Improved treatment planning for boron neutron capture therapy for glioblastoma multiforme using fluorine-18 labeled boronophenylalanine and positron emission tomography

Boronneutron capture therapy (BNCT) is a cancerbrachytherapy based upon the thermal neutronreaction: 10 B (n,α) 7 Li . The efficacy of the treatment depends primarily upon two conditions being met: (a) the preferential concentration of a boronated compound in the neoplasm and (b) an adequate fluence of thermal neutrons delivered to the neoplasm. The boronated amino acid,para-boronophenylalanine (BPA), is the agent widely used in clinical trials to deliver 10 B to the malignancy.Positron emission tomography(PET) can be used to generate in vivoboron distribution maps by labeling BPA with the positron emitting nuclide fluorine-18. The incorporation of the PET-derived boron distribution maps into current treatment planning protocols is shown to provide improved treatment plans. Using previously established protocols, six patients with glioblastoma had 18 BPA PET scans. The PET distribution maps obtained were used in the conventional BNCT treatment codes. The isodose curves derived from the PET data are shown to differ both qualitatively and quantitatively from the conventional isodose curves that were derived from calculations based upon the assumption of uniform uptake of the pharmaceutical in tumor and normal brain regions. The clinical course of each of the patients who eventually received BNCT (five of the six patients) was compared using both sets of isodose calculations. The isodose contours based upon PET derived distribution data appear to be more consistent with the patients’ clinical course.