Keiji Kanda

Diffusion coefficient measurement of lithium ion in sintered Li1.33Ti1.67O4 by means of neutron radiography

Neutron radiography (NR) using cold neutron beam was applied to the tracer diffusion coefficient measurement of lithium ion in Li1.33Ti1.67O4. The diffusion couples with different lithium isotope concentrations were annealed at 860 to 900°C and the isotope profiles of lithium ion in the sample were measured by NR. The diffusion profiles obtained for the samples annealed at higher temperatures show good agreement with Fick’s law, whereas the diffusion was not carried out well at the interface for the lower-temperature-annealed samples. The values of diffusion coefficients obtained from the profile fitting were a little smaller than those expected from the electric conductivity. The NR method was found to be the most useful method to measure the tracer diffusion coefficient of lithium ion in solids.

Analytical Calculation of Boron-10 Dosage in Cell Nucleus for Neutron Capture Therapy

The following measures of physical effects in a spherical cell nucleus, resulting from heavy charged particles caused by thermal neutron reactions in tissue, were evaluated by analytical calculatio...

Microanalysis system of ppm-order 10B concentrations in tissue for neutron capture therapy by prompt gamma-ray spectrometry

For neutron capture therapy, a new technique for measuring 10B concentrations of ppm order in tissue has been developed by using 10B(n, α)7Li∗ prompt gamma-ray spectrometry. The measuring system consists of a Ge(Li) detector and a 6LiF tile neutron shield attached to the neutron guide tube of the Kyoto University Reactor (KUR) with very low background gamma-rays. The 10B concentrations of unknown samples were determined in comparison with gamma-ray data obtained from known samples. The detection limit of the system is 0.1-0.5 ppm 10B concentration. In the practical use of the system for neutron capture therapy, 10B concentrations of 10 ppm, which is ordinarily pre-injected into the tumor, can be measured in less than 30 s with 10% accuracy by using 1 g samples. Moreover, the system has the advantage that pre-treatment of the sample is not required. As a neutron monitor in a homogeneous sample, gamma-rays emitted from H(n, γ)D reactions are used. Therefore, neutron irradiation conditions of this system, i.e. fluence rate, energy spectrum, and distribution in the sample do not affect the analyzing results, and the quantity and dimensions of the sample are also not restricted.

Boron Neutron Capture Therapy of Malignant Melanoma Using 10B-Paraboronophenylalanine with Special Reference to Evaluation of Radiation Dose and Damage to the Normal Skin

A treatment regimen for boron neutron capture therapy of malignant melanomas is described using 10B-paraboronophenylalanine as the tumor-targeting compound. As a therapeutic dose, we adopted the maximum tolerable dose for the skin regardless of tumor 10B concentration. In practice, the maximum neutron fluence should be decided prior to starting irradiation. For this purpose, the kinetics of the concentration of 10B in the blood and skin and the skin-to-blood ratios were analyzed in the six patients who received 170 mg/kg of the compound intravenously, and skin concentrations during irradiation were predicted using a standard skin factor curve. This yields a skin concentration at time T based on the blood concentration at time 0. We calculated the maximum tolerable fluence yielding but not exceeding 18 RBE-Gy by assuming that the RBE of 14N(n,p)14C and 10B(n, alpha)7Li reaction for skin damage is 2.5. Actual skin reactions in three of five patients treated with the therapy were, as predicted, within tolerable limits, and we were able to obtain complete tumor regression in four cases. The results indicate that application of our logical approach will be useful for subsequent cases and further development of this therapy.

Measurement of Prompt Neutron Decay Constant and Large Subcriticality by the Feynman-α Method

The Feynman-{alpha} experiments have been carried out using light-water-moderated and -reflected cores loaded with highly enriched uranium fuel at the Kyoto University critical assembly. An experimental technique using a multichannel scaler was developed to improve the accuracy of measurement and to shorten measuring time. Then, the {beta}{sub eff}/l values of single and coupled cores with different neutron spectra were measured to demonstrate the capability of the present technique for measuring the prompt neutron decay constant {alpha}. Moreover, the Feynman-{alpha} method was applied to measuring large subcriticalities. Through these experiments, it is found that the present technique greatly improves the accuracy of {alpha} measurement, and the one-point reactor approximation is applicable to a tightly coupled core. It is also found that the subcriticality down to approximately {minus} 35

The Remodeling and Basic Characteristics of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor, Mainly for Neutron Capture Therapy

can be measured by this method if the position of the neutron detector is chosen carefully, and the present Feynman-{alpha} method can be applied to a subcriticality monitoring system.

Neutron-capture therapy of murine ascites tumor with gadolinium-containing microcapsules

The Heavy Water Thermal Neutron Facility of the Kyoto University Research Reactor (KUR) was wholly updated in March 1996 mainly for neutron capture therapy. The performance as a neutron irradiation facility was improved using the epithermal neutron moderator of the aluminum-heavy water mixture (Al/D2O = 80/20 vol%), the neutron energy spectrum shifter of heavy water, and the thermal neutron filters of cadmium and boral plates. The clinical irradiation utilization under the full-power (5-MW) continuous KUR operation was realized employing both the radiation shielding system, consisting of the shielding door and irradiation room, and the remote carrying system for a patient. The safety and utility of the facility were improved due to the safety observation system.

Advances in the Control of Human Cutaneous Primary and Metastatic Melanoma by Thermal Neutron Capture Therapy

SummaryGadolinium-containing microcapsules were evaluated as an agent for gadolinium neutron-capture therapy. Mice were inoculated intraperitoneally with 107 Ehrlich ascites tumor cells and gadolinium microcapsules and exposed to thermal neutrons for 12 min (approximately 1.86×1012 neutrons cm−2). Significantly more mice given gadolinium microcapsules than those given placebo microcapsules or control survived for 60 days and considerably longer (P<0.0001), indicating that gadolinium neutron-capture reactions effectively suppressed the growth of ascites tumor cells in mice. The results suggest that these microcapsules are an effective gadolinium carrier for neutron-capture therapy.

Lithium batteries: Application of neutron radiography

Differing in principle from boron neutron capture therapy (NCT) of brain tumors using passive accumulation of 10B, since 1972 our ideal) has been to develop a new 10B delivery system actively targeting cancers by utilizing their enhanced specific metabolic activity. As a prototype, we have been working with melanoma using 10B1-p-boronophenylalanine (10B1-BPA), a 10B-dopaanalogue, melanogenesis-seeking melanin polymer substrate2).

Visualization of hydrogen in hydrogen storage alloys using neutron radiography

Abstract Several kinds of primary and secondary commercial lithium batteries, such as CR1/3 · 1H (Fujitsu), CR1220 and BR435 (Panasonic), ML1220 (Sanyo Excel) were investigated using neutron radiography; the variation of the lithium distribution inside these batteries upon discharging (and charging) were clarified by analyzing their visualized images. It was demonstrated that neutron radiography is a potential and useful method, especially in evaluating the reversibility of rechargeable batteries, which have been used under different discharging/charging conditions.