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To report acute toxicity and health-related quality of life (HRQoL) outcomes of a phase II clinical trial of magnetic resonance imaging (MRI)-guided prostate high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy.Patients with intermediate- and high-risk prostate cancer (PCa) were eligible. Treatment consisted of a single 15 Gy MRI-guided HDR-BT followed by external beam radiotherapy (37.5-46 Gy depending on their risk category). Dosimetry, toxicity and HRQoL outcomes were collected prospectively at baseline, 1 and 3 months using Common Terminology Criteria for Adverse Events Version 4.0 and the expanded PCa index composite, respectively. General linear mixed modeling was conducted to assess the changes in expanded PCa index composite domain scores over time. A minimally important difference was defined as a deterioration of HRQoL scores at 3 months compared to baseline ≥ 0.5 standard deviation. A p value ≤ 0.05 was considered statistically significant.Sixty-one patients were included. Acute grade (G)2 urinary toxicity was observed in 18 (30%) patients while 1 (2%) patient had G3 toxicity, and none had G4 toxicity. Two patients had an acute urinary retention. G2 gastrointestinal toxicity was reported by 5 (8%) patients with no G3-4. Compared to baseline, urinary HRQoL scores significantly declined at 1 month (p0.001) but recovered at 3 months (p0.05). Bowel (p0.001) and sexual (p0.001) domain scores showed a significant decline over the 3-month follow-up period. At 3 months, 44%, 49% and 57% of patients reported a minimally important difference respectively in the urinary bowel and sexual domains.MRI-guided HDR-BT boost is a safe and well tolerated treatment of intermediate- and high-risk PCa in the acute setting. A longer follow-up and a comparison to ultrasound-based HDR-BT are needed to assess the potential benefit of MRI-guided prostate HDR-BT.

To demonstrate the feasibility of treating cervical cancer patients with MRI-guided brachytherapy (MRgBT) using 24 Gy in 3 fractions (F) versus a standard, more resource-intensive regimen of 28 Gy in 4F, and its ability to meet EMBRACE II planning aims.A retrospective review of 224 patients with FIGO Stage IB-IVA cervical cancer treated with 28 Gy/4F (n = 91) and 24 Gy/3F (n = 133) MRgBT between 2016-2021 was conducted. Multivariable linear regression models were fitted to compare dosimetric parameters between the two groups, adjusting for CTVMost patients had squamous cell carcinoma, T2b disease, and were treated with intracavitary applicator plus interstitial needles (96%). The 28 Gy/4F group had higher CTVCervical cancer patients treated with 24 Gy/3F MRgBT had comparable target doses and lower OAR doses compared to those treated with 28 Gy/4F. A less-resource intense fractionation schedule of 24 Gy/3F is an alternative to 28 Gy/4F in cervix MRgBT.

