Hybrid Multipixel Array X-Ray Detectors for Real-Time Direct Detection of Hard X-Rays

X-ray detectors currently employed in dosimetry suffer from a number of drawbacks including the inability to conform to curved surfaces and being limited to smaller dimensions due to available crystal sizes. In this study, a hybrid X-ray detector (HXD) has been developed which offers real-time response with added advantages of being highly sensitive over a broad energy range, mechanically flexible, relatively inexpensive, and able to be fabricated over large areas on the desired surface. The detector comprises an organic matrix embedded with high-atomic-number inorganic nanoparticles which increase the radiation attenuation and within the device allows for simultaneous transfer of electrons and holes. The HXD delivers a peak response of 14 nA cm^-2, which corresponds to a sensitivity of 30.8 μC Gy^-1 cm^-2, under the exposure of 6-MV hard X-rays generated by a medical linear accelerator. The angular dependence of the HXD has been studied, which offers a maximum variation of 26% in the posterior versus lateral beam directions. The flexible HXD can be conformed to the human body shape and is expected to eliminate variations due to source-to-skin distance with reduced physical evaluation complexities.

I. Introduction

Detection of ionizing radiation is a priority in radiation protection, radiotherapy quality assurance (QA), and in medical applications involving imaging and determination of dose distributions for radiotherapy. The latter case is widely used in radiation oncology, which mainly uses linear particle accelerators (LINAC) to provide precision targeting of a tumor from a beam of X-rays. During the past 60 years, medical LINACs have evolved through many generations, where today, high-precision radiotherapy technologies have increased with the emergence of volumetric-modulated radiation therapy (VMAT) and stereotactic body radiation therapy (SBRT) [1]. Individual treatment verification is gaining attention in such high-precision radiotherapy, where accurate dose delivery to a patient is essential.