Extending neutron autoradiography technique for boron concentration measurements in hard tissues

Abstract

The neutron autoradiography technique using polycarbonate nuclear track detectors (NTD) has been extended to quantify the boron concentration in hard tissues, an application of special interest in Boron Neutron Capture Therapy (BNCT). Chemical and mechanical processing methods to prepare thin tissue sections as required by this technique have been explored. Four different decalcification methods governed by slow and fast kinetics were tested in boron-loaded bones. Due to the significant loss of the boron content, this technique was discarded. On the contrary, mechanical manipulation to obtain bone powder and tissue sections of tens of microns thick proved reproducible and suitable, ensuring a proper conservation of the boron content in the samples. A calibration curve that relates the B concentration of a bone sample and the track density in a Lexan NTD is presented. Bone powder embedded in boric acid solution with known boron concentrations between 0 and 100 ppm was used as a standard material. The samples, contained in slim Lexan cases, were exposed to a neutron fluence of 10 cm at the thermal column central facility of the RA-3 reactor (Argentina). The revealed tracks in the NTD were counted with an image processing software. The effect of track overlapping was studied and corresponding corrections were implemented in the presented calibration curve. Stochastic simulations of the track densities produced by the products of the B thermal neutron capture reaction for different boron concentrations in bone were performed and compared with the experimental results. The remarkable agreement between the two curves suggested the suitability of the obtained experimental calibration curve. This neutron autoradiography technique was finally applied to determine the boron concentration in pulverized and compact bone samples coming from a sheep experimental model. The obtained results for both type of samples agreed with boron measurements carried out by ICP-OES within experimental uncertainties. The fact that the histological structure of bone sections remains preserved allows for future boron microdistribution analysis.

The effects of BPA-BNCT on normal bone: determination of the CBE value in mice

“…Furthermore, the recent establishment of the superposition method with tissue samples has made it possible to detect 10 B microdistribution; however, few methods are available for hard tissues, such as the bone [ 26–28 ]. Recently, a study reported that the use of ARG for hard tissues attained a high correlation with ICP-AES measurements and was useful for measuring boron concentrations [ 29 ]. However, to the authors’ knowledge, this is the first study in which 10 B mapping was performed for the bone.…”

Neutron autoradiography with nuclear tracks detectors: an imaging technique for Boron Neutron Capture Therapy

“…The technique was also adapted to study boron microdistribution in lung histological sections from the rat lung metastasis model, considering the physiological holes of the tissue structure [17]. Additionally, we have extended the autoradiography methodology to the quantitative analysis of bone tissue, which required obtaining the tissue sections by erosion [38].…”

Enhanced Resolution of Neutron Autoradiography with UV-C Sensitization to Study Boron Microdistribution in Animal Models

“…The feasibility to treat limb osteosarcoma has been analyzed through the study of boron uptake by neoplastic and normal tissue, not only for BNCT mediated by BPA [13] but also for boric acid [25]. The extension of the neutron autoradiography to hard tissues was reported in [26]. Moreover, neutron autoradiography has also been implemented to evaluate the potential changes in boron microdistribution and its effects while incorporating new modalities to improve the efficacy of BNCT.…”