Fariba Ghassemi, 1–3 Shahab Sheibani, 4 Mojtaba Arjmand, 3 Hosein Poorbaygi, 4 Emad Kouhestani, 1 Siamak Sabour, 5 Farhad Samiei, 6 Akbar Beiki-Ardakani, 7 Mahmood Jabarvand, 1 Ali Sadeghi Tari 1 1Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, IR, Iran; 2Retina & Vitreous Service, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, IR, Iran; 3Ocular Oncology Service, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, IR, Iran; 4Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, Iran; 5Safety Promotion and Injury Prevention Research Centre, Department of Clinical Epidemiology, School of Health,Shahid Beheshti University of Medical Sciences, Tehran, IR, Iran; 6Radiation Oncology Department, Cancer Institute, Imam Hospital and Medical Complex, Tehran University of Medical Sciences, Tehran, Iran; 7Radiation Physics Department, Princess Margaret Hospital, Toronto, ON, CanadaCorrespondence: Fariba GhassemiEye Research Center, Farabi Eye Hospital, Qazvin Square, Tehran 1336616351, IranTel +98-21-55421006Fax +98-21-55416134Email fariba.ghassemi@gmail.comBackground: To compare iodine-125 ( 125I) with ruthenium-106 ( 106Ru) episcleral plaque radiation therapy in terms of the effectiveness and non-inferiority for choroidal melanoma treatment.Objective: To report the non-inferiority of new made iodine-125 ( 125I) compared with ruthenium-106 ( 106Ru) episcleral plaque radiation.Patients and Methods: A retrospective, non-randomized comparative case series. In this series the patients treated with 125I and 106Ru episcleral plaques for choroidal melanoma between September 2013 and August 2017 at Farabi Hospital are compared. Local control of choroidal melanomas after 125I and 106Ru plaques implantation and vision changes are the main outcome measures.Results: A total of 35 patients were identified ( 125I = 15, 106Ru = 20). No significant difference between two groups in visual acuity, diameter and thickness changes were observed after treatment. Multivariate linear regression (MLR) analysis showed that final diameter was only, independently and significantly, correlated with the pre-treatment diameter of the tumor (β =  0.59, 95% confidence interval [CI]: 0.29, 1.34, P =  0.003). The same MLR analysis for the final thickness and visual acuity, after adjusting for age and sex showed no significant difference between two groups. A single patient treated with 106Ru had local tumor recurrence with no one in the 125I group. No statistical difference in the rate of ocular complications was observed.Conclusion: The treatment with our 125I plaques is as effective as 106Ru plaques in controlling choroidal melanoma tumor and preserving the vision during the two and half year of follow-up. The complication rates are alike. It means that the effectiveness of 125I is not only comparable to 106Ru but also superior when the outcome of the interest is the thickness of the tumors.Keywords: brachytherapy, choroidal melanoma, complication, local tumor control, 125I, radiation, 106Ru, tumor size, vision preservation

Background To compare iodine-125 (125I) with ruthenium-106 (106Ru) episcleral plaque radiation therapy in terms of the effectiveness and non-inferiority for choroidal melanoma treatment. Objective To report the non-inferiority of new made iodine-125 (125I) compared with ruthenium-106 (106Ru) episcleral plaque radiation. Patients and methods A retrospective, non-randomized comparative case series. In this series the patients treated with 125I and 106Ru episcleral plaques for choroidal melanoma between September 2013 and August 2017 at Farabi Hospital are compared. Local control of choroidal melanomas after 125I and 106Ru plaques implantation and vision changes are the main outcome measures. Results A total of 35 patients were identified (125I = 15, 106Ru = 20). No significant difference between two groups in visual acuity, diameter and thickness changes were observed after treatment. Multivariate linear regression (MLR) analysis showed that final diameter was only, independently and significantly, correlated with the pre-treatment diameter of the tumor (β = 0.59, 95% confidence interval [CI]: 0.29, 1.34, P = 0.003). The same MLR analysis for the final thickness and visual acuity, after adjusting for age and sex showed no significant difference between two groups. A single patient treated with 106Ru had local tumor recurrence with no one in the 125I group. No statistical difference in the rate of ocular complications was observed. Conclusion The treatment with our 125I plaques is as effective as 106Ru plaques in controlling choroidal melanoma tumor and preserving the vision during the two and half year of follow-up. The complication rates are alike. It means that the effectiveness of 125I is not only comparable to 106Ru but also superior when the outcome of the interest is the thickness of the tumors.

Purpose To develop a treatment planning platform for episcleral Collaborative Ocular Melanoma Study plaque therapy in an established treatment planning software and to improve an existing quality assurance (QA) process for nonuniformly loaded plaques that measures air kerma strengths (AKSs) and loading profile. Materials and Methods Treatment planning is performed in Pinnacle using scripts that let the planner choose plaque size and notching. Scripts load seed positions for each plaque and five source groups corresponding to available stock seeds that can be placed into each seed position. Contours are loaded that display the model eye and the plaque itself. Plaque QA is performed using a modification of our previous pinhole apparatus by replacing x-ray film exposure with an optical camera and scintillating film system. The captured image is processed to remove background and to correct the intensity of seeds on the plaque periphery. Measured total optical counts provide an estimate of total plaque AKS. Results Treatment planning of eye plaques using Pinnacle, in conjunction with our stock inventory of seeds, is established as standard practice at our center. Planned plaques can vary from uniformly loaded to asymmetrically loaded notched plaques. Using the optical camera system for assessment of the seed loadings has decreased QA time from 40 min/plaque to 10 min/plaque. Total AKS of each plaque can be measured using the optical camera with an accuracy of 10%. Conclusions Treatment planning is performed on a Health Canada–approved software that accommodates nonuniform plaque loading. Optical imaging of the plaque provides absolute total AKS and the relative seed arrangement in the plaque.

