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Background Since intensity-modulated radiation therapy (IMRT) has become popular for the treatment of gynecologic cancers, the contouring process has become more critical. This study evaluated the feasibility of atlas-based auto-segmentation (ABAS) for contouring in patients with endometrial and cervical cancers. Methods A total of 75 sets of planning CT images from 75 patients were collected. Contours for the pelvic nodal clinical target volume (CTV), femur, and bladder were carefully generated by two skilled radiation oncologists. Of 75 patients, 60 were randomly registered in three different atlas libraries for ABAS in groups of 20, 40, or 60. ABAS was conducted in 15 patients, followed by manual correction (ABASc). The time required to generate all contours was recorded, and the accuracy of segmentation was assessed using Dice’s coefficient (DC) and the Hausdorff distance (HD) and compared to those of manually delineated contours. Results For ABAS-CTV, the best results were achieved with groups of 60 patients (DC, 0.79; HD, 19.7 mm) and the worst results with groups of 20 patients (DC, 0.75; p = 0.012; HD, 21.3 mm; p = 0.002). ABASc-CTV performed better than ABAS-CTV in terms of both HD and DC (ABASc [n = 60]; DC, 0.84; HD, 15.6 mm; all p c required 191.1 s; both methods required less time than the manual methods (p 0.9 and HD ≤10.0 mm), with significant time reduction compared to that needed for manual delineation (p 40 mm). Furthermore, ABASc-Bladder required a longer processing time than manual contouring to achieve the same accuracy. Conclusions ABAS could help physicians to delineate the CTV and organs-at-risk (e.g., femurs) in IMRT planning considering its consistency, efficacy, and accuracy.

Aim To compare the radiotherapy technique used in a randomised trial with VMAT and an in-house technique for prostate cancer. Background Techniques are evolving with volumetric modulated arc therapy (VMAT) commonly used. The CHHiP trial used a 3 PTV forward planned IMRT technique (FP_CH). Our centre has adopted a simpler two PTV technique with locally calculated margins. Materials and methods 25 patients treated with FP_CH to 60 Gy in 20 fractions were re-planned with VMAT (VMAT_CH) and a two PTV protocol (VMAT_60/52 and VMAT_60/48). Target coverage, conformity index (CI), homogeneity index (HI), monitor units (MU) and dose to the rectum, bladder, hips and penile bulb were compared. Results PTV coverage was high for all techniques. VMAT_CH plans had better CI than FP_CH (p ≤ 0.05). VMAT_60/52/48 plans had better CI than VMAT_CH. FP_CH had better HI and fewer MU than VMAT (p ≤ 0.05). More favourable rectum doses were found for VMAT _CH than FP_CH (V48.6, V52.8, V57, p ≤ 0.05) with less difference for bladder (p ≥ 0.05). Comparing VMAT_CH to VMAT_60/52/48 showed little differences for the bladder and rectum but VMAT_CH had larger penile bulb doses (V40.8, V48.6, mean, D2, p ≤ 0.05). Femoral head doses (V40.8) were similarly low for all techniques (p = ≥ 0.05). Conclusion VMAT produced more conformal plans with smaller rectum doses compared to FP_CH albeit worse HI and more MU. VMAT_60/52 and VMAT_60/48 plans had similar rectal and bladder doses to VMAT_CH but better CI and penile bulb doses which may reduce toxicity.

Background: The aim of this study was to assess the differences in lower cranial nerve (LCN) complications predicted by the normal tissue complication probability (NTCP) model between Radiation Therapy Oncology Group (RTOG) and reduced-volume intensity-modulated radiotherapy (IMRT) planning for nasopharyngeal carcinoma (NPC) radiotherapy. Methods: A total of fifty patients with NPC were divided into two groups according to T-stages of T1-2 and T3-4, and the LCNs of each patient were contoured on CT simulation images. The targets were contoured based on the RTOG 0225 clinical trial and a working committee for clinical stage NPC in China in 2010. The NTCP differences in LCNs between the two plans were calculated. Results: The LCN volume of the 50 patients was 10.07 cc. The Dmax and Dmean of LCNs in RTOG plans were significantly larger than those in reduced-volume plans (7,453 vs . 7,401 cGy, 6,740 vs . 6,436 cGy, P=0.004, 0.000), and these values were lower in the T1-2 group than in the T3-4 group (7,390 vs . 7,464 cGy, 6,442 vs . 6,733 cGy, P=0.019, 0.000). NTCP in RTOG plans was significantly higher than that in reduced- volume plans (59.98% vs . 51.62%, P=0.000), among which NTCP was significantly lower in the T1-2 group than in the T3-4 group (51.72% vs . 59.88%, P=0.002). There were strong correlations of NTCP with Dmean and irradiation volume for more than 6,600 cGy (R=0.847, P=0.000; R=0.841, P=0.000). Conclusions: the clinical T-stage, a high Dmean and a large irradiation volume are important factors in predicting LCN complications. Of the two most common IMRT guidance plans in China, the LCN NTCP based on the reduced-volume plan is significantly lower than that based on the RTOG plan.

