ABSTRACT
Boron neutron capture therapy is a method based on 10B (n,α) 7Li reaction to achieve malignancy treatment. Upon entry into the human body, the 10B compound carrier can selectively enriched in tumor cells and reacts with external irradiation neutrons. Because 7Li (4 μm) and α particles (7 μm) will be deposited in a cell magnitude (10 μm), the purpose of directional local killing of tumor cells and causing less harm to normal tissue can be achieved successfully. So far, boron neutron capture therapy has been clinically studied in a variety of malignant diseases, including glioblastoma multiforme, meningeoma, head and neck cancer, lung cancer, etc. In this article, the clinical research progress of boron neutron capture treatment in head and neck carcinomas was mainly introduced.
ABSTRACT
Boron neutron capture therapy (BNCT) is an emerging treatment modality. BNCT is performed by injecting patients with the boron containing drugs, which has strong affinity with cancer cells. After undergoing irradiation with neutrons, the boron containing drugs can yield alpha and lithium particles, which can kill tumor cells precisely. To date, clinical studies of BNCT have been conducted in a variety of tumors, including glioblastoma multiforme, meningioma, head and neck cancer, sarcoma, malignant skin tumor, malignant melanoma and recurrent cancers, etc. With continuous construction of BNCT treatment centers around the world, this new technology will be quickly and comprehensively spread. In this article, clinical research progress in the application of BNCT for glioma treatment was reviewed.
ABSTRACT
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.
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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.
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Boron neutron capture therapy(BNCT), a promising radiotherapy, belongs to precision treatment for cancers. BNCT can accurately kill cancer cells and protect normal cells at the same time relying on 10B compounds with high efficacy. The research about developing new 10B compounds is in progress, and novel and efficient 10B compounds are emerging, which greatly facilitate broadening the advantages and efficacy of BNCT. Considering the mixed rays generated from the BNCT process, its biological effects on tumor cells are relatively complex, and related studies are still lacking. The molecular mechanisms underlying BNCT need to be elucidated further. BNCT has been applied in the treatment of malignant brain tumors, head and neck cancers, and malignant melanoma with favorable curative effects. This review mainly focuses on the development of 10B compounds, biological mechanisms, potential advantages, and clinical applications.
ABSTRACT
Boron neutron capture therapy (BNCT) is an advanced method of precision radiotherapy for tumors. In BNCT, 10B enriched boron carriers enter and gather within tumor cells, then a thermal neutron beam triggers the 10B (n, α) 7Li reaction to release alpha and 7Li particle with low energy, which can kill tumor cells. Compared with conventional radiotherapy, BNCT has the characteristics of higher biological effect, more precise targeting, less damage to normal tissues and less treatment times. In this article, recent progress and existing problems of BNCT-related clinical research were reviewed.
ABSTRACT
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.
ABSTRACT
La simulación de un haz de neutrones se realizó para determinar la mejor energía de estos en el tratamiento de tumores bien profundos en la terapia por captura de neutrones del boro. Dos figuras de mérito, la máxima dosis absorbida en tejido sano y la dosis absorbida en el tumor a determinada profundidad dentro del cerebro, se utilizaron para evaluar la eficiencia del tratamiento. Se estudiaron el tiempo de irradiación, la ganancia terapéutica y la cantidad de potencia generada en el blanco, como parámetros de la calidad del haz. Se diseñaron y optimizaron moderadores, reflectores y delimitadores para moderar los neutrones de alta energía, producidos en la reacción de fusión 
(d;n)
, hasta un espectro de energías útiles para la terapia. Se utilizaron uranio metálico y manganeso para la moderación de neutrones rápidos a epitérmicos, mientras que el compuesto Fluental
se utilizó para el ajuste final del espectro. Se propuso un blanco semiesférico para disipar el doble de la cantidad de potencia generada en el blanco, y disminuir las dimensiones del moderador. Todos los cálculos se realizaron utilizando el código de simulación MCNP-4C. Una vez obtenida la mejor configuración del moderador, se obtuvieron las distribuciones de dosis en la cabeza y el cerebro. La ganancia terapéutica se aumentó en un 9%, a la vez que la corriente requerida para una hora de tratamiento, así como las dimensiones del moderador disminuyeron en un 50%.
A monoenergetic neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy. Two figures-of-merit, i.e. the absorbed dose for healthy tissue and the absorbed tumor dose at a given depth in the brain are used to measure the neutron beam quality. Also irradiation time, therapeutic gain and the power generated in the target are utilized as beam assessment parameters. Moderators, reflectors and delimiters are designed and optimized to moderate the high-energy neutrons from the fusion reactions 
(d;n)
and (d;n)
down to a suitable energy spectrum. Metallic uranium and manganese are successfully tested for fast-to-epithermal neutron moderation as well as FluentalTM for the neutron spectrum shifting. A semispherical target is proposed in order to dissipate twice the amount of power generated in the target, and decrease all the dimensions of the BSA. The cooling system of the target is also included in the calculations. Calculations are performed using the MCNP code. After the optimization of our beam-shaper a study of the dose distribution in the head had been made. The therapeutic gain is increased in 9% while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for Boron Neutron Capture Therapy.
ABSTRACT
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.
Subject(s)
Fast Neutrons , Neutron Capture Therapy , Neutrons , Relative Biological Effectiveness , WaterABSTRACT
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
ABSTRACT
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.
Subject(s)
Argon , Bismuth , Boron Neutron Capture Therapy , Boron , Cyclotrons , Electric Power Supplies , Fast Neutrons , Hope , Korea , Magnesium , Neutrons , Nuclear Reactors , Paraffin , Plastics , WaterABSTRACT
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