Purpose The treatment of locally advanced cervical cancer with definitive chemoradiation (CRT) is associated with vaginal toxicity and altered sexual satisfaction. This prospective study assessed patient-reported sexual adjustment, vaginal dosimetry, and physician-reported vaginal toxicity in patients with cervical cancer treated with CRT and MR-guided brachytherapy (BT). Materials and Methods Between 2008 and 2010, International Federation of Gynecologists and Obstetricians stage IB-IVA patients with cervical cancer receiving definitive CRT were enrolled in a feasibility study assessing MR-guided BT. Patients completed the validated sexual adjustment questionnaire (SAQ) before BT (baseline) and during followup. Physician-reported vaginal toxicity was recorded. The International Commission on Radiation Units and Measurements rectovaginal point, mean vaginal dose, and D2cm3 were calculated. Mean SAQ scores at baseline and followup assessments were calculated. Mean time effects were estimated using a linear mixed-effects model. A multivariable linear mixed-effects model was used to examine the association between total and individual scores (repeated measures) and covariates. Results Sixty patients were approached to participate: 29 consented and 27 completed the SAQ at baseline and followup. The diagnosis of cervical cancer and treatment negatively impacted sexual relationships in 61% and 39%, respectively. There were no significant changes in sexual adjustment over time (p = 0.599). There were no associations between sexual adjustment and the International Commission on Radiation Units and Measurements rectovaginal point dose or clinical vaginal involvement. Patients with higher International Federation of Gynecologists and Obstetricians stages (≥IIB) had significantly worse sexual adjustment (p = 0.005). Conclusion CRT and MR-guided BT negatively impacted sexual relationships in patients with cervix cancer; however, there were no significant longitudinal changes in patient-reported sexual adjustment. Worse sexual adjustment may be associated with more advanced disease presentations.

Background To compare iodine-125 (125I) with ruthenium-106 (106Ru) episcleral plaque radiation therapy in terms of the effectiveness and non-inferiority for choroidal melanoma treatment. Objective To report the non-inferiority of new made iodine-125 (125I) compared with ruthenium-106 (106Ru) episcleral plaque radiation. Patients and Methods A retrospective, non-randomized comparative case series. In this series the patients treated with 125I and 106Ru episcleral plaques for choroidal melanoma between September 2013 and August 2017 at Farabi Hospital are compared. Local control of choroidal melanomas after 125I and 106Ru plaques implantation and vision changes are the main outcome measures. Results A total of 35 patients were identified (125I = 15, 106Ru = 20). No significant difference between two groups in visual acuity, diameter and thickness changes were observed after treatment. Multivariate linear regression (MLR) analysis showed that final diameter was only, independently and significantly, correlated with the pre-treatment diameter of the tumor (β = 0.59, 95% confidence interval [CI]: 0.29, 1.34, P = 0.003). The same MLR analysis for the final thickness and visual acuity, after adjusting for age and sex showed no significant difference between two groups. A single patient treated with 106Ru had local tumor recurrence with no one in the 125I group. No statistical difference in the rate of ocular complications was observed. Conclusion The treatment with our 125I plaques is as effective as 106Ru plaques in controlling choroidal melanoma tumor and preserving the vision during the two and half year of follow-up. The complication rates are alike. It means that the effectiveness of 125I is not only comparable to 106Ru but also superior when the outcome of the interest is the thickness of the tumors.

Management options for locally recurrent sarcoma of the pelvis in patients previously treated with external beam radiation and surgery are limited. Pelvic exenteration is often the only viable but unattractive option. We present a patient with recurrent myxoid round cell liposarcoma of the ischiorectal fossa treated in 2013 with preoperative radiation (50 Gy in 25 fractions) and subsequent wide local resection. Four years later, a follow-up magnetic resonance imaging (MRI) scan demonstrated a 1 x 1 cm T2 hypointense soft tissue pre-sacral nodule consistent with local recurrence (LR). The patient declined posterior pelvic exenteration and was treated with 12 Gy using high dose rate brachytherapy (BT) under MRI-guidance followed by a further external beam radiation to a dose of 30 Gy in 15 fractions.

