guided radiotherapy ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Purpose: Dose calculation for MR-guided radiotherapy (MRgRT) at the 0.35 T MR-Linac is currently based on deformation of planning CTs (defCT) acquired for each patient. We present a simple and robust bulk density overwrite synthetic CT (sCT) method for abdominal treatments in order to streamline clinical workflows. Method: Fifty-six abdominal patient treatment plans were retrospectively evaluated. All patients had been treated at the MR-Linac using MR datasets for treatment planning and plan adaption and defCT for dose calculation. Bulk density CTs (4M-sCT) were generated from MR images with four material compartments (bone, lung, air, soft tissue). The relative electron densities (RED) for bone and lung were extracted from contoured CT structure average REDs. For soft tissue, a correlation between BMI and RED was evaluated. Dose was recalculated on 4M-sCT and compared to dose distributions on defCTs assessing dose differences in the PTV and organs at risk (OAR). Results: Mean RED of bone was 1.17 ± 0.02, mean RED of lung 0.17 ± 0.05. The correlation between BMI and RED for soft tissue was statistically significant (p
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- 2024
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5. Elekta Unity System
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Wolthaus, Jochem W. H., Omari, Eenas A., Chen, Xinfeng, van Asselen, Bram, Das, Indra J., editor, Alongi, Filippo, editor, Yadav, Poonam, editor, and Mittal, Bharat B., editor
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- 2024
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6. Surface guided radiotherapy practice in paediatric oncology: a survey on behalf of the SIOPE Radiation Oncology Working Group.
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Seravalli, Enrica, Kroon, Petra S, Bolle, Stephanie, Dunlea, Cathy, Harrabi, Semi B, Laprie, Anne, Lassen-Ramshad, Yasmin, Whitfield, Gillian, and Janssens, Geert O
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PEDIATRIC oncology , *RADIOTHERAPY , *ONCOLOGY , *RADIATION , *PEDIATRICS , *CHILD patients - Abstract
Introduction Surface guided radiotherapy (SGRT) is increasingly being implemented to track patient's surface movement and position during radiation therapy. However, limited information is available on the SGRT use in paediatrics. The aim of this double survey was to map SIOPE (European Society for Paediatric Oncology)-affiliated centres using SGRT and to gain information on potential indications, observed, or expected benefits. Methods A double online survey was distributed to 246 SIOPE-affiliated radiotherapy (RT) centres. Multiple choices, yes/no, and open answers were included. The first survey (41 questions) was active from February to March 2021. A shortened version (13 questions) was repeated in March 2023 to detect trends in SGRT use within the same community. Results Respectively, 76/142 (54%) and 28/142 (20%) responding centres used and planned to use SGRT clinically, including 4/34 (12%) new centres since 2021. Among the SGRT users, 33/76 (43%) already applied this technology to paediatric treatments. The main benefits of improved patient comfort, better monitoring of intrafraction motion, and more accurate initial patient set-up expected by future users did not differ from current SGRT-users (P = .893). Among non-SGRT users, the main hurdles to implement SGRT were costs and time for installation. In paediatrics, SGRT is applied to all anatomical sites. Conclusion This work provides information on the practice of SGRT in paediatrics across SIOPE-affiliated RT centres which can serve as a basis for departments when considering the purchase of SGRT systems. Advances in knowledge Since little information is available in the literature on the use of SGRT in paediatrics, the results of this double survey can serve as a basis for departments treating children when considering the purchase of an SGRT system. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Prospective evaluation of patient-reported outcomes of invisible ink tattoos for the delivery of external beam radiation therapy: the PREFER trial.
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Hardy-Abeloos, Camille, Gorovets, Daniel, Lewis, Aurora, Wenyan Ji, Lozano, Alicia, Chih Chun Tung, Yu, Francis, Hanlon, Alexandra, Haibo Lin, Anh Kha, Yoshiya Yamada, Kabarriti, Rafi, Lazarev, Stanislav, Hasan, Shaakir, Chhabra, Arpit M., Simone II, Charles B., and Choi, J. Isabelle
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EXTERNAL beam radiotherapy ,RADIOTHERAPY ,TATTOOING ,PROTON therapy ,PATIENT preferences - Abstract
Introduction: Invisible ink tattoos (IITs) avoid cosmetic permanence of visible ink tattoos (VITs) while serving as more reliable landmarks for radiation setup than tattooless setups. This trial evaluated patient-reported preference and feasibility of IIT implementation. Methods and materials: In an IRB-approved, single institution, prospective trial, patients receiving proton therapy underwent IIT-based treatment setup. A survey tool assessed patient preference on tattoos using a Likert scale. Matched patients treated using our institutional standard tattooless setup were identified; treatment times and image guidance requirements were evaluated between tattooless and IIT-based alignment approaches. Distribution differences were estimated using Wilcoxon rank-sum tests or Chi-square tests. Results: Of 94 eligible patients enrolled, median age was 58 years, and 58.5% were female. Most common treatment sites were breast (18.1%), lung (17.0%) and pelvic (14.9%). Patients preferred to receive IITs versus VITs (79.8% pre-treatment and 75.5% post-treatment, respectively). Patients were willing to travel farther from home to avoid VITs versus IITs (p<0.01). Females were willing to travel (45.5% vs. 23.1%; p=0.04) and pay additional money to avoid VITs (34.5% vs. 5.1%; p<0.01). Per-fraction average +treatment time and time from on table/in room to first beam were shorter with IIT-based vs. tattooless setup (12.3min vs. 14.1min; p=0.04 and 24.1min vs. 26.2min; p=0.02, respectively). Discussion: In the largest prospective trial on IIT-based radiotherapy setup to date, we found that patients prefer IITs to VITs. Additionally, IIT-based alignment is an effective and efficient strategy in comparison with tattooless setup. Standard incorporation of IITs for patient setup should be strongly considered. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Comparison of patient setup accuracy for optical surface-guided and X-ray-guided imaging with respect to the impact on intracranial stereotactic radiotherapy.
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Schöpe, Michael, Sahlmann, Jacob, Jaschik, Stefan, Findeisen, Anne, and Klautke, Gunther
- Abstract
Purpose: The objective of this work is to estimate the patient positioning accuracy of a surface-guided radiation therapy (SGRT) system using an optical surface scanner compared to an X‑ray-based imaging system (IGRT) with respect to their impact on intracranial stereotactic radiotherapy (SRT) and intracranial stereotactic radiosurgery (SRS). Methods: Patient positioning data, both acquired with SGRT and IGRT systems at the same linacs, serve as a basis for determination of positioning accuracy. A total of 35 patients with two different open face masks (578 datasets) were positioned using X‑ray stereoscopic imaging and the patient position inside the open face mask was recorded using SGRT. The measurement accuracy of the SGRT system (in a "standard" and an SRS mode with higher resolution) was evaluated using both IGRT and SGRT patient positioning datasets taking into account the measurement errors of the X‑ray system. Based on these clinically measured datasets, the positioning accuracy was estimated using Monte Carlo (MC) simulations. The relevant evaluation criterion, as standard of practice in cranial SRT, was the 95th percentile. Results: The interfractional measurement displacement vector of the SGRT system, σ
SGRT , in high resolution mode was estimated at 2.5 mm (68th percentile) and 5 mm (95th percentile). If the standard resolution was used, σSGRT increased by about 20%. The standard deviation of the axis-related σSGRT of the SGRT system ranged between 1.5 and 1.8 mm interfractionally and 0.5 and 1.0 mm intrafractionally. The magnitude of σSGRT is mainly due to the principle of patient surface scanning and not due to technical limitations or vendor-specific issues in software or hardware. Based on the resulting σSGRT , MC simulations served as a measure for the positioning accuracy for non-coplanar couch rotations. If an SGRT system is used as the only patient positioning device in non-coplanar fields, interfractional positioning errors of up to 6 mm and intrafractional errors of up to 5 mm cannot be ruled out. In contrast, MC simulations resulted in a positioning error of 1.6 mm (95th percentile) using the IGRT system. The cause of positioning errors in the SGRT system is mainly a change in the facial surface relative to a defined point in the brain. Conclusion: In order to achieve the necessary geometric accuracy in cranial stereotactic radiotherapy, use of an X‑ray-based IGRT system, especially when treating with non-coplanar couch angles, is highly recommended. [ABSTRACT FROM AUTHOR]- Published
- 2024
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9. Management of tumor volume changes during preoperative radiotherapy for extremity soft tissue sarcoma: a new strategy of adaptive radiotherapy
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De Lamarliere Marion Geneau, Lusque Amélie, Khalifa Justine Attal, Esteyrie Vincent, Chevreau Christine, Valentin Thibaud, Gangloff Dimitri, Meresse Thomas, Courtot Louis, Rochaix Philippe, Boulet Bérénice, Graulieres Eliane, and Ducassou Anne
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soft tissue sarcoma ,preoperative radiotherapy ,adaptive radiotherapy ,image guided radiotherapy ,volumes changes ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Using adaptive radiotherapy (ART), to determine objective clinical criteria that identify extremity soft tissue sarcoma (ESTS) patients requiring adaptation of their preoperative radiotherapy (RT) plan.
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- 2023
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10. Prospective evaluation of patient-reported outcomes of invisible ink tattoos for the delivery of external beam radiation therapy: the PREFER trial
- Author
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Camille Hardy-Abeloos, Daniel Gorovets, Aurora Lewis, Wenyan Ji, Alicia Lozano, Chih Chun Tung, Francis Yu, Alexandra Hanlon, Haibo Lin, Anh Kha, Yoshiya Yamada, Rafi Kabarriti, Stanislav Lazarev, Shaakir Hasan, Arpit M. Chhabra, Charles B. Simone, and J. Isabelle Choi
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proton therapy ,radiation therapy ,radiation tattoos ,quality of life ,image guided radiotherapy ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
IntroductionInvisible ink tattoos (IITs) avoid cosmetic permanence of visible ink tattoos (VITs) while serving as more reliable landmarks for radiation setup than tattooless setups. This trial evaluated patient-reported preference and feasibility of IIT implementation.Methods and materialsIn an IRB-approved, single institution, prospective trial, patients receiving proton therapy underwent IIT-based treatment setup. A survey tool assessed patient preference on tattoos using a Likert scale. Matched patients treated using our institutional standard tattooless setup were identified; treatment times and image guidance requirements were evaluated between tattooless and IIT-based alignment approaches. Distribution differences were estimated using Wilcoxon rank-sum tests or Chi-square tests.ResultsOf 94 eligible patients enrolled, median age was 58 years, and 58.5% were female. Most common treatment sites were breast (18.1%), lung (17.0%) and pelvic (14.9%). Patients preferred to receive IITs versus VITs (79.8% pre-treatment and 75.5% post-treatment, respectively). Patients were willing to travel farther from home to avoid VITs versus IITs (p
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- 2024
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11. Predicting cervical cancer target motion using a multivariate regression model to enable patient selection for adaptive external beam radiotherapy
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Lei Wang, Dualta McQuaid, Matthew Blackledge, Helen McNair, Emma Harris, and Susan Lalondrelle
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Cervical cancer ,Interfraction motion ,Adaptive radiotherapy ,Image guided radiotherapy ,Mathematical modelling ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background and purpose: Interfraction motion during cervical cancer radiotherapy is substantial in some patients, minimal in others. Non-adaptive plans may miss the target and/or unnecessarily irradiate normal tissue. Adaptive radiotherapy leads to superior dose-volume metrics but is resource-intensive. The aim of this study was to predict target motion, enabling patient selection and efficient resource allocation. Materials and methods: Forty cervical cancer patients had CT with full-bladder (CT-FB) and empty-bladder (CT-EB) at planning, and daily cone-beam CTs (CBCTs). The low-risk clinical target volume (CTVLR) was contoured. Mean coverage of the daily CTVLR by the CT-FB CTVLR was calculated for each patient. Eighty-three investigated variables included measures of organ geometry, patient, tumour and treatment characteristics. Models were trained on 29 patients (171 fractions). The Two-CT multivariate model could use all available data. The Single-CT multivariate model excluded data from the CT-EB. A univariate model was trained using the distance moved by the uterine fundus tip between CTs, the only method of patient selection found in published cervix plan-of-the-day studies. Models were tested on 11 patients (68 fractions). Accuracy in predicting mean coverage was reported as mean absolute error (MAE), mean squared error (MSE) and R2. Results: The Two-CT model was based upon rectal volume, dice similarity coefficient between CT-FB and CT-EB CTVLR, and uterine thickness. The Single-CT model was based upon rectal volume, uterine thickness and tumour size. Both performed better than the univariate model in predicting mean coverage (MAE 7 %, 7 % and 8 %; MSE 82 %2, 65 %2, 110 %2; R2 0.2, 0.4, −0.1). Conclusion: Uterocervix motion is complex and multifactorial. We present two multivariate models which predicted motion with reasonable accuracy using pre-treatment information, and outperformed the only published method.
