The work considers "transverse" and "longitudinal" photoconductivity modes, regarding the direction of radiation, photoconductivity in semiconductor detectors of CdZnTe. Mathematical calculations were made from the representation of the internal area of the detector in the form of radiation absorption sites. The results of the calculations are compared with experimentally measured photocurrent of the detector with a cross section of 2x2 mm CdZnTe from the direction of its radiation by X-ray. From the ratio of photocurrents in the range of X-ray radiation energies 35-72 keV for these two cases, a linear coefficient of X-ray absorption by the CdZnTe detector is determined.
<p><i>Position sensitive CdZnTe Compton imaging cameras are currently being studied for their use of proton beam range verification for radiotherapy applications. This work presents the use of an experimental large volume CdZnTe detector for the detection of prompt gamma rays that are emitted from proton-nuclei interaction within plastic (C2H4) targets. Two experiments were conducted where the incident angle and the dose profile of the beam were varied. The energy spectra from these experiments show that the angle at which the beam enters the target can influence the photopeak to Compton continuum ratios, resulting in more than 18% increase at 718 keV when the beam is parallel to the detector. Images of the 718 keV and 4.44 MeV characteristic prompt gamma ray emission from carbon-proton interactions are reconstructed using list-mode maximum likelihood expectation maximization (MLEM). Images from these prompt gamma emissions line up well with the expected location of the proton beam within the plastic targets.</i><br></p>
This manuscript discusses the use of a large volume array CZT detector for experimental prompt gamma-ray imaging. Namely, the 718 keV and the 4.44 MeV photopeaks produced from proton-carbon interactions are imaged using maximum likelihood expectation maximization (MLEM). Various proton beam irradiations are used to characterize the feasibility of using both photopeaks for beam range verification.