Purpose Varian Halcyon linear accelerator version 2 (The Halcyon 2.0) was recently released with new upgraded features. The aim of this study was to report our clinical experience with Halcyon 2.0 for a dual‐isocenter intensity‐modulated radiation therapy (IMRT) planning and delivery for gynecological cancer patients and examine the feasibility of in vivo portal dosimetry. Methods Twelve gynecological cancer patients were treated with extended‐field IMRT technique using two isocenters on Halcyon 2.0 to treat pelvis and pelvic/or para‐aortic nodes region. The prescription dose was 45 Gy in 25 fractions (fxs) with simultaneous integrated boost (SIB) dose of 55 or 57.5 Gy in 25 fxs to involved nodes. All treatment plans, pretreatment patient‐specific QA and treatment delivery records including daily in vivo portal dosimetry were retrospectively reviewed. For in vivo daily portal dosimetry analysis, each fraction was compared to the reference baseline (1st fraction) using gamma analysis criteria of 4 %/4 mm with 90% of total pixels in the portal image planar dose. Results All 12 extended‐field IMRT plans met the planning criteria and delivered as planned (a total of 300 fractions). Conformity Index (CI) for the primary target was achieved with the range of 0.99–1.14. For organs at risks, most were well within the dose volume criteria. Treatment delivery time was from 5.0 to 6.5 min. Interfractional in vivo dose variation exceeded gamma analysis threshold for 8 fractions out of total 300 (2.7%). These eight fractions were found to have a relatively large difference in small bowel filling and SSD change at the isocenter compared to the baseline. Conclusion Halcyon 2.0 is effective to create complex extended‐field IMRT plans using two isocenters with efficient delivery. Also Halcyon in vivo dosimetry is feasible for daily treatment monitoring for organ motion, internal or external anatomy, and body weight which could further lead to adaptive radiation therapy.

To evaluate the performance of 2 methods predicting liver dosimetric indices for hepatocellular cancer patients treated with intensity modulated radiation therapy (IMRT). Two predicting methods were implemented to build correlation between geometric and dosimetric information of hepatocellular cancer IMRT plans. One method used Principle Component Analysis method to simplify information and Support Vector Machine (SVM) regression method to build correlation. The other method used a simple linear function to map volumes of certain regions to dosimetic indices. Thirty eight hepatocellular cancer IMRT plans were randomly selected to train the 2 methods. The effectiveness of the 2 methods was validated using another 8 plans. Liver dosimetric indices V10, V20, V30, and mean dose of the 8 plans in validation cohort were calculated using the predicting methods. The predicted indices were compared with the indices derived from the clinically accepted treatment plans. The absolute differences of V10 calculated with the SVM method and the actual values of treatment plans had a mean value of 7.87%. And the values for V20, V30, and mean dose were 4.37%, 4.41%, and 4.20%, respectively. The absolute differences of V10 calculated with the linear formulation method and the actual values of treatment plans had a mean value of 6.09%. And the values for V20, V30, and mean dose were 5.28%, 5.05%, and 5.92%, respectively. These 2 methods have similar accuracy in predicting dosimetric indices V10, V20, V30 of livers. The predicting of V30 and V20 is more accurate than the predicting of V10. The SVM method is more accurate in predicting mean liver dose.

