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Izadi Vasafi G, Firoozabadi MM. 10B Concentration, Phantom Size and Tumor Location Dependent Dose Enhancement and Neutron Spectra in Boron Neutron Capture Therapy. J Biomed Phys Eng 2019; 9:653-660. [PMID: 32039096 PMCID: PMC6943846 DOI: 10.31661/jbpe.v0i0.799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 07/23/2017] [Indexed: 12/02/2022]
Abstract
Background: The amount of average dose enhancement in tumor loaded with 10B may vary due to various factors in boron neutron capture therapy Objective: This study aims to evaluate dose enhancement in tumor loaded with 10B under influence of various factors and investigate the dependence of this dose enhancement on neutron spectra changes Material and Methods: In this simulation study, using 252Cf as a neutron source, the average in-tumor dose enhancement factor (DEF) and neutron energy spectra were calculated for various 10B concentrations, phantom with different sizes and for different tumor locations, through MCNPX code. Results: Obtained results showed that the values of average DEF rise with increasing 10B concentration, phantom diameter (˂ 30 cm) and tumor distance from the source, but this increment is not linear Conclusion: It was concluded that inequality in average dose enhancement rates, in tumor loaded with 10B under influence of various factors in boron neutron capture therapy, is due to non-identical changes of both the thermal neutron flux with increasing same number of 10B atoms and same thickness of scattering material, and the thermal to fast neutron flux ratio with increasing equal distances of tumor from the source
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Affiliation(s)
- Gh Izadi Vasafi
- PhD, Department of Physics, Faculty of Sciences, University of Birjand, Birjand, Iran
| | - M M Firoozabadi
- PhD, Department of Physics, Faculty of Sciences, University of Birjand, Birjand, Iran
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Farhood B, Samadian H, Ghorbani M, Zakariaee SS, Knaup C. Physical, dosimetric and clinical aspects and delivery systems in neutron capture therapy. Rep Pract Oncol Radiother 2018; 23:462-473. [PMID: 30263016 PMCID: PMC6158036 DOI: 10.1016/j.rpor.2018.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/08/2018] [Accepted: 07/04/2018] [Indexed: 12/19/2022] Open
Abstract
Neutron capture therapy (NCT) is a targeted radiotherapy for cancer treatment. In this method, neutrons with a spectra/specific energy (depending on the type of agent used for NCT) are captured with an agent that has a high cross-section with these neutrons. There are some agents that have been proposed in NCT including 10B, 157Gd and 33S. Among these agents, only 10B is used in clinical trials. Application of 157Gd is limited to in-vivo and in-vitro research. In addition, 33S has been applied in the field of Monte Carlo simulation. In BNCT, the only two delivery agents which are presently applied in clinical trials are BPA and BSH, but other delivery systems are being developed for more effective treatment in NCT. Neutron sources used in NCT are fission reactors, accelerators, and 252Cf. Among these, fission reactors have the most application in NCT. So far, BNCT has been applied to treat various cancers including glioblastoma multiforme, malignant glioma, malignant meningioma, liver, head and neck, lung, colon, melanoma, thyroid, hepatic, gastrointestinal cancer, and extra-mammary Paget's disease. This paper aims to review physical, dosimetric and clinical aspects as well as delivery systems in NCT for various agents.
