A non-invasive LSO-APD blood radioactivity monitor for PET imaging studies

Abstract

A study has been carried out to investigate the possibility of using a pair of LSO + APD detector arrays to obtain a non-invasive measurement of the arterial input function for use in PET. The main focus of this study was to determine the spatial resolution and sensitivity required to obtain a high quality image that would permit a precise determination of the region of interest around the wrist artery. From these data a quantitative arterial input function that has minimal interference from the tissue and vein background can be obtained. The detector arrays were operated in coincidence counting mode to obtain planar images of various phantoms to demonstrate the feasibility of the concept.

Spatial resolution of a noninvasive measurement of the arterial and venous input function using a wrist monitor

“…Using these wrist phantom dimensions, it can be shown that the two detectors have an azimuthal angle efficiency of 8% and an axial efficiency of 36%. From previous calculations, the system efficiency still contains a 60% stopping power within a 10 mm crystal and an electronic discrimation of 40% resulting in a measured system efficiency of 24% [21]. Therefore, the combined theoretical detector sensitivity was calculated to be: 37 dps/nCi* (0.08*0.36*0.24 2 ) cps/dps = 0.061 cps/nCi.…”

“…Each crystal in the array has the dimensions of 2x2x10 mm. The crystal array is attached directly to an avalanche photodiode (APD) for the conversion of scintillation photons to electronic signals [21]. Pairs of these arrays will be used to count the photons in coincidence over the radial artery of a wrist.…”