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- 2024
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12. PINPOINT Feasibility Study
- Published
- 2022
13. Fan beam CT-guided online adaptive external radiotherapy of uterine cervical cancer: a dosimetric evaluation
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Haibo Peng, Jie Zhang, Ningyue Xu, Yangang Zhou, Huigang Tan, and Tao Ren
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Online adaptive radiotherapy ,Uterine cervical cancer ,Image guided radiotherapy ,In vivo dose verification ,Dosimetry ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Purpose To discuss the dosimetric advantages and reliability of the accurate delivery of online adaptive radiotherapy(online ART) for uterine cervical cancer(UCC). Methods and materials Six UCC patients were enrolled in this study. 95% of the planning target volume (PTV) reached 100% of the prescription dose (50.4 Gy/28fractions/6weeks) was required. The patients were scanned with uRT-Linac 506c KV-FBCT then the target volume (TV) and organs at risk (OARs) were delineated by doctors. The dosimeters designed and obtained a routine plan (Plan0). KV-FBCT was used for image guidance before subsequent fractional treatment. The online ART was processed after registration, which acquired a virtual nonadaptive radiotherapy plan (VPlan) and an adaptive plan (APlan). VPlan was the direct calculation of Plan0 on the fractional image, while APlan required adaptive optimization and calculation. In vivo dose monitoring and three-dimensional dose reconstruction were required during the implementation of APlan. Results The inter-fractional volumes of the bladder and rectum changed greatly among the treatments. These changes influenced the primary gross tumor volume (GTVp) and the position deviation of GTVp and PTV and positively affected the prescription dose coverage of TV. GTVp decreased gradually along with dose accumulation. The Dmax, D98, D95, D50, and D2 of APlan were superior to those of VPlan in target dose distribution. APlan had good conformal index, homogeneity index and target coverage. The rectum V40 and Dmax, bladder V40, the small bowel V40 and Dmax of APlan were better than that of VPlan. The APlan’s fractional mean γ passing rate was significantly higher than the international standard and the mean γ passing rate of all cases after the three-dimensional reconstruction was higher than 97.0%. Conclusion Online ART in external radiotherapy of UCC significantly improved the dose distribution and can become an ideal technology to achieve individualized precise radiotherapy.
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- 2023
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14. Optimisation of image guidance for improving radiation delivery in children's cancer
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Bryce-Atkinson, Abigail and Van Herk, Marcel
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image guided radiotherapy ,cone beam CT ,radiotherapy ,paediatric - Abstract
Cone beam CT (CBCT) is the most common technique used for modern image guided radiotherapy (IGRT). Children are more radiosensitive and at greater risk of radiation-induced malignancies than adults. Adult CBCT exposures can lead to excessively high doses in children and may not yield optimal image quality due to their differences in size and anatomy. Currently, protocols tailored to children are lacking, and the limits of dose reduction have not yet been studied. This thesis aims to evaluate the feasibility of introducing "ultra-low" dose CBCT protocols, such that children can benefit from highly accurate treatment delivery, without concern over additional imaging dose. In this thesis, a method was developed to simulate low dose CBCT using clinical ("standard dose") scans as input. This allowed for new protocols to be assessed in patients without additional "experimental" scans, and hence no additional dose. Image quality was assessed qualitatively and quantitatively throughout this thesis. Image quality assessment directly relevant to the IGRT task was performed by visual grading analysis (VGA) and by comparing registration accuracy to current protocols. To further explore the limits of dose reduction, a novel method of image quality assessment was used in acquired and simulated paediatric CBCT scans (ranging from ultra-low to adult doses) to determine the noise contributions of quantum noise (from dose reduction), and "anatomical noise" arising due to motion (e.g. respiratory or bowel motion) and artefacts (e.g. gas in the abdomen). Novel hardware was developed, since the lowest CBCT exposures cannot yet be clinically implemented. The paediatric bowtie filter was designed with built-in attenuation and the shape tailored to children to achieve ultra-low doses. The impact of the filter use was evaluated in paediatric patients by further developing the simulation method. A combination of simulated and acquired scans were used to test the limits of reduced scan time (and dose) 4D CBCT, assessed in lung cancer patients. Results showed that paediatric CBCT dose can be reduced down to 16% (0.125mGy) of the current paediatric protocol (0.8mGy), while maintaining accurate visual assessment and registration of bony anatomy. The novel filter resulted in five-fold dose reduction compared to the standard "adult" filter, and image quality remained appropriate for setup on bony anatomy even at the lowest doses. In contrast, soft tissue registration was accurate for moderately reduced doses, performing worse for doses below 1mGy. Increasing paediatric CBCT dose above 1mGy held no benefit in improving image quality, since above this threshold, anatomical noise is the dominating component of total noise. 4D CBCT scan time could be halved whilst maintaining accurate 4D registration to the tumour. Further reduction caused considerable degradation in visual quality and performance of 4D registration. Overall, the results in this thesis have informed recommendations for ultra-low dose CBCT protocols for children that can be easily implemented in clinic by choosing appropriate exposure settings and/or use of the novel paediatric bowtie filter, whilst maintaining image quality suitable for IGRT purposes. Further, the short scan time 4D CBCT protocol was implemented clinically at The Christie NHS Foundation Trust.
- Published
- 2021
15. Prostate cancer image guided radiotherapy: Why the commotion over rectal volume and motion?
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S.E. Alexander, U. Oelfke, R. Westley, H.A. McNair, and A.C. Tree
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Prostate cancer ,Intrafraction motion ,Rectal volume ,Patient preparation ,Image guided radiotherapy ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Introduction: Distended rectums on pre-radiotherapy scans are historically associated with poorer outcomes in patients treated with two-dimensional IGRT. Subsequently, strict rectal tolerances and preparation regimes were implemented. Contemporary IGRT, daily online registration to the prostate, corrects interfraction motion but intrafraction motion remains. We re-examine the need for rectal management strategies when using contemporary IGRT by quantifying rectal volume and its effect on intrafraction motion. Materials and methods: Pre and during radiotherapy rectal volumes and intrafraction motion were retrospectively calculated for 20 patients treated in 5-fractions and 20 treated in 20-fractions. Small (rectal volume at planning-CT ≤ median), and large (volume > median) subgroups were formed, and rectal volume between timepoints and subgroups compared. Rectal volume and intrafraction motion correlation was examined using Spearman’s rho. Intrafraction motion difference between small and large subgroups and between fractions with rectal volume < or ≥ 90 cm3 were assessed. Results: Median rectal volume was 74 cm3, 64 cm3 and 65 cm3 on diagnostic-MRI, planning-CT and treatment imaging respectively (ns). No significant correlation was found between patient’s rectal volume at planning-CT and median intrafraction motion, nor treatment rectal volume and intrafraction motion for individual fractions. No significant difference in intrafraction motion between small and large subgroups presented and for fractions where rectal volume breached 90 cm3, motion during that fraction was not significantly greater. Conclusion: Larger rectal volumes before radiotherapy and during treatment did not cause greater intrafraction motion. Findings support the relaxation of strict rectal diameter tolerances and do not support the need for rectal preparation when delivering contemporary IGRT to the prostate.
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- 2023
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16. Interfractional Liver Positional Motion Under Exhaled Breath Holding Based on Cone Beam Computed Tomography.
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HIDEHARU MIURA, YOSHIKO DOI, MINORU NAKAO, SHUICHI OZAWA, MASAHIRO KENJO, and YASUSHI NAGATA
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BREATH holding ,LIVER physiology ,CONE beam computed tomography ,IMAGE analysis ,STANDARD deviations - Abstract
Background/Aim: We measured interfractional liver positional motion in liver stereotactic body radiotherapy (SBRT) with exhaled breath holding (BH) based on kilovoltage (kV) cone-beam computed tomography (CBCT) images. Patients and Methods: We collected 528 pre-treatment kVCBCT images from 132 patients who underwent liver SBRT under exhaled BH using the Abches system, a non-electronic contact-based respiratory monitoring device, and analyzed them to investigate interfractional liver positional motion. Planning computed tomography (CT) scans were obtained using the Abches system when the patients were under exhaled BH. Translational 3-degree-of-freedom (DOF) soft-tissuebased image registration was performed using the kV-CBCT images under exhaled BH after 6-DOF vertebral bone image registration. Interfractional liver positional motions in the left-right (LR), anteroposterior (AP), and craniocaudal (CC) directions were defined based on the differences in the position of the liver relative to the vertebral bones. Results: For all fractions, the absolute mean±standard deviation for the interfractional liver positional motion in the LR, AP, and CC directions was 0.7±1.0 mm, 1.0±1.5 mm, and 2.8±3.1 mm, respectively. The liver interfractional systematic/random positional motions in the LR, AP, and CC directions were 0.9/1.2 mm, 1.4/1.8 mm, and 2.9/3.9 mm, respectively. For all fractions, 100.0%, 98.3%, and 86.9% of the interfractional liver positional motions in the LR, AP, and CC directions, respectively, were less than 5 mm. Conclusion: CBCT-guided online correction should be used to correct interfractional liver positions errors present in liver SBRT with exhaled BH. [ABSTRACT FROM AUTHOR]
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- 2023
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17. Evaluation of geometrical and dosimetrical uncertainties in MR guided radiotherapy to derive appropriate safety margins
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Shortall, Jane, Vasquez Osorio, Eliana, Kirkby, Karen, and Van Herk, Marcel
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610 ,Toxicity ,Medical Physics ,Pelvic cancer ,Cervical cancer ,Prostate cancer ,Rectal toxicity ,Electron Return Effect ,MR guided Radiotherapy ,Organ At Risk ,IGRT ,MRgRT ,Dose ,Uncertainty in radiotherapy ,Dosimetry ,Magnetic Resonance guided Radiotherapy ,Image guided Radiotherapy ,Cancer ,Radiotherapy - Abstract
Magnetic Resonance guided Radiotherapy (MRgRT) is a new technology that combines MR imaging with a radiotherapy treatment machine. Due to the improved soft tissue visibility compared with Computed Tomography (CT) or Cone-Beam CT (CBCT), MRgRT promises more accurate treatments with improved normal tissue sparing for sites including prostate and cervix. MRgRT brings new clinical challenges. Not least of these is the effect that the permanent magnetic field has on the dose deposition within the patient. Of particular concern is the Electron Return Effect (ERE), where dose depositing electrons return back into tissue when they traverse a density boundary. The dosimetric effects of ERE around "unplanned" air cavities in Organs At Risk (OAR) has not been well studied. The aim of this thesis is to determine the dosimetric effects of rectal gas, when the rectum is an OAR, during pelvic MRgRT. Monte Carlo dose calculations irradiating virtual phantoms containing spherical air cavities of varying sizes, under the influence of a 1.5 T transverse magnetic field, were performed. To calculate the local dose perturbation around the cavities, the dose distributions in the phantoms containing air were compared to that of a reference phantom containing no air. Results show that dose perturbations up-to ~70 % occur around large air cavities in the path of a single beam. Further, it was found that large volumes of rectal gas in the path of a single beam could result in 1cc of the rectal wall receiving 45 % more dose than planned. Results also show that effects do not cancel out for multiple overlapping beams; dose differences of ~20 % were observed around large air cavities. Next, a single equation to predict the local dose perturbation due to ERE and differences of beam attenuation around a gas cavity of given size was derived. The equation is intended to be incorporated into the MRgRT work-flow to alert when the presence of gas causes dose constraints to be violated. In this thesis, the equation was incorporated into a illustrative web-based simulation tool to calculate the total uncertainties associated with MRgRT. The likelihood of large volumes of gas remaining stable in the rectum of pelvic cancer patients on inter- and intra-fractional time-scales was investigated. Results indicate that not only is rectal gas likely to remain stable during a 20-25 minute treatment fraction, it is also likely to return to the same place in multiple fractions. The derived equation was used to estimate the dose perturbation due to rectal gas over a single fraction and a 4 or 20 fraction treatment. The dosimetric benefit of accounting for gas in the daily adaption was also demonstrated. Finally the Treatment Planning System (TPS) dose calculation around air cavities, used throughout this thesis, was experimentally verified using GafChromic EBT3 film. Overall, results in this thesis show, for the first time, that unplanned rectal gas forming during pelvic MRgRT is likely to result in clinically concerning dosimetric effects, potentially increasing the risk of grade 2+ rectal toxicity.
