Fixed and Adaptive Multiple-Pinhole Apertures for Brain SPECT Imaging

Abstract

Single-Photon Emission Computed Tomography (SPECT) is a medical imaging modality where a radiopharmaceutical's emissions are captured with one or more gamma cameras deployed about the patient. During tomographic acquisitions, the SPECT camera(s) collect gamma-ray projection images created by physical collimation methods at a sufficient number of angles that the data can be reconstructed into a 3-dimensional representation of the radio-tracer distributions within the patient. In addition to existing applications in cancer and heart disease, SPECT offers promise as a tool for studies of neurodegenerative disorders where detection and quantification of neuronal receptors and protein deposits can be used for drug development and/or screening for early signs of disease. Virtually all gamma cameras currently in use in nuclear medicine clinics are so-called Anger cameras that use parallel-hole collimators for image formation. In this work we are investigating novel collimator designs for brain SPECT imaging designed to support early detection of biomarkers indicating neurodegenerative disease as well as research related to drug discovery. This dissertation focuses on the design and implementation of novel multiple-pinhole aperture systems with both fixed arrangements of "always open" pinholes as well as adaptive ones where pinhole diameters and "open" pattern are adjustable. The fixed multi-pinhole aperture was developed to mount to an existing clinical two-headed SPECT system, the Philips Brightview, such that one camera collects images with conventional collimation while the second uses our custom design. The adaptive multi-pinhole aperture was developed for a novel stationary brain imager called AdaptiSPECT-C. We describe the design and implementation of the hardware and electronics that create a computer-controlled pinhole-aperture system that allows for many different choices of resolution and sensitivity to employed during AdaptiSPECT-C imaging studies.