Spine stereotactic radiosurgery (SSRS) is a noninvasive treatment for metastatic spine lesions. MD Anderson Cancer Center reports a quality assurance (QA) failure rate approaching 15% for SSRS cases, which we hypothesized is due to difficulties in accurately calculating dose resulting from a large number of small-area segments. Clinical plans typically use 9 beams with an average of 10 segments per beam and minimum segment area of 2 to 3 cm2. The purpose of this study was to identify a set of intensity-modulated radiation therapy (IMRT) planning parameters that attempts to optimize the balance among QA passing rate, plan quality, dose calculation accuracy, and delivery time for SSRS plans. Using Pinnacle version 9.10, we evaluated the effects of 2 IMRT parameters: maximum number of segments and minimum segment area. Initial evaluation of the data revealed that 5 segments per beam along with minimum segment area of 4 cm2 and 4 minimum Monitor Units (MU) per segment (544 plans) was the most promising. IMRT QA was performed using an OCTAVIUS 4D phantom with a 2D detector array. Our data showed no significant plan quality change with decreased number of segments and increased minimum segment area. The average coverage of GTV and CTV was 82.5 ± 13% (clinical) vs 82.5 ± 13% (544) and 92.3 ± 8% (clinical) vs 91.5 ± 8% (544). Maximum point dose to cord was 11.4 ± 3.5 Gy (clinical) vs 11.0 ± 4.0 Gy (544). Total plan delivery time was decreased by an average of 11.3% for the 544 plans. In addition, the QA passing rate for the original plan vs the 544 plan averaged 90.3% and 91.9%, respectively. In conclusion, IMRT parameters of 5 segments per beam and 4 cm2 minimum segment area provided a better balance of plan quality, delivery efficiency, and plan dose calculation accuracy for SSRS.

Purpose To evaluate the respiratory motion influence on the tridimensional (3D) dose delivery to breast-shaped phantoms using conformal radiotherapy (3D-RT), Field-in Field (FiF), and IMRT planning techniques. Methods This study used breast-shaped phantoms filled with MAGIC-f gel dosimeter to simulate the breast, and an oscillation platform to simulate the respiratory motion. The platform allowed motion in the anterior-posterior direction with oscillation amplitudes of 0.34 cm, 0.88 cm, and 1.22 cm. CT images of the static phantom were used for the 3D-RT, FiF, and IMRT treatment planning. Five phantoms were prepared and irradiated for each planning technique evaluated. Phantom 1 was irradiated static, phantoms 2–4 were irradiated moving with the three different motion amplitudes, and phantom 5 was used as a reference. The 3D dose distributions were obtained by relaxometry of magnetic resonance imaging, and the respiratory motion influence in the doses distribution was accessed by gamma evaluations (3%/3mm/15% threshold) comparing the measurements of the phantoms irradiated under movement with the static ones. Results The mean gamma approvals for three oscillatory amplitudes were 96.44%, 93.23%, and 91.65%; 98.42%, 95.66%, and 94.31%; and 94.49%, 93.51%, and 86.62% respectively for 3D-RT, FiF and IMRT treatments. A gamma results profile per slice along the phantom showed that for FiF and IMRT irradiations, most of the failures occurred in the central region of the phantom. Conclusions By increasing the respiratory motion movement, the dose distribution variations for the three planning techniques were more pronounced, being the FiF technique variations the smallest one.

In this study, we sought to examine the variation in intensity modulated radiation therapy (IMRT) use among radiation oncology providers.The Medicare Physician and Other Supplier Public Use File was queried for radiation oncologists practicing during 2014. Healthcare Common Procedural Coding System code 77301 was designated as IMRT planning with metrics including number of total IMRT plans, rate of IMRT utilization, and number of IMRT plans per distinct beneficiary.Of 2759 radiation oncologists, the median number of total IMRT plans was 26 (mean, 33.4; standard deviation, 26.2; range, 11-321) with a median IMRT utilization rate of 36% (mean, 43%; standard deviation, 25%; range, 4% to 100%) and a median number of IMRT plans per beneficiary of 1.02 (mean, 1.07; range, 1.00-3.73). On multivariable analysis, increased IMRT utilization was associated with male sex, academic practice, technical fee billing, freestanding practice, practice in a county with 21 or more radiation oncologists, and practice in the southern United States (P.05). The top 1% of users (28 providers) billed a mean 181 IMRT plans with an IMRT utilization rate of 66% and 1.52 IMRT plans per beneficiary. Of these 28 providers, 24 had billed technical fees, 25 practiced in freestanding clinics, and 20 practiced in the South.Technical fee billing, freestanding practice, male sex, and location in the South were associated with increased IMRT use. A small group of outliers shared several common demographic and practice-based characteristics.

