A thermal neutron beam facility utilizing a typical tangential beam port for Neutron Capture Therapy was installed at the HANARO, 30 MW multi-purpose research reactor. Mixed beams with different physical characteristics and relative biological effectiveness would be emitted from the BNCT irradiation facility, so a quantitative analysis of each component of the mixed beams should be performed to determine the accurate delivered dose. Thus, various techniques were applied including the use of activation foils, TLDs and ionization chambers. All the dose measurements were performed with the water phantom filled with distilled water. The results of the measurement were compared with MCNP4B calculation. The thermal neutron fluxes were 1.02E9 n/cm2 s and 6.07E8 n/cm2 s at 10 and 20 mm depth respectively, and the fast neutron dose rate was insignificant as 0.11 Gy/hr at 10 mm depth in water. The gamma-ray dose rate was 5.10 Gy/hr at 20 mm depth in water. Good agreement within 5%, has been obtained between the measured dose and the calculated dose using MCNP for neutron and gamma component and discrepancy with 14% for fast neutron flux. Considering the difficulty of neutron detection, the current study support the reliability of these results and confirmed the suitability of the thermal neutron beam as a dosimetric data for BNCT clinical trials.
Fast Neutrons ; Neutron Capture Therapy* ; Neutrons* ; Relative Biological Effectiveness ; Water

Creating new germplasms and breeding new cultivars in peanut by radiation mutagenesis and tissue culture were conducted in this study, aiming to develop new breeding method of peanut. Mature seeds from Luhua 11, the most commonly grown peanut cultivar in Northern China, were treated by fast neutron irradiation. Then the embryo leaflets were separated from the irradiated seeds and inoculated on the media, and the regenerated seedlings were obtained through somatic embryogenesis pathway. The regenerated seedlings were grafted, acclimated and then transplanted into field and the selfed pods were harvested from 83 regenerated plants. The progenies were selected by the pedigree method, and 107 mutants were obtained from the progenies of the 83 regenerated plants. Different mutants showed obvious variation in many agronomic traits, including main stem height, branch number, pod shape and size, seed coat color, inner seed coat color, oil content and protein content etc. Yuhua 7, a new peanut variety with low oil content, early maturity and waterlogging tolerance was obtained. The yield of Yuhua 7 was over 14% higher than that of the mutagenic parent Luhua 11, and the oil content of kernels was 47.0%, lower than that of parent Luhua 11 with 52.1% oil content. Yuhua 7 had passed peanut variety regional multi-location trials in Liaoning Province in 2016 and its average yield was 13.8% higher than that of the control variety Baisha 1017. It had also passed national peanut variety registration, and the registration ID is "GPD peanut (2018) 370105". The results show that irradiation mutagenesis combined with tissue culture is an effective method for creating new germplasm and breeding new varieties of peanut.
Arachis ; Breeding ; China ; Fast Neutrons ; Plant Breeding ; Seeds

For evaluation of biological effect of p+(50.5 MeV) Be neutron beam produced by Korea Cancer Center Hospital(KCCH) cyclotron the RBE had been measured in experimental tumor Walker 256 carcinosarcoma as well as normal tissue, mouse intestine and bone marrow, in single and fractionated irradiation. As pilot study, the RBE had been measured for the mouse jejunal crypt cells in single whole body irradiation of which the result was 2.8. The obtained RBE values of TCD 50 of Walker 256 tumor, bone marrow and intestine in single irraiation were 1.9, 1.9 and 1.5 respectively. In fractionated irradiation, the RBE value of tumor Walker 256 was decreased as increasing of fraction number and increased as increaing of fraction size.
Animals ; Bone Marrow ; Carcinosarcoma* ; Cyclotrons ; Fast Neutrons* ; Intestines ; Korea ; Mice ; Neutrons ; Pilot Projects ; Whole-Body Irradiation

PURPOSE: It has been well established that response of cells and tissues to low LET radiations(X- or grmma-ray) can enhanced by comdining with hyperthermia. However, There has been relatively little of hyperthermia on the possible modification of either cellular or tissue responses to other types of radiation. So, We investigated the combined effect of fast neutron irradiation and hyperthermia according to the sequence and time interval of the two MATERIALS AND METHODS: In MKN-45 cells, a human stomach cancer cell line, Surviving fractions were measured according to the sequence treatment of 6,4,2,0 hour interval for fast neutron irradiation(1.5Gy) combined with hyperthermia(41 degrees C for 30 min or 43 degrees C for 30 min). RESULTS: D(0) and n of MKN-45 for neutron were 0.8Gy and 2.5, respectively. The surviving fraction by 1.5 Gy of neutron was 0.36+/-0.34. Interacting powers were mostly. The surviving fraction by 1.5 Gy of neutron was 0.36+/-0.34. Interacting powers were mostly ranged between 1 and 2, bur they were 3.0Gy 2.7, respectively for hyperthermia (41 degrees C for 30 min) followed by neutron irradiation 6 and 4 hours later. CONCLUSION: The combined effect of fast neutron (1.5Gy) and hyperthermia (41 degrees C or 43 degrees C for 30min) is largely independently additive. Preceding mild hyperthermia (41 degrees C for 30 min) 4 or 6 hours before neutron may cause decreased sensitivity to subsequent neutron irradiation.
Cell Line ; Fast Neutrons* ; Fever* ; Humans ; Linear Energy Transfer ; Neutrons ; Stomach Neoplasms