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Affiliation(s)
- Bagher Farhood
- Department of Medical Physics and Radiology, Faculty of Paramedicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Hadi Samadian
- Nano Drug Delivery Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Mahdi Ghorbani
- Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Salman Zakariaee
- Department of Medical Physics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Courtney Knaup
- Comprehensive Cancer Centers of Nevada, Las Vegas, NV, USA
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Tissue composition effect on dose distribution in neutron brachytherapy/neutron capture therapy. Rep Pract Oncol Radiother 2016; 21:8-16. [PMID: 26900352 DOI: 10.1016/j.rpor.2015.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 03/07/2015] [Accepted: 05/10/2015] [Indexed: 11/22/2022] Open
Abstract
AIM The aim of this study is to assess the effect of the compositions of various soft tissues and tissue-equivalent materials on dose distribution in neutron brachytherapy/neutron capture therapy. BACKGROUND Neutron brachytherapy and neutron capture therapy are two common radiotherapy modalities. MATERIALS AND METHODS Dose distributions were calculated around a low dose rate (252)Cf source located in a spherical phantom with radius of 20.0 cm using the MCNPX code for seven soft tissues and three tissue-equivalent materials. Relative total dose rate, relative neutron dose rate, total dose rate, and neutron dose rate were calculated for each material. These values were determined at various radial distances ranging from 0.3 to 15.0 cm from the source. RESULTS Among the soft tissues and tissue-equivalent materials studied, adipose tissue and plexiglass demonstrated the greatest differences for total dose rate compared to 9-component soft tissue. The difference in dose rate with respect to 9-component soft tissue varied with compositions of the materials and the radial distance from the source. Furthermore, the total dose rate in water was different from that in 9-component soft tissue. CONCLUSION Taking the same composition for various soft tissues and tissue-equivalent media can lead to error in treatment planning in neutron brachytherapy/neutron capture therapy. Since the International Commission on Radiation Units and Measurements (ICRU) recommends that the total dosimetric uncertainty in dose delivery in radiotherapy should be within ±5%, the compositions of various soft tissues and tissue-equivalent materials should be considered in dose calculation and treatment planning in neutron brachytherapy/neutron capture therapy.
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Neutron capture therapy: a comparison between dose enhancement of various agents, nanoparticles and chemotherapy drugs. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:541-9. [PMID: 24961208 DOI: 10.1007/s13246-014-0284-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 06/05/2014] [Indexed: 10/25/2022]
Abstract
The aim of this study is to compare dose enhancement of various agents, nanoparticles and chemotherapy drugs for neutron capture therapy. A (252)Cf source was simulated to obtain its dosimetric parameters, including air kerma strength, dose rate constant, radial dose function and total dose rates. These results were compared with previously published data. Using (252)Cf as a neutron source, the in-tumour dose enhancements in the presence of atomic (10)B, (157)Gd and (33)S agents; (10)B, (157)Gd, (33)S nanoparticles; and Bortezomib and Amifostine chemotherapy drugs were calculated and compared in neutron capture therapy. Monte Carlo code MCNPX was used for simulation of the (252)Cf source, a soft tissue phantom, and a tumour containing each capture agent. Dose enhancement for 100, 200 and 500 ppm of the mentioned media was calculated. Calculated dosimetric parameters of the (252)Cf source were in agreement with previously published values. In comparison to other agents, maximum dose enhancement factor was obtained for 500 ppm of atomic (10)B agent and (10)B nanoparticles, equal to 1.06 and 1.08, respectively. Additionally, Bortezomib showed a considerable dose enhancement level. From a dose enhancement point of view, media containing (10)B are the best agents in neutron capture therapy. Bortezomib is a chemotherapy drug containing boron and can be proposed as an agent in boron neutron capture therapy. However, it should be noted that other physical, chemical and medical criteria should be considered in comparing the mentioned agents before their clinical use in neutron capture therapy.
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Brandão SF, Campos TPR. Brain tumour and infiltrations dosimetry of boron neutron capture therapy combined with 252Cf brachytherapy. RADIATION PROTECTION DOSIMETRY 2012; 149:289-296. [PMID: 21705767 DOI: 10.1093/rpd/ncr250] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This article presents a dosimetric investigation of boron neutron capture therapy (BNCT) combined with (252)Cf brachytherapy for brain tumour control. The study was conducted through computational simulation in MCNP5 code, using a precise and discrete voxel model of a human head, in which a hypothetical brain tumour was incorporated. A boron concentration ratio of 1:5 for healthy-tissue: tumour was considered. Absorbed and biologically weighted dose rates and neutron fluency in the voxel model were evaluated. The absorbed dose rate results were exported to SISCODES software, which generates the isodose surfaces on the brain. Analyses were performed to clarify the relevance of boron concentrations in occult infiltrations far from the target tumour, with boron concentration ratios of 1:1 up to 1:50 for healthy-tissue:infiltrations and healthy-tissue:tumour. The average biologically weighted dose rates at tumour area exceed up to 40 times the surrounding healthy tissue dose rates. In addition, the biologically weighted dose rates from boron have the main contribution at the infiltrations, especially far from primary tumour. In conclusion, BNCT combined with (252)Cf brachytherapy is an alternative technique for brain tumour treatment because it intensifies dose deposition at the tumour and at infiltrations, sparing healthy brain tissue.
