Boron Neutron Capture Therapy

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There are not many cancers for which it has been confirmed that particle therapy is more effective than general radiotherapy.Can be used to treat almost all types of malignancies.*Difficult to apply to recurrent or multiple cancers.●Choroid melanoma●Bone and soft-tissue tumors, sarcomas●Head and neck cancers that exhibit resistance to radiation●Choroid melanoma●Bone and soft-tissue tumors, sarcomas●Head and neck cancers that exhibit resistance to radiation●Untreated malignant brain tumors●Untreated malignant melanoma●Untreated malignant brain tumors●Untreated malignant melanoma●Untreated malignant brain tumors●Untreated malignant melanoma●Untreated malignant brain tumors●Untreated malignant melanoma●Recurrent malignant brain tumors●Recurrent malignant melanoma●Malignant pleural mesothelioma●Multiple lung metastases●Local recurrent breast cancer●Multiple liver tumors●Carcinoma in situ of the bladder●Recurrent malignant brain tumors●Recurrent malignant melanoma●Malignant pleural mesothelioma●Multiple lung metastases●Local recurrent breast cancer●Multiple liver tumors●Carcinoma in situ of the bladder●Recurrent malignant brain tumors●Recurrent malignant melanoma●Malignant pleural mesothelioma●Multiple lung metastases●Local recurrent breast cancer●Multiple liver tumors●Carcinoma in situ of the bladder●Recurrent malignant brain tumors●Recurrent malignant melanoma●Malignant pleural mesothelioma●Multiple lung metastases●Local recurrent breast cancer●Multiple liver tumors●Carcinoma in situ of the bladder●Recurrent head and neck cancers●Multiple brain metastases●Recurrent head and neck cancers●Multiple brain metastasesGeneral radiotherapySingle liver cancerEarly-stage lung cancerProstate cancerSingle liver cancerEarly-stage lung cancerProstate cancer●●●ParticleradiotherapyBNCTBoron neutron capture therapyRecently, high-precision radiotherapy has been praised for the ability to selectively target tumors with pinpoint preci-sion, allowing them to be selectively targeted and irradiated while leaving normal tissue unexposed. This characteriza-tion constitutes a misapprehension and is not at all correct. Proton therapy and carbon ion therapy that use the Bragg peak expose normal tissue to large doses of radiation before the particles reach the tumor, as shown in the figure. Moreover, normal tissue (cells) surrounding the tumor and inside the tumor receive the same dose as the tumor itself. By contrast, BNCT, which allows selective irradiation of cells, differs radically from these approaches. Even normal cells inside the GTV receive a dose that differs completely from tumor cells. The difference is clear when illustrated with DVH (see figure): observe that the curves for the normal tissue dose and the tumor (cell) dose do not intersect anywhere. Except for BNCT, there is no treatment in which the DVH curves are completely dissociated from one another. BNCT can administer a dose of radiation to tumors (cells) selectively, making it appropriate to call the technique pinpoint radiotherapy.X-ray therapy, which offers coverage for a broad range of cancer types and stages, plays a major role in cancer radiotherapy, and this fact is unlikely to change in the future. It is thought that the application of both proton thera-py and carbon ion therapy overlaps considerably with X-ray therapy. By contrast, insofar as it allows cells to be selec-tively irradiated, BNCT has an advantage in that it can be used to treat cancers and stages to which X-ray therapy, proton therapy, and carbon ion therapy are ill suited due to the principles on which they are based. If boron compounds that accumulate even more selectively in tumors can be developed in the future and the limits on treatment depth resolved, the time may come when BNCT can be used to treat as broad a range of cancers as X-ray therapy. The following figure illustrates likely applications and distinctions from other radiotherapy approaches.Characteristics and role of BNCT in cancer radiotherapyCancer radiotherapy with different high-level selectivityRoles and applications of BNCT in cancer radiotherapy1009080706050403020100501001500100755025002468101214161820X-rays (10 MV)ProtonsDepth (cm)BrainTumorVolume(%)Dose(Gy-eq)Dose peak created by overlapping proton beams with different energy levels (to form an expanded Bragg peak)681012141X-raysas-X-rays (Depth (cm)CancerThe dose at the entrance rises when an expanded Bragg peak is created.6

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