Generation and comparison of 3D dosimetric reference datasets for COMS eye plaque brachytherapy using model‐based dose calculations

Abstract

PurposeA joint Working Group of the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) was created to aid in the transition from the AAPM TG‐43 dose calculation formalism, the current standard, to model‐based dose calculations. This work establishes the first test cases for low‐energy photon‐emitting brachytherapy using model‐based dose calculation algorithms (MBDCAs).Acquisition and Validation MethodsFive test cases are developed: (1) a single model 6711 125I brachytherapy seed in water, 13 seeds (2) individually and (3) in combination in water, (4) the full Collaborative Ocular Melanoma Study (COMS) 16 mm eye plaque in water, and (5) the full plaque in a realistic eye phantom. Calculations are done with four Monte Carlo (MC) codes and a research version of a commercial treatment planning system (TPS). For all test cases, local agreement of MC codes was within ∼2.5% and global agreement was ∼2% (4% for test case 5). MC agreement was within expected uncertainties. Local agreement of TPS with MC was within 5% for test case 1 and ∼20% for test cases 4 and 5, and global agreement was within 0.4% for test case 1 and 10% for test cases 4 and 5.Data Format and Usage NotesDose distributions for each set of MC and TPS calculations are available online (https://doi.org/10.52519/00005) along with input files and all other information necessary to repeat the calculations.Potential ApplicationsThese data can be used to support commissioning of MBDCAs for low‐energy brachytherapy as recommended by TGs 186 and 221 and AAPM Report 372. This work additionally lays out a sample framework for the development of test cases that can be extended to other applications beyond eye plaque brachytherapy.

Current and Emerging Radiotherapy Options for Uveal Melanoma

“…Historically, the prescription dose evolved from 100 Gy to 85 Gy to the tumor apex, with physical doses to tissue and accounting for realistic plaque materials being an additional 25% lower [ 4 , 27 , 28 ]. Treatments are delivered over 3 to 7 days [ 29 , 30 ].…”