Radiation effects of boron neutron capture therapy on brain, skin, and eye of rats.
OBJECTIVE
The present study was carried out to evaluate the radiation effects of boron neutron capture therapy (BNCT) on the brain, skin, and eyes of nude rats following systemic administration of boronophenylalanine (BPA) and neutron irradiation to the head.


METHODS
A solution containing 120 mg of 10B-enriched-L-BPA complexed with fructose was administered IP to nude rats. Boron concentrations were approximately 8.4, 9.4, 10.0, and 11.0 micrograms/g in the brain, blood, skin, and eyes, respectively, at 6 h when the animals were irradiated at the Brookhaven Medical Research Reactor (BMRR). As determined in a study carried out in parallel with this one, the BNCT radiation doses were sufficient to cause tumor regression in nude rats carrying intracerebral implants of the human melanoma cell line MRA 27.


RESULTS
Mild to moderate increases in loose fibrous tissue were observed in the choroid plexus at estimated physical doses to the brain and blood that ranged from 4.3-7.1 Gy and 4.6-7.7 Gy, respectively, and these appeared to be dose and time dependent. Other changes in the choroid plexus included occasional infiltrates of macrophages and polymorphonuclear leukocytes and vacuolation of epithelial cells. Dose-dependent moist desquamation of the skin was observed in all rats, but this had healed by 28 days following irradiation. Cataracts and keratitis developed in the eyes of most animals, and these were dose dependent.


CONCLUSIONS
The minimal histopathological changes seen in the brain at doses that were sufficient to eradicate intracerebral melanoma indicates that BNCT has the potential to cure a tumor bearing host without producing the normal brain injury usually associated with conventional external beam radiation therapy. Studies in canines, which currently are in progress, should further define the dose-effect relationships of BNCT on critical neuroanatomic structures within the brain.
Matalka
K Z
KZ
Department of Pathology, Ohio State University, Columbus 43210.
Barth
R F
RF
Bailey
M Q
MQ
Wilkie
D A
DA
Koestner
A
A
Hopewell
J W
JW
D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D001896:Boron Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use; D016754:Boron Neutron Capture Therapy; D001921:Brain / Q000473:pathology / Q000528:radiation effects*; D005123:Eye / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000627:therapeutic use; D051381:Rats; D011923:Rats, Nude; D012867:Skin / Q000473:pathology / Q000528:radiation effects*
D001896:Boron Compounds; D010649:Phenylalanine; C033685:4-boronophenylalanine