PURPOSE: For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. METHOD AND MATERIALS: For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, EIC-1 ion chambers manufactured by A-150 plastic and used IC-17M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was 5 cc per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. RESULTS: The absorbed dose of fast neutron beams was 6.47x10-3 cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was 65.2+/-0.9% at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, D20/D10, of the total dose was 0.718. CONCLUSION: Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.
Argon ; Bismuth ; Boron Neutron Capture Therapy* ; Boron* ; Cyclotrons ; Electric Power Supplies ; Fast Neutrons* ; Hope ; Korea ; Magnesium ; Neutrons ; Nuclear Reactors ; Paraffin ; Plastics ; Water

This study compared the effects of high linear energy transfer (LET) fast neutrons on the induction of apoptosis in the hair follicles of ICR mice with those of low LET (60)Co gamma-rays. The changes that occurred from 0 to 24 h after exposing the mice to either 2 Gy of gamma-rays (2 Gy/min) or 0.8 Gy of neutrons (94 mGy/min, 35 MeV) were examined. The maximum frequency was found at 12 h (gamma-rays) or 8 h (neutrons) after irradiation. The mice that received 0-8 Gy of gamma-rays or 0-1.6 Gy of neutrons were examined 8 h after irradiation. The dose-response curves were analyzed using the best-fit curve model. The dose-response curves were linear-quadratic, and a significant relationship was found between the frequency of apoptotic cells and the dose. The morphological findings in the irradiated groups were typical apoptotic fragments in the matrix region of the hair follicle, but the spontaneous existence of apoptotic fragments was rarely observed in the control group. In the presence of an apoptosis frequency between 2 and 14 per follicle, the relative biological effectiveness values of neutrons in small and large follicles were 2.09 +/- 0.30 and 2.15 +/- 0.18, respectively.
Animals ; Apoptosis/*radiation effects ; Dose-Response Relationship, Radiation ; *Fast Neutrons ; *Gamma Rays ; Hair Follicle/pathology/*radiation effects ; Linear Energy Transfer ; Male ; Mice ; Mice, Inbred ICR ; Time Factors

Object recognition memory and contextual fear conditioning task performance in adult C57BL/6 mice exposed to cranial fast neutron irradiation (0.8 Gy) were examined to evaluate hippocampus-related behavioral dysfunction following acute exposure to relatively low doses of fast neutrons. In addition, hippocampal neurogenesis changes in adult murine brain after cranial irradiation were analyzed using the neurogenesis immunohistochemical markers Ki-67 and doublecortin (DCX). In the object recognition memory test and contextual fear conditioning, mice trained 1 and 7 days after irradiation displayed significant memory deficits compared to the sham-irradiated controls. The number of Ki-67- and DCX-positive cells decreased significantly 24 h post-irradiation. These results indicate that acute exposure of the adult mouse brain to a relatively low dose of fast neutrons interrupts hippocampal functions, including learning and memory, possibly by inhibiting neurogenesis.
Animals ; Cranial Irradiation ; *Fast Neutrons ; Hippocampus/metabolism/physiology/*radiation effects ; Immunohistochemistry ; Ki-67 Antigen/metabolism ; Male ; Memory/physiology/*radiation effects ; Mice ; Mice, Inbred C57BL ; Microtubule-Associated Proteins/metabolism ; Neurogenesis/physiology/*radiation effects ; Neuropeptides/metabolism

OBJECTIVETo study the radiobiological effects of fast neutron/photon mixed irradiation on human cancer cell in vitro and to discuss the mechanism in relation with cell cycle and apoptosis, thus to provide experimental support for the further application of fast neutron radiotherapy of cancer.

METHODSExponentially growing human nasopharyngeal cancer cell line CNE-1 was irradiated in vitro with 35 MeV p-->Be fast neutron and 6 MV-X ray in grading doses (0 cGy, 40 cGy, 80 cGy, 120 cGy, 160 cGy, 240 cGy, 320 cGy and 400 cGy for neutron, and 0 cGy, 100 cGy, 200 cGy, 300 cGy, 400 cGy, 600 cGy, 800 cGy and 1000 cGy for X ray). Clonogenic assay was performed, and relative biological effectiveness (RBE) of fast neutron was determined with D(10) by means of cell survival curves. Isoeffective doses of 35 MeV p-->Be fast neutron and 6 MV-X ray were obtained according to the RBE. The cells were assigned into two irradiation regimens, (1) the one-week-fractionation regimen, which adopted the radiation pattern of X x 5, N x 2 and X-N-X-X-N. After irradiation the clonogenic assay was performed to compare their survival fractions; (2) the two-dose regimen, with the radiation pattern of X + N, N + X and X + X. Flow cytometry was done at different time points after irradiation to analyze cell cycle distribution and apoptosis. Fast neutron dose was delivered on Tuesday and Friday, and all the other irradiation intervals were 24 h.

RESULTSThe RBE of fast neutron to X ray in CNE-1 cells according to the D(10) ratio was 2.40. The neutron isoeffective dose for a single dose of 200 cGy of 6 MV-X ray was approximately 80 cGy. In clonogenic assay, the cell survival fractions were significantly lower in X-N-X-X-N group (0.0079) than those in X x 5 (0.018) and N x 2 (0.017) groups. The flow cytometry suggested a higher percentage of apoptotic cells after mixed irradiation, and different sequence of X ray and neutron irradiations caused varying changes in cell cycle arrest.

CONCLUSIONMixed irradiation of fast neutron and X ray showed a synergic effect in vitro on CNE-1 cell killing. Cell cycle arrest and apoptosis may play some role in the radiation damage repair mechanisms of mixed beam irradiation.

Apoptosis ; radiation effects ; Carcinoma, Squamous Cell ; pathology ; Cell Cycle ; radiation effects ; Cell Line, Tumor ; Dose-Response Relationship, Radiation ; Fast Neutrons ; therapeutic use ; Humans ; Nasopharyngeal Neoplasms ; pathology ; Photons ; therapeutic use