Initial evaluation of Advanced Collapsed cone Engine dose calculations in water medium for I‐125 seeds and COMS eye plaques

• Published in: Medical physics (Lancaster) 2018-03, Vol.45 (3), p.1276-1286
• Main Authors: Morrison, Hali, Menon, Geetha, Larocque, Matthew P., Veelen, Bob, Niatsetski, Yury, Weis, Ezekiel, Sloboda, Ron S.
• Format: Article
• Language: English
• Subjects: ACE; dosimetry; Eye Neoplasms - radiotherapy; eye plaque brachytherapy; Iodine Radioisotopes - therapeutic use; Melanoma - radiotherapy; model‐based dose calculations; Monte Carlo; Monte Carlo Method; Radiation Dosage; Radiotherapy Dosage; Software; Water
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1002/mp.12776

Purpose To investigate the dose calculation accuracy in water medium of the Advanced Collapsed cone Engine (ACE) for three sizes of COMS eye plaques loaded with low‐energy I‐125 seeds. Methods A model of the Oncura 6711 I‐125 seed was created for use with ACE in Oncentra® Brachy (OcB) using primary‐scatter separated (PSS) point dose kernel and Task Group (TG) 43 datasets. COMS eye plaque models of diameters 12, 16, and 20 mm were introduced into the OcB applicator library based on 3D CAD drawings of the plaques and Silastic inserts. To perform TG‐186 level 1 commissioning, treatment plans were created in OcB for a single source in water and for each COMS plaque in water for two scenarios: with only one centrally loaded seed, or with all seed positions loaded. ACE dose calculations were performed in high accuracy mode with a 0.5 × 0.5 × 0.5 mm3 calculation grid. The resulting dose data were evaluated against Monte Carlo (MC) calculated doses obtained with MCNP6, using both local and global percent differences. Results ACE doses around the source for the single seed in water agreed with MC doses on average within