For volumes up to 2 cm3 of the bladder and possibly up to 5 cm3 of the rectum, doses computed from the whole organ were good estimates of the doses in the wall in cervix brachytherapy, and there were no significant differences between patients treated with or without interstitial needles.

PURPOSE: MR-guided brachytherapy (MRgBT) with interstitial needles is associated with improved outcomes in cervical cancer patients. However, there are implementation barriers, including magnetic resonance (MR) access, practitioner familiarity/comfort, and efficiency. This study explores a graded MRgBT implementation strategy that included the adaptive use of needles, strategic use of MR imaging/planning, and team learning.METHODS AND MATERIALS: Twenty patients with cervical cancer were treated with high-dose-rate MRgBT (28 Gy in four fractions, two insertions, daily MR imaging/planning). A tandem/ring applicator alone was used for the first insertion in most patients. Needles were added for the second insertion based on evaluation of the initial dosimetry. An interdisciplinary expert team reviewed and discussed the MR images and treatment plans.RESULTS: Dosimetry-trigger technique adaptation with the addition of needles for the second insertion improved target coverage in all patients with suboptimal dosimetry initially without compromising organ-at-risk (OAR) sparing. Target and OAR planning objectives were achieved in most patients. There were small or no systematic differences in tumor or OAR dosimetry between imaging/planning once per insertion vs. daily and only small random variations. Peer review and discussion of images, contours, and plans promoted learning and process development.CONCLUSIONS: Technique adaptation based on the initial dosimetry is an efficient approach to implementing MRgBT while gaining comfort with the use of needles. MR imaging and planning once per insertion is safe in most patients as long as applicator shifts, and large anatomical changes are excluded. Team learning is essential to building individual and programmatic competencies.

Aims To compare the treatment efficacy and radiation complications between 125 Iodine brachytherapy and stereotactic radiotherapy in the management of juxtapapillary choroidal melanoma. Methods Consecutive juxtapapillary melanoma patients treated with radiotherapy were included. Patients were divided into two cohorts: patients treated with 125 Iodine brachytherapy and patients with stereotactic radiotherapy. Comparison included the rates postradiotherapy local recurrence, secondary enucleation, metastasis and radiotherapy complications. Kaplan–Meier estimates were used to determine the actuarial rates, and logrank test to compare between the estimates. Results We included 94 patients with juxtapapillary melanoma treated with radiotherapy. The brachytherapy cohort included 30 patients and stereotactic radiotherapy was 64. The median follow-up was 46 months in both cohorts. No statistically significant differences existed between the two cohorts on comparing pretreatment clinical data and tumour characteristics. On comparing treatment efficacy, the actuarial rates at 50 months for tumour recurrence were 11% and 7% (p=0.61), secondary enucleation was 11% and 21% (p=0.30) and for metastasis were 4% and 16% (p=0.11), respectively. On comparing treatment complications, the actuarial rates at 50 months for cataracts were 62% and 75% (p=0.1), for neovascular glaucoma 8% and 47% (p=0.002), for radiation retinopathy 59% and 89% (p=0.0001), and for radiation papillopathy 39% and 74% (p=0.003), respectively. Conclusions Both 125 Iodine brachytherapy and stereotactic radiotherapy demonstrate comparable efficacy in the management of juxtapapillary choroidal melanoma. However, stereotactic radiotherapy shows statistically significant higher radiation-induced ocular morbidities at 4 years postradiotherapy.

