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Background: Ocular melanoma is a rare kind of eye malignancy that threatens the patient's eyesight. Radiotherapy and surgical removal are the most commonly used therapeutic modalities, and nanomedicine has lately entered this field. Brachytherapy using Ruthenium‐106 (106Ru) ophthalmic plaques has been used for decades to treat ocular melanoma, with the applicator placed on the patient's eyes until the prescribed dose reaches the tumor apex. Purpose: To investigate the efficiency of hydrogen nanobubbles (H2‐NBs) employment during intraocular melanoma brachytherapy using a 106Ru electron emitter plaque. Methods: The Monte Carlo (MC) simulation and experimental investigation using a 3D‐designed phantom and thermoluminescence dosimetry (TLD) were employed. Various concentrations of H2‐NBs with a diameter of 100 nm were simulated inside tumor tissue. The results were presented as deposited energy and dose enhancement factor (DEF). An equivalent Resin phantom of the human eyeball was made using AutoCAD and 3D‐Printer technologies. The glass‐bead TLDs dosimeter were employed and placed inside the phantom. Results: Using a 1% concentration of H2‐NBs, a DEF of 93% and 98% were achieved at the tumor apex of 10 mm from the experimental setup and MC simulation, respectively. For simulated concentrations of 0.1%, 0.3%, 0.5%, 1%, and 4% H2‐NBs, a maximum dose enhancement of 154%, 174%, 188%, 200%, and 300% were achieved, respectively, and a dose reduction was seen at about 3 mm from the plaque surface. Conclusion: H2‐NBs can be used as an absorbed dose enhancer in 106Ru eye brachytherapy because of their unique physical characteristics. Reducing plaque implantation time on the patient's eye, reducing sclera absorbed dose, and decreasing the risk of patients' healthy organs irradiation are reported as some of the potential benefits of using H2‐NBs. [ABSTRACT FROM AUTHOR]

Dose escalation to target volume during High Dose Rate brachytherapy was effectively employed to treat locally advanced cervical cancer patients who experienced prolongation of Overall Treatment Time (OTT) due to the COVID-19 pandemic. It was tried to achieve acceptable oncological outcomes while respecting the dose constraints of Organs at Risk (OARs). Key Clinical Message: It was a severe challenge to obey the optimum treatment schedule of LACC cases during the coronavirus crisis. Increased risk of recurrence and mortality due to increased overall treatment time in cervical cancer patients proposes prioritizing. [ABSTRACT FROM AUTHOR]

Purpose: Post-surgery radiation can reduce the risk of loco-regional relapse in high-intermediate-risk endometrial cancer. High-dose-rate vaginal cuff brachytherapy (HDR-BRT) is an acceptable method of radiation in majority of endometrial cancer cases. Although 2D planning is frequently used for treatment based on physical examination without any imaging, measurement of the dose received by organs-at-risk (OARs) is not possible. Therefore, the present study was the first to compare dose delivered to target and OARs in 2D vs. 3D planning in patients treated with cobalt-60 source. Material and methods: In this study, organs including vagina wall, bladder, rectum, and sigmoid were contoured on computed tomography (CT) scan images of 37 endometrial cancer patients, and doses delivered to organs were recorded. Statistics, such as D90, D99, V100, V150, V200, D0.1cc, D1cc, and D2cc were determined. Results: D90 and D99 were lower in 3D treatment planning in comparison with 2D. Although V100 was more in 3D planning, V150 and V200 were less. Analyzing D0.1cc, D1cc, and D2cc of OARs revealed that doses given to rectum, sigmoid, and bladder were less in 3D planning compared to 2D. Conclusions: Comparison of 2D and 3D planning results showed that 3D planning could deliver an appropriate dose to the target while sparing more OARs. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate the application of the exit skin dose (ESD) in verifying the accuracy of intra-cavitary brachytherapy treatments performed by the BEBIG 60Co machine using thermoluminescent dosimeters (TLDs). Materials and methods: Eleven patients who were treated for gynaecological (GYN) malignancy by high-dose-rate (HDR) brachytherapy machine have been considered in this study. A combination of tandem, cylinder and interstitial needles was applied for eight patients while tandem ovoid (TO) applicators were used for the rest (three patients). In order to measure ESD, thermoluminescent dosimetry was performed for each patient. TLDs were placed precisely on the patient's skin along her symphysis pubis bone (anterior) and left (L)/right (R) sides of her pelvic. Positioning of the dosimeter was accurately determined using fiducial markers in computed tomography (CT) scan imaging, prior to the treatment. Finally, a comparison was made between the calculated dose from the treatment planning system (TPS) and the dose measured by TLDs. Results: About 90% of all cases showed a good agreement (while considering TLD uncertainty ∼5·5%) between TPS dose calculations and TLD measurements. The measured mean values of ESD received to anterior, left and right positions were 56·72, 12·18 and 12·82 cGy, respectively. For three patients, differences up to 11·9% were detected. Conclusion: To conclude, ESD measurement method can be a suitable practical approach for verifying the accuracy of GYN HDR treatment delivery. [ABSTRACT FROM AUTHOR]