- Published
- 2020
18. Leaf-individual calibration for a double stack multileaf collimator in photon radiotherapy
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Carolin Rippke, C. Katharina Renkamp, Charbel Attieh, Fabian Schlüter, Carolin Buchele, Jürgen Debus, Markus Alber, and Sebastian Klüter
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MR-Linac ,Adaptive radiotherapy ,Image guided radiotherapy ,MR-guided radiotherapy ,Quality assurance ,Quality control ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background and Purpose: In online adaptive stereotactic body radiotherapy treatments, linear accelerator delivery accuracy is essential. Recently introduced double stack multileaf collimators (MLCs) have new facets in their calibration. We established a radiation-based leaf-individual calibration (LIMCA) method for double stack MLCs. Materials and Methods: MLC leaf positions were evaluated from four cardinal angles with test patterns at measurement positions throughout the radiation field on EBT3 radiochromic film for each single stack. The accuracy of the method and repeatability of the results were assessed. The effect of MLC positioning errors was characterized for a measured output factor curve and a clinical patient plan. Results: All positions in the motor step – position calibration file were optimized in the established LIMCA method. The resulting double stack mean accuracy for all angles was 0.2 ± 0.1 mm for X1 (left bank) and 0.2 ± 0.2 mm for X2 (right bank). The accuracy of the leaf position evaluation was 0.2 mm (95% confidence level). The MLC calibration remained stable over four months. Small MLC leaf position errors (e.g. 1.2 mm field size reduction) resulted in important dose errors (−5.8 %) for small quadratic fields of 0.83 × 0.83 cm2. Single stack position accuracy was essential for highly modulated treatment plans. Conclusions: LIMCA is a new double stack MLC calibration method that increases treatment accuracy from four angles and for all moving leaves.
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- 2023
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19. Fan beam CT-guided online adaptive external radiotherapy of uterine cervical cancer: a dosimetric evaluation.
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Peng, Haibo, Zhang, Jie, Xu, Ningyue, Zhou, Yangang, Tan, Huigang, and Ren, Tao
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CERVICAL cancer , *MEDICAL dosimetry , *RADIOTHERAPY , *SMALL intestine - Abstract
Purpose: To discuss the dosimetric advantages and reliability of the accurate delivery of online adaptive radiotherapy(online ART) for uterine cervical cancer(UCC). Methods and materials: Six UCC patients were enrolled in this study. 95% of the planning target volume (PTV) reached 100% of the prescription dose (50.4 Gy/28fractions/6weeks) was required. The patients were scanned with uRT-Linac 506c KV-FBCT then the target volume (TV) and organs at risk (OARs) were delineated by doctors. The dosimeters designed and obtained a routine plan (Plan0). KV-FBCT was used for image guidance before subsequent fractional treatment. The online ART was processed after registration, which acquired a virtual nonadaptive radiotherapy plan (VPlan) and an adaptive plan (APlan). VPlan was the direct calculation of Plan0 on the fractional image, while APlan required adaptive optimization and calculation. In vivo dose monitoring and three-dimensional dose reconstruction were required during the implementation of APlan. Results: The inter-fractional volumes of the bladder and rectum changed greatly among the treatments. These changes influenced the primary gross tumor volume (GTVp) and the position deviation of GTVp and PTV and positively affected the prescription dose coverage of TV. GTVp decreased gradually along with dose accumulation. The Dmax, D98, D95, D50, and D2 of APlan were superior to those of VPlan in target dose distribution. APlan had good conformal index, homogeneity index and target coverage. The rectum V40 and Dmax, bladder V40, the small bowel V40 and Dmax of APlan were better than that of VPlan. The APlan's fractional mean γ passing rate was significantly higher than the international standard and the mean γ passing rate of all cases after the three-dimensional reconstruction was higher than 97.0%. Conclusion: Online ART in external radiotherapy of UCC significantly improved the dose distribution and can become an ideal technology to achieve individualized precise radiotherapy. [ABSTRACT FROM AUTHOR]
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- 2023
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20. Hypofractionation and SABR: 25 years of evolution in medical physics and a glimpse of the future.
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Rong, Yi, Ding, Xuanfeng, and Daly, Megan E.
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MEDICAL physics , *DOSE fractionation , *STEREOTACTIC radiotherapy , *MEDICAL technology , *TREATMENT effectiveness - Abstract
As we were invited to write an article for celebrating the 50th Anniversary of Medical Physics journal, on something historically significant, commemorative, and exciting happening in the past decades, the first idea came to our mind is the fascinating radiotherapy paradigm shift from conventional fractionation to hypofractionation and stereotactic ablative radiotherapy (SABR). It is historically and clinically significant since as we all know this RT treatment revolution not only reduces treatment duration for patients, but also improves tumor control and cancer treatment outcomes. It is also commemorative and exciting for us medical physicists since the technology development in medical physics has been the main driver for the success of this treatment regimen which requires high precision and accuracy throughout the entire treatment planning and delivery. This article provides an overview of the technological development and clinical trials evolvement in the past 25 years for hypofractionation and SABR, with an outlook to the future improvement. [ABSTRACT FROM AUTHOR]
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- 2023
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21. Creation, evolution, and future challenges of ion beam therapy from a medical physicist's viewpoint (Part 2). Chapter 2. Biophysical model, treatment planning system and image guided radiotherapy.
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Endo, Masahiro
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When an ion beam penetrates deeply into the body, its kinetic energy decreases, and its biological effect increases due to the change of the beam quality. To give a uniform biological effect to the target, it is necessary to reduce the absorbed dose with the depth. A bio-physical model estimating the relationship between ion beam quality and biological effect is necessary to determine the relative biological effectiveness (RBE) of the ion beam that changes with depth. For this reason, Lawrence Berkeley Laboratory, National Institute of Radiological Sciences (NIRS) and GSI have each developed their own model at the starting of the ion beam therapy. Also, NIRS developed a new model at the starting of the scanning irradiation. Although the Local Effect Model (LEM) at the GSI and the modified Microdosimetric Kinetic Model (MKM) at the NIRS, the both are currently used, can similarly predict radiation quality-induced changes in surviving fraction of cultured cell, the clinical RBE-weighted doses for the same absorbed dose are different. This is because the LEM uses X-rays as a reference for clinical RBE, whereas the modified MKM uses carbon ion beam as a reference and multiplies it by a clinical factor of 2.41. Therefore, both are converted through the absorbed dose. In PART 2, I will describe the development of such a bio-physical model, as well as the birth and evolution of a treatment planning system and image guided radiotherapy. [ABSTRACT FROM AUTHOR]
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- 2023
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22. Stereotactic Magnetic Resonance-Guided Adaptive and Non-Adaptive Radiotherapy on Combination MR-Linear Accelerators: Current Practice and Future Directions.
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Bryant, John Michael, Weygand, Joseph, Keit, Emily, Cruz-Chamorro, Ruben, Sandoval, Maria L., Oraiqat, Ibrahim M., Andreozzi, Jacqueline, Redler, Gage, Latifi, Kujtim, Feygelman, Vladimir, and Rosenberg, Stephen A.
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PARTICLE accelerators , *CONNECTIVE tissues , *MAGNETIC resonance imaging , *PATIENT-centered care , *TREATMENT effectiveness , *RADIATION doses , *DRUG synergism , *TUMORS , *RADIOSURGERY , *MEDICAL practice , *COMPUTER-assisted image analysis (Medicine) - Abstract
Simple Summary: Stereotactic body radiotherapy (SBRT) is an effective radiation therapy technique that heavily relies upon daily image guidance to achieve the necessary precision. Magnetic resonance imaging (MRI) offers significant advantages over computed tomography (CT), which has traditionally been used for daily image guidance for SBRT. Hybrid MRI and linear accelerators (MRLs) allow for the delivery of stereotactic MR-guided adaptive radiotherapy (SMART) and improve patient outcomes for many types of tumors. In this review, we summarized the evidence for SMART as it related to ablative treatments and explored how multi-parametric MRIs could continue to improve patient outcomes. Stereotactic body radiotherapy (SBRT) is an effective radiation therapy technique that has allowed for shorter treatment courses, as compared to conventionally dosed radiation therapy. As its name implies, SBRT relies on daily image guidance to ensure that each fraction targets a tumor, instead of healthy tissue. Magnetic resonance imaging (MRI) offers improved soft-tissue visualization, allowing for better tumor and normal tissue delineation. MR-guided RT (MRgRT) has traditionally been defined by the use of offline MRI to aid in defining the RT volumes during the initial planning stages in order to ensure accurate tumor targeting while sparing critical normal tissues. However, the ViewRay MRIdian and Elekta Unity have improved upon and revolutionized the MRgRT by creating a combined MRI and linear accelerator (MRL), allowing MRgRT to incorporate online MRI in RT. MRL-based MR-guided SBRT (MRgSBRT) represents a novel solution to deliver higher doses to larger volumes of gross disease, regardless of the proximity of at-risk organs due to the (1) superior soft-tissue visualization for patient positioning, (2) real-time continuous intrafraction assessment of internal structures, and (3) daily online adaptive replanning. Stereotactic MR-guided adaptive radiation therapy (SMART) has enabled the safe delivery of ablative doses to tumors adjacent to radiosensitive tissues throughout the body. Although it is still a relatively new RT technique, SMART has demonstrated significant opportunities to improve disease control and reduce toxicity. In this review, we included the current clinical applications and the active prospective trials related to SMART. We highlighted the most impactful clinical studies at various tumor sites. In addition, we explored how MRL-based multiparametric MRI could potentially synergize with SMART to significantly change the current treatment paradigm and to improve personalized cancer care. [ABSTRACT FROM AUTHOR]
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- 2023
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23. A dose escalated fiducial marker‑based image guided radical radiotherapy in locally advanced prostate cancers: A single institute experience from India.
