Analysis of neutron beam quality control test items in boron neutron capture therapy (BNCT) equipment / 中华放射医学与防护杂志

Objective:To provide reference for establishing the testing method for quality control of neutron beam in boron neutron capture therapy (BNCT) equipment in China by testing the radiation characteristic parameters and dosimetry characteristic parameters of epithermal neutron beam in hospital neutron irradiator (IHNI).Methods:By comparing the uncertainties in the result of various test items with the deviation values recommended by the European Joint Research Center (EC-JRC), the feasibility of the relevant of testing method was analyzed and evaluated.Results:The uncertainty in epithermal neutron fluence rate was 2.7%. The uncertainty in ratio of thermal to epithermal neutron fluence rate was 3.1%. The uncertainty in ratio of fast neutron air kerma to epithermal neutron fluence rate was 9.3%. The uncertainty in ratio of gamma air kerma to epithermal neutron fluence rate was 8.7%. The uncertainty in spatial distribution of neutron fluence rate was 2.7%. The uncertainty in thermal neutron fluence rate in phantom was 1.8%. The uncertainty in neutron and gamma-ray dose rate in phantom was 17.1% and 4.0%, respectively.Conclusions:The uncertainty in neutron dose rate measurement result in phantom is higher, and further research is needed to improve the accuracy of the testing method. The uncertainty in the measurement result of other test items is lower, and the accuracy of the test result is expected to meet the allowable deviation value recommended by the European Joint Research Center, and the test method is feasible.

Development of dose verification methods for boron neutron capture therapy / 中华放射医学与防护杂志

To summarize the progress in BNCT dose verification method in the world and discusses their development prospects. Boron neutron capture therapy (BNCT) utilizes the specific capture reaction between the neutrons and boron drugs enriched in tumor cells to selectively kill tumor cells. In order to verify the accuracy of the radiotherapy plan and ensure the therapeutic effect on patients, it is necessary to measure the dose before treatment and compare the experimental radiation dose with the planned dose. The current BNCT dose measurement method mainly include point dose measurement method based on ionization chambers, thermoluminescence dosimeters and activation foils, two-dimensional dose measurement method based on films, and three-dimensional dose measurement method based on gel dosimeters.

Curent advances and stretegies for reducing the side effects of radiation therapies used for various types of cancers.

Cancer originates from the abnormal expression or activation of positive regulators and functional suppression of negative regulators. The World Health Organization (WHO) estimates that 84 million people will die of cancer between 2005 and 2015 without intervention. Research suggests that one-third of cancer deaths can be avoided through prevention. Major cancer treatment modalities are surgery, radiation therapy and chemotherapy. Radiation therapy is an important cancer treatment method and is used for approximately 50% of all cancer patients with varying success. Therapy uses high-energy waves or particles to destroy cancer cells. It can be used basically for three main reasons: to achieve high radiation dose into tumors; minimizing dose into surrounding normal tissues; to avoid complications as far as possible. The recent advances in this treatment method have led to the improvement in cancer death statistics. It can also be combined with surgery or chemotherapy for better results. This review covers general applications, various side effects/agents and factors affecting to get rid of these effects and strategies to improve radiation therapy.

Boron neutron capture inducing apoptosis in C6 glioma cells / 中华放射肿瘤学杂志

Objective To investigate the effect and mechanism of boron neutron capture therapy(BNCT) in C6 glioma cell line.Methods C6 cells in exponential phase were divided into 6 groups: untreated control,(~(60)Co?)(4 Gy),~(60)Co? 8 Gy,nuclear reactor exposure without boronophenylalanine(BPA) 3 Gy,BNCT(4 Gy) and BNCT 8 Gy.Cellular morphological change was observed by an inverted microscope,light microscope,fluorescence microscope and electronic microscope.Flow cytometry was used to determine the percentage of apoptosis,necrosis and normal cells 48h after irradiation.Colony forming assay was used to calculate cell surviving fraction.Results Typical morphological changes of apoptosis were observed early after irradiation in BNCT group,with a significant increase in apoptotic rates was observed 48 h after irradiation with 63.2% and 88.3% for BNCT(4 Gy) and 8 Gy group,respectively(P

Dosimetry of the Low Fluence Fast Neutron Beams for Boron Neutron Capture Therapy / 대한방사선종양학회지

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.

In vitro study of incorporation of p-boronophenylalanine (BPA) by glioma cells and its relationship with cell cycle / 解放军医学杂志

Objective To evaluate the incorporation of BPA, which was synthesized by ourselves, by two different glioma cell lines, and to observe its relationship with the time of cultivation and cell cycle. Methods Two glioma cell lines of C6 and SHG-44 were studied and the primarily cultured rat astrocytes were used as control. The growth curves of the two glioma cell lines and rat astrocytes were plotted, and their doubling time was identified respectively from the curves. All three kinds of cells were incubated in a culture medium, in which 10 B concentration was 50?g/ml for 4h, 8h, 16h, 20h or 24h. Boron concentration in the cells was measured by induced couple plasma atomic emission spectroscopy (ICP-AES) after respective culture period. After 24h of incubation, the cells in the G 0 /G 1 phase and those in the G 2 /M phase were isolated by flow cytometry, and boron concentration in each fraction was obtained by ICP-AES. Results The doubling time was 18.5h for both C6 and SHG-44 cells, but 28h for the astrocytes. The boron concentration in glioma cells was constantly higher than that in astrocytes throughout the experiment(P