Radiation Hard X-Ray Detector for Image-Guided Proton Beam Cancer Therapy

描述（由申请人提供）：质子束癌症治疗正在迅速成为美国的主流技术，提供了成功治疗癌症的潜力，同时对邻近健康组织的损伤最小。质子束治疗的主要优点是它能够靶向患者体内的小组织体积，具有非常高的精度，可能精确到一毫米的分数。精确度远高于x射线放射治疗。减少对健康组织的损害直接转化为更少的副作用和更短的患者恢复时间。实现质子束治疗的最大效益需要一种图像引导的方法，因为质子束治疗的靶向准确性很容易受到患者运动的影响，无论是由于固定不足还是由于患者呼吸或心血管活动导致的不可避免的运动。目前质子束癌治疗的实践并没有使用图像引导的方法。通常，在质子束照射之前进行数字x射线摄影（通常从两个正交视图），以构建肿瘤的三维x射线图像以进行靶向。这种x射线成像必须在关闭质子束的情况下离线进行，因为质子辐照会产生巨大的中子通量，这会迅速破坏硅基x射线探测器面板。实际的质子束治疗通常是延迟的，直到x射线探测器被收回到屏蔽物后面。在SBIR的努力中，结构材料工业公司（SMI） www.structuredmaterials.com将开发一种x射线成像系统，该系统对质子和中子等粒子束辐射的破坏具有很高的抵抗力。所提出的x射线探测器系统可以在质子束癌症治疗之前直接使用，甚至在质子束癌症治疗期间就地使用，使癌症治疗选择能够最大限度地利用质子束的好处。我们的技术方法将使用人造金刚石薄膜作为x射线探测器中的活性半导体材料，而不是目前的技术硅。金刚石用于辐射探测器有许多优点，包括高灵敏度、低噪声和优异的辐射硬度，这将在本提案中进一步详细说明。合成金刚石技术的最新发展使这种材料可用于电子应用，而且价格低廉。

DESCRIPTION (provided by applicant): Proton beam cancer therapy is fast becoming a mainstream technology in the US, offering the potential for successful cancer treatment with minimum damage to adjacent healthy tissue. The main advantage of proton beam therapy is its ability to target small tissue volumes within a patient, with very high precision, potentially down to fractions of a millimeter. Precisions far greater than can be achieved with x-ray radiotherapy. The reduced damage to healthy tissue translates directly to fewer side effects and shorter patient recovery times. Achieving the maximum benefit of proton beam therapy requires an image-guided approach, since the targeting accuracy of proton beam therapy is easily compromised by patient motion, either as a result of insufficient immobilization or the inevitable motion due to patient respiration or cardiovascular action. Present practice for proton beam cancer therapy does not use an image-guided approach. Typically, digital x-ray radiography is done prior to proton beam irradiation, (usually from two orthogonal views), to construct a 3-D x-ray image of the tumor for targeting. This x-ray imaging must be done off-line, with the proton beam switched off, since proton irradiation creates a significant neutron flux, which rapidly destroys silicon-based x-ray detector panels. The actual proton beam treatment is typically delayed, until the x-ray detectors are retracted behind shielding. In this SBIR effort, Structured Materials Industries, Inc., (SMI) www.structuredmaterials.com, will develop an x-ray imaging system, which is highly resistant to damage by particle beam radiation such as protons and neutrons. The proposed x-ray detector system can be used directly prior to, or even in-situ during proton beam cancer therapy, enabling cancer treatment options that take maximum advantage of the benefits of proton beams. Our technical approach will use thin films of man-made diamond, as the active semiconductor material in the x-ray detector, instead of present technology silicon. Diamond has a number of advantages for use in radiation detectors, including high-sensitivity, low-noise and excellent radiation hardness, as will be detailed further in this proposal. Recent developments in technology to produce synthetic diamond are now making this material available and affordable for electronic applications. PUBLIC HEALTH RELEVANCE: The proposed x-ray imaging system will enable high precision dose delivery, during proton beam cancer therapy. This increased accuracy will enable destruction of cancerous tissue, with minimal damage to adjacent healthy tissue, even with the inevitable organ movement due to patient respiration and cardiovascular action. Greater beam position accuracy will enable treatment of advanced tumors, small tumors and tumors intimately adjacent to healthy organs, as well as lead to shorten recovery times.