Monitoring of Blood-¹⁰B Concentration for Boron Neutron Capture Therapy Using Prompt Gamma-Ray Analysis

Abstract

The aim of the present study was to monitor the blood-¹⁰B concentration of laboratory dogs receiving boron neutron capture therapy, in order to obtain optimal agreement between prescribed and actual dose. A prompt gamma-ray analysis system was developed for this purpose at the High Flux Reactor in Petten. The technique was compared with inductively coupled plasma-atomic emission spectrometry and showed good agreement. A substantial variation in ¹⁰B clearance pattern after administration of borocaptate sodium was found between the different dogs. Consequently, the irradiation commencement was adjusted to the individually determined boron elimination curve. Mean blood-¹⁰B concentrations during irradiation of 25.8 ± 2.2 μg/g (1 SD, n = 18) and 49.3 ± 5.3 μg/g (1 SD, n = 17) were obtained for intended concentrations of 25 μg/g and 50 μg/g, respectively. These variations are a factor of two smaller than irradiations performed at a uniform post-infusion irradiation starting time. Such a careful blood-¹⁰B monitoring procedure is a prerequisite for accurately obtaining such steep dose-response curves as observed during the dog study.