Author: Enzo Charles Aucca, Roger Challco, Andres M. Gonzales Galvez, Carmen SANDRA Guzman Calcina, Jimmy Hernandez-Bello, Modesto Montoya, Renzo Aaron Ocampo, Erick Paniagua, Miguel Alberto Risco-Castillo, Dante E. Roa, Renzo E. Romero, William Souza Santos, Mirko Salomón Alva Sánchez 👨🔬
Affiliation: Graduate Program in Information Technologies and Health Management, University of Porto AlegreFederal University of Health Sciences of Porto Alegre, Universidad Tecnologica del Peru, Pontificia Universidad Catolica del Peru, Electronic Engineering Department, Leonard Cancer Institute - Radiation Oncology, Universidad Nacional de Ingenieria, Universidad Nacional de Ingenieria, Electronic Engineering Department, Federal University of Sergipe, HRS Oncology International, Universidad Nacional Federico Villareal 🌍
Purpose: Provide Monte Carlo (MC) and experimental dosimetric assessments of a 3D cubic electronic detector array based on percent depth doses (PDDs), profiles, linearity, and dose rate response of photon beams from a radiotherapy linac.
Methods: A 30 x 30 x 15 cm3 PMMA 3D cubic electronic detector array prototype of 2645 detector elements distributed in five active matrices (AMs) of 18 x 18 cm2 sensitive area, along with AM connectivity arrangement, was modeled in GEANT-4. Furthermore, a clinical 3D detector array of 50 x 50 x 35 cm3, 20 AMs and 24,000 detector elements with 1,200 detector elements per AM and connectivity, was also modeled in GEANT-4. Experimental: PDD and profile data for 5x5, 10x10, and 20x20 cm2; 10, 20, 40, 50, 80, 100, 200, and 400 MUs linearity data; and 100, 200, 300, 400, and 600 MU/min dose rate data, for a Varian 6 MV photon beam were collected with the prototype and PDDs/profiles compared to MC results. Meanwhile, PDD/profile MC data analysis for 30x30 and 40x40 cm2, were performed for the clinical model for 6 MV and 10 MV Varian photon energies.
Results: Experimental vs MC PDD and profile data differences for all field sizes were within 1.5 % and 3.3 %. Linearity and dose rate response varied from 0.8-3.3 % from a linear reference, and 0.4-3.5 % from 600 MU/min. For the clinical model, differences in PDD/profile MC data for all field sizes were within 6.3 % for 6 MV, and within 4.8 % for 10 MV.
Conclusion: A 3D cubic electronic detector array could provide reliable PDD, profile, linearity, and dose rate data from a radiotherapy photon beam that is comparable to existing devices. It could be a paradigm shift in linac commissioning/QA that offers significant time and financial savings while maintaining accuracy.