Optimizing Si detectors and ASIC readouts for high resolution energy resolved x-ray imaging

Abstract

Developments in room temperature solid state imaging arrays for energy-resolved single photon counting in medical x-ray imaging are discussed. A number of x-ray imaging applications can benefit from these developments including mammography which requires very good spatial resolution. Energy resolved photon counting can provide reduced dose through optimal energy weighting and compositional analysis through multiple basis function material decomposition. Extremely high flux can occur in x-ray imaging and energy integrating detectors with a large dynamic range and good detection efficiency have been conventionally used. To achieve the benefits of energy resolved photon counting, imaging arrays with a large count rate range and good detection efficiency are required. Si based semiconductor radiation detectors with strip anode arrays electrically connected to application specific integrated circuits (ASICs) can provide fast, efficient, low-noise performance with good energy and spatial resolution for use in mammography however this can only be achieved with a careful optimization of the Si sensors and ASICs together. We have designed and constructed a Si imaging array, with a 1 x 1024 grid of electrical 100 micron wide strip contacts inter connected to multi channel ASICs, with a counting range up to 1 x 10 6 counts per second per pixel.