Purpose/Objective(s) Like other specialties, radiation oncology (RO) has seen declines in Medicare reimbursement (MCR). There are no recent studies analyzing how changes in MCR for specific billing codes contribute to changes over time in overall reimbursement for RO. We compared total MCR for specific Healthcare Common Procedure Coding System (HCPCS) codes in 2019 to MCR for those codes in 2010 & 2015, corrected for inflation, to see how the same basket of RO services in 2019 would have been reimbursed in 2010 & 2015 (projected MCR). We hypothesized that the decline in MCR from 2010-2019 would be driven disproportionately by decreased reimbursement for IMRT codes. Materials/Methods The CMS Physician/Supplier Procedure Summary database was used for MCR data for 2010, 2015 & 2019. All charges were classified by HCPCS codes, mapping old codes to their current equivalents. Actual MCR for 2010, 2015 & 2019 was calculated as the inflation-adjusted sum of allowed charges. For each code, the total allowed charge was divided by the number of submitted claims to calculate the average MCR per claim in 2010, 2015 & 2019. The 2019 billing frequency for each code was then multiplied by the inflation-adjusted average MCR for those codes in 2010 & 2015 to determine what the MCR would have been in 2010 & 2015 using 2019 dollars and utilization rates. These results were compared to actual 2019 MCR to calculate the projected difference. Results Actual MCR for all RO services in 2019 was $2,006 million (M), which was a $353M (15%) & $76M (4%) cut vs MCR in 2010 & 2015 expressed in 2019 dollars. For the codes examined in this analysis, 2019 MCR was $1,822M, which was a $687M (27%) & $183M (9%) cut vs inflation and utilization corrected MCR in 2010 & 2015 for these same codes. Table 1 shows the difference in MCR by treatment codes. IMRT delivery & IMRT planning account for 50% (-$341M) & 53% (-$97M) of the total projected difference from 2010-2019 & 2015-2019. Conclusion MCR in 2019 declined compared to actual inflation corrected 2010 & 2015 MCR & declined even more precipitously when compared to MCR for 2010 & 2015 corrected for both inflation and utilization, which holds constant factors that could potentially increase MCR over time (e.g., population growth; increased use of IMRT) or decrease MCR (hypofractionation). Decline in IMRT reimbursement was the primary driver of the decline in MCR. Policymakers should consider the significant cuts to reimbursement that have already occurred when considering further cuts and the impact such cuts could have on quality and access to care.

A study has been carried out to explore the impact by varying the number of arcs and beam arrangement on dose distributions. For this volumetric modulated arc therapy and 7-field, intensity-modulated radiation therapy plans have use for prostate cancer cases. The eclipse treatment planning system version 13.6 (Varian California, USA) was used to assess dosimetry data for 20 patients. All patients received intensity-modulated radiation therapy and volumetric modulated arc therapy plans with a varying number of arcs. 6MV X-Ray photon beam energy uses for each patient. Statistical plan assessments have been carried out for various dosimetric parameters to evaluate execution efficiency. There were no statistically significant changes (p>0.05) observed in D98% dose coverage while D2%, conformity index, homogeneity index, monitor unit, and treatment delivery time were showing statistically significant changes (p

Purpose To compare dosimetric and treatment delivery parameter differences between volumetric‐modulated arc radiotherapy (VMAT) and intensity‐modulated radiotherapy (IMRT) for large volume retroperitoneal sarcomas (RPS). Materials and Methods Both VMAT and IMRT planning were performed on CT datasets of 10 patients with RPS who had been previously treated with preoperative radiotherapy. Plans were optimized to deliver ≥95% dose to the PTV and were evaluated for conformity and homogeneity. Dose to the organs at risk (OARs) (kidney, liver, spinal cord, and bowel space), unspecified tissue, and dose evaluation volumes (DEVs) at 1, 2, and 5 cm from PTV were calculated and compared. Monitor units (MUs) and treatment delivery times were recorded and compared between the two techniques. The deliverability of the large volume RPS VMAT plans was verified by portal dosimetry on a Truebeam™ linac. Results VMAT and IMRT plans were equivalent for PTV coverage and homogeneity (P > 0.05); however, VMAT plans had slightly better conformity index, CI (P < 0.001). Doses to the OARs were not significantly different between VMAT and IMRT plans (P > 0.05). Mean doses to the unspecified tissue as well as at 1, 2, and 5 cm DEVs were lower with VMAT compared with IMRT, P = 0.04 and P < 0.01, respectively. MUs and average beam‐on times were both significantly lower in the VMAT vs IMRT plans, P < 0.001 and P = 0.001, respectively. All VMAT plans passed portal dosimetry delivery verification with an average gamma passing rate of 99.6 ± 0.4%. Conclusions VMAT planning for large volume RPS improved CI, and achieved comparable OAR sparing, as compared with IMRT. As treatment delivery time was lower, the use of VMAT for RPS may translate into improved treatment delivery efficiency.

