Electroluminescence Absorption Detector Compton Camera

DESCRIPTION (provided by applicant): The goal of this project is the proof of feasibility of a novel imaging gamma spectrometer working as an absorption detector of Compton camera for prostate radioisotope imaging. The Compton camera consists of a scatter detector (SD) and absorption detector (AD) in coincidence detecting pairs of gamma ray interactions: Compton scatter in SD followed by photoabsorption in AD. Compton imaging does not require a collimator that may lead to significant gain in sensitivity against conventional SPECT systems. The proposed detector, called a multi-layer electroluminescent camera (MELC), contains a stacked electrode structure immersed in pressurized xenon. The detector employs the effect of xenon electroluminescence to amplify ionization signals in an optical channel. Fiber optics is used for digital readout of information about the energy of absorbed gamma quantum and localization of the absorption point in three-dimensional space. Preliminary computer simulations have shown that the MELC allows about 1 mm three-dimensional position resolution with an energy of about 1-2% at 140 keV. The number of readout channels can be about 300 per layer per square meter of field of view, or hundreds of times less than the number of channels for a semiconductor detector array with the same performance. Total detection efficiency depends on the number of layers and the gas pressure, and can be comparable to that of solid-state detectors. The count rate can be up to 10 MHz per layer. This study is focused on the investigation of the feasibility of a single layer of the MELC. After successful development of the Single Layer Electroluminescence Camera (Phase 1), a full-scale absorption detector will be constructed for a compact Compton camera dedicated to early diagnostics of prostate cancer (Phase 2). A silicon probe developed at the University of Michigan will be used as a scatter detector of the Compton camera.