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Gupta, Pramod K., Rastogi, Neeraj, Maria Das, Koilpillai Joseph, and Kumar, Shaleen
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PROSTATE cancer , *PROSTATE cancer patients , *SUPINE position , *GLEASON grading system , *RADIOTHERAPY , *PROGRESSION-free survival - Abstract
Purpose: Image guided radiotherapy(IGRT) is one of the most commonly used treatment in LAPC. Dose escalation >74 Gy has shown to improve the biochemical control and freedom from failure rate in LAPC.We started treating LAPC patients with dose escalated IGRT in our institute since 2008. We did a retrospective analysis to see the biochemical relapse‑free survival, cancer‑specific survival, and bladder and rectal toxicity. Methods: A total of 50 consecutive prostate cancer patients were treated with dose escalated IGRT between January 2008 to Dec 2013. Out of these, 37 patients of LAPC were analyzed and their medical records were retrieved. All were biopsy proven adenocarcinoma of prostate with D’Amico high risk category (PSA >20 ng/mL or Gleason score (GS) >7 or T2c‑T4). Three gold fiducial markers were placed in the prostate. Patients were immobilized in supine position with either ankle or knee rest. Partial bladder filling and rectum emptying protocol was followed. Clinical target volume (CTV) segmentation was done according to EORTC recommendation. Population based PTV expansion from CTV of 10 mm (cranio‑caudal), 10 mm (medio‑lateral), 10 mm (anterior) and 5 mm (posterior) was given. In patients with radiologically enlarged pelvic lymph node, whole pelvis intensity modulated radiation therapy (IMRT) to a dose of 50.4 Gy/28# followed by prostatic boost 26Gy/13# by IMRT using image guidance. Rest of the patients received prostate only RT to a dose of 76Gy/38# by IGRT. Daily On board KV images were taken and 2D‑2D fiducial marker matching was done and shifts were applied on machine before treatment. Biochemical relapse was defined as per Phoenix definition (nadir + 2 ng/mL). Radiation Therapy Oncology Group (RTOG) toxicity grading system was used to document acute and late toxicity. Results: Median age of patients was 66 years. Median pre‑treatment PSA was 22 ng/mL. Thirty patients (81%) had T3/T4 lesions and nodal metastasis was seen in 11 (30%). Median GS was 8. Median radiotherapy dose was 76 Gy. Imaging before radiation delivery was done in 19(51%) patients and 100% in 14 (38%) patients. With a median follow up of 6.5 years, 5‑year biochemical relapse‑free survival (bRFS) and cancer‑specific survival (CSS) was 66% and 79% respectively. Mean bRFS and CSS were 71 months and 83 months however Median bRFS and CSS were not reached. Distant metastasis was seen in 8 (22%). RTOG grade III bladder and rectal toxicity was seen in 2 (6%) and 2 (6%) patients respectively. Conclusion: Dose escalated IGRT with fiducial marker positional verification for LAPC is doable in Indian setup provided more emphasis given on daily on‑board imaging with rigorous bladder filling and rectal emptying protocol. Long term follow up is needed to assess the effect on distant disease‑free survival and CSS. [ABSTRACT FROM AUTHOR]
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- 2023
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24. Application value of liquid fiducial marker in image-guided radiotherapy
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HUANG Yulin, YANG Haifang, JIANG Bin, ZHANG Wang, ZHANG Chao, LIU Jianping, and TIAN Long
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liquid fiducial marker ,image guided radiotherapy ,application value ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
This study was conducted to evaluate the application value of a degradable liquid fiducial marker (LFM) in image-guided radiotherapy. In vitro experiment: using a solid fiducial marker (SFM) as a reference, the visibility, artifact, and optimal injection volume of an LFM under different cone beam CT tube voltage conditions were evaluated. In vivo experiment: using the SFM as a reference, the stability and degradation status of the LFM in nude mice were evaluated. Nude mice implanted with tumor cells were randomly divided into four groups: single fraction radiotherapy group (16 Gy/fraction) without LFM injection, single fraction radiotherapy group (16 Gy/fraction) with LFM injection, 2 fractions radiotherapy group (8 Gy/fraction) with LFM injection, and 4 fractions radiotherapy group (4 Gy/fraction) with LFM injection. The impact of LFM on tumor growth was evaluated based on the irradiation results. Compared with SFM, the LFM artifacts were significantly smaller (all p
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- 2023
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25. A clinical study comparing polymer and gold fiducials for prostate cancer radiotherapy
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Daryl Lim Joon, Colleen Berry, Benjamin Harris, Mark Tacey, Drew Smith, Nathan Lawrentschuk, Michal Elisabeth Schneider, Olivia Fraser, Megan Hall, Michael Chao, Farshad Foroudi, Trish Jenkins, David Angus, Morikatsu Wada, Shomik Sengupta, and Vincent Khoo
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radiotherapy ,prostate cancer ,polymer fiducials ,image guided radiotherapy ,verification ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
IntroductionImage guidance with gold fiducials improves outcomes of prostate radiotherapy. However, gold produces artefact on CT imaging, interfering with contouring and verification. The purpose of this study was to compare polymer to standard gold fiducials using radiotherapy imaging modalities to assess the visibility and artefact.MethodsTwenty eight patients with locally advanced prostate cancer were enrolled, half had three polymer fiducials implanted into the prostate and half underwent insertion of gold fiducials. Patients were imaged with CT, T2 weighted MRI, cone-beam CT (CBCT) and planar KV images. Fiducials were scored for visibility and assessed for CT artefact in surrounding prostate tissue. The artefact was quantified from Hounsfield number histograms and separated into percentile ranges and proportion of voxels in HU normal tissue range of a 2cm sphere surrounding the fiducial.ResultsGold and polymer fiducials were sufficiently visible for CT and CBCT verification. The gold fiducials could be visualized well on KV planar imaging; however, the polymer markers were obscured by pelvic bones. Neither polymer nor gold fiducials could be visualized on MRI. The polymer fiducial produced less artefact than gold on CT, having less voxel spread for the HU percentile ranges and a greater proportion of voxels in the normal tissue range.ConclusionsPolymer fiducials are a more suitable fiducial than gold for CT/CBCT in prostate cancer radiotherapy, demonstrating minimal artefact and good visibility on CT. However, they were not well seen on MRI or KV imaging and thus not suitable for co-registration or planar KV verification.
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- 2023
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26. TIGRE-VarianCBCT for on-board cone-beam computed tomography, an open-source toolkit for imaging, dosimetry and clinical research.
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Du, Yi, Wang, Ruoxi, Biguri, Ander, Zhao, Xuzhi, Peng, Yahui, and Wu, Hao
- Abstract
• Open-source Toolkit Matlab-GPU for Varian On-board CBCT for IGRT. • Bridge the gap between clinical usage of CBCT scan data and research algorithms. • Entire imaging chain from data conditioning to post processing are incorporated. • Research in CBCT imaging, dosimetry and virtual clinical trial can be performed. We presented TIGRE-VarianCBCT, an open-source toolkit Matlab-GPU for Varian on-board cone-beam CT with particular emphasis to address challenges in raw data preprocessing, artifacts correction, tomographic reconstruction and image post-processing. The aim of this project is to provide not only a tool to bridge the gap between clinical usage of CBCT scan data and research algorithms but also a framework that breaks down the imaging chain into individual processes so that research effort can be focused on a specific part. The entire imaging chain, module-based architecture, data flow and techniques used in the creation of the toolkit are presented. Raw scan data are first decoded to extract X-ray fluoro image series and set up the imaging geometry. Data conditioning operations including scatter correction, normalization, beam-hardening correction, ring removal are performed sequentially. Reconstruction is supported by TIGRE with FDK as well as a variety of iterative algorithms. Pixel-to-HU mapping is calibrated by a Catphan
TM 504 phantom. Imaging dose in CTDIw is calculated in an empirical formula. The performance was validated on real patient scans with good agreement with respect to vendor-designed program. Case studies in scan protocol optimization, low dose imaging and iterative algorithm comparison demonstrated its substantial potential in performing scan data based clinical studies. The toolkit is released under the BSD license, imposing minimal restrictions on its use and distribution. The toolkit is accessible as a module at https://github.com/CERN/TIGRE. [ABSTRACT FROM AUTHOR]- Published
- 2022
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27. Virtual clinical trial-based study for clinical evaluation of projection-reduced low-dose cone-beam CT for image guided radiotherapy.
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Wang M, Yao K, Zhao Y, Geng J, Zhu X, Liu Z, Li Y, Wu H, and Du Y
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Purpose: Repeated cone-beam CT (CBCT) scans for image-guided radiotherapy (IGRT) increase the health risk of radiation-induced malignancies. Patient-enrolled studies to optimize scan protocols are inadequate. We proposed a virtual clinical trial-based approach to evaluate projection-reduced low-dose CBCT for IGRT., Materials and Methods: A total of 71 patients were virtually enrolled with 26 head, 23 thorax and 22 pelvis scans. Projection numbers of full-dose CBCT scans were reduced to 1/2, 1/4, and 1/8 of the original to simulate low-dose scans. Contrast-to-noise ratio (CNR) values in fat and muscle were measured in the full-dose and low-dose images. CBCT images were registered to planning CT to derive 6-degree-of-freedom couch shifts. Registration errors were statistically analyzed with the Wilcoxon paired signed-rank test., Results: As projection numbers were reduced, CNR values descended and the magnitude of registration errors increased. The mean CNR values of full-dose and half-dose CBCT were >3.0. For full-dose and low-dose CBCT (i.e. 1/2, 1/4 and 1/8 full-dose), the mean registration errors were< ± 0.4 mm in translational directions (LAT, LNG, VRT) and ±0.2 degree in rotational directions (Pitch, Roll, Yaw); the mean magnitude of registration errors were< 1 mm in translation and< 0.5 degree in rotation. The couch shift differences between full-dose and low-dose CBCT were not statistically significant (p>0.05) in all the directions., Conclusion: The results indicate that while the impact of dose-reduction on CBCT couch shifts is not significant, the impact on CNR values is significant. Further validation on optimizing CBCT imaging dose is required., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Yao, Zhao, Geng, Zhu, Liu, Li, Wu and Du.)
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- 2024
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28. A simulated comparison of lung tumor target verification using stereoscopic tomosynthesis or radiography.