Radiotherapy of extensive malignant scalp lesions has always been a challenge for radiation oncologists considering the proximity of critical structures. We treated a 39-year-old patient with extensive scalp squamous cell carcinoma with application of adjuvant concurrent chemoradiation and external beam radiation therapy (EBRT), followed by high-dose-rate (HDR) surface brachytherapy boost using an exclusively designed mould, and assessed the radiation dose reaching planning target volume, brain, and optic structures. Comparison between conventional planning with sole EBRT and combined treatment planning with EBRT and brachytherapy, assured the use of the latter treatment to avoid high radiation doses from reaching critical organs at risk without compromising the required dose for planning target volume. [ABSTRACT FROM AUTHOR]

Purpose: This study was designed to assess the dose accumulation (DA) of bladder and rectum between brachytherapy fractions using hybrid-based deformable image registration (DIR) and compare it with the simple summation (SS) approach of GEC-ESTRO in cervical cancer patients. Material and methods: Patients (n = 137) with cervical cancer treated with 3D conformal radiotherapy and three fractions of high-dose-rate brachytherapy were selected. CT images were acquired to delineate organs at risk and targets according to GEC-ESTRO recommendations. In order to determine the DA for the bladder and rectum, hybrid- based DIR was done for three different fractions of brachytherapy and the results were compared with the standard GEC-ESTRO method. Also, we performed a phantom study to calculate the uncertainty of the hybrid-based DIR algorithm for contour matching and dose mapping. Results: The mean ± standard deviation (SD) of the Dice similarity coefficient (DICE), Jaccard, Hausdorff distance (HD) and mean distance to agreement (MDA) in the DIR process were 0.94 ±0.02, 0.89 ±0.03, 8.44 ±3.56 and 0.72 ±0.22 for bladder and 0.89 ±0.05, 0.80 ±0.07, 15.46 ±10.14 and 1.19 ±0.59 for rectum, respectively. The median (Q1, Q3; maximum) GyEQD2 differences of total D2cc between DIR-based and SS methods for the bladder and rectum were reduced by -1.53 (-0.86, -2.98; -9.17) and -1.38 (-0.80, -2.14; -7.11), respectively. The mean ± SD of DICE, Jaccard, HD, and MDA for contour matching were 0.98 ±0.008, 0.97 ±0.01, 2.00 ±0.70 and 0.20 ±0.04, respectively for large deformation. Maximum uncertainty of dose mapping was about 3.58%. Conclusions: The hybrid-based DIR algorithm demonstrated low registration uncertainty for both contour matching and dose mapping. The DA difference between DIR-based and SS approaches was statistically significant for both bladder and rectum and hybrid-based DIR showed potential to assess DA between brachytherapy fractions. [ABSTRACT FROM AUTHOR]

Purpose: Skin cancers are the most common human malignancy with increasing incidence. Currently, surgery is standard of care treatment for non-melanoma skin cancers. However, brachytherapy is a growing modality in the management of skin cancers. Therefore, we aimed to assess the outcome of patients with non-melanoma skin cancers treated by high-dose-rate (HDR) brachytherapy with surface mold technique. Material and methods: In this prospective study, we recruited patients with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin who were candidates for definitive or adjuvant brachytherapy during 2013-2014. Alginate was used for making the individualized surface molds for each patient. Patients were treated with afterloading radionuclide HDR brachytherapy machine, with a total dose of 30-52 Gy in 10-13 fractions. Participants were followed for 2 years for radiation toxicity, cosmetic results, and local failures. Results: A total of 60 patients (66.7% male; median age, 71 years) were included, of which 42 (70.0%) underwent definitive radiotherapy. Seventy-five percent of lesions were BCC. The mean total dose was 39.6 ± 5.4 Gy. Of patients in definitive group, 40/42 (95.2%) experienced complete clinical response after 3 months. The recurrence rate was 2/18 (11.11%) and 1/42 (2.38%) in adjuvant and definitive groups, respectively. The percentage of grade 3-4 acute (3-month post-treatment) and late toxicities (2 years post-treatment) was 6.7% and 0%, respectively. The cosmetic results were good/excellent in 96.2% of patients after 2 years of follow-up. Conclusions: With appropriate patient selection and choosing as lowest dose per fraction as possible, HDR brachytherapy with customized surface molds yields good oncological and cosmetic results for the treatment of localized skin BCC and SCC. [ABSTRACT FROM AUTHOR]

