In-vivo measurement of low energy photon emitters: room-temperature semiconductor diodes vs. large scintillators and germanium crystals.

Abstract

The in-vivo monitoring of low energy x- and gamma-ray emitters gained importance with the increasing use of these radionuclides in nuclear medicine and nuclear energy production. The main problems encountered are the lack of accuracy in the measurement and the high detection limits obtained with the classical techniques [proportional counters, thin NaI(TI) or phoswich scintillators]. The best technique available today is the array of planar germanium detectors. The purpose of this paper is to analyze specific problems in the assessment of low energy photon emitters in the body and to describe applications of room-temperature diodes (silicon and CdZnTe) using a new technique involving a portable jacket. In certain cases, the device can be used outside a shielded room, making possible an immediate long counting, reducing the psychological stress, and optimizing the medical treatment and the intervention. By considering the attenuation effect, this work shows that an optimized volume of the diodes reduces the detection limits of the counting. The developed methodology offers new possibilities in the assessment of radioactive deposition in the body and in the long term follow-up of the metabolism of radionuclides in small quantities.