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Affiliation(s)
- Sâmia F Brandão
- Departamento de Engenharia Nuclear, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte 31270-010, Brasil
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Ghassoun J, Mostacci D, Molinari V, Jehouani A. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement. Appl Radiat Isot 2010; 68:265-70. [DOI: 10.1016/j.apradiso.2009.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 09/02/2009] [Accepted: 10/08/2009] [Indexed: 11/30/2022]
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Liu BL, Cheng JX, Zhang X, Zhang W. Controversies concerning the application of brachytherapy in central nervous system tumors. J Cancer Res Clin Oncol 2010; 136:173-85. [PMID: 19956971 DOI: 10.1007/s00432-009-0741-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Accepted: 11/19/2009] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Brachytherapy (BRT) is defined as a therapy technique where a radioactive source is placed a short distance from or within the tumor being treated. Much expectation has been placed on its efficacy to improve the outcome for patients with central nervous system (CNS) tumors due to the initial promising results from single institution retrospective studies. However, these optimistic findings have been highly debated since the selection criteria itself is preferable to other therapeutic modalities. The fact that BRT demonstrated no significant survival advantage in two prospective studies, together with the emerging role of stereotactic convergence therapy as a promising alternative, has further decreased the enthusiasm for BRT. Despite all the negative aspects, BRT continues to be conducted for the management of CNS tumors including gliomas, meningiomas and brain metastases. MATERIAL AND METHODS As many controversies have been aroused concerning the experience and future application of BRT, this article reviews the existing heterogeneities in terms of implants choice, optimal dose rate, targeting volume, timing of BRT, patients selection, substantial efficacy, BRT in comparison with stereotactic convergence therapy techniques and BRT in combination with other treatment modalities (data were identified by Pubmed searches). RESULTS AND CONCLUSION Though it is inconvincible to argue for the routine use of BRT, BRT may provide a choice for patients with large recurrent or inoperable deep-seated tumors, especially with the Glia-site technique. Radiotherapies including BRT may hold more promise if biologic mechanisms of radiation could be better understand and biologic modifications could be added in clinical trials.
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Affiliation(s)
- Bo-Lin Liu
- Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, West Changle Road, Shaanxi Province, People's Republic of China
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Abstract
Over the past several decades neurooncologists have attempted to find an adjuvant treatment that prolongs survival for patients with malignant brain tumors. Brachytherapy, radiotherapy delivered by placing radioactive sources directly into the tumor, was initially thought to be the solution to this problem. Initial single institution studies showed very promising results; however, this technique has failed to show a significant survival advantage in two randomized studies. Despite this, brachytherapy continues to be used in a number of centers throughout the world for the treatment of various types of brain tumors including low-grade gliomas, anaplastic astrocytomas, glioblastomas, meningiomas and metastases. This article reviews brachytherapy's rationale, radiobiology, complications, indications, and results from numerous studies that have focused on its application for brain tumors with emphasis on its application for glial tumors.
