Dosimetry of small radiation field in inhomogeneous medium using alanine/EPR minidosimeters and PENELOPE Monte Carlo simulation

Alanine/K-Band EPR minidosimeters (miniALAs) were tested in the dosimetry of inhomogeneous medium through the determination of percentage depth dose curves (PDD) for small radiation fields. Field sizes of 3 × 3, 2 × 2, 1 × 1 and 0.5 × 0.5 cm² were used at 100 cm source-surface distance. The minidosimeters were placed inside an inhomogeneous cylindrical phantom consisting of several slices of cortical bone equivalent material positioned between slices of soft tissue-equivalent material. The phantom with the minidosimeters was irradiated in a 6 MV Primus Siemens linear accelerator. EDR-2 Kodak radiographic film was used for comparison purposes. The PDD curves were also obtained with PENELOPE Monte Carlo code for the same field sizes and irradiation and geometry conditions. The results show a suitable response from the miniALA dosimeters and a better match between miniALAs and MC simulation than with film in both interfaces.