Detection of ¹⁰B Distributions in Histological Samples by Neutron Capture Autoradiography Using Cold Neutron Beams and Photoluminescent Imaging Plates

Abstract

The Neutron Capture Autoradiography (NCAR) using various Solid State Nuclear Track Detectors (SSNTDs) is a well established method to detect and measure the distributions of ¹⁰B in the ppm range on macroscopic and microscopic level in histological sections of tissues loaded with ¹⁰B compounds used for BNCT.1,2 The SSNTD techniques require relatively high neutron fluences, chemical etching and somewhat time consuming quantitative evaluation. Two exposures are normally needed—for B distribution visualization (10^l2-10¹³n/cm²) and 2–3 orders of magnitude lower exposure for quantitative boron determination by various track counting techniques. Recently a new technique of NCAR using sensitive photoluminescent storage phosphors (Imaging Plates or IP) has been proposed to detect heavy charged particles from the ¹⁰B(n,α)⁷Li reactions for the topography of ¹⁰B distributions in histological sections.3 The new method exploits excellent detection properties of IP systems such as very high detection sensitivity and quantum detection efficiency, broad linear response and dynamic range, very small image distortion, reusability of IP and possibilities of digital autoradiography with direct quantitative evaluation.4,5 A severe problem for using IP in NCAR is their high sensitivity to all types of ionizing radiations. The background of direct and induced gamma-rays as well as of epithermal and fast neutrons has to be suppressed or filtered out of the neutron beam. To improve the signal/background ratio and to increase the detectability of ¹⁰B we proposed the use of rather gamma ray free cold neutron beams for the IP-NCAR of ¹⁰B distributions in histological samples.6 In this work the first results of preliminary experiments in IP-NCAR with cold neutrons are presented.