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Hsieh, Scott S., Ng, Lydia W., Cao, Minsong, and Lee, Percy
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FIDUCIAL markers (Imaging systems) , *LUNGS , *LUNG tumors , *TOMOSYNTHESIS , *MONTE Carlo method , *RADIOGRAPHY - Abstract
Purpose: Mobile lung tumors are increasingly being treated with ablative radiotherapy, for which precise motion management is essential. In‐room stereoscopic radiography systems are able to guide ablative radiotherapy for stationary cranial lesions but not optimally for lung tumors unless fiducial markers are inserted. We propose augmenting stereoscopic radiographic systems with multiple small x‐ray sources to provide the capability of imaging with stereoscopic, single frame tomosynthesis. Methods: In single frame tomosynthesis, nine x‐ray sources are placed in a 3 × 3 configuration and energized simultaneously. The beams from these sources are collimated so that they converge on the tumor and then diverge to illuminate nine non‐overlapping sectors on the detector. These nine sector images are averaged together and filtered to create the tomosynthesis effect. Single frame tomosynthesis is intended to be an alternative imaging mode for existing stereoscopic systems with a field of view that is three times smaller and a temporal resolution equal to the frame rate of the detector. We simulated stereoscopic tomosynthesis and radiography using Monte Carlo techniques on 60 patients with early‐stage lung cancer from the NSCLC‐Radiomics dataset. Two board‐certified radiation oncologists reviewed these simulated images and rated them on a 4‐point scale (1: tumor not visible; 2: tumor visible but inadequate for motion management; 3: tumor visible and adequate for motion management; 4: tumor visibility excellent). Each tumor was independently presented four times (two viewing angles from radiography and two viewing angles from tomosynthesis) in a blinded fashion over two reading sessions. Results: The fraction of tumors that were rated as adequate or excellent for motion management (scores 3 or 4) from at least one viewing angle was 53% using radiography and 90% using tomosynthesis. From both viewing angles, the corresponding fractions were 7% for radiography and 48% for tomosynthesis. Readers agreed exactly on 62% of images and within 1 point on 98% of images. The acquisition technique was estimated to be 75 mAs at 120 kVp per treatment fraction assuming one verification image per breath, approximately one order of magnitude less than a standard dose cone beam CT. Conclusions: Stereoscopic tomosynthesis may provide a noninvasive, low dose, intrafraction motion verification technique for lung tumors treated by ablative radiotherapy. The system architecture is compatible with real‐time video capture at 30 frames per second. Simulations suggest that most, but not all, lung tumors can be adequately visualized from at least one viewing angle. [ABSTRACT FROM AUTHOR]
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- 2022
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29. Stereotactic Magnetic Resonance-Guided Adaptive and Non-Adaptive Radiotherapy on Combination MR-Linear Accelerators: Current Practice and Future Directions
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John Michael Bryant, Joseph Weygand, Emily Keit, Ruben Cruz-Chamorro, Maria L. Sandoval, Ibrahim M. Oraiqat, Jacqueline Andreozzi, Gage Redler, Kujtim Latifi, Vladimir Feygelman, and Stephen A. Rosenberg
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radiation therapy ,RT ,ultra-hypofractionated radiation therapy ,ablative radiation therapy ,adaptive radiation therapy ,image guided radiotherapy ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Stereotactic body radiotherapy (SBRT) is an effective radiation therapy technique that has allowed for shorter treatment courses, as compared to conventionally dosed radiation therapy. As its name implies, SBRT relies on daily image guidance to ensure that each fraction targets a tumor, instead of healthy tissue. Magnetic resonance imaging (MRI) offers improved soft-tissue visualization, allowing for better tumor and normal tissue delineation. MR-guided RT (MRgRT) has traditionally been defined by the use of offline MRI to aid in defining the RT volumes during the initial planning stages in order to ensure accurate tumor targeting while sparing critical normal tissues. However, the ViewRay MRIdian and Elekta Unity have improved upon and revolutionized the MRgRT by creating a combined MRI and linear accelerator (MRL), allowing MRgRT to incorporate online MRI in RT. MRL-based MR-guided SBRT (MRgSBRT) represents a novel solution to deliver higher doses to larger volumes of gross disease, regardless of the proximity of at-risk organs due to the (1) superior soft-tissue visualization for patient positioning, (2) real-time continuous intrafraction assessment of internal structures, and (3) daily online adaptive replanning. Stereotactic MR-guided adaptive radiation therapy (SMART) has enabled the safe delivery of ablative doses to tumors adjacent to radiosensitive tissues throughout the body. Although it is still a relatively new RT technique, SMART has demonstrated significant opportunities to improve disease control and reduce toxicity. In this review, we included the current clinical applications and the active prospective trials related to SMART. We highlighted the most impactful clinical studies at various tumor sites. In addition, we explored how MRL-based multiparametric MRI could potentially synergize with SMART to significantly change the current treatment paradigm and to improve personalized cancer care.
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- 2023
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30. Validation of an MRI-only planning workflow for definitive pelvic radiotherapy.
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O'Connor, Laura M., Dowling, Jason A., Choi, Jae Hyuk, Martin, Jarad, Warren-Forward, Helen, Richardson, Haylea, Best, Leah, Skehan, Kate, Kumar, Mahesh, Govindarajulu, Geetha, Sridharan, Swetha, and Greer, Peter B.
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ANUS , *RADIOTHERAPY treatment planning , *RECTUM , *MAGNETIC resonance imaging - Abstract
Purpose: Previous work on Magnetic Resonance Imaging (MRI) only planning has been applied to limited treatment regions with a focus on male anatomy. This research aimed to validate the use of a hybrid multi-atlas synthetic computed tomography (sCT) generation technique from a MRI, using a female and male atlas, for MRI only radiation therapy treatment planning of rectum, anal canal, cervix and endometrial malignancies. Patients and methods: Forty patients receiving radiation treatment for a range of pelvic malignancies, were separated into male (n = 20) and female (n = 20) cohorts for the creation of gender specific atlases. A multi-atlas local weighted voting method was used to generate a sCT from a T1-weighted VIBE DIXON MRI sequence. The original treatment plans were copied from the CT scan to the corresponding sCT for dosimetric validation. Results: The median percentage dose difference between the treatment plan on the CT and sCT at the ICRU reference point for the male cohort was − 0.4% (IQR of 0 to − 0.6), and − 0.3% (IQR of 0 to − 0.6) for the female cohort. The mean gamma agreement for both cohorts was > 99% for criteria of 3%/2 mm and 2%/2 mm. With dose criteria of 1%/1 mm, the pass rate was higher for the male cohort at 96.3% than the female cohort at 93.4%. MRI to sCT anatomical agreement for bone and body delineated contours was assessed, with a resulting Dice score of 0.91 ± 0.2 (mean ± 1 SD) and 0.97 ± 0.0 for the male cohort respectively; and 0.96 ± 0.0 and 0.98 ± 0.0 for the female cohort respectively. The mean absolute error in Hounsfield units (HUs) within the entire body for the male and female cohorts was 59.1 HU ± 7.2 HU and 53.3 HU ± 8.9 HU respectively. Conclusions: A multi-atlas based method for sCT generation can be applied to a standard T1-weighted MRI sequence for male and female pelvic patients. The implications of this study support MRI only planning being applied more broadly for both male and female pelvic sites. Trial registration This trial was registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) (www.anzctr.org.au) on 04/10/2017. Trial identifier ACTRN12617001406392. [ABSTRACT FROM AUTHOR]
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- 2022
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31. Survival benefits for non-small cell lung cancer patients treated with adaptive radiotherapy.
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Møller, Ditte Sloth, Lutz, Christina Maria, Khalil, Azza Ahmed, Alber, Markus, Holt, Marianne Ingerslev, Kandi, Maria, Schmidt, Hjørdis Hjalting, Tvilum, Marie, Appelt, Ane, Knap, Marianne Marquard, and Hoffmann, Lone
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NON-small-cell lung carcinoma , *CONE beam computed tomography , *MANN Whitney U Test , *RADIOTHERAPY treatment planning , *PROGRESSION-free survival - Abstract
• Tumor match and adaptive radiotherapy allows for decreased margins while maintaining loco-regional control. • Tumor match and adaptive radiotherapy significantly reduces the risk of pneumonitis. • After tumor match and adaptive radiotherapy, we observed a significantly improved progression-free and overall survival. Tumor match and adaptive radiotherapy based on on-treatment imaging increases the precision of RT. This allows a reduction of treatment volume and, consequently, of the dose to organs at risk. We investigate the clinical benefits of tumor match and adaptive radiotherapy for a cohort of non-small cell lung cancer patients (NSCLC). In 2013, tumor match and adaptive radiotherapy based on daily cone-beam CT scans was introduced to ensure adaption of the radiotherapy treatment plan for all patients with significant anatomical changes during radiotherapy. Before 2013, the daily cone-beam CT scans were matched on the vertebra and anatomical changes were not evaluated systematically. To estimate the effect of tumor match and adaptive radiotherapy, 439 consecutive NSCLC patients treated with definitive chemo-radiotherapy (50–66 Gy/25–33 fractions, 2010–2018) were investigated retrospectively. They were split in two groups, pre-ART (before tumor match and adaptive radiotherapy, 184 patients), and ART (after tumor match and adaptive radiotherapy, 255 patients) and compared with respect to clinical, treatment-specific and dosimetric variables (χ 2 tests, Mann Whitney U tests), progression, survival and radiation pneumonits (CTCAEv3). Progression-free and overall survival as well as radiation pneumonitis were compared with log-rank tests. Hazard ratios were estimated from Cox proportional hazard regression. No significant differences in stage (p = 0.36), histology (p = 0.35), PS (p = 0.12) and GTV volumes (p = 0.24) were observed. Concomitant chemotherapy was administered more frequently in the ART group (78%) compared to preART (64%), p < 0.001. Median[range] PTV volumes decreased from 456 [71;1262] cm3 (preART) to 270 [31;1166] cm3 (ART), p < 0.001, thereby significantly reducing mean doses to lungs (median, preART 16.4 [1.9;24.7] Gy, ART 12.1 [1.7;19.4] Gy, p < 0.001) and heart (median, preART 8.0 [0.1;32.1] Gy, ART 4.4 [0.1;33.9] Gy, p < 0.001). The incidence of RP at nine months decreased significantly with ART (50% to 20% for symptomatic RP (≥G2), 21% to 7% for severe RP (≥G3), 6% to 0.4% for lethal RP (G5), all p < 0.001). The two-year progression free survival increased from 22% (preART) to 30% (ART), while the overall survival increased from 43% (preART) to 56% (ART). The median overall survival time increased from 20 (preART) to 28 months (ART). Tumor match and adaptive radiotherapy significantly decreased radiation pneumonitis, while maintaining loco-regional control. Further, we observed a significantly improved progression-free and overall survival. [ABSTRACT FROM AUTHOR]
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- 2022
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32. Static-junction craniospinal irradiation: verification of daily dose and long-term treatment results.
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Napieralska, Aleksandra, Radwan, Michał, Brąclik, Iwona, and Blamek, Sławomir
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MEDULLOBLASTOMA , *RADIOTHERAPY , *RADIOTHERAPY treatment planning , *HOMOGENEITY , *PATIENTS - Abstract
Introduction. The study was performed to evaluate the repeatability and effectiveness of the static-junctions image guided (SJIG) method of craniospinal irradiation. Material and methods. An analysis of 40 treatment plans was performed. All treatment plans were reviewed with regard to the distances between isocentres between in every single field of each fraction during all treatment days. Based on that data, second (actually treated) plans were created. The planned and treated parameters were compared. Results. The study group consisted of 40 patients irradiated in the craniospinal region. Data on 902 fractions and 1635 isocentres positions was collected. 1-, 2- and 5-year overall survival was 95%, 89% and 78%, respectively. Spine metastases were observed in regions which were covered with a homogenous dose during treatment. Conclusions. SJIG is safe and produces very good long-term outcomes. Treatment planning and delivery is simple with good reproduction of the planned dose distribution during the actual treatment. [ABSTRACT FROM AUTHOR]
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- 2021
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33. Low dose cone beam CT for paediatric image-guided radiotherapy: Image quality and practical recommendations.