Background and purpose We examined the utility of dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted MRI (DWI), and FDG-PET imaging for brachytherapy target delineation in patients with locally advanced cervical cancer. Materials and methods Twenty-two patients had DWI, DCE-MRI, and FDG-PET/CT scans after brachytherapy applicator insertion, in addition to standard T2-weighted (T2w) 3T MRI. Gross tumor volume (GTV B ) and high-risk clinical target volume (HRCTV) were contoured first on T2w images, and then modified if indicated upon review of DWI/DCE-MRI/FDG-PET images by two observers. The primary endpoint was utility, determined by the number of patients whose volumes were modified, and interobserver variability. Results Eleven patients' T2w-GTV B were modified based on DWI/DCE-MRI/FDG-PET by observer 1, due to clearer demarcation (7) and residual disease not well visualized on T2w MRI (4). GTV B was modified in 17 patients by observer 2 (11 and 6, respectively). Incorporation of functional imaging improved the conformity index (CI) for GTV B from 0.54 (T2w alone) to 0.65 ( P =0.003). HRCTV was modified in 3 and 8 patients by observers 1 and 2, respectively, with a trend toward higher CI using functional imaging (0.71 to 0.76, P =0.06). Conclusions DWI/DCE-MRI/FDG-PET imaging as a supplement to T2w MRI decreased interobserver variability in GTV B delineation.

Purpose Perform a comprehensive dosimetric investigation of photon- and beta-emitting esophageal stents for the treatment of advanced esophageal cancer. Methods Using Geant4 toolkit, esophageal stents carrying 125I, 103Pd and 131Cs brachytherapy seeds as well as esophageal stents coated with 166Ho and 188Re radioisotopes were simulated and their dose distributions were investigated. The effects of stent material, the presence of a magnetic field and the arrangement of the seeds on dose distributions were investigated. For validation, radiochromic EBT3 film dosimetry was performed for 125I seed-loaded and 166Ho impregnated esophageal stents. Furthermore, the accumulated dose of each radioactive stent (at the dose reference points), was calculated for different activities. Results Peak to valley dose (PVD) ratio is defined as a measure of dose uniformity for esophageal stents loaded with brachytherapy seeds to show the difference of dose intensity between the location of the presence of a radioactive seed and the adjacent vacant place. Due to the short penetration depth of beta particles in tissue, only palliative treatment is expected for beta-emitting esophageal stents. 103Pd and 131Cs seed-loaded stents cannot deliver the sufficient dose at the reference point, due to their short half-lives. It is shown that the edge restenosis in beta-emitting esophageal stents is more probable than in photon-emitters due to their rapid dose falloff on the stent edges. The presence of a magnetic field (>1.5 Tesla) along the stent axis, has a significant effect on dose distributions of beta-emitting stents. Conclusions The interval distance between two adjacent seeds (center to center) should not exceed 15 mm, due to the presence of cold spots in the spaces between seeds that are the locations of the tumor recurrence and it is more critical for 103Pd seeds. Since the radioactive esophageal stents are permanent implants, 125I with 28.4 keV mean energy and 59.4 days half-life is the best choice among the low energy brachytherapy seeds.

A quality assurance system has been designed to verify the location and strength of seeds loaded in a brachytherapy eye plaque. This system consists of (1) a pinhole camera in conjunction with a Lumisys ACR-2000i computed radiography (CR) unit to image the location and measure the relative strength of the seeds with autoradiography, and (2) a source strength jig with a survey meter to estimate the total activity of the seeds in the plaque. Five holders of different sizes were made for fixation of the COMS (Collaborative Ocular Melanoma Study) plaques (12, 14, 16, 18, and 20 mm) in the camera. The plaque-to-pinhole distance (dpp) has been optimized to be 30 mm to give approximately uniform intensity on the CR image for uniformly loaded COMS plaques. The pinhole-to-detector distance (dpd) can be kept at either 30 mm for 1:1 scale, or at larger distances for higher magnification. For a 1:1 scaling and pinhole diameter of 0.345 mm, useful images are obtained with time-activity product (mCi sec) ranging from 5 to 250 mCi sec. Within this range, the pinhole system is able to differentiate seed activities of >10%. The resulting pinhole autoradiograph is able to (1) confirm the correct number of seeds loaded in the plaque, (2) verify the proper sitting of the seeds in the silastic carrier and the plaque, (3) verify the relative activity distribution of the seeds loaded in the plaque, and (4) potentially evaluate the integrity of the seed. The source strength measurement system is able to measure the total strength of seeds in the plaque ranging from 10 to 80 mCi with an uncertainty of 5%.

