Experimental Study of Using a 3-D Position Sensitive CdZnTe Detector for
Proton Beam Range Verification
Abstract
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.
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