The Relative Biological Effectiveness of Thermal Neutrons and of the Heavy Particles from the B<sup>10</sup>(n, α) Li<sup>7</sup>Reaction for Acute Effects in the Mouse

Bond, V.P.; Easterday, O. D.; Stickley, E. E.; Robertson, James S.

doi:10.1148/67.5.650

Cited by 19 publications

(4 citation statements)

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“…1 Table 4 that RB -2.6. The compatibility of this result with in vivo measurements of RB (27)(28)(29) lends credence to an endothelial pathogenesis of the CNS radiation lethality syndrome and thereby underlines the significance of 10B in the blood during boron neutron capture therapy of brain tumors (30,31).…”

Section: Resultssupporting

confidence: 56%

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

Slatkin

Stoner

Rosander

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

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Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal i'jection of '°B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since '°B concentrations were =3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from a and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LDjO dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a maijor determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo.Irradiation of the head of a mouse by more than 120 Gy of xrays usually causes death from the acute central nervous system (CNS) radiation syndrome within 3.5 days after irradiation (1). Blood vessels are damaged in the acute CNS syndrome (2). If a 10B-enriched substance is injected rapidly into a mouse and then penetrates the blood-brain barrier slowly, endothelial cells and parenchymal cells of the brain will be irradiated unequally by heavy charged particles (HCP) from the 10B(n,a)7Li nuclear reaction (3) ms-1, the average neutron speed at 200C (8,9). In 6% of such captures, the 10B(n,a)7Li reaction leads to the lower 7Li energy state (Ea = 1.777 MeV; ELU = 1.014 MeV; 1 eV = 1.602 x 10-19 J), whereas in 94% of captures, the reaction leads to the first excited state of 7Li, from which a 478-keV photon is emitted (Ea = 1.471 MeV; ELI = 0.839 MeV). For uniform distribution of boron, the kinetic energy released in matter (kerma) rate due to these HCP is, therefore, 7.68 x 10-12 FBq Gy-s-', where FB is the 10B mass fraction in the tissue and 4 is the thermal neutron fluence rate (s-1.m-2).tt For endothelial cells, the usual assumption of equivalence between the kerma rate and the absorbed dose rate is inapplicable. Since endothelial cells demarcate the physiological blood-brain barrier anatomically (10,11), and since blood 10B concentrations were about 3 times greater than parenchymal 10B concentrations during exposure to neutrons (Fig. 2 [:14 ,um long (a 9 um, 7Li 5 ,um; ref. 13) and :0.1 ,um in diameter] that envelop the colinear paths of the two mutually recoiling HCP. The radial gradiAbbreviations: CNS, central nervous system; GyE, Gy equivalent; HCP, heavy charged particle; kerma, kinetic energy released in matter; kVp, kilovolt peak; RBE, relative biological effectiveness.

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Section: Resultssupporting

confidence: 56%

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

Slatkin

Stoner

Rosander

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

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“…Few studies have been made on the RBE of thermal neutrons and 'OB(~,CX)~L~ reaction in mammals. Bond et al [1956] at Brookhaven reported RBE values of 3.4 for thermal neutrons, compared with 250-kVp X-ray radiation, and 1.05 for lOB(n,~x)~Li reaction to 250-kVp X-ray radiation, both estimated from the degree of spleen and thymus weight depression at 3.5 days after exposure. Archambeau et al [19711 also reported the RBE of thermal neutrons and l0B(n,d7Li reaction on the skin of swine using the Brookhaven reactor, compared with 250-kVp X-ray.…”

Section: Discussionmentioning

confidence: 99%

RBEs of Thermal Neutron Capture Therapy and ¹⁰B(n,α)⁷ Li Reaction on Melanoma‐Bearing Hamsters

Hoshino

Kono

Mishima

1989

Pigment Cell Research

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Using Greene's melanoma transplanted into Syrian (golden) hamsters, we determined the relative biological effectiveness (RBE) of thermal neutron capture therapy (TNCT) using 10B-paraboronophenylalanine (10B-BPA) in comparison with a 9-MeV electron beam. We also obtained the RBE of the 10B(n, alpha)7 Li reaction by calculation based on summed dose data from TNCT. Throughout this study, the Kyoto University Research Reactor was used as the source for thermal neutrons; the reactor was specially altered to attain a low contamination level both for gamma-rays and fast neutrons. 10B-BPA was administered 8 hours before thermal neutron irradiation to the hamsters with melanoma. The tumor was then irradiated at 5 MW for 90 minutes. The absorbed dose from this TNCT was calculated by the method of Fairchild and Goodman (Phys. Med. Biol. 1966; 2:15-30). The RBEs of the TNCT and the 10B(n, alpha)7 Li reaction obtained by the tumor growth delay time (TGDT) method were 2.22 and 2.51, respectively, at 10.5 days of TGDT. These RBE values varied with TGDT and the absorbed dose. The RBE value of TNCT had a peak at 7.0 days of TGDT; that of the 10B(n, alpha)7Li reaction was higher at a low absorbed dose level and lower at a high absorbed dose level.

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“…It is concluded that the unsaponifiable matter of 100 g of corn oil lowers serum cholesterol by something between 6 and 12 mg 100 nil. Although this effect is statistically non-significant.…”

Section: Toxic Factors IX the Serum Of I R R A D I A~d Ratsmentioning

confidence: 99%

“…Gamma irradiation procedure has been described (6). Radiation factors were as follows : radiation was delivered by General Electric Maxitron therapy unit at 250 KVP; 30 ma; 0.5 mm Cu, 1 mm A1 filter: HVl 1.5 mm Cu; TSD 70 cni.…”

Section: Toxic Factors IX the Serum Of I R R A D I A~d Ratsmentioning

confidence: 99%

Failure to Demonstrate Toxic Factors in the Serum of Irradiated Rats.

Campo

Bond

Cronkite

1958

Experimental Biology and Medicine

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The Relative Biological Effectiveness of Thermal Neutrons and of the Heavy Particles from the B¹⁰(n, α) Li⁷Reaction for Acute Effects in the Mouse

Cited by 19 publications

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Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

RBEs of Thermal Neutron Capture Therapy and ¹⁰B(n,α)⁷ Li Reaction on Melanoma‐Bearing Hamsters

Failure to Demonstrate Toxic Factors in the Serum of Irradiated Rats.

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The Relative Biological Effectiveness of Thermal Neutrons and of the Heavy Particles from the B10(n, α) Li7Reaction for Acute Effects in the Mouse

Cited by 19 publications

References 0 publications

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

RBEs of Thermal Neutron Capture Therapy and 10B(n,α)7 Li Reaction on Melanoma‐Bearing Hamsters

Failure to Demonstrate Toxic Factors in the Serum of Irradiated Rats.

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The Relative Biological Effectiveness of Thermal Neutrons and of the Heavy Particles from the B¹⁰(n, α) Li⁷Reaction for Acute Effects in the Mouse

RBEs of Thermal Neutron Capture Therapy and ¹⁰B(n,α)⁷ Li Reaction on Melanoma‐Bearing Hamsters