This study evaluates the performance and planning efficacy of the Auto-Planning (AP) module in the clinical version of Pinnacle 9.10 (Philips Radiation Oncology Systems, Fitchburg, WI, USA). Twenty automated intensity-modulated radiotherapy (IMRT) plans were compared with the original manually planned clinical IMRT plans from patients with oropharyngeal cancer. Auto-Planning with IMRT offers similar coverage of the planning target volume as the original manually planned clinical plans, as well as better sparing of the contralateral parotid gland, contralateral submandibular gland, larynx, mandible, and brainstem. The mean dose of the contralateral parotid gland and contralateral submandibular gland could be reduced by 2.5 Gy and 1.7 Gy on average. The number of monitor units was reduced with an average of 143.9 (18%). Hands-on planning time was reduced from 1.5–3 h to less than 1 h. The Auto-Planning module was able to produce clinically acceptable head and neck IMRT plans with consistent quality.

The goal of this study was to evaluate the use of multi-criteria optimization (MCO) in the planning and optimization of intensity-modulated radiotherapy (IMRT). Twenty (20) IMRT patients (ten (10) with prostate cancer and ten (10) with lung cancer) were randomly selected. The treatment plans for these patients were designed using direct machine parameter optimization (DMPO). Based on these plans, new plans were designed using multi-criteria optimization (MCO), keeping the optimization objectives and constraints unchanged. Comparisons were made between the new plans, which were based on MCO and DMPO, including the dose distribution, dose volume histogram (DVH), the optimization time and the number of monitor units (MUs). The plan designed using both optimization approaches satisfied all clinical requirements. For similar or better target coverage, the rectum, bladder and small bowel were better protected using MCO than when using DMPO. Additionally, MCO reduced the time for optimization by 58% on average, whereas the MUs increased the time for optimization by 32% on average for prostate cancer. For lung cancer cases, the entire lung, heart and spinal cord were better protected using MCO compared to DMPO. Similarly, MCO reduced the time for optimization by 59% on average, whereas the MUs increased the time for optimization by 11% on average. Compared to DMPO, MCO reduces the dose of the organs at risk (OAR) and shortens the time required for optimization.

Background and purpose To investigate the feasibility of synthesizing computed tomography (CT) images from magnetic resonance (MR) images using generative adversarial networks (GANs) for nasopharyngeal carcinoma (NPC) intensity-modulated radiotherapy (IMRT) planning. Materials and methods Conventional T1-weighted MR images and CT images were acquired from 173 NPC patients. The MR and CT images of 28 patients were randomly chosen as the independent tested set. The remaining images were used to build a conditional GAN (cGAN) and a cycle-consistency GAN (cycleGAN). A U-net was used as the generator in cGAN, whereas a residual-Unet was used as the generator in cycleGAN. The cGAN was trained using the deformable registered MR-CT image pairs, whereas the cycleGAN was trained using the unregistered MR and CT images. The generated synthetic CT (SCT) images from cGAN and cycleGAN were compared with the true CT images with respect to their Hounsfield Unit (HU) discrepancy and dosimetric accuracy for NPC IMRT plans. Results The mean absolute errors within the body were 69.67 ± 9.27 HU and 100.62 ± 7.39 HU for the cGAN and cycleGAN, respectively. The 2%/2-mm γ passing rates were (98.68 ± 0.94)% and (98.52 ± 1.13)% for the cGAN and cycleGAN, respectively. Meanwhile, the absolute dose discrepancies within the regions of interest were (0.49 ± 0.24)% and (0.62 ± 0.36)%, respectively. Conclusion Both cGAN and cycleGAN could swiftly generate accurate SCT volume images from MR images, with high dosimetric accuracy for NPC IMRT planning. cGAN was preferable if high-quality MR-CT image pairs were available.

Background Different planning methods of IMRT planning techniques (IMRT (DMLC) and RapidArc) vs. stander techniques (three-dimensional radiation therapy (3DCRT)) will be evaluated for prostate cancer patients’ planning and verification. Three groups of localized prostate cancer patients are planned and evaluated regarding DVHs and practical radiation dosimetry, and ten 3DCRT plans are assessed statistically for each patient. Results Plan (7) with parameters of five equally weighted fields with angles of 0°, 45°, 90°, 270°, and 315° and energy of 15MV is the most suitable plan both for PTV coverage and for OAR sparing with a fewer number of fields and fewer number of gantry angles. IMRT complexity involves the requirement of long treatment times and additional effort for planning, safety checks, and quality control before the patient start the treatment and proceed. Conclusions The selected plan also is more safe on patients up to 7400 cGy than other plans and is easier to be applied compared to IMRT and RapidArc plans, depending on patient geometry. IMRT radiation doses are more effective and can safely be delivered to PTV with little side effects compared with 3D conformal and conventional techniques. RapidArc has the advantage of re-optimizing and small arcs of variable parameters in dose delivery, taking into account the maximum speed of gantry and MLCs.

