Boron concentrations in brain during boron neutron capture therapy: in vivo measurements from the phase I trial EORTC 11961 using a gamma-ray telescope.
OBJECTIVE
Gamma-ray spectroscopic scans to measure boron concentrations in the irradiated volume were performed during treatment of 5 patients suffering from brain tumors with boron neutron capture therapy (BNCT). In BNCT, the dose that is meant to be targeted primarily to the tumor is the dose coming from the reaction 10B(n,alpha)7Li, which is determined by the boron concentration in tissue and the thermal neutron fluence rate. The boron distribution throughout the head of the patient during the treatment is therefore of major interest. The detection of the boron distribution during the irradiation was until now not possible.


METHODS
Five patients suffering from glioblastoma multiforme and treated with BNCT in a dose escalation study were administered the boron compound, boron sulfhydryl (BSH; Na(2)B(12)H(11)SH). Boron concentrations were reconstructed from measurements performed with the gamma-ray telescope which detects locally the specific gamma rays produced by neutron capture in 10B and 1H.


RESULTS
For all patients, at a 10B concentration in blood of 30 ppm, the boron concentration in nonoperated areas of the brain was very low, between 1 and 2.5 ppm. In the target volume, which included the area where the tumor had been removed and where remaining tumor cells have to be assumed, much higher boron concentrations were measured with large variations from one patient to another. Superficial tissue contained a higher concentration of 10B than the nonoperated areas of the brain, ranging between 8 and 15 ppm.


CONCLUSIONS
The measured results correspond with previous tissue uptake studies, confirming that normal brain tissue hardly absorbs the boron compound BSH. Gamma-ray telescope measurements seem to be a promising method to provide information on the biodistribution of boron during therapy. Furthermore, it also opens the possibility of in vivo dosimetry.
Verbakel
Wilko F A R
WF
Nuclear Research and Consultancy Group (NRG), Petten, The Netherlands. verbakel@nrg-nl.com
Sauerwein
Wolfgang
W
Hideghety
Katalin
K
Stecher-Rasmussen
Finn
F
D001895:Boron / Q000032:analysis* / Q000493:pharmacokinetics; D001896:Boron Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use; D016754:Boron Neutron Capture Therapy; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D001932:Brain Neoplasms / Q000378:metabolism / Q000532:radiotherapy*; D005909:Glioblastoma / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D013438:Sulfhydryl Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use
D001896:Boron Compounds; D013438:Sulfhydryl Compounds; D001895:Boron