Purpose The dose delivered to the most exposed 2 cm3 ( D 2 cm 3 ) of the rectum and bladder is predictive of late rectal and bladder toxicity in cervix cancer patients. We investigated the predictive value of intermediate doses to the rectum and bladder for late rectal/bladder toxicity after MRI-guided brachytherapy for patients with locally advanced cervix cancer. Methods and Materials Toxicity was prospectively graded using Common Toxicity Criteria for Adverse Events v4.0 and retrospectively verified for women with Stage IB–IVA cervix cancer treated consecutively with MRI-guided brachytherapy between 2008 and 2013. The minimum equivalent dose in 2 Gy fractions delivered to 0.1, 1, 2, 5, and 10 cm3 of the rectum and bladder and the absolute volume of the rectum receiving 55, 60, 65, 70, and 75 Gy3 (V55–75) were collected. The association between dose–volume parameters and Grade 2+ rectal/bladder toxicity was examined using logistic regression. Results With a median followup of 44 months, cumulative incidences of Grade 2+ rectal and bladder toxicity among the 106 patients were 29% and 15% at 3 years, respectively. All the dose–volume parameters were significantly associated with late Grade 2+ rectal and bladder toxicity (p D 0 . 1 cm 3 . On multivariable logistic regression, both D 2 cm 3 > 70 Gy3 and V55 > 11 cm3 (p D 2 cm 3 > 70 Gy3 alone. Conclusions In this study, V55 was predictive of late Grade 2+ rectal toxicity. Adding V55 to D 2 cm 3 improved prediction accuracy.

Purpose To present the American Brachytherapy Society (ABS) guidelines for plaque brachytherapy of choroidal melanoma and retinoblastoma. Methods and Materials An international multicenter Ophthalmic Oncology Task Force (OOTF) was assembled to include 47 radiation oncologists, medical physicists, and ophthalmic oncologists from 10 countries. The ABS-OOTF produced collaborative guidelines, based on their eye cancer–specific clinical experience and knowledge of the literature. This work was reviewed and approved by the ABS Board of Directors as well as within the journal's peer-reivew process. Results The ABS-OOTF reached consensus that ophthalmic plaque radiation therapy is best performed in subspecialty brachytherapy centers. Quality assurance, methods of plaque construction, and dosimetry should be consistent with the 2012 joint guidelines of the American Association of Physicists in Medicine and ABS. Implantation of plaque sources should be performed by subspecialty-trained surgeons. Although there exist select restrictions related to tumor size and location, the ABS-OOTF agreed that most melanomas of the iris, ciliary body, and choroid could be treated with plaque brachytherapy. The ABS-OOTF reached consensus that tumors with gross orbital extension and blind painful eyes and those with no light perception vision are unsuitable for brachytherapy. In contrast, only select retinoblastomas are eligible for plaque brachytherapy. Prescription doses, dose rates, treatment durations, and clinical methods are described. Conclusions Plaque brachytherapy is an effective eye and vision-sparing method to treat patients with intraocular tumors. Practitioners are encouraged to use ABS-OOTF guidelines to enhance their practice.

To compare the dose distributions and late radiation toxicities for (125)I brachytherapy (IBT) and stereotactic radiation therapy (SRT) in the treatment of juxtapapillary choroidal melanoma.Ninety-four consecutive patients with juxtapapillary melanoma were reviewed: 30 have been treated with IBT and 64 with SRT. Iodine-125 brachytherapy cases were modeled with plaque simulator software for dosimetric analysis. The SRT dosimetric data were obtained from the Radionics XKnife RT3 software. Mean doses at predetermined intraocular points were calculated. Kaplan-Meier estimates determined the actuarial rates of late toxicities, and the log-rank test compared the estimates.The median follow-up was 46 months in both cohorts. The 2 cohorts were balanced with respect to pretreatment clinical and tumor characteristics. Comparisons of radiation toxicity rates between the IBT and SRT cohorts yielded actuarial rates at 50 months for cataracts of 62% and 75% (P=.1), for neovascular glaucoma 8% and 47% (P=.002), for radiation retinopathy 59% and 89% (P=.0001), and for radiation papillopathy 39% and 74% (P=.003), respectively. Dosimetric comparisons between the IBT and SRT cohorts yielded mean doses of 12.8 and 14.1 Gy (P=.56) for the lens center, 17.6 and 19.7 Gy (P=.44) for the lens posterior pole, 13.9 and 10.8 Gy (P=.30) for the ciliary body, 61.9 and 69.7 Gy (P=.03) for optic disc center, and 48.9 and 60.1 Gy (P.0001) for retina at 5-mm distance from tumor margin, respectively.Late radiation-induced toxicities were greater with SRT, which is secondary to the high-dose exposure inherent to the technique as compared with IBT. When technically feasible, IBT is preferred to treat juxtapapillary choroidal melanoma.