The aim of this study was to describe a detailed instruction of intensity modulated radiotherapy (IMRT) planning simulation using BEAMnrc-DOSXYZnrc code system (EGSnrc package) and present a new graphical user interface based on MATLAB code (The MathWorks) to combine more than one. 3ddose file which were obtained from the IMRT plan. This study was performed in four phases: the commissioning of Varian Clinac iX6 MV, the simulation of IMRT planning in EGSnrc, the creation of in-house VDOSE GUI, and the analysis of the isodose contour and dose volume histogram (DVH) curve from several beam angles. The plan paramaters in sequence and control point files were extracted from the planning data in Tan Tock Seng Hospital Singapore (multileaf collimator (MLC) leaf positions – bank A and bank B, gantry angles, coordinate of isocenters, and MU indexes). VDOSE GUI which was created in this study can display the distribution dose curve in each slice and beam angle. Dose distributions from various MLC settings and beam angles yield different dose distributions even though they used the same number of simulated particles. This was due to the differences in the MLC leaf openings in every field. The value of the relative dose error between the two dose ditributions for “body” was 51.23 %. The Monte Carlo (MC) data was normalized with the maximum dose but the analytical anisotropic algorithm (AAA) data was normalized by the dose in the isocenter. In this study, we have presented a Monte Carlo simulation framework for IMRT dose calculation using DOSXYZnrc source 21. Further studies are needed in conducting IMRT simulations using EGSnrc to minimize the different dose error and dose volume histogram deviation.

Purpose Intensity modulated radiation therapy (IMRT) is widely used to achieve a highly conformal dose and improve treatment outcome. However, plan quality and planning time are institute and planner dependent, and no standardized tool exists to recognize an optimal plan. RapidPlan, a knowledge-based algorithm, can generate constraints to assist optimization and produce high-quality IMRT plans. This report evaluated the quality and efficiency of using RapidPlan in nasopharyngeal carcinoma (NPC) IMRT planning. Methods and Materials RapidPlan was configured using 79 radical IMRT plans for NPC; 20 consecutive NPC patients indicated for radical radiation therapy between October 2014 and May 2015 were then recruited to assess its performance. The ability of RapidPlan to produce acceptable plans was evaluated. For plans that could not achieve clinical acceptance, manual touch-up was performed. The IMRT plans produced without RapidPlan (manual plans) and with RapidPlan (RP-2 plans, including those with manual touch-up) were compared in terms of dosimetric quality and planning efficiency. Results RapidPlan by itself could produce clinically acceptable plans for 9 of the 20 patients; manual touch-up increased the number of acceptable plans (RP-2 plans) to 19. The target dose coverage and conformity were very similar. No difference was found in the maximum dose to the brainstem and optic chiasm. RP-2 plans delivered a higher maximum dose to the spinal cord (46.4 Gy vs 43.9 Gy, P =.002) but a lower dose to the parotid (mean dose to right parotid, 37.3 Gy vs 45.4 Gy; left, 34.4 Gy vs 43.1 Gy; P P =.02). The total planning time for RP-2 plans was significantly less than that for manual plans (64 minutes vs 295 minutes, P Conclusions This study shows that RapidPlan can significantly improve planning efficiency and produce quality IMRT plans for NPC patients.

PurposePatients treated with intensity-modulated radiation therapy (IMRT) for head-and-neck cancer are often positioned supine on a carbon fibre board to which a thermoplastic mask is attached to immobilise the head and shoulders. For patients unable to tolerate a supine position, we developed a tilting board that accommodates a full-scale head-and-shoulder mask.Materials and methodsPhantom measurements were obtained to confirm the dosimetric accuracy of our treatment planning system when using this board. A patient was simulated in the flat and tilted positions on the board. The two corresponding treatment plans were evaluated by comparing the target coverage and doses with organs at risk. The patient’s intra-fraction motion was quantified during his tilted treatments.ResultsPhantom measurements confirmed the accuracy of the dosimetric calculations. The tilted plan met dosimetric standards for clinical acceptability. The intra-fraction motion of the patient in the tilted position was >3 mm in any direction.ConclusionsThe tilting board met clinical requirements for IMRT planning and delivery. Full-scale head-and-shoulder immobilisation was achieved in a more tolerable tilted position.