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Bryce-Atkinson, Abigail, De Jong, Rianne, Marchant, Tom, Whitfield, Gillian, Aznar, Marianne C., Bel, Arjan, and van Herk, Marcel
- Subjects
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CONE beam computed tomography , *IMAGE-guided radiation therapy , *PEDIATRICS , *QUANTUM noise , *CHILD patients - Abstract
• Anatomical noise is the dominant source of image noise in paediatric CBCT. • CNR between fat and muscle was maintained in over 90% of cases for doses ≥1 mGy. • Increasing dose above 1 mGy does not improve image quality or registration accuracy. • Low dose paediatric CBCT protocols are recommended based on the imaging need. Cone beam CT (CBCT) is used in paediatric image-guided radiotherapy (IGRT) for patient setup and internal anatomy assessment. Adult CBCT protocols lead to excessive doses in children, increasing the risk of radiation-induced malignancies. Reducing imaging dose increases quantum noise, degrading image quality. Patient CBCTs also include 'anatomical noise' (e.g. motion artefacts), further degrading quality. We determine noise contributions in paediatric CBCT, recommending practical imaging protocols and thresholds above which increasing dose yields no improvement in image quality. Sixty CBCTs including the thorax or abdomen/pelvis from 7 paediatric patients (aged 6–13 years) were acquired at a range of doses and used to simulate lower dose scans, totalling 192 scans (0.5–12.8 mGy). Noise measured in corresponding regions of each patient and a 10-year-old phantom were compared, modelling total (including anatomical) noise, and quantum noise contributions as a function of dose. Contrast-to-noise ratio (CNR) was measured between fat/muscle. Soft tissue registration was performed on the kidneys, comparing accuracy to the highest dose scans. Quantum noise contributed <20% to total noise in all cases, suggesting anatomical noise is the largest determinant of image quality in the abdominal/pelvic region. CNR exceeded 3 in over 90% of cases ≥ 1 mGy, and 57% of cases at 0.5 mGy. Soft tissue registration was accurate for doses > 1 mGy. Anatomical noise dominates quantum noise in paediatric CBCT. Appropriate soft tissue contrast and registration accuracy can be achieved for doses as low as 1 mGy. Increasing dose above 1 mGy holds no benefit in improving image quality or registration accuracy due to the presence of anatomical noise. [ABSTRACT FROM AUTHOR]
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- 2021
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34. Dosimetric impact of edema on inguinal lymph node boost in locally advanced vulvar cancer.
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Mohamed, Sandy, Fokdal, Lars, Assenholt, Marianne S., Kallehauge, Jesper, Lindegaard, Jacob C., and Tanderup, Kari
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VULVAR cancer ,LYMPH nodes ,EDEMA ,GROIN ,CANCER patients - Abstract
We aimed to evaluate the extent of groin edema and its dosimetric effect in boosted inguinal lymph nodes (LN) for vulvar cancer patients. The level of edema was determined in 10 patients treated with radical radiotherapy. A dosimetric evaluation of six LNs in the patient with the maximum level of edema was performed. The accumulated dose across CBCT fractions was acceptable for all six LNs (>94% of prescribed dose) even with the development of up to 13 mm of edema. The major contributor to fractional dose degradation was geographical displacement of the nodes. We suggest evaluation of edema on daily CBCT. [ABSTRACT FROM AUTHOR]
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- 2021
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35. Investigation of the accuracy of deep inspiration breath hold left-sided breast cancer radiotherapy using a surface guiding system
- Author
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S. Nankali, A. Zirak, A. Movafeghi, and P.R. Poulsen
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surface guided radiotherapy ,deep inspiration breath hold ,left-sided breast cancer ,image guided radiotherapy ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Vision-RT system is one of the most effective methods for real-time estimation of target location in external beam radiotherapy. Vision-RT tracks the patient’s surface before and during radiation therapy to improve treatment accuracy. Using proprietary 3D stereo camera units, Vision-RT system tracks the skin surface, compares it to the ideal position, and can automatically signal to the treatment delivery system. The purpose of this study is to investigate the accuracy of Vision RT guided deep inspiration breath-hold left-sided breast cancer radiotherapy. Five patients with left-sided breast cancer were treated by Vision RT guided deep inspiration breath-hold at Aarhus university hospital. Based on the results, in one out of five patients, the undesired heart extended to 0.6-0.9 cm into the treatment fields in 5 out of 15 treatment fractions. Moreover, the required PTV margin to account for patient setup error and intra-fractional error of the first and second treatment field was 2.38 mm, 3 mm and 4.12 mm, respectively.
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- 2020
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36. Intra-fractional lung tumor motion monitoring using arbitrary gantry angles during radiotherapy treatment.
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Hatamikia S, Elmirad S, Furtado H, Kronreif G, Steiner E, and Birkfellner W
- Abstract
Intensity-based 2D/3D registration using kilo-voltage (kV) and mega-voltage (MV) on-board imaging is a promising approach for real-time tumor motion tracking. So far, the performance of the kV images as well as kV-MV image pairs for 2D/3D registration using only one gantry angle (in anterior-posterior (AP) direction) has been investigated on patient data. In stereotactic body radiation therapy (SBRT), however, various gantry angles are typically used. This study attempts to answer the question of whether automatic 2D/3D registration is possible using kV images as well as kV-MV image pairs for gantry angles other than the AP direction. We also investigated the effect of additional portal MV images paired with kV images to improve 2D/3D registration in extracting cranio-caudal (CC) and AP displacement at arbitrary gantry angles and different fractions. The kV and MV image sequences as well as 3D volume data from five patients suffering from non-small cell lung cancer undergoing SBRT were used. Diaphragm motion served as the reference signal. The CC and AP displacements resulting from the registration results were compared with the corresponding reference motion signal. Pearson correlation coefficients (R value) was used to calculate the similarity measure between reference signal and the extracted displacements resulting from the registration. Signals we found that using 2D/3D registration tumor motion in 5 degrees of freedom (DOF) with kV images and in 6 degrees of freedom with kV-MV image pairs can be extracted for most gantry angles in all patients. Furthermore, our results have shown that the use of kV-MV image pairs increases the overall chance of tumor visibility and therefore leads to more successful extraction of CC as well as AP displacements for almost all gantry angles in all patients. We observed an improvement in registration of at least 0.29% more gantry angle for all patients when we used kV-MV images compared to kV images alone. In addition, an improvement in the R-value was observed in up to 16 fractions in various patients., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier GmbH.)
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- 2024
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37. Preliminary Study of the Intel RealSense D415 Camera for Monitoring Respiratory Like Motion of an Irregular Surface.
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Fielding, Andrew L., Pandey, Ajay K., Jonmohamadi, Yaqub, Via, Riccardo, Weber, Damien C., Lomax, Antony J., and Fattori, Giovanni
- Abstract
Motion of the tumour during a radiotherapy treatment can compromise the clinical outcome for the cancer patient. To address this challenge the suitability and performance of the Intel RealSense™ D415 depth camera has been investigated as a tool for measuring the respiratory motion of the body surface. The precision of the camera depth data has been characterised as a function of the measurement distance up to 1.2 meters from a stationary and moving surface. The latency of the camera system was also measured. The average standard deviation of depth data in stationary measurements ranged from less than 0.2 mm for the shortest camera-surface distance of 400 mm to 3 mm for a distance of 1200 mm. Similar accuracy is reported for the acquisition of breathing motion with a discrepancy from nominal amplitudes of around 0.5 mm and 5 mm for the two extreme measurement distances. No dependence on the measurement precision has been observed as a function of the motion pattern. Finally, the camera was shown to be able to measure the more patient-like motion of a deformable respiratory motion phantom with an amplitude of surface motion varying from 1.5 – 2.5 mm. Although noisier, the camera data showed good agreement when compared with a NDI Polaris Spectra system. The latency of the Realsense™ system was measured to be 68.6 ms ± 9.6 ms. The results of this work indicate that the D415 RealSense™ depth camera is capable of measurement of external respiratory type motion of an irregular surface. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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38. Development and Longitudinal Analysis of Plan-Based Streamlined Quality Assurance on Multiple Positioning Guidance Systems With Single Phantom Setup
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Shun Zhou, Junyu Li, Yi Du, Songmao Yu, Meijiao Wang, Hao Wu, and Haizhen Yue
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quality assurance ,positioning guidance ,robotic couch ,surface imaging ,image guided radiotherapy ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
PurposeThis study was to propose and validate an efficient and streamlined quality assurance (QA) method with a single phantom setup to check performances of patient positioning guidance systems including six-degree-of-freedom (6DoF) couch, X-ray modalities (kV–kV, MV–MV and CBCT), optical surface imaging system (AlignRT), lasers and optical distance indicator (ODI).Methods and MaterialsThe QA method was based on a pseudo-patient treatment plan using the AlignRT cube phantom. The cube was first randomly set up on the couch, and the initial position offsets were acquired by AlignRT and CBCT. The cube was restored to its reference position by 6DoF couch shift, during which the couch motion accuracy and tracking performances of AlignRT and CBCT were derived. After that, the residual offsets were acquired by kV–kV, MV–MV and AlignRT to derive the isocenter discrepancies. Finally, the laser alignment and ODI values were visually inspected. The QA procedure had been internally approved as a standard weekly QA test, and the results over 50 weeks were longitudinally analyzed for clinical validation.ResultsThe 6DoF couch motion errors as well as the tracking errors of AlignRT were sub-millimeter and sub-degree, and no deviation over 1 mm or 1 deg was identified. The ROI mode of isocenter (ISO) in AlignRT exhibited more consistent results than the centroid (CEN). While the isocenter discrepancy between CBCT and kV–kV was negligible, the maximal discrepancies between CBCT and MV–MV were 0.4 mm in LNG and 0.3 deg in PITCH. The isocenter discrepancies between CBCT and AlignRT were
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- 2021
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39. Development and Longitudinal Analysis of Plan-Based Streamlined Quality Assurance on Multiple Positioning Guidance Systems With Single Phantom Setup.
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Zhou, Shun, Li, Junyu, Du, Yi, Yu, Songmao, Wang, Meijiao, Wu, Hao, and Yue, Haizhen
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QUALITY assurance ,IMAGING systems ,PATIENT positioning ,SINGLE-degree-of-freedom systems ,OPTICAL images - Abstract
Purpose: This study was to propose and validate an efficient and streamlined quality assurance (QA) method with a single phantom setup to check performances of patient positioning guidance systems including six-degree-of-freedom (6DoF) couch, X-ray modalities (kV–kV, MV–MV and CBCT), optical surface imaging system (AlignRT), lasers and optical distance indicator (ODI). Methods and Materials: The QA method was based on a pseudo-patient treatment plan using the AlignRT cube phantom. The cube was first randomly set up on the couch, and the initial position offsets were acquired by AlignRT and CBCT. The cube was restored to its reference position by 6DoF couch shift, during which the couch motion accuracy and tracking performances of AlignRT and CBCT were derived. After that, the residual offsets were acquired by kV–kV, MV–MV and AlignRT to derive the isocenter discrepancies. Finally, the laser alignment and ODI values were visually inspected. The QA procedure had been internally approved as a standard weekly QA test, and the results over 50 weeks were longitudinally analyzed for clinical validation. Results: The 6DoF couch motion errors as well as the tracking errors of AlignRT were sub-millimeter and sub-degree, and no deviation over 1 mm or 1 deg was identified. The ROI mode of isocenter (ISO) in AlignRT exhibited more consistent results than the centroid (CEN). While the isocenter discrepancy between CBCT and kV–kV was negligible, the maximal discrepancies between CBCT and MV–MV were 0.4 mm in LNG and 0.3 deg in PITCH. The isocenter discrepancies between CBCT and AlignRT were <0.5 mm in translation and <0.3 deg in rotation. For AlignRT, the isocenter discrepancies between the DICOM and SGRT references were about 0.6 mm in VRT, 0.5 mm in LNG and 0.2 deg in PITCH. As the therapists became familiar with the workflow, the average time to complete the whole procedure was around 23 min. Conclusions: The streamlined QA exhibits desirable practicality as an efficient multipurpose performance check on positioning guidance systems. The stability, tracking performance and isocenter congruence of the positioning guidance systems have been fully validated for all clinical image guidance RT application, even SRS/SBRT, which requires the strictest tolerance. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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40. Résultats dosimétriques et cliniques d'une stratégie de radiothérapie adaptativede type "bibliothèque de plans" des cancers de la vessie localisés.
