The paper briefly interprets the obvious progress of the boron neutorn capture therapy (BNCT) in the new era. It includes the BNCT clinical positioning, the tumour recurrence exploring, the boron concentration quantifed detecting, the targeting boron compound composing and the in hospitor neutron source irradintors setting up. The enlargement of these bottle necks in BNCT developing might be the preview of personalizing and routine BNCT.
As China's nuclear industry flagship in developing overseas nuclear market, China Zhongyuan Engineering Corp., with project development as its engine, makes unremitting efforts in the development of 1 000 MWe nuclear power plants, nuclear research reactors, In hospital nuclear irradiation and modular small type reactor, and contributes to the peaceful use of nuclear energy and technology.
The construction of in-hospital neutron irradiator (IHNI) started in 2007. Its building construction was completed in Dec. 2008, and the installation and test of the relevant systems were completed in Mar. 2009. The first criticality was achieved on Dec. 7, 2010. The reactor reached the full power on Jan. 22, 2010. The test results show that the final excess reactivity is 4.2 mk; the maximum continuous operation time at full power is 12 h and the power wave is less then 0.3 % during full power operation; when the positive reactivity with 4.2 mk is inserted into the reactor suddenly, the power will be increased to 85.7 kW at the time of 229 s, and then, it will turn to the normal value due to the negative temperature effect.The release result of reactivity shows the inherent safety of reactor.
The design of in hospital neutron irradiator (IHNI) and its systems were introduced, and the performance and characteristics of IHNI were described. In order to test the inherent safety of IHNI, the experiment of 4.2 mk reactivity release was done. The experimental results showed that the peak power of IHNI was 85.7 kW at the time of 229 s after 4.2 mk reactivity release, and then, the power decreased owing to the negative temperature coefficient of moderator. The radiation dose rates at different rooms were lower than the standard value.
In 2010, the commissioning of in-hospital neutron irradiator (IHNI) and its systems were completed. The operation with power started since then. The IHNI has operated by 99 times. The release of total energy is 1 832.42 kW·h with the corresponding integral neutron flux of 2.198 9×1017 cm-2. The test operation data shows that the operation values of IHNI and its relevant systems are smaller than the limited value, which manifests that IHNI is safe and reliable.
The preliminary design of PGNAA system of IHNI was completed and the system in accordance with the design was set up. For both detector shielding part and the neutron beam shielding part, the inner layer was natural LiF powder and the outer was lead.Then boron concentration measurement experiments using this system were finished.The results show that the the system can measure 10B concentration of 10 ppm, with 2 mL of the sample volume. 10B element measurement sensitivity was 0.822 cps/ppm. Also it was found that the natural LiF powder would produce a high background in the target part of the energy spectrum and affect the measurement accuracy.
Optimization design for the moderation layer and reflection layer of the epithermal neutron duct at in-hospital neutron irradiator mark 1(IHNI-1) reactor is carried out by using MCNP in this paper. Firstly, six moderator schemes combined with FLUENTAL are compared with Al materials, and two moderation optimization schemes which can obtain intensive epithermal neutron flux density at exit of this duct are chosen. Secondly, based on these two moderation schemes, the optimization design for reflectors around the moderator is introduced, and the recommended reflector schemes are given. Finally, based on the moderation layer and reflection layer optimization schemes, the neutron and gamma space distribution of the epithermal neutron beam at exit of this duct are detailed calculated.
Using WIMS & CITATION program, the neutronic parameters calculating model of in-hospital neutron irradiator mark 1(IHNI-1) reactor is presented in this paper.The power distribution, reactivity worth of control rod and top beryllium, temperature coefficient and burnup are calculated. It proves that the results are consistent with the literature values and the method is appropriate to physical calculation of IHIN-1 reactor.
A temperature-dependent neutron cross-section library for MCNP in in-hospital neutron irradiator mark 1 reactor was generated using NJOY software. Accounting for the temperature range for reactor operation, a compact ENDF (ACE) data library was created. The accuracy of the self-making library was validated by comparing data with MCNP/4B standard library and the results were tested by ICSBEP (International Criticality Safety Benchmark Evaluation Project) benchmark problems, which was used in the calculation of Doppler temperature coefficient. Influence of different parameters in the processing was also analyzed. The results showed that the ACE format library produced in this paper was correct and could be used reliably for physics design at IHNI-1 reactor.