A quality assurance system has been designed to verify the location and strength of seeds loaded in a brachytherapy eye plaque. This system consists of (1) a pinhole camera in conjunction with a Lumisys ACR-2000i computed radiography (CR) unit to image the location and measure the relative strength of the seeds with autoradiography, and (2) a source strength jig with a survey meter to estimate the total activity of the seeds in the plaque. Five holders of different sizes were made for fixation of the COMS (Collaborative Ocular Melanoma Study) plaques (12, 14, 16, 18, and 20 mm) in the camera. The plaque-to-pinhole distance (dpp) has been optimized to be 30 mm to give approximately uniform intensity on the CR image for uniformly loaded COMS plaques. The pinhole-to-detector distance (dpd) can be kept at either 30 mm for 1:1 scale, or at larger distances for higher magnification. For a 1:1 scaling and pinhole diameter of 0.345 mm, useful images are obtained with time-activity product (mCi sec) ranging from 5 to 250 mCi sec. Within this range, the pinhole system is able to differentiate seed activities of10%. The resulting pinhole autoradiograph is able to (1) confirm the correct number of seeds loaded in the plaque, (2) verify the proper sitting of the seeds in the silastic carrier and the plaque, (3) verify the relative activity distribution of the seeds loaded in the plaque, and (4) potentially evaluate the integrity of the seed. The source strength measurement system is able to measure the total strength of seeds in the plaque ranging from 10 to 80 mCi with an uncertainty of 5%.

Recently the EDR2 (extended dose range) film has been introduced commercially for applications in radiation therapy dosimetry. In addition to characterizing the wide dynamic range, several authors have reported a reduced energy dependence of this film compared to that of X-Omatic Verification (XV) films for megavoltage photon beams. However, those investigations were performed under limited geometrical conditions. We have investigated the dosimetric performance of EDR2 film for the verification of IMRT fields at more clinically relevant conditions by comparing the film doses with the doses measured with an ion chamber and XV films. The effects of using a low energy scattered photon filter on EDR2 film dosimetry was also studied. In contrast to previous reports our results show that EDR2 film still exhibits considerable energy dependence (a maximum discrepancy of 9%, compared with an ion chamber) at clinically relevant conditions (10 cm depth for IMRT fields). However, by using the low-energy filters the discrepancy is reduced to within 3%. Therefore, EDR2 film, in combination with the filters, is found to be a promising two-dimensional dosimeter for verification of IMRT treatment fields.

leads to more conservative treatments. For pelvic tumors, measurement of the rectal wall dose will facilitate optimal treatment delivery. We report on the clinical performance of a fibre optic dosimetry (FOD ) system customized to measure the dose in real time in an array configuration. This system enables definitive assessment of the dose delivered, with the potential for intervention if required. Materials and Methods: An array of FODs in an insertable applicator has been designed and built. The clinician can select to position all the dosimeters along the anterior wall of the rectum or in any other arrangement. Dosimeters were optically interfaced to a light detection system, located outside the treatment bunker. Customized software recorded the dose from each dosimeter as the real time dose rate and as the accumulated dose at that point. Prior to use the dosimeters were simultaneously calibrated in a purpose built jig. Results: The performance of the array was demonstrated first by simulating brachytherapy treatments in a water phantom. Preliminary clinical trial with gynecological patients established that rectal wall dose mapping was convenient and accurate. In Figure 1 the radioopaque markers on the end of the rectal applicator are visible.