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Cabaillé, M., Gaston, R., Belhomme, S., Giraud, A., Rouffilange, J., Roubaud, G., and Sargos, P.
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BLADDER cancer diagnosis , *CANCER radiotherapy , *RADIATION doses , *CYSTECTOMY , *CANCER chemotherapy - Published
- 2021
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41. Radiothérapie adaptative des cancers de la vessie : état de l'art et perspectives pratiques.
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Cabaillé, M., Khalifa, J., Tessier, A.M., Belhomme, S., Créhange, G., and Sargos, P.
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BLADDER cancer treatment , *CANCER radiotherapy , *INTENSITY modulated radiotherapy , *STATISTICAL correlation , *CLINICAL trials - Abstract
La radiothérapie des tumeurs de la vessie infiltrant le muscle doit prendre en considération les variations de forme et de taille de la vessie pour la couverture du volume cible. Avec la visualisation des tissus mous par l'imagerie de repositionnement, il apparaissait possible de développer une approche de radiothérapie adaptative. Une recherche bibliographique sur la base de données PubMed a été effectuée en janvier 2019. Les études traitant de la radiothérapie adaptative, pour des patients atteints d'une tumeur de la vessie, étaient éligibles. L'objectif de cette revue était de définir les différentes techniques de radiothérapie adaptative, de discuter leurs avantages par rapport à la radiothérapie classique en termes de couverture des volumes cibles et d'épargne des organes à risque et de décrire leur faisabilité pour une implémentation en pratique. Au total, 30 études ont été retenues. Les stratégies dites « offline composite », « plan of the day » non-individualisé ou individualisé, et la « ré-optimisation » ont été identifiées. Toutes les études ont montré un bénéfice dosimétrique de radiothérapie adaptative en termes de couverture d'un volume cible et d'épargne des organes à risque. Tous les plans de radiothérapie adaptative des bibliothèques de plans réalisées n'étaient pas utilisés, avec une variabilité entre les observateurs pour la sélection de ces plans. La mise en place pratique au sein d'un département nécessitait la formation des personnels et augmentait la durée de préparation du traitement. La radiothérapie adaptative est la technique de choix pour l'irradiation des cancers de la vessie. L'approche « plan of the day » individualisée selon la méthodologie A-POLO (Adaptive-predictive organ localization) semble la plus efficiente. L'émergence de la ré-optimisation quotidienne est prometteuse. La corrélation des bénéfices dosimétriques avec des résultats cliniques d'efficacité et de tolérance devra être démontrée dans les futurs essais. Radiation therapy (RT) for muscle invasive bladder cancer (MIBC) is challenging, with observed variations in bladder shape and size resulting in inappropriate coverage of the target volumes (CTV). Large margins were historically applied around the CTV, increasing the dose delivered to organs at risk (OAR). With repositioning imaging and visualization of soft tissues during image guided RT, an opportunity to consider these movements and deformations appeared possible with an adaptive RT approach (ART). A bibliographic search on the PubMed database has been done in January 2019. Studies focusing on patients with MIBC, treating on ART, with the objectives of feasibility, clinical and/or dosimetric evaluation and comparison with a standard irradiation technique were eligible. The purpose of this review was to define the different ART techniques used in clinical practice, to discuss their advantages compared to conventional RT in terms of target volume's coverage and OAR dose and to describe their feasibility in clinical practice. A total of 30 studies were selected. The strategies known as "composite offline", "plan of the day" not individualized or individualized, and "re-optimization" have been identified. All the studies have shown a significant benefit of ART in target coverage and dose of OAR, especially the rectum and small bowel. All ART plans produced are not used during RT sessions. Inter-observer variability for the selection of these plans can be observed. The practical implementation within a department required staff education and training, and increases the duration of treatment preparation. The "A-POLO" approach seems to be the most suitable for practice. ART is the technique of choice for bladder cancer RT. The "plan of the day" approach, individualized according to the A-POLO methodology, seems to be the most effective. The emergence of daily re-optimization, especially using MRI-Linac, is promising. The correlation between dosimetric benefits and clinical efficacy and safety results should be demonstrated into future trials. [ABSTRACT FROM AUTHOR]
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- 2021
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42. A Ten-year-long Update on Radiation Proctitis Among Prostate Cancer Patients Treated With Curative External Beam Radiotherapy.
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FERINI, GIANLUCA and PERGOLIZZI, STEFANO
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PROSTATE cancer patients ,PROSTATE cancer treatment ,PROCTITIS ,RADIOTHERAPY ,RADIATION dosimetry - Abstract
This comprehensive synopsis summarizes the most relevant information obtained from a systematic analysis of studies of the last decade on radiation proctitis, one of the most feared radioinduced side effects among prostate cancer patients treated with curative external beam radiotherapy. The present review provides a useful support to radiation oncologists for limiting the onset or improving the treatment of radiation proctitis. This work shows that the past decade was a harbinger of significant new evidence in technological advances and technical tricks to avoid radiation proctitis, in addition to dosimetric perspectives and goals, understanding of pathogenesis, diagnostic work-up and treatment. We believe that a well-rounded knowledge of such an issue is fundamental for its appropriate management. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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43. Helical tomotherapy for prostate cancer radiation therapy: An audit of early toxicity and quality of life.
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Kunheri, Beena, Lakshmi, J, Ravindran, Greeshma, Haridas, Marwaha, Vishal, Lakshmi, J S, and Ravindran, Greeshma C
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QUALITY of life , *CANCER treatment , *PROSTATE cancer , *BACKGROUND radiation , *RADIOTHERAPY , *GROUP psychotherapy , *PROSTATE tumors treatment , *COMPUTERS in medicine , *PROSTATECTOMY , *PROSTATE , *RADIATION injuries , *LONGITUDINAL method - Abstract
Background: Radiation plays a major role in the management of localized prostate cancer (CaP). There are limited studies reporting the quality of life (QOL) and toxicity with CaP tomotherapy.Materials and Methods: This is a single-institutional prospective observational study evaluating the acute toxicity and QOL of patients with CaP receiving tomotherapy from May 2018 to October 2019. Toxicity assessed using radiation therapy oncology group toxicity grading. QOL assessed using International Prostate Symptom Score (IPSS) and QOL score.Results: A total number of 74 patients received radiation therapy (RT), of which 25 had postoperative RT and 49 had radical RT. The median age was 71 years. During RT, 8 (10.8%) had Grade 2 gastrointestinal (GI) and 4 (5.4%) had Grade 2 genito urinary (GU) toxicities. At 3 months, 1 (1.4%) had Grade 2 GI, 1 (1.4%) had Grade 2 GU, and 1 (1.4%) had Grade 3 GU toxicities. At 6 months, 1 patient had Grade 2 GU and no Grade 2 GI toxicity noted. In postoperative RT Group, 2 (8%) Grade 2 GI and 1 (1.4%) Grade 2 genitourinary toxicity reported during radiation. At 3 months, 1 (1.4%) Grade 2 GI, 1 (1.4%) G2 GU, and 1 (1.4%) G3 GU toxicities noted. At 6 months, no ≥ Grade 2 noted. In radical RT group, during radiation 6 (12.2%) Grade 2 GI and 3 (6.1%) Grade 2 GU recorded. At 3 and 6 months, no ≥ Grade 2 GI/GU toxicity was recorded. No Grade 3/Grade 4 observed in radical RT group. One patient in radical RT and one in postoperative RT had severe IPSS symptom score. Results are comparable to reported studies.Conclusion: Our initial clinical experience with helical tomotherapy in CaP confirms lower rate of toxicities and no significant worsening of QOL with RT. [ABSTRACT FROM AUTHOR]- Published
- 2021
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44. A Simulated Dosimetric Study of Contribution to Radiotherapy Accuracy by Fractional Image Guidance Protocol of Halcyon System
- Author
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Haiyang Wang, Yuliang Huang, Qiaoqiao Hu, Chenguang Li, Hongjia Liu, Xuejuan Wang, Weibo Li, Wenjun Ma, Yichen Pu, Yixiao Du, Hao Wu, and Yibao Zhang
- Subjects
image guided radiotherapy ,deformable image registration ,quality assurance ,cone beam CT ,Halcyon ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
PurposeFrequency of conventional kV-image guidance is sometimes sacrificed to reduce concomitant risk, leaving deviations of unguided fractions unknown. MV-imaging and treatment dose can be collectively optimized on Halcyon, where fractional MVCBCT provides complete anatomic records for course-wide dose reconstruction. By retrospective dose accumulation, this work simulated the impact of imaging frequency on patient treatment dose on the platform of Halcyon.MethodsFour hundred and sixteen MVCBCT image sets from 16 patients of various tumor sites treated with radiotherapy on Halcyon were retrospectively selected. After applying the image-guided couch shifts of the clinical records, deformable image registration was performed using Velocity software, to deform the planning CTs to the corresponding MVCBCTs, generating pseudo CTs representing the actual anatomies on the treatment day. Fractional treatment dose was reconstructed on pseudo CTs for accumulation, representing the actual patient dose (Ddaily). To simulate weekly image guidance, fractional dose was reconstructed and accumulated by incorporating 1 CBCT-guided corrections and 4 laser-guided setups of each week (Dweekly). Limited by partially imaged volumes and different organs-at-risk of various sites, only target dose-volume parameters were evaluated across all patients.ResultsGTV_D98%, CTV_D98%, PTV_D90%, PTV_D95%, PGTV_D90%, and PGTV_D95% were evaluated, where Dx% means the minimal dose received by x% volume. Pairwise comparisons were made between plan dose and Ddaily, Ddaily and Dweekly respectively. PGTV_D95% of accumulated Dweekly were significantly lower than those of accumulated Ddaily by up to 32.90% of prescription dose, suggesting that weekly-guidance may result in unacceptable under dose to the target. The broad distribution of fractional differences between Ddaily and Dweekly suggested unreliable patient positioning based on aligning surface markers to laser beams, as a popular approach broadly used on conventional Linac systems. Slight target under-dose was observed on daily reconstructed results compared with planned dose, which provided quantitative data to guide clinical decisions such as the necessity of adaptive radiotherapy.ConclusionFractional image guided radiotherapy on Halcyon provides more reliable treatment accuracy than using sacrificed imaging frequency, which also provides complete anatomic records for deformable dose reconstruction supporting more informed clinical decisions.
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- 2021
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45. Electron Paramagnetic Resonance pO2 Image Tumor Oxygen-Guided Radiation Therapy Optimization
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Epel, Boris, Maggio, Matt, Pelizzari, Charles, Halpern, Howard J., COHEN, IRUN R., Series editor, LAJTHA, ABEL, Series editor, LAMBRIS, JOHN D., Series editor, PAOLETTI, RODOLFO, Series editor, Halpern, Howard J., editor, LaManna, Joseph C., editor, Harrison, David K., editor, and Epel, Boris, editor
- Published
- 2017
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46. Simulated daily plan adaptation for magnetic resonance-guided liver stereotactic body radiotherapy.
