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Evaluation of a multistage CdZnTe Compton camera for prompt γ imaging for proton therapy

2015; Elsevier BV; Volume: 785; Linguagem: Inglês

10.1016/j.nima.2015.02.030

1872-9576

M. McCleskey, Willy Kaye, Dennis Mackin, Sam Beddar, Z. Y. He, J Polf,

Nuclear Physics and Applications

A new detector system, Polaris J from H3D, has been evaluated for its potential application as a Compton camera (CC) imaging device for prompt γ rays (PGs) emitted during proton radiation therapy (RT) for the purpose of dose range verification. This detector system consists of four independent CdZnTe detector stages and a coincidence module, allowing the user to construct a Compton camera in different geometrical configurations and to accept both double and triple scatter events. Energy resolution for the 662 keV line from 137Cs was found to be 9.7 keV FWHM. The raw absolute efficiencies for double and triple scatter events were 2.2×10−5 and 5.8×10−7, respectively, for γs from a 60Co source. The position resolution for the reconstruction of a point source from the measured CC data was about 2 mm. Overall, due to the low efficiency of the Polaris J CC, the current system was deemed not viable for imaging PGs emitted during proton RT treatment delivery. However, using a validated Monte Carlo model of the CC, we found that by increasing the size of the detectors and placing them in a two stage configuration, the efficiency could be increased to a level to make PG imaging possible during proton RT.