Purpose/Objective(s): The purpose of this study is to retrospectively evaluate the dosimetric coverage of I‐125 plaque brachytherapy (IBT) in treating Juxtapapillary Choroidal Melanoma (JCM) using the Plaque Simulator treatment planning system. Materials and Methods: Thirty cases of JCM patients with a medium‐sized tumor were treated by COMS IBT loaded non‐uniformly but with circular symmetry from 1997–2005. Median follow‐up was 48 months. The tumor was 0.75–2.5 mm from the optic disc. The median tumor thickness was 4.3 mm and the median longest tumor diameter was 9.9 mm. An in‐house treatment planning system had been used for actual treatments. The proximity of the tumor to the optic nerve did not allow the plaque to be centered over the tumor, so the tumor edge closest to the optic nerve did not receive the dose specified in the COMS study. We used the Plaque Simulator treatment planning system (BEBIG, Germany) for replanning and assessing dose coverage of the tumor for these patients. Results When all corrections for dose calculation in the Plaque Simulator were taken into account, mean dose to tumor edge nearest the optic nerve were significantly lower than COMS recommendations (62Gy vs. 69Gy, p

Purpose: To investigate application of 3D gel dosimetry in verification of intensity modulated stereotactic radiotherapy (IMSRT) of intracranial lesions. Method and Materials: Radionics treatment planning (XK-RT3) and delivery systems, including a Mini Multileaf Collimator (MMLC) were used in this study. A PVC Head phantom filled with MAGAT polymer gel (Normoxic MAGIC gel with THP as anti oxidant) attached to the GTC frame and stereotactic localizer. The phantom was CT and MR scanned using stereotactic protocols and image fusion was performed for the localization. A four field non-coplanar IMSRT plan was generated using a 6 MV beam with the Radionics planning system and delivered according to our routine stereotactic treatment procedures. For comparison with the planned isodose distribution, the R2 maps were converted to relative dose maps using an R2-dose calibration curve. The polymer dose maps were then co-registered with the planning dose distributions in an in-house Matlab program which provides reconstructed sagittal and coronal images for 3D evaluation of measured and planned dose. Various isodose levels in the 3D dose map have been compared between the treatment plan calculations and gel measurement. Results: Results of this study have shown good agreement between the gel dosimetry and treatment planning calculation. The 2D and 3D agreement was overall better than 5% in dose or to within 3 mm distance for the 80% and 95% isodose levels. The maximum difference for these isodose levels was 10%. Conclusion: In this work we have demonstrated that the Polymer gel dosimetry have the ability to accurately localize the high dose regions delivered by intensity modulated stereotactic radiotherapy.

Purpose/Objective(s): To compare dosimetric parameters of linac‐based stereotactic radiotherapy (LB‐SRT), to Gamma Knife Perfexion (GK‐SRT) and 125 Iodine Brachytherapy (IBT) in treating Juxtapapillary Choroidal Melanoma (JCM). Materials/Methods: Three JCM cases of small, medium and large size tumours, based on the COMS definition, which previously received LB‐SRT using our current protocol of 70 Gy in 5 fractions over 10 days, were selected and re‐planned on GK‐SRT and IBT. Dosimetric parameters chosen for comparison were tumourdose coverage, including maximum, minimum and mean doses, as well as dose to tumour base and apex. Dose to organs at risk, such as optic disc, lens and D70 of the involved eye were also compared. All doses were normalized such that 99% of the tutors received at least a dose of 70 Gy. Tumourcontrol and treatment complications, such as radiation retinopathy, optic neuropathy and neovascular glaucoma, have been reported that can be directly related to the above dosimetric parameters. Results: Overall tumour mean doses by LB‐SRT, GK‐SRT and IBT were 73.11, 98.86 and 117.72 Gy, and maximum doses 74.33, 137.12 and 229.05 Gy, respectively. Corresponding overall doses to the lens center were 2.24, 8.75 and 12.49 Gy, and D70 of the eye were 17.91, 10.01 and 13.55 Gy, respectively. Conclusion: In this study we have shown that LB‐SRT, GK‐SRT and IBT provide comparable treatment for Choroidal Melanoma. Linac‐based SRT delivers most uniform dose to the tumour and smaller dose to the lens and anterior chamber, however has a higher D70, compared to the other two.