Feasibility study of a 2D Amorphous Silicon-based Detector for Proton Therapy

New particle therapy modalities, including ultra-high dose rate (UHDR) proton therapy, present various challenges for particle detectors used in patient-specific quality assurance (PSQA). Amorphous Silicon (a-Si) Flat Panel (FP) detectors are a powerful tool used to create a 2D image of an administered dose map. They are known for high radiation hardness and image resolution. To investigate and characterize the behavior of a-Si pixels under particle therapy irradiation, specifically proton irradiation, a 2.4 x 2.4 mm pixel array of a-Si pixels, photodiodes coupled with thin-film-transistors (TFTs), was acquired and tested. Before irradiation, electronic probing was performed to generate the I-V curves and to qualify the stability of the pixel current for different bias and gate voltages to understand the proper voltage regime for optimal pixel functionality. In addition, proton irradiation was performed using pencil beam scanning (PBS) in a medical facility for charge linearity verification through direct detection. The test was done in conjunction with an IBA RazorTM Detector to compare each detector’s performance. Finally, irradiation with a high-power green laser was performed to examine the performance of the individual components of the pixels under high-intensity irradiation.