Multichannel Miniature Semiconductor Detector System with On-Line Computer Analysis for Measurement of Miniregional Cerebral Blood Flow

Abstract

This paper outlines our experience over the past decade, with a multichannel miniature semiconductor detector system for measurement of miniregional cerebral blood flow. 8 channels of a lithium drifted silicon detector system with on-line computer analysis are satisfactorily operating in monitoring quantitative regional cerebral blood flow on multisites of the brain in vivo in humans as well as animals. More recently, our experience with a highly gamma sensitive Cadmium Telluride detector (CdTe) was disappointing. For 133Xe clearance studies, the CdTe detector gave a 5 times higher counting efficiency than the Si(Li) detector. However, blood flow values obtained by Stochastic analysis from the CdTe detector are 25 to 40% less than the values obtained from the Si(Li) detector. This problem appears to be mainly due to a trapping phenomenon occurring in the CdTe detector which gives a non-linear response between radioactivity and count rate, and over exceeds random fluctuation of count rate. These genetic and temperamental features of the CdTe detector make it unsuitable for use in measurement of cerebral blood flow at the present time. Our clinical and laboratory experience with miniature semiconductor systems will be reviewed.