Purpose: Intra-fractional organs at risk (OARs) deformations can lead to dose variation during image-guided adaptive brachytherapy (IGABT). The aim of this study was to modify the final accepted brachytherapy treatment plan to dosimetrically compensate for these intra-fractional organs-applicators position variations and, at the same time, fulfilling the dosimetric criteria. Material and methods: Thirty patients with locally advanced cervical cancer, after external beam radiotherapy (EBRT) of 45-50 Gy over five to six weeks with concomitant weekly chemotherapy, and qualified for intracavitary high-dose-rate (HDR) brachytherapy with tandem-ovoid applicators were selected for this study. Second computed tomography scan was done for each patient after finishing brachytherapy treatment with applicators in situ. Artificial neural networks (ANNs) based models were used to predict intra-fractional OARs dose-volume histogram parameters variations and propose a new final plan. Results: A model was developed to estimate the intra-fractional organs dose variations during gynaecological intracavitary brachytherapy. Also, ANNs were used to modify the final brachytherapy treatment plan to compensate dosimetrically for changes in 'organs-applicators', while maintaining target dose at the original level. Conclusions: There are semi-automatic and fast responding models that can be used in the routine clinical work- flow to reduce individually IGABT uncertainties. These models can be more validated by more patients' plans to be able to serve as a clinical tool. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the optimum organ filling point for organs at risk (OARs) dose in cervical cancer high-doserate (HDR) brachytherapy. Material and methods: In a retrospective study, 32 locally advanced cervical cancer patients (97 insertions) who were treated with 3D conformal external beam radiation therapy (EBRT) and concurrent chemotherapy during 2010- 2013 were included. Rotterdam HDR tandem-ovoid applicators were used and computed tomography (CT) scanning was performed after each insertion. The OARs delineation and GEC-ESTRO-based clinical target volumes (CTVs) contouring was followed by 3D forward planning. Then, dose volume histogram (DVH) parameters of organs were recorded and patients were classified based on their OARs volumes, as well as their inserted tandem length. Results: The absorbed dose to point A ranged between 6.5-7.5 Gy. D0.1cm3 and D2cm3 of the bladder significantly increased with the bladder volume enlargement (p value < 0.05). By increasing the bladder volume up to about 140 cm3, the rectum dose was also increased. For the cases with bladder volumes higher than 140 cm3, the rectum dose decreased. For bladder volumes lower than 75 cm3, the sigmoid dose decreased; however, for bladder volumes higher than 75 cm3, the sigmoid dose increased. The D2cm3 of the bladder and rectum were higher for longer tandems than for shorter ones, respectively. The divergence of the obtained results for different tandem lengths became wider by the extension of the bladder volume. The rectum and sigmoid volume had a direct impact on increasing their D0.1cm3 and D2cm3, as well as decreasing their D10, D30, and D50. Conclusions: There is a relationship between the volumes of OARs and their received doses. Selecting a bladder with a volume of about 70 cm3 or less proved to be better with regards to the dose to the bladder, rectum, and sigmoid. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the outcomes of ruthenium-106 (106Ru) brachytherapy in terms of radiation parameters in patients with thick uveal melanomas. Material and methods: Medical records of 51 patients with thick (thickness ≥ 7 mm and < 11 mm) uveal melanoma treated with 106Ru brachytherapy during a ten-year period were reviewed. Radiation parameters, tumor regression, best corrected visual acuity (BCVA), and treatment-related complications were assessed. Results: Fifty one eyes of 51 consecutive patients including 25 men and 26 women with a mean age of 50.5 ± 15.2 years were enrolled. Patients were followed for 36.1 ± 26.5 months (mean ± SD). Mean radiation dose to tumor apex and to sclera were 71 (± 19.2) Gy and 1269 (± 168.2) Gy. Radiation dose rates to tumor apex and to sclera were 0.37 (±0.14) Gy/h and 6.44 (± 1.50) Gy/h. Globe preservation was achieved in 82.4%. Preoperative mean tumor thickness of 8.1 (± 0.9) mm decreased to 4.5 (± 1.6) mm, 3.4 (± 1.4) mm, and 3.0 (± 1.46) mm at 12, 24, and 48 months after brachytherapy (p = 0.03). Four eyes that did not show regression after 6 months of brachytherapy were enucleated. Secondary enucleation was performed in 5 eyes because of tumor recurrence or neovascular glaucoma. Tumor recurrence was evident in 6 (11.8%) patients. Mean Log MAR (magnification requirement) visual acuity declined from 0.75 (± 0.63) to 0.94 (± 0.5) (p = 0.04). Best corrected visual acuity of 20/200 or worse was recorded in 37% of the patients at the time of diagnosis and 61.7% of the patients at last exam (p = 0.04). Non-proliferative and proliferative radiation-induced retinopathy was observed in 20 and 7 eyes. Conclusions: Thick uveal melanomas are amenable to 106Ru brachytherapy with less than recommended apex radiation dose and dose rates. [ABSTRACT FROM AUTHOR]