Two recent clinical trials, phase III RTOG 0614 and phase II RTOG 0933, showed some effectiveness of Memantine and IMRT planning for hippocampus sparing, among patients receiving whole brain radiotherapy (WBRT) for brain metastases; however, their use in routine clinical practice is unknown.A survey was sent to 1933 radiation oncologists in the US. Data collected included utilization of Memantine and hippocampus sparing, reasons for adoption and non-adoption, and demographic variables.A total of 196 radiation oncologists responded to the survey, with 64% reporting using Memantine in almost none of the patients receiving WBRT for brain metastases, and only 11% considering Memantine for10% of their patients. The most common reason for not using Memantine was a poor patient performance status, and limited life expectancy. Likewise, 56% of radiation oncologists would not change their clinical practice to include hippocampus sparing IMRT in patients receiving WBRT based on the results of RTOG 0933. Further validation of hippocampus sparing in a phase III trial was supported by 71% of radiation oncologists, whereas further exploration of Memantine for this purpose in a phase III trial was supported by 42%.At this time, the majority of surveyed radiation oncologists in the US do not use Memantine, or IMRT planning for hippocampus sparing in patients receiving WBRT. Further validation of the hippocampus sparing concept in a phase III trial was supported, before adopting it in routine clinical practice.

Introduction: Field-in-Field (FIF) and Intensity Modulated Radiation Therapy (IMRT) are two advanced radiation therapy planning techniques. Both of them are being used to achieve the same two related aims which are, to expose the targeted tumor to the full radiation dose and to spare the nearby normal tissues (or organs) from being exposed to high amounts of radiation more than its tolerance dose limits. FIF is a forward planning while IMRT is an inverse planning and FIF is a forward IMRT. Aim: The purpose of this study was to compare between Field-in-Field and IMRT techniques in prostate cancer radiotherapy. Method: A treatment planning system supporting both inverse and forward planning facilities is used. Ten prostate cancer patients were planned with both FIF and IMRT planning techniques. Doses received by the Planning Target Volume (PTV) and Organs at Risk (OARs) were compared in the two methods quantitatively from Dose Volume Histograms (DVHs) and qualitatively from (axial cuts). Results: The results showed that the IMRT planning technique achieved better dose coverage to the PTV than the FIF planning technique but, except RT and LT Femoral Heads, FIF achieved a better protection to the Rectum and the Bladder (OARs) than IMRT. Conclusions: The results showed that the inverse planning based IMRT technique is better and recommended in the prostate cancer radiotherapy than the FIF technique.

The purpose of this work was to develop a deep learning (DL) based algorithm, Automatic intensity-modulated radiotherapy (IMRT) Planning via Static Field Fluence Prediction (AIP-SFFP), for automated prostate IMRT planning with real-time planning efficiency. The following method was adopted: AIP-SFFP generates a prostate IMRT plan through predictions of fluence maps using patient anatomy. No inverse planning is required. AIP-SFFP is centered on a custom-built deep learning (DL) neural network for fluence map prediction. Predictions are imported to a commercial treatment-planning system for dose calculation and plan generation. AIP-SFFP was demonstrated for prostate IMRT simultaneously-integrated-boost planning (58.8 Gy/70 Gy to PTV58.8 Gy/PTV70 Gy in 28 fx, PTV = Planning Target Volume). Training data was generated from 106 patients using a knowledge-based planning (KBP) plan generator. Two types of 2D projection images were designed to represent structures' sizes and locations, and a total of eight projections were utilized to describe targets and organs-at-risk. Projections at nine template beam angles were stacked as inputs for artificial intelligence (AI) training. 14 patients were used as independent tests. The generated test plans were compared with the plans from the KBP training plan generator and clinic practice. The following results were obtained: After normalization (PTV70 Gy V70 Gy = 95%), all 14 AI plans met institutional criteria. The coverage of PTV58.8 Gy in the AI plans was comparable to KBP and clinic plans without statistical significance. The whole body (BODY) D1cc and rectum D0.1cc of AI plans were slightly higher (