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Affiliation(s)
- Todd W Vitaz
- Neurosurgical Service Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
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Burmeister J, Kota C, Maughan RL. Measured Microdosimetric Spectra and Therapeutic Potential of Boron Neutron Capture Enhancement of 252Cf Brachytherapy. Radiat Res 2005; 164:312-8. [PMID: 16137204 DOI: 10.1667/rr3409.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Californium-252 is a neutron-emitting radioisotope used as a brachytherapy source for radioresistant tumors. Presented here are microdosimetric spectra measured as a function of simulated site diameter and distance from applicator tube 252Cf sources. These spectra were measured using miniature tissue-equivalent proportional counters (TEPCs). An investigation of the clinical potential of boron neutron capture (BNC) enhancement of 252Cf brachytherapy is also provided. The absorbed dose from the BNC reaction was measured using a boron-loaded miniature TEPC. Measured neutron, photon and BNC absorbed dose components are provided as a function of distance from the source. In general, the absorbed dose results show good agreement with results from other measurement techniques. A concomitant boost to 252Cf brachytherapy may be provided through the use of the BNC reaction. The potential magnitude of this BNC enhancement increases with increasing distance from the source and is capable of providing a therapeutic gain greater than 30% at a distance of 5 cm from the source, assuming currently achievable boron concentrations.
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Affiliation(s)
- J Burmeister
- Gershenson Radiation Oncology Center, Karmanos Cancer Institute, Harper University Hospital and Wayne State University, Detroit, MI 48201, USA.
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Smoum R, Srebnik M. Boronated saccharides: potential applications. CONTEMPORARY ASPECTS OF BORON: CHEMISTRY AND BIOLOGICAL APPLICATIONS 2005. [DOI: 10.1016/s0169-3158(06)80008-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Shull BK, Spielvogel DE, Head G, Gopalaswamy R, Sankar S, Devito K. Studies on the Structure of the Complex of the Boron Neutron Capture Therapy Drug, L‐p‐Boronophenylalanine, with Fructose and Related Carbohydrates: Chemical and 13C NMR evidence for the β‐D‐Fructofuranose 2,3,6‐(p‐Phenylalanylorthoboronate) Structure. J Pharm Sci 2000. [DOI: 10.1002/(sici)1520-6017(200002)89:2%3c215::aid-jps8%3e3.0.co%3b2-p] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Shull BK, Spielvogel DE, Head G, Gopalaswamy R, Sankar S, Devito K. Studies on the structure of the complex of the boron neutron capture therapy drug, L-p-boronophenylalanine, with fructose and related carbohydrates: chemical and 13C NMR evidence for the beta-D-fructofuranose 2,3,6-(p-phenylalanylorthoboronate) structure. J Pharm Sci 2000; 89:215-22. [PMID: 10688750 DOI: 10.1002/(sici)1520-6017(200002)89:2<215::aid-jps8>3.0.co;2-p] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The complex of L-L-boronophenylalanine (L-p-BPA) with fructose has been used for the past 5 years in clinical trials of boron neutron capture therapy to treat both melanoma and glioblastoma multiforme. However, the structure of this complex in water buffered at physiologic pH has not been established. In the (1)H NMR spectra (D(2)O buffered at pD 7.4) of the complex of L-p-BPA with various carbohydrates, the upfield chemical shifts of the aromatic protons of L-p-BPA confirm that the boron atom is negatively charged and tetrahedral. In the (13)C NMR spectrum of the complex of L-p-BPA with U-(13)C labeled fructose, the chemical shifts and (1)J(CC) coupling constants are consistent with fructose adopting the beta-D-fructofuranose form. In addition, the (1)J(CC) coupling constants along with the binding constants measured for L-p-BPA with a series of monosaccharides and disaccharides seem to suggest that the beta-D-fructofuranose 2,3,6-(p-phenylalanylorthoboronate) structure strongly predominates, with free L-p-BPA and fructose the only other species detected.
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Affiliation(s)
- B K Shull
- Glycosyn Pharmaceuticals, Inc., Cary, North Carolina 27513, USA.