Introduction In order to treat uveal Melanoma, first, radioactive seeds are laid on a silicone- made substance which is called Silastic after that they are inserted in the plaque, and finally, this plaque containing silicone-made substance is stitched to the sclera surface. The dose gradient within the tumor and healthy tissues can be varied due to changing the Silastic thickness between sclera surface and radioactive seeds. In turn, this leads to difference in the amount of absorbed dose of tumor and healthy tissues. Present study is to investigate the optimum Silastic thickness in uveal Melanoma brachytherapy. Materials and Methods To measure changes of depth dose of the plaque in a sphere with a radius of 12 mm, MCNP4C code was applied. Exact specifications of a 20-mm Collaborative Ocular Melanoma Study (COMS) plaque, Silastic and three I-125 seed sources, 6711 model were integrated in simulation. Dose calculations were performed using F6 tally in spheres with a radius of 0.2 mm. Results By measuring the changes of dose rate of plaque in distances of 0.2 to 18 mm from the sclera surface and having the prescribed dose for the absolute treatment of eye melanoma, final absorbed doses by tumor and healthy tissues for each different Silastic thicknesses of 0, 0.5, 1, 1.5, and 2 were calculated. Conclusion Considering the results and sclera tolerance, it was concluded that the thickness of Silastic must not exceed 0.5 mm, because increasing the Silastic thickness from this area, increases absorbed dose by healthy tissues and also the treatment time. [ABSTRACT FROM AUTHOR]

Aims: This study investigates to what extent the dose received by lungs from a commercially available treatment planning system, Ir-192 high-dose-rate (HDR), in breast brachytherapy, is accurate, with the emphasis on tissue heterogeneities, and taking into account the presence of ribs, in dose delivery to the lung. Materials and Methods: A computed tomography (CT) scan of a breast was acquired and transferred to the 3-D treatment planning system and was also used to construct a patient-equivalent phantom. An implant involving 13 plastic catheters and 383 programmed source dwell positions were simulated, using the Monte Carlo N-Particle eXtended (MCNPX) code. The Monte Carlo calculations were compared with the corresponding commercial treatment planning system (TPS) in the form of percentage isodose and cumulative dose-volume histogram (DVH) in the breast, lungs, and ribs. Results: The comparison of the Monte Carlo results and the TPS calculations showed that a percentage of isodose greater than 75% in the breast, which was located rather close to the implant or away from the breast curvature surface and lung boundary, were in good agreement. TPS calculations overestimated the dose to the lung for lower isodose contours that were lying near the breast surface and the boundary of breast and lung and were relatively away from the implant. Conclusions: Taking into account the ribs and entering the actual data for breasts, ribs, and lungs, revealed an average overestimation of the dose by a factor of 8% in the lung for TPS calculations. Therefore, the accuracy of the TPS results may be limited to regions near the implants where the treatment is planned, and is a more conservative approach for regions at boundaries with curvatures or tissues with a different material than that in the breast. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the actual dose delivered to the rectum and compare it with the treatment planning system (TPS) reports. In this study, the dose delivered to the rectum was measured by semiconductor diode detectors (PTW, Germany). The factors that influence diode response were investigated as well. Calibration factors of diodes were measured weekly to investigate the effect of time interval on the accuracy of calibration. Then 40 applications of patients with cervix carcinoma were evaluated. Rectum dose was measured by means of rectal dosemeter and compared with the TPS-calculated dose. In this research, the differences between the measured and the calculated dose were investigated. The mean difference between the TPS-calculated dose and the measured dose was 6.5 % (range: −22 to +39) for rectum. The TPS-calculated maximum dose was typically higher than the measured maximum dose. The study showed that the main reason for the difference was due to the movements of the patient and applicator shift in the elapsed time between the imaging and treatment stage. It is recommended that in vivo dosimetry should be performed in addition to treatment planning computation. In vivo dosimetry is a reliable solution to compare the planned and actual dose delivered to organs at risk. [ABSTRACT FROM PUBLISHER]