The kinetic parameters of in-hospital neutron irradiator mark 1 (IHNI-1) reactor, effective delayed neutron fraction and neutron generation time are calculated by CKPWC（calculating kinetic parameters based on WIMS and CITATION）program based on the calculated results of WIMS and CITATION. The cell homogenized cross section and 69-group flux density are calculated by WIMS. Flux density and adjoint flux density are obtained based on 4-group diffusion calculation using CITATION. The kinetic parameters are calculated by CKPWC based on the results of WIMS and CITATION. The analysis based on the calculation indicates that the energy group structure has a significant effect on the result of kinetic parameter. An appropriate energy group structure is given in this paper. To verify the accuracy of the method, Xi’an Pulsed Reactor is benchmarked and the result is corresponded to its design value.
According to the characteristics and operation condition of IHNI-1 reactor, a subchannel model is developed in this paper. It also has been verified that the model is reasonable and effective in IHNI-1's thermal hydraulic analysis. Using the model, some thermal parameters of IHNI-1reactor are calculated. The relation between the core's coolant inlet flux and outlet temperature is analyzed, and the variation of rod temperature with reactor power is also calculated.
Numerical calculation for the equivalent surface source of the thermal neutron duct of in-hospital neutron irradiator mark 1(IHNI-1) reactor is carried out using MCNP Monte Carlo code. Cold clean criticality of B core is searched. Neutron beam parameters at the exit of thermal neutron duct are calculated. Equivalent neutron and γ surface sources for BNCT are built using equivalent surface source model. And these sources are reliable to calculate absorbed dose distribution in equivalent model of head quickly.
RELAP5/SCDAP/MOD3.4 is used to simulate and analyze the transient proceeding of in-hospital neutron irradiator mark 1(IHNI-1) reactor in accident condition.Large reactivity insertion accident and loss of coolent of pool accident are calculated and analyzed.The results show that IHNI-1 reactor is characterized with inherent safety. The negative coolant temperature feedback limits the nuclear power to an stable level and the reactor is safe under the accident.
The paper set up the coupled calculation methods of criticality and burnup based on WIMS code and MCNP code, and validated the method. Through the calculation results of cells and the comparison of burnup experiments of Xi’an pulsed reactor, the validity and rationality of the coupled code were proved. The article utilized the coupled code to compute and analyze the burnup of in hospital neutron irradiator mark 1(IHNI-1) reactor at last.
To calculate the fission product poisoning and burnup of the reactor accurately, the paper sets up the coupled calculation methods based on MCNP code and ORIGEN2 code and program data translation, cross section revision and date interface codes. Making use of elaborate reactor model to calculate the fission product poisoning and burnup for in-hospital neutron irradiator mark 1 reactor.
MCDB is developed for boron neutron capture therapy (BNCT). This system consists of a medical pre-processor, a dose computation and a post-processor. MCDB automatically produces the input file from CT and MRI image data. In Monte Carlo dose calculation, several accelerated measures, such as the fast track technique, mesh tally matrix and material matrix, are developed. In this paper, we proposed a real model simulated by MCNP and MCDB, respectively. The almost same results as MCNP are achieved. MCDB is faster in computational speed than MCNP.
