PURPOSE: The contrast provided by conventional portal imagers is constrained by inefficient conversion of the incident radiation, and by the small diagnostic x-ray component of the treatment beam. Toward improved visualization of the @entity5 region prior to treatment, as well as improved @entity5 tracking during treatment, progress is reported on the design of a pair of novel detectors that would address these constraints. METHODS: A dual-energy imager based on a segmented scintillator is being designed using a hybrid model to simulate radiation and optical transport. The simulations, which model operation with a megavoltage treatment beam and with a @entity1493 imaging beam with a significant diagnostic component, employ parameters extracted from a previously developed prototype. Separately, the conceptual design of a second imager incorporating a 2D array of photon counting pixels is being explored through extrapolation of the design of the first prototype photon counting arrays fabricated using thin-film processing, a process scalable to very large area detectors. RESULTS: The simulations identified a segmented scintillator imager design that, when operated with a @entity1493 imaging beam, provides spatial resolution and contrast comparable to that of gantry-mounted kV imagers. When operated with a treatment beam, the design provides significantly improved DQE and contrast compared to conventional portal imagers. Extrapolation of initial photon counting array designs indicates that the circuitry necessary to provide energy-windowing of the diagnostic portion of a therapy beam can be achieved at the pixel pitch associated with current treatment room imagers. CONCLUSION: These early studies demonstrate potential for improved contrast in projection and volumetric images obtained with the megavoltage beam prior to treatment, while also providing good performance when used with @entity1493 imaging beams. In addition, these studies also support the possibility of improved capability for @entity5 tracking with such dual-energy imagers as well as by photon counting array imagers. NIH grant R01-EB000558.

TH-EF-BRB-03: Enhancement of Image Contrast Along the Beam's-Eye-View ( XXXX ) Direction Through Development of Imagers Based On Segmented Scintillators and Photon-Counting Arrays.

@entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity1493 :: ('12064', 'Species') :: ['BEV']
@entity1493 :: (12064,Species) :: ['BEV']