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Barth RF, Soloway AH, Goodman JH, Gahbauer RA, Gupta N, Blue TE, Yang W, Tjarks W. Boron neutron capture therapy of brain tumors: an emerging therapeutic modality. Neurosurgery 1999; 44:433-50; discussion 450-1. [PMID: 10069580 DOI: 10.1097/00006123-199903000-00001] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield alpha particles and recoiling lithium-7 nuclei. For BNCT to be successful, a large number of 10B atoms must be localized on or preferably within neoplastic cells, and a sufficient number of thermal neutrons must be absorbed by the 10B atoms to sustain a lethal 10B (n, alpha) lithium-7 reaction. There is a growing interest in using BNCT in combination with surgery to treat patients with high-grade gliomas and possibly metastatic brain tumors. The present review covers the biological and radiobiological considerations on which BNCT is based, boron-containing low- and high-molecular weight delivery agents, neutron sources, clinical studies, and future areas of research. Two boron compounds currently are being used clinically, sodium borocaptate and boronophenylalanine, and a number of new delivery agents are under investigation, including boronated porphyrins, nucleosides, amino acids, polyamines, monoclonal and bispecific antibodies, liposomes, and epidermal growth factor. These are discussed, as is optimization of their delivery. Nuclear reactors currently are the only source of neutrons for BNCT, and the fission reaction within the core produces a mixture of lower energy thermal and epithermal neutrons, fast or high-energy neutrons, and gamma-rays. Although thermal neutron beams have been used clinically in Japan to treat patients with brain tumors and cutaneous melanomas, epithermal neutron beams now are being used in the United States and Europe because of their superior tissue-penetrating properties. Currently, there are clinical trials in progress in the United States, Europe, and Japan using a combination of debulking surgery and then BNCT to treat patients with glioblastomas. The American and European studies are Phase I trials using boronophenylalanine and sodium borocaptate, respectively, as capture agents, and the Japanese trial is a Phase II study. Boron compound and neutron dose escalation studies are planned, and these could lead to Phase II and possibly to randomized Phase III clinical trials that should provide data regarding therapeutic efficacy.
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Affiliation(s)
- R F Barth
- Department of Pathology, Comprehensive Cancer Center, The Ohio State University, Columbus 43210, USA
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Schmidt B, Maughan RL, Yudelev M, Kota C, Wanwilairat S. Experimental determination of the thermal neutron flux around two different types of high intensity 252Cf sources. Med Phys 1999; 26:83-6. [PMID: 9949402 DOI: 10.1118/1.598471] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The application of neutron emitting radioisotopes in brachytherapy facilitates the use of the higher biological effectiveness of neutrons compared to photons in treating some cancers. Different types of high intensity 252Cf sources are in use for the treatment of different cancers. To improve the therapy of bulky tumors the dose can be augmented by the additional use of the boron capture reaction of thermal neutrons. This requires information about the thermal neutron dose component around the Cf source. In this work, a Mg/Ar-ionization chamber internally coated with 10B was used to measure the thermal neutrons. These measurements were performed on two different 252Cf sources, one in use in the Gershenson Radiation Oncology Center at Harper Hospital in Detroit, MI, and one at the University Hospital of Chiang Mai in Chiang Mai, Thailand. The results of these measurements are compared and indicate that the differences in the construction of the sources influence the thermal dose component.
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Affiliation(s)
- B Schmidt
- Department for Radiation Oncology, University Hospital Eppendorf, University of Hamburg, Germany
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Gahbauer R, Gupta N, Blue T, Goodman J, Barth R, Grecula J, Soloway AH, Sauerwein W, Wambersie A. Boron neutron capture therapy: principles and potential. Recent Results Cancer Res 1998; 150:183-209. [PMID: 9670292 DOI: 10.1007/978-3-642-78774-4_12] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This book on the therapeutic applications of neutrons and high-LET radiations in cancer therapy would not have been complete without a review of the present situation of boron neutron capture therapy (BNCT) and a discussion of its future perspectives. BNCT is a special type of high-LET radiation therapy that attempts to achieve a selectivity at the cellular level. The rationale is to incorporate boron atoms selectively in the cancer cells and then bombard those atoms with thermal neutrons to produce a neutron capture reaction and subsequent decay that emits alpha and lithium particles. The efficiency of the technique depends upon achieving selective incorporation of the boron atoms in the cancer cells and not (or to a lesser extent) in the normal cells. The present status and future directions are described, with emphasis on boron carriers (drugs) and their delivery, as well as physical and treatment planning aspects.