To prepare folate-targeted liposomes with high encapsulation efficiency is an effective targeted drug delivery agent for boron neutron capture therapy (BNCT). The double emulsion method is used to prepare liposomes. The combination of thin film hydration and ultrasonic dispersion method is used to prepare liposomes loaded with HBA,TBA or BBA. The content and the encapsulation efficiency of HBA,TBA or BBA liposomes are evaluated by high performance liquid chromatography (HPLC). As the basis of the encapsulation efficiency, the optimal conditions for preparing liposomes were explored by the single factor method. The optimal chromatographic conditions of the three drugs were filtered out. They had a good linear relation in a range of 1~100 μg/mL. The encapsulation efficiency of HBA, TBA and BBA liposomes were 25.7 %, 38.9 % and 94.8 % at the optimal preparation and condition. The optimal conditions for preparing BBA liposomes are as follows: the mass ratio of cholesterol and phospholipid is 1∶1, the ratio of drug and lipid is 1∶50 and the optimal pH value is 7.4. The entrapment efficiency for BBA liposomes in the optimal groups reached 94.8 %.The technique of preparing folate-targeted liposomes is feasible and the method of quality control is simple and high accuracy. Theliposomes appeare to be round, and well separated with high entrapment efficiency.
Boron neutron capture therapy (BNCT) is a selective radiotherapy of damage tumor cells, and α particle produced by which is effective to prevent glioblastoma multiform recurrence. Clinical trails of BNCT were carried out in fifties to sixties of 20 century in developed countries, but it was limited because of the development of boron carrier and neutron source. This is a review of BNCT prospect on glioblastoma multiform.
Objective: to evaluate the incorporation of BPA by glioma cell lines, and to observe its relationship with the temperature and the concentration of BPA. Methods: C6, U251 and rat astrocyte cells were incubated in a culture medium, in which 10B concentration was 20, 40, 60, 80, 100 μg/mL for 24 h. Boron concentration in the cells was measured induced couple plasma-atomic emission spectroscopy (ICP-AES). C6 cells were pre-incubated for 24 h with different boron concentrations in growth medium. Then the mediums were changed to boron-free ones, and boron content was assessed after 1, 2, 3 h. Results: The content of the 10B in cells was increasing with the increasing concentration of BPA, and the boron concentration ratios of glioma cells to astrocyte are 2.2. The BPA efflux is slower at the lower temperature. Conclusion: BPA has a selectivity for glioma cells, and the results of the efflux assay confirm the temperature dependence of the BPA transport out of the cells.
Objective: U251 cells were exposed to fast neutrons of 14 MeV energy, and dose-response relationships were derived; Methods:cell samples were exposed to fast neutrons. Radiation doses were 1 Gy, 3 Gy, 5 Gy and 7 Gy respectively. The cell survival, apoptotic rate and proliferation were tested after irradiation; Result: with the growth of the radiation dose, cell survival was declined, and apoptotic rate was promoted; the speed of the cell proliferation, which was observed 48 h after irradiation, was slowed down viously; Conclusion: compared to γ ray, fast neutrons have higher relative biological effectiveness.
Clinical study of boron neutron capture therapy (BNCT) for gliomas has progressed rapidly over the past several decades. However, efficacy of BNCT for brain tumors is far from being perfect at present because of the lack of selectivity of the boron carriers and the characteristics of malignant glioma. Moreover, BNCT may have a significant therapeutic effect on refractory pituitary adenomas which have the malignant characters as well as glioma. This paper reviews the current status of BNCT for human liomas and the possibility to treat refractory pituitary adenomas with BNCT.
Boron neutron capture therapy (BNCT) method was applied to about one thousand clinical patients and achieved good results internationally. In this paper, the principle of BNCT, the development history and international BNCT clinical progress were mainly introduced. The BNCT clinical treatment situation and evaluation in glioblastoma (GBM), malignant melanoma, recurrent head and neck cancer and metastatic liver cancer were discussed in detail.
The characteristic parameters of the neutron radiation fields produced by an in-hospital neutron irradiatior for boron neutron capture therapy(BNCT), such as neutron energy spectra, neutron flux density and neutron absorbed dose rate and their spatial distributions in free air, etc., were measured to verify the design effect. According to the traits of the irradiators, a measuring system composed of a multi-sphere spectrometer, a 235U fission ionization chamber, gold foils, a tissue equivalent proportional counter and thermoluminescent detectors was established. In order to improve the energy resolution in epithermal energy range and the ability to discriminate different neutron components, the Monte Carlo method was used for optimizing the detectors. The preliminary results show that the neutron flux densities of the irradiators achieve the expected levels.