Selective Photon Counting Technology for Medical Imaging Applications

February 14, 2006
Location: Vancouver Hospital, Div. Nuclear Medicine - Library G607
Presenter: Dr. Karim Karim, Assistant Professor of School of Engineering, SFU

An alternative approach to traditional semiconductor based digital photon integration pixel arrays is photon counting where the value of each image pixel is equal to the number of photons that interact with the detector. In the energy selective photon counting method, the photon-generated charge in the pixel is compared to two pre-determined thresholds used to form the desirable energy window. Note that the lower window threshold voltage is chosen to be greater than the background noise. If the X-ray photon signal falls within the window thresholds, the value of a counter is incremented and the photon is assigned a weight of one (i.e. single photon counter). The advantages of photon counting pixels include better weighting of information from photons of different energies, larger linear dynamic range, and higher noise suppression. In this research, we present a circuit architecture for an energy selective photon counting pixel and discuss its applications to emerging sophisticated diagnostic medical imaging modalities such as mammography tomosynthesis.

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