A new concept in detector design for radiation therapy: simultaneous imaging and dosimetry for comprehensive treatment verification

Radiation therapy treatment verification is currently limited to image-guided radiotherapy to verify patient and target location. There is no widely available method for direct verification of the delivered dose. Imaging has been widely implemented with amorphous silicon (a-Si) flat panel imagers. a- Si imagers can also be used to verify dose delivered to the patient, but current detector designs are problematic for dosimetry. Our group is investigating new detector designs optimized for simultaneous imaging and dosimetry. Detector specifications for megavoltage radiographic imaging and radiation dosimetry are in some respects contradictory to each other, presenting a significant technical challenge for detector design. The first generation of our prototype detectors consist of plastic scintillator fiber arrays interfaced directly onto a-Si imagers. Experimental and modeling studies are being conducted to optimize this design and determine the feasibility. Results to-date demonstrate excellent dosimetry and promising imaging performance, with significant potential for improvement. Ongoing detector developments are focused on improving detective quantum efficiency for imaging performance. We have demonstrated the feasibility of the plastic scintillator based detector and continue to optimize the design to develop a detector for comprehensive radiation therapy treatment verification.