Needle type solid state detectors for in vivo measurement of tracer activity

Abstract

The construction and properties of a set of miniature detector probes for in vivo measurement of beta - and gamma -tracer activity are described. The probes use a lithium-compensated p-i-n silicon detector as sensing element. The basic needle probe contains a cylindrical detector 0.9 mm in diameter and 3 mm long, enclosed in a stainless steel tube 1.1 mm in outer diameter and with walls 0.05 mm thick. For particular applications several modified types have been developed: probes with larger sensing elements, probes with extra thin walls for low-energy beta -detection, probes with two or three sensing elements in the same needle and probes containing a movable sensing element.