The purpose of this study is to develop and evaluate a statistics-based model to predict the achievability of the planning criteria for intensity-modulated radiation therapy planning. A statistics-based model was proposed to predict the achievability of the planning criteria based on the structure set. A retrospective study was performed to validate the proposed model. A total of 160 prostate cases and 134 nasopharynx (NP) cases were used as the training set to build the model while 200 cases for each treatment site were used to validate the proposed model. An overlapping ratio and the minimum distance between organ at risks (OARs) and planning target volumes were used to predict the achievability of the planning criteria for serial organs. Since both prostate and NP cases were treated with simultaneous boost using multiple targets with different prescription doses, the effect of each parameter on the OARs was studied by binary logistic regression. For parallel organs, average distance to dose level was introduced and it described the dose falloff gradient within each OAR. By studying the distribution of average distance to dose level in the training set for each OAR, the result was used to predict the dose volume and average dose criteria. The accuracy of the proposed model was evaluated by comparing the predicted proportion and the actual proportion of the validation group that can achieve the clinical planning criteria. For prostate cases, the differences between the actual and predicted proportions were small for all criteria of rectum and bladder. The maximum deviations were 7% for bladder, 9% for rectum, and 5% for femur. For NP cases, the difference ranged from 0% to 7% with the largest difference found at the criterion D50%30 Gy of the parotids. In conclusion, the proposed statistics based plan prediction model was presented and the results showed the model could achieve acceptable prediction accuracy. The proposed tools could be used to calculate the probability of the OARs to achieve the clinical goals. This statistics based model can be further developed to adapt into the planning objective estimation in the auto-planning process.

Beam angle configuration is a major planning decision in Intensity Modulated Radiation Treatment (IMRT) that has a significant impact on dose distributions and thus quality of treatment, especially in complex planning cases such as those for lung cancer treatment. We propose a novel method to automatically determine beam configurations that incorporates noncoplanar beams. We then present a completely automated IMRT planning algorithm that combines the proposed method with a previously reported OAR DVH prediction model. Finally, we validate this completely automatic planning algorithm using a set of challenging lung IMRT cases. A beam efficiency index (BEI) map is constructed to guide the selection of beam angles. This index takes into account both the dose contributions from individual beams and the combined effect of multiple beams by introducing a beam-spread term. The effect of the beam-spread term on plan quality was studied systematically and the weight of the term to balance PTV dose conformity against OAR avoidance was determined. For validation, complex lung cases with clinical IMRT plans that required the use of one or more noncoplanar beams were re-planned with the proposed automatic planning algorithm. Important dose metrics for the PTV and OARs in the automatic plans were compared with those of the clinical plans. The results are very encouraging. The PTV dose conformity and homogeneity in the automatic plans improved significantly. And all the dose metrics of the automatic plans, except the lung V(5Gy), were statistically better than or comparable with those of the clinical plans. In conclusion, the automatic planning algorithm can incorporate non-coplanar beam configurations in challenging lung cases and can generate plans efficiently with quality closely approximating that of clinical plans.

Background The purpose of this work is to benchmark RapidPlan against clinical plans for liver Intensity-modulated radiotherapy (IMRT) treatment of patients with special anatomical characteristics, and to investigate the prediction capability of the general model (Model-G) versus our specific model (Model-S). Methods A library consisting of 60 liver cancer patients with IMRT planning was used to set up two models (Model-S, Model-G), using the RapidPlan knowledge-based planning system. Model-S consisted of 30 patients with special anatomical characteristics where the distance from planning target volume (PTV) to the right kidney was less than three centimeters and Model-G was configurated using all 60 patients in this library. Knowledge-based IMRT plans were created for the evaluation group formed of 13 patients similar to those included in Model-S by Model-G, Model-S and manually (M), named RPG-plans, RPS-plans and M-plans, respectively. The differences in the dose-volume histograms (DVHs) were compared, not only between RP-plans and their respective M-plans, but also between RPG-plans and RPS-plans. Results For all 13 patients, RapidPlan could automatically produce clinically acceptable plans. Comparing RP-plans to M-plans, RP-plans improved V95% of PTV and had greater dose sparing in the right kidney. For the normal liver, RPG-plans delivered similar doses, while RPS-plans delivered a higher dose than M-plans. With respect to RapidPlan models, RPS-plans had better conformity index (CI) values and delivered lower doses to the right kidney V20Gy and maximizing point doses to spinal cord, while delivering higher doses to the normal liver. Conclusion The study shows that RapidPlan can create high-quality plans, and our specific model can improve the CI of PTV, resulting in more sparing of OAR in IMRT for individual liver cancer patients.