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Affiliation(s)
- R Gahbauer
- Division of Radiation Oncology, Ohio State University, Columbus 43210, USA
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Intercomparative studies of brachytherapy techniques combined with 252CF Boron neutron capture therapy. RADIAT MEAS 1997. [DOI: 10.1016/s1350-4487(97)00116-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Carlsson J, Hartman T, Grusell E. Dose enhancement in fast neutron tumour therapy due to neutron captures in 10B. Acta Oncol 1994; 33:315-22. [PMID: 8018361 DOI: 10.3109/02841869409098423] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
High energy neutrons, applied in fast neutron tumour therapy, lose energy when passing through tissue and are at the end of their trajectories captured in nitrogen, hydrogen or other normally occurring elements. If the tissue contains 10B, which has a very high cross section for capture of thermal neutrons, then disintegration products of this process, helium and lithium ions, give a dose enhancement which, if the boron is targeted to tumour cells, may be beneficial. The dose enhancement was in the present study calculated as a function of the 10B concentration in the cells and as a function of different thermal neutron fluencies. If the tumour cells contained 10 or 100 microns 10B/g the average dose enhancement was about 20 or 200 mGy respectively. This was obtained with the thermal neutron fluency 2.0 x 10(10) n/cm2. The relative biological effectiveness of the neutron capture process is unknown but assuming the factor 2, these doses correspond to 0.04 or 0.4 CGE (cobolt-60 gray equivalent) respectively, which could directly be compared to the 2-3 Gy of low-LET radiation that is daily applied in conventional radiotherapy. However, if thermal or epithermal neutron fields are directly applied to the patients a hundred times higher thermal neutron fluency can be used. This gives, in the cases with 10 or 100 micrograms 10B/g, about a hundred times higher average doses so that 2-20 Gy, corresponding to about 4-40 CGE, can be given to the patients. Thus, a successful targeting with high amounts of 10B in the tumour cells gives a significant dose enhancement when applied in fast neutron therapy but it is then more reasonable to treat the patient directly with thermal or epithermal neutrons since the average dose enhancement in the latter case is about a hundred times higher and curable doses might be obtained by the tumour specific capture processes alone.
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Affiliation(s)
- J Carlsson
- Department of Radiation Sciences, Uppsala University, Sweden
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Abstract
Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when a stable isotope, boron-10 (10B), is irradiated with low-energy thermal neutrons (nth) to yield (4He) alpha-particles and 7Li nuclei (10B+nth-->[11B]-->4He+7Li+2.31 MeV). The success of BNCT as a tumoricidal modality is dependent on the delivery of a sufficient quantity of 10B and nth to individual cancer cells to sustain a lethal 10B(n, alpha) 7Li reaction. The current review covered the radiobiologic considerations on which BNCT is based, including a brief discussion of microdosimetry and normal tissue tolerance. The development of tumor-localizing boron compounds was discussed, including the sulfhydryl-containing polyhedral borane, sodium borocaptate (Na2B12H11SH), and boronophenylalanine (BPA), both of which are currently being used clinically in Japan as capture agents for malignant brain tumors and melanomas, respectively. Compounds currently under evaluation, such as boronated porphyrins, nucleosides, liposomes, and monoclonal antibodies (MoAbs), were also considered. Nuclear reactors have been used as the exclusive source of neutrons for BNCT. The use of low-energy (0.025 eV) thermal neutrons and higher-energy (1-10,000 eV) epithermal beams, beam optimization, and possible alternative neutron sources (accelerators) were also discussed. Clinical studies performed in the United States during the 1950s and 1960s for the treatment of malignant brain tumors were reviewed. Current studies in Japan and future studies in Europe and the United States concerning the treatment of glioblastomas and melanomas by BNCT were discussed, as were critical issues that must be addressed if BNCT is ever to be a useful therapeutic modality.