Summary: Aim: Dependence of diode dosimeters on variation of temperature, distance, dose rate and incident beam angle for MDR/LDR intracavitary brachytherapy was investigated. Materials/Methods: Flexible probes from PTW/Germany were irradiated using Cs-137 sources. The rectum probe (type 9112) had five semiconductors and the bladder probe had one. Firstly, detectors'' dependence on temperature was studied. The probes were immersed into a water tank and the temperature was slowly increased. To investigate the angular dependence of the diodes, the sources were placed at 5cm distance from diodes at four different angles. Probes were placed at 3cm distance from the centre of the source arrays and the responses for three different dose rates were evaluated. To assess the dependency of responses on distance, probes were placed at three different distances with constant dose rate. Results: A slight linear increase of the diode signal with temperature was found. The diodes exhibited a variation in sensitivity with dose rate less than 0.15% and with distance less than 0.04% per mm. A linear decrease of the diode responses was also observed with increase of the radiation beam angle. Conclusions: The current study showed that there is no significant variation in the response of diodes with temperature, dose rate and distance for MDR brachytherapy. However, the increase of radiation beam angle led to a significant decrease of diode response. In conclusion, the observed temperature, dose rate and distance effects are negligible but the diode correction factor as a function of the incidence beam angle must be applied to these diodes. [Copyright &y& Elsevier]

Iridium-192 brachytherapy dose enhancement by gold nanoparticles was investigated in five different tumor tissues to observe the tissue-related differences as an effective environmental factor in the applications of nanoparticles as radio-enhancer agents. The brachytherapy high-dose-rate source of BEBIG Ir-192, a tumor volume with five different tissues including water, Plexiglas, soft tissue, adipose, and bone with and without a uniform distribution of gold nanoparticles were mimicked by MCNPX Monte Carlo simulation code using lattice feature. Dose enhancement factors in the tumor volume were measured separately regarding the types of tissue, and a previous study using GEometry ANd Tracking 4 simulation was used for result validation. The results demonstrated that various types of tissue, as the host of gold nanoparticles, lead to different dose enhancement level, so that the bone and adipose have the lowest and the highest amount of dose enhancement factor with values 20.8% and 39.75%, respectively. The maximum difference of 4.8% was achieved from data benchmarking. The results of this study indicate that the MCNPX code can be used as a valid tool for dose measurement in the presence of nanoparticles. Moreover, tissue types of tumor as an environmental feature, alongside with the nanoparticle's size and concentration as well as the conditions of radiotherapy, should be considered in the dose calculation. [ABSTRACT FROM AUTHOR]

