High‐dose‐rate (HDR) brachytherapy is a popular modality for treating cancers of the prostate, cervix, endometrium, breast, skin, bronchus, esophagus, and head and neck as well as soft‐tissue sarcomas. Because of different source designs and licensing issues, there is a need for specific dosimetry dataset for each HDR source model. The main objective of the present work is to measure 2D relative dose distribution around a new prototype  192Ir source, referred to as IRAsource‐HDR, in PMMA phantom in the framework of AAPM TG‐43 and TG‐55 recommendations for radial distances of 0.5 cm to 4 cm. Radiochromic films (RCFs) Gafchromic EBT and HD‐810 were used for measurements. The dose rate constant, Λ, of the source was determined to be 1.084±4.6%,1.129±4.4%, and 1.112±0.8% cGyh−1normalU−1 using EBTRCF, HD‐810 RCF, and Monte Carlo (MC) simulation, respectively. The results obtained in this study are in good agreement with previously published data for HDR interstitial  192Ir‐HDR sources with a maximum discrepancy of ±4.5%. An acceptable agreement (within ±2%) between MC calculations and RCFs measurements showed that HD‐810 RCF dosimetry is as good as EBTRCF, within HDR brachytherapy, and justifies the use of specific data for this new source. These data could be used as a benchmark for dose calculations in the conventional brachytherapy treatment planning systems.PACS number(s): 87.56.bg

Background: To compare iodine-125 ( 125 I) with ruthenium-106 ( 106 Ru) 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 ( 125 I) compared with ruthenium-106 ( 106 Ru) episcleral plaque radiation. Patients and Methods: A retrospective, non-randomized comparative case series. In this series the patients treated with 125 I and 106 Ru episcleral plaques for choroidal melanoma between September 2013 and August 2017 at Farabi Hospital are compared. Local control of choroidal melanomas after 125 I and 106 Ru plaques implantation and vision changes are the main outcome measures. Results: A total of 35 patients were identified ( 125 I = 15, 106 Ru = 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 106 Ru had local tumor recurrence with no one in the 125 I group. No statistical difference in the rate of ocular complications was observed. Conclusion: The treatment with our 125 I plaques is as effective as 106 Ru 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 125 I is not only comparable to 106 Ru but also superior when the outcome of the interest is the thickness of the tumors.

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