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Affiliation(s)
- R F Barth
- Department of Pathology, Ohio State University, Columbus 43210
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Abstract
The neutron capture reaction 10B(1n,4He)7Li produces two energetic particles, 4He2+ and 7Li3+ that are strongly cell toxic. Due to the short range of these nuclear fragments (5-9 microns) mainly those cells that have bound or internalized a 10B-containing substance are growth-inactivated. The most critical and difficult step in an efficient boron neutron capture therapy (BNCT) is the tumour targeting. It is today possible to synthesize a large number of boron compounds and conjugate them to tumour-seeking macromolecules, such as monoclonal antibodies or different polypeptides. The boron-containing substances presently considered for therapy are sulfhydryl boron hydride (BSH) and boron-phenylalanine, (BPA) for the treatment of gliomas and malignant melanomas respectively. Other boronated compounds considered are ligands for receptor-amplified tumour cells, antibodies for tumour cells with specific antigens and thioureas for treatment of melanotic melanomas. The required boron concentration is given by the relative dose due to neutron capture in 10B and that of the competing capture reactions in nitrogen and hydrogen. Capture in nitrogen produces protons with a range of about 10-11 microns and this gives a radiation dose to all cells in the neutron activated area. Calculations show that the local concentration of 10B near the critical radiation target, DNA, must be higher than 10 ppm (10 micrograms/g). Increased emphasis will be put on the development of combinations of treatments that fulfil the requirements for attacking the microscopic spread of the tumour.
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Affiliation(s)
- J Carlsson
- Department of Radiation Sciences, Uppsala University, Sweden
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Maruyama Y, Wierzbicki J, Ashtari M, Yaes RJ, Beach JL, Yanch J, Zamenhof R, Schroy CB. Cf-252 neutron capture therapy and teletherapy. Int J Radiat Oncol Biol Phys 1992; 23:255. [PMID: 1572827 DOI: 10.1016/0360-3016(92)90580-b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Maruyama Y, van Nagell JR, Yoneda J, Donaldson ES, Gallion HH, Powell D, Kryscio RJ. A review of californium-252 neutron brachytherapy for cervical cancer. Cancer 1991; 68:1189-97. [PMID: 1873769 DOI: 10.1002/1097-0142(19910915)68:6<1189::aid-cncr2820680602>3.0.co;2-f] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Since 1976 a clinical trial has been conducted to test the feasibility, the potential, and to develop methods for using the neutron-emitting radioactive isotope, californium-252 (Cf-252), for the treatment of cervical cancer. A total of 218 patients were treated in the initial study period from 1976 until 1983. The trials initially treated advanced (Stages III and IV) cervical cancer patients using different doses and schedules; they were extended to include unfavorable presentations of Stages I and II because of favorable results in the initial trials. The authors began to treat patients with Stage IB bulky or barrel-shaped tumors and the majority were treated with both radiation and hysterectomy. Actuarial survival was determined for Stage IB disease and was 87% at 5 years and 82% at 10 years. For those tested with preoperative radiation it was 92% at 5 and 87% at 10 years. For Stage II, it was 62% 5 years and 61% at 10. Survival 5 years after combined radiation and surgical therapy for Stage II disease was 68%. For Stage III, it was 33% at 5 years and 25% at 10. However, 5-year survival using the early neutron implant was 46% versus approximately 19% for delayed Cf-252 or cesium 137. Different schedules and sequences of neutrons and photons greatly altered outcome. Neutron treatment before external photon therapy was better for all stages of disease. Only about 5% of all patients developed complications after neutron therapy. No hematologic or mesenchymal second tumors were observed. Neutron brachytherapy was found to be very effective for producing rapid response and greatly improved local control of bulky, barrel, or advanced cervical cancers. The clinical trial identified and evolved schedules, doses, doses per session, and developed methods different from standard photon therapy but highly effective for local control and cure of cervical cancers of all stages. Clinical and radiobiologic understanding for the use of neutron therapy was greatly advanced by this trial. Future trials will focus on patients with advanced disease and will require evaluation of adjuvant chemotherapy studies and neutron-enhancing chemicals.
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Affiliation(s)
- Y Maruyama
- Department of Radiation Medicine, University of Kentucky Medical Center, Lexington 40536-0084
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