RBE of a Thermal Neutron Beam and the¹⁰B(n, α)⁷Li Reaction on Cultured B-16 Melanoma Cells

Abstract

The RBE of a thermal neutron beam and the 10B(n, alpha)7Li reaction were determined in cultured B-16 melanoma cells. The Kyoto University Research Reactor (KUR) was used as a thermal neutron source which had a very low contamination of gamma-rays and fast neutrons. The cells were irradiated with the beam in the presence or absence of 10B-boric acid. The absorbed dose from the neutron capture reaction to the cells was calculated by a method of Kitao (1975). Survival curves in both conditions had no shoulder and Do values were 0.506 or 0.604 Gy in the presence or absence of 5 micrograms 10B/ml-medium, respectively. The Do value of the 10B(n, alpha)7Li reaction was also estimated at 0.466 Gy, assuming each component of radiation was additive. The RBEs of the KUR thermal neutron beam and the 10B(n, alpha)7Li reaction relative to 60Co gamma-rays were estimated as 4.62 and 6.01 at 0.1 surviving fraction, respectively. Using these results, we calculated the absorbed dose from the 10B-compound and estimated the specific accumulation in the cultured cells of 10B-compounds which we have previously reported but not quantified (Nakanishi et al. 1980, Ichihashi et al. 1982).

The radiobiology of 24 keV neutrons

“…This is in broad agreement with the results of Fukuda et al (1987) and Kobayashi and Kandon (1982), who report an RBE of 6 for 10 B-capture products in melanoma cells, but rather higher than the value of 3.7 reported by Davies et al (1970). However, the effectiveness of the capture products depends to a large degree on the distribution of 10 B in the cell (Nakanishi et al, 1980).…”

Neutron Capture Therapy Research in Australia

“…The 418 showed the greatest effect but barely significant changes were seen for the 96E and 96L cell lines. Neutron fluence and absorbed dose Do values were as follows: The Do neutron fluence values are comparable to those reported at Kobe for boron-10 negative experiments, but are much larger ( x 2) than those reported for BPA positive (Fukuda et al, 1987;Ichihashi et al, 1982;Nakanishi et al, 1980). Absorbed dose Do values are about a factor of two greater, but if the dose evaluation of Fukuda et al (1987) is followed for monolayer cells, then comparable Do absorbed dose values are found.…”

Preparations for phase I clinical trials of boron neutron capture therapy at the mit reactor and the New England Medical Center

“…An improved prompt gamma activation analysis facility has been constructed at MITR-I1 Date: Wed, Jan 19,1994 Current Time: 9 Beam aperture with a 15 cm sapphire single-crystal filter. The n-type Ge gamma-ray detector is shielded with 6Li enriched Li,CO, and lead.…”