Purpose To demonstrate the utility of “3D Slicer” for easy treatment verification by comparing dose-volume histograms (DVHs) calculated on pretreatment and posttreatment images. Methods and materials Thirty cervical cancer patients were CT scanned twice: first for treatment planning and a second time after the dose delivery. The initial plan was manually duplicated on the posttreatment image set in Flexiplan treatment planning system, and DVH parameters were calculated. Pretreatment and posttreatment images, organ structures, and plan data were exported from the treatment planning system to 3D Slicer to validate DVH parameter calculation with 3D Slicer. The gamma analysis was used to compare Flexiplan and 3D Slicer DVHs. Posttreatment images were rigidly fused on the initial CT to automatically transfer the data of the pretreatment plan onto the posttreatment images. DVH parameters were calculated in 3D Slicer for both image sets, and their relative variations were compared. Results In calculating DVH parameter variations, no significant differences were observed between Flexiplan and 3D Slicer. Where the registration accuracy was better than 0.03, they returned similar results for D 2 cm 3 of bladder, rectum, and sigmoid. Mean and standard deviation of DVH parameters were calculated on pretreatment and posttreatment images for several organs; both the manually duplicated plan and the automatically registered plan in SlicerRT returned comparable relative variations of these parameters. For 88% of the organs, more than 95% of the DVH dose bins passed the gamma analysis. Conclusions We tested an automated DVH assessment method with an imaging freeware, 3D Slicer, for use in image-guided adaptive brachytherapy. SlicerRT is a viable verification tool to report and detect DVH variations between different contoured images series. [ABSTRACT FROM AUTHOR]

• Guidelines on skin superficial BT do not fully reflect the clinical practice of large tumors. • No dosimetry parameters-PROM relationships are found in skin cancer superficial BT. • Publications using constraints beyond recommendations meet excellent results. The aim of this publication is the assessment of the existing guidelines for non-melanoma skin cancer (NMSC) superficial brachytherapy (BT) and make a critical review based on the existing literature about the maximum dose prescription depth, bolus thickness and maximum skin surface dose (D max) of the published clinical practice. A systematic review of NMSC superficial BT published articles was carried out by the GEC-ESTRO Head & Neck and Skin (HNS) Working Group (WG). 10 members and 2 external reviewers compared the published clinical procedures with the recommendations in the current guidelines and examined the grade of evidence. Our review verified that there is a large variation among centres with regards to clinical practice in superficial BT and identified studies where published parameters such as maximum dose prescription depth, bolus thickness and D max exceed the constraints recommended in the guidelines, while showing excellent results in terms of local control, toxicity and cosmesis. This review confirmed that current recommendations on skin superficial BT do not include published experience on tumours treated with superficial BT that require dose prescription depth beyond the recommended 5 mm under the skin surface and that the existing literature does not provide sufficient evidence to relate dosimetry of superficial BT to patient reported outcome measures. The GEC-ESTRO HNS WG considers acceptable to prescribe superficial BT dose at a depth above 5 mm beyond the skin surface, and modify the bolus thickness to optimize the treatment plan and adjust the acceptable maximum dose on the skin surface, all pending clinical situation. [ABSTRACT FROM AUTHOR]

Rhabdomyosarcoma (RMS) is the most common pediatric soft-tissue sarcoma, mostly involving the genitourinary (GU) tract, head and neck, and extremities. This study reports the long-term outcome of two infants with recurrent GU-RMS who underwent combination therapy with chemotherapy (ChT) and salvage brachytherapy (BT). An 18-month-old girl with vaginal bleeding and a 7-month-old boy with urinary retention presented with a diagnosis of vaginal, and bladder/prostate embryonal RMS, respectively. Surgical resection and ChT were done for both patients. However, both developed local recurrences after one year and subsequently, underwent second-line ChT and salvage interstitial high dose rate BT. The clinical target volumes for the first and second patients were treated to a totaldose of 32 Gy in 10 fractions and 35 Gy in 10 fractions, respectively, with two fractions delivered per day with a 6-h interval between fractions. After 9 years of follow-up, both patients are alive with natural growth and no late complication or evidence of recurrence. Our report shows that BT (for patients with no prior history of irradiation) could result in long-term disease-free survival in well-selected pediatric patients with recurrent GU embryonal RMS without inflicting expected adverse effects of external beam radiotherapy. [ABSTRACT FROM AUTHOR]

