The study of characteristics of flat panel detectors without semiconductor conversion layers for therapeutic high-energy X-ray radiation

Abstract

We evaluated a novel 2-D flat-panel detector (FPD) adapting it for megavoltage (MV) therapeutic imaging and radiation QA. The prototype uses a thick dielectric layer to create a semi-transmissive structure, changing and eliminating structure conventional semiconductor conversion layers. Performance was tested on a Harmony Pro LINAC (Elekta, Sweden) with a 20 x 20 cm(2) field at an SSD of 100 cm. Datasets were acquired at 50-300 MU for 6, 10, and 15 MV beams. Linearity with MU was excellent (R-2 = 0.99). Reproducibility and repeatability showed coefficients of variation of 1-2 %. In energy dependency, the 6/10 MV response ratio remained near 80 %, rising to 84 % at 300 MU, while the 6/15 MV ratio was 70.8 % at 50 MU and stabilized at 75-80 % thereafter, with R-2 > 0.99 for all energies. Spatial resolution satisfied AAPM TG-142 tolerances. The detector demonstrates performance characteristics comparable to those of conventional electronic portal imaging device (EPID), exhibiting robust durability in high-energy irradiation and excellent portability enabled by its compact design.