Scintillation fiber detector for in-vivo endoscopic internal dosimetry

This document reports on a feasibility study to design and construct a scintillation fiber radiation detector for in-vivo endoscopic internal dosimetry. The instrument design utilizes an alpha/beta particle-sensitive plastic scintillation fiber to detect and measure internally deposited radionuclides that cannot be suitably assayed using other techniques. Scintillations are optically guided to a photomultiplier for detection. The computerized electronics provides preamplification, amplification, analog-to-digital conversion and storage in a multi-channel analyzer. The microcomputer provides data storage, retrieval, and graphical display. Alpha detection and attenuation were conducted with a calibrated P0-210 source. Ten scintillation fibers of varying diameters (0.5--3 mm) and properties were tested to determine their relative sensitivity for alpha particle detection as a function of distance of the source to the photomultiplier tube. The sensitivity in counts per minute was approximately proportional to the diameter of the fiber for samples of the same composition and manufacturer. 20 refs., 8 figs., 3 tabs