- Author
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Taylor, Edward, Lukovic, Jelena, Velec, Michael, Shessel, Andrea, Stanescu, Teodor, Dawson, Laura, Létourneau, Daniel, and Lindsay, Patricia
- Subjects
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COMPARATIVE studies , *COMPUTED tomography , *LIVER tumors , *MAGNETIC resonance imaging , *COMPUTERS in medicine , *RADIATION doses , *RADIOSURGERY , *RADIOTHERAPY , *REFERENCE values , *RETROSPECTIVE studies , *DESCRIPTIVE statistics - Abstract
Liver cancers are challenging to treat using image-guided radiotherapy (IGRT) due to motion and deformation of target volumes and organs at risk (OARs), as well as difficulties in visualising liver tumours using cone-beam computed tomography (CBCT) based IGRT. Liver cancer patients may thus benefit from magnetic resonance (MR)-guided daily adaptive re-planning. We evaluated the dosimetric impact of a daily plan adaptation strategy based on daily MR imaging versus CBCT-based IGRT. Ten patients were studied who were treated with CBCT-guided five-fraction stereotactic body radiotherapy (SBRT) and underwent MR imaging before each fraction. Simulated reference plans were created on computer tomography (CT) images and adapted plans were created on the daily MR images. Two plan adaptation strategies were retrospectively simulated: (1) translational couch shifts to match liver, mimicking standard CBCT guidance and (2) daily plan adaptation based on reference plan clinical goals and daily target and OAR contours. Dose statistics were calculated for both strategies and compared. Couch shifts resulted in an average reduction in GTV D99% relative to reference plan values of 5.2 Gy (−12.5% of reference values). Daily plan adaptation reduced this to 0.8 Gy (−2.0%). For six patients who were OAR dose-limited on reference plans, couch shifts resulted in OAR dose violations in 28 out of 28 simulated fractions, respectively; no violations occurred using daily plan adaptation. No OAR dose violations occurred using either strategy for the four cases not OAR dose-limited at reference planning. MR-guided daily plan adaptation ensured OAR dose constraints were met at all simulated treatment fractions while CBCT-based IGRT resulted in a systematic over-dosing of OARs in patients whose doses were limited by OAR dose at the time of reference planning. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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- View/download PDF
47. A Simulated Dosimetric Study of Contribution to Radiotherapy Accuracy by Fractional Image Guidance Protocol of Halcyon System.
- Author
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Wang, Haiyang, Huang, Yuliang, Hu, Qiaoqiao, Li, Chenguang, Liu, Hongjia, Wang, Xuejuan, Li, Weibo, Ma, Wenjun, Pu, Yichen, Du, Yixiao, Wu, Hao, and Zhang, Yibao
- Subjects
IMAGE registration ,CONE beam computed tomography ,RADIOTHERAPY ,LASER beams ,MEDICAL records - Abstract
Purpose: Frequency of conventional kV-image guidance is sometimes sacrificed to reduce concomitant risk, leaving deviations of unguided fractions unknown. MV-imaging and treatment dose can be collectively optimized on Halcyon, where fractional MVCBCT provides complete anatomic records for course-wide dose reconstruction. By retrospective dose accumulation, this work simulated the impact of imaging frequency on patient treatment dose on the platform of Halcyon. Methods: Four hundred and sixteen MVCBCT image sets from 16 patients of various tumor sites treated with radiotherapy on Halcyon were retrospectively selected. After applying the image-guided couch shifts of the clinical records, deformable image registration was performed using Velocity software, to deform the planning CTs to the corresponding MVCBCTs, generating pseudo CTs representing the actual anatomies on the treatment day. Fractional treatment dose was reconstructed on pseudo CTs for accumulation, representing the actual patient dose (D
daily ). To simulate weekly image guidance, fractional dose was reconstructed and accumulated by incorporating 1 CBCT-guided corrections and 4 laser-guided setups of each week (Dweekly ). Limited by partially imaged volumes and different organs-at-risk of various sites, only target dose-volume parameters were evaluated across all patients. Results: GTV_D98%, CTV_D98%, PTV_D90%, PTV_D95%, PGTV_D90%, and PGTV_D95% were evaluated, where Dx% means the minimal dose received by x% volume. Pairwise comparisons were made between plan dose and Ddaily , Ddaily and Dweekly respectively. PGTV_D95% of accumulated Dweekly were significantly lower than those of accumulated Ddaily by up to 32.90% of prescription dose, suggesting that weekly-guidance may result in unacceptable under dose to the target. The broad distribution of fractional differences between Ddaily and Dweekly suggested unreliable patient positioning based on aligning surface markers to laser beams, as a popular approach broadly used on conventional Linac systems. Slight target under-dose was observed on daily reconstructed results compared with planned dose, which provided quantitative data to guide clinical decisions such as the necessity of adaptive radiotherapy. Conclusion: Fractional image guided radiotherapy on Halcyon provides more reliable treatment accuracy than using sacrificed imaging frequency, which also provides complete anatomic records for deformable dose reconstruction supporting more informed clinical decisions. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
48. Inter‐ and intra‐fractional stability of rectal gas in pelvic cancer patients during MRIgRT.
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Shortall, J., Vasquez Osorio, E., Cree, A., Song, Y., Dubec, M., Chuter, R., Price, G., McWilliam, A., Kirkby, K., Mackay, R., and Herk, M.
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PSILOCYBIN , *COMPUTED tomography , *CANCER patients , *PROSTATE cancer patients , *MAGNETIC resonance imaging - Abstract
Purpose: Due to the electron return effect (ERE) during magnetic resonance imaging guided radiotherapy (MRIgRT), rectal gas during pelvic treatments can result in hot spots of over‐dosage in the rectal wall. Determining the clinical impact of this effect on rectal toxicity requires estimation of the amount and mobility (and stability) of rectal gas during treatment. We therefore investigated the amount of rectal gas and local inter‐ and intra‐fractional changes of rectal gas in pelvic cancer patients. Methods: To estimate the volume of gas present at treatment planning, the rectal gas contents in the planning computed tomography (CT) scans of 124 bladder, 70 cervical and 2180 prostate cancer patients were calculated. To estimate inter‐ and intra‐fractional variations in rectal gas, 174 and 131 T2‐w MRIs for six cervical and eleven bladder cancer patients were used. These scans were acquired during four scan‐sessions (~20–25 min each) at various time‐points. Additionally, 258 T2‐w MRIs of the first five prostate cancer patients treated using MRIgRT at our center, acquired during each fraction, were analyzed. Rectums were delineated on all scans. The area of gas within the rectum delineations was identified on each MRI slice using thresholding techniques. The area of gas on each slice of the rectum was used to calculate the inter‐ and intra‐fractional group mean, systematic and random variations along the length of the rectum. The cumulative dose perturbation as a result of the gas was estimated. Two approaches were explored: accounting or not accounting for the gas at the start of the scan‐session. Results: Intra‐fractional variations in rectal gas are small compared to the absolute volume of rectal gas detected for all patient groups. That is, rectal gas is likely to remain stable for periods of 20–25 min. Larger volumes of gas and larger variations in gas volume were observed in bladder cancer patients compared with cervical and prostate cancer patients. For all patients, local cumulative dose perturbations per beam over an entire treatment in the order of 60 % were estimated when gas had not been accounted for in the daily adaption. The calculated dose perturbation over the whole treatment was dramatically reduced in all patients when accounting for the gas in the daily set‐up image. Conclusion: Rectal gas in pelvic cancer patients is likely to remain stable over the course of an MRIgRT fraction, and also likely to reappear in the same location in multiple fractions, and can therefore result in clinically relevant over‐dosage in the rectal wall. The over‐dosage is reduced when accounting for gas in the daily adaption. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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49. Predicting cervical cancer target motion using a multivariate regression model to enable patient selection for adaptive external beam radiotherapy.
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Wang L, McQuaid D, Blackledge M, McNair H, Harris E, and Lalondrelle S
- Abstract
Background and Purpose: Interfraction motion during cervical cancer radiotherapy is substantial in some patients, minimal in others. Non-adaptive plans may miss the target and/or unnecessarily irradiate normal tissue. Adaptive radiotherapy leads to superior dose-volume metrics but is resource-intensive. The aim of this study was to predict target motion, enabling patient selection and efficient resource allocation., Materials and Methods: Forty cervical cancer patients had CT with full-bladder (CT-FB) and empty-bladder (CT-EB) at planning, and daily cone-beam CTs (CBCTs). The low-risk clinical target volume (CTV
LR ) was contoured. Mean coverage of the daily CTVLR by the CT-FB CTVLR was calculated for each patient. Eighty-three investigated variables included measures of organ geometry, patient, tumour and treatment characteristics. Models were trained on 29 patients (171 fractions). The Two-CT multivariate model could use all available data. The Single-CT multivariate model excluded data from the CT-EB. A univariate model was trained using the distance moved by the uterine fundus tip between CTs, the only method of patient selection found in published cervix plan-of-the-day studies. Models were tested on 11 patients (68 fractions). Accuracy in predicting mean coverage was reported as mean absolute error (MAE), mean squared error (MSE) and R2 ., Results: The Two-CT model was based upon rectal volume, dice similarity coefficient between CT-FB and CT-EB CTVLR , and uterine thickness. The Single-CT model was based upon rectal volume, uterine thickness and tumour size. Both performed better than the univariate model in predicting mean coverage (MAE 7 %, 7 % and 8 %; MSE 82 %2 , 65 %2 , 110 %2 ; R2 0.2, 0.4, -0.1)., Conclusion: Uterocervix motion is complex and multifactorial. We present two multivariate models which predicted motion with reasonable accuracy using pre-treatment information, and outperformed the only published method., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lei Wang is part-funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London; and part-funded by Elekta Ltd. Helen McNair is funded by a National Institute for Health Research and Health Education England (HEE/NIHR) Senior Clinical Lectureship (ICA-SCL-2018–04-ST2-002). Emma Harris has received research funding from Elekta Ltd and Cancer Research UK Programme Foundation Award A23557. Susan Lalondrelle has received research funding and speaking fees from Elekta Ltd., (© 2024 The Author(s).)- Published
- 2024
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50. A Fast Online Replanning Algorithm Based on Intensity Field Projection for Adaptive Radiotherapy
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Xiaomeng Liu, Yueqiang Liang, Jian Zhu, Gang Yu, Yanyan Yu, Qiang Cao, X. Allen Li, and Baosheng Li
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online replanning ,adaptive radiotherapy ,interfractional variations ,image guided radiotherapy ,deformable image registration ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Purpose: The purpose of this work was to propose an online replanning algorithm, named intensity field projection (IFP), that directly adjusts intensity distributions for each beam based on the deformation of structures. IFP can be implemented within a reasonably acceptable time frame.Methods and Materials: The online replanning method is based on the gradient-based free form deformation (GFFD) algorithm, which we have previously proposed. The method involves the following steps: The planning computed tomography (CT) and cone-beam CT image are registered to generate a three-dimensional (3-D) deformation field. According to the 3-D deformation field, the registered image and a new delineation are generated. The two-dimensional (2-D) deformation field of ray intensity in each beam direction is determined based on the 3-D deformation field in the region of interest. The 2-D ray intensity distribution in the corresponding beam direction is deformed to generate a new 2-D ray intensity distribution. According to the new 2-D ray intensity distribution, corresponding multi-leaf collimator (MLC), and jaw motion data are generated. The feasibility and advantages of our method have been demonstrated in 20 lung cancer intensity modulated radiation therapy (IMRT) cases.Results: Substantial underdosing in the CTV is seen in the original and the repositioning plans. The average prescription dose coverage (V100%) and D95 for CTV were 100% and 60.3 Gy for the IFP plans compared to 82.6% (P < 0.01) and 44.0 Gy (P < 0.01) for original plans, 86.7% (P < 0.01), and 58.5 Gy (P < 0.01) for repositioning plans. On average, the mean total lung doses were 12.2 Gy for the IFP plan compared to the 12.4 Gy (P < 0.01) and 12.6 Gy (P < 0.01) for the original and the repositioning plans. The entire process of IFP can be completed within 3 min.Conclusions: We proposed an online replanning strategy for automatically correcting interfractional anatomy variations. The preliminary results indicate that the IFP method substantially increased planning speed for online adaptive replanning.
- Published
- 2020
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