Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy.
To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.
Kadosawa
Tsuyoshi
T
Laboratory of Veterinary Surgery, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan. kado@vetmed.hokudai.ac.jp
Ohashi
Fumihito
F
Nishimura
Ryohei
R
Sasaki
Nobuo
N
Saito
Isao
I
Wakabayashi
Hiroaki
H
Takeuchi
Akira
A
D000818:Animals; D004285:Dogs; D004307:Dose-Response Relationship, Radiation; D005214:Fast Neutrons / Q000009:adverse effects* / Q000627:therapeutic use; D017247:Neutron Capture Therapy / Q000009:adverse effects* / Q000379:methods; D011836:Radiation Tolerance; D012062:Relative Biological Effectiveness; D012867:Skin / Q000473:pathology* / Q000528:radiation effects*; D012871:Skin Diseases / Q000209:etiology* / Q000473:pathology*