Sci‐PM Sat ‐ 02: Development of a novel high quantum efficiency flat panel detector for megavoltage cone beam CT: An experimental study

Abstract

Soft tissue imaging in the treatment room is one of the main challenges faced today in high precision radiotherapy. Megavoltage cone‐beam CT (MVCT) is a promising new imaging technique for image‐guided radiotherapy due to its simplicity and its potentially higher accuracy. However, currently the dose required to achieve sufficient soft tissue contrast to visualize and delineate, e.g., the prostate using MVCT is prohibitively large for daily verification. This is due to the low x‐ray absorption of the electronic portal imaging devices (EPIDs) used, i.e., low quantum efficiency (QE), which is typically on the order of 2–4%. Our overall goal is to develop a new generation of area detectors for MVCT, with a QE an order of magnitude higher than that of current EPIDs and yet an equivalent spatial resolution. With this new generation of detectors, the large dose currently required to visualize and delineate soft‐tissue targets with MVCT will be significantly reduced, and image‐guided radiotherapy using MVCT can be realized. In this work, we constructed a prototype single‐pixel detector based on the novel design introduced recently by Pang and Rowlands. Some fundamental imaging properties including the QE, spatial resolution, and sensitivity of the prototype detector were measured with a 6MV beam. It has been shown that the experimental results agree with our theoretical predictions and further development based on the novel design including the construction of a prototype area detector is warranted. This work was supported by the Department of Defense Prostate Cancer Research Program (DAMD17‐04‐1‐0276).