This study investigated the correlation between the prescription dose and dose to the Manchester and International Commission on Radiation Units and Measurements-report 38 (ICRU-38) lymphatic trapezoid points during high-dose-rate (HDR) brachytherapy of locally advanced cervical cancer with (Cobalt-60) 60Co. A retrospective study was designed for; patients with locally advanced cervical cancer, treated by external beam radiotherapy and concurrent weekly Cisplatin-based chemotherapy, had no extended parametrial invasion and was treated by tandem-ovoid set, from 2017 to 2020. Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) based target's volume, ICRU-89 revised version of Manchester points A and B, and ICRU-38 lymph node surrogate points were determined, and their dose was recorded. Paired sample t -test, linear regression analysis, and Pearson correlation analyses were done considering a statistical significance level of 0.05 and using IBM SPSS statistics (Version 23, IBM Crop.). Seventy-four brachytherapy cases were included. A positive and strong correlation was observed between D 90 of clinical target volume (CTV HR) and points A and B dose for CTV HR 〈 15 cc and 〉 35 cc. Strong and significant (p < 0.05) correlations were achieved between pelvic wall points dose and D 90 and D 100 of the obturator and between D 50 and hot points of internal iliac lymph nodes. A strong correlation was obtained between D 50 and D 90 of external iliac lymph nodes and their ICRU points. Strong correlations were obtained between dose to the pelvic lymphatic chains and their historical ICRU-38 surrogate points during HDR brachytherapy of locally advanced cervical cancer patients with 60Co tandem-ovoid applicator sets. The correlation strength between point A and prescription dose highly depends on the CTV HR volume. [ABSTRACT FROM AUTHOR]

Ruthenium-106 (106Ru) plaques are specific applicators dedicated for intraocular brachytherapy. Small tumor volume and presence of vital organs in its close vicinity as well as appearance of very high dose gradient regions around the employed plaques cause unique challenges in plaque-based brachytherapy. Therefore, access to 3D dose distribution for each brachytherapy plaque is quite helpful to decide about tumor volume coverage and overexposure of surrounding sensitive organs. Current study aims to measure the 3D dose distribution for two commercially available 106Ru plaques using film dosimetry. COB (a notched-shape plaque) and CGD (a fully circular plaque) 106Ru plaques were used and dose distributions in different planes were measured by simultaneously employing a 3D printed eyeball phantom and Gafchromic EBT3 films. Finally, 3D dose distributions were acquired by interpolating the measured 2D dose data at different planes. The results showed that employing the COB plaque tilts the isodose curves toward the non-notched edge of the plaque, while no isodose tilting was observed for CGD plaque. The obtained 3D dose distributions were different for studied plaques. Non-uniform 3D dose distributions were found for both plaques which can be attributed to the plaque design and reference point position on plaque central axis. Finally, it can be concluded that the obtained 3D dose distributions can specify the optimal tumor shape which can be adequately covered by brachytherapy plaque with minimizing the dose non-uniformity and hot point formation inside the treated volume. Obtained 3D dose distribution for each plaque can be employed for patient treatment planning. • Film dosimetry of two commercially available 106Ru intraocular brachytherapy plaques. • COB (notched shape) and CGD (fully circular shape) plaques were considered. • 3D dose distribution data was measured for each plaque inside an eyeball phantom. • Non-uniform dose distribution were observed for both plaques understudy. • Followed approach can be used for plaque-based brachytherapy quality assurance. [ABSTRACT FROM AUTHOR]

In vivo dosimetry (IVD) is a powerful method for treatment dose verification which has been applied in brachytherapy (BT) using different dosimetry systems and technologies. However, implementation of IVD in routine clinical workflow and patient quality control is limited in many departments. This is due to challenges related to the high gradient dose distribution, large dose range and dose rate around BT sources. The apparent lack of utilization of high accuracy IVD systems, which are straightforward to use in a clinic, is currently a significant missed opportunity for quality and safety assurance. Commercial silica bead thermoluminescent dosimeters (TLDs) (Jafari et al., 2014a, 2014b) appear suitable for IVD in high dose rate (HDR) BT. The dose response of silica bead TLDs was characterized in a water phantom and a constructed anthropomorphic pelvis phantom by exposing them with 60Co source as the used source in our BT department. Also dose response of bead TLDs was defined in a CTDI phantom with 120 kV energy exposure. It was found that measured dose differences to planning system calculations varied from −2.0% to 2.9% during pelvis phantom investigations. Mean experimental dose differences did not exceed the standard uncertainty 7.0% (k = 2) estimated for this study. The phantom results presented indicate that silica beads TLDs may be used to provide in vivo verification of delivered dose in intracavitary HDR BT although this work verifies use only for 60Co source. • Dosimetric response of bead TLDs was evaluated for 60Co HDR brachytherapy source(s). • Dose differences of bead TLDs to TPS varied from −2.0% to 2.9% in phantom dosimetry. • Dosimetric response of bead TLDs was evaluated in a CTDI phantom by exposing to 120 kV. [ABSTRACT FROM AUTHOR]