Dosimetry and Radiobiology for Laser Induced Proton Beams

激光产生的离子束有潜力用于未来的癌症治疗，因为它们可能为目前用于质子和碳离子治疗的离子束提供更紧凑、更便宜的替代来源。离子束治疗相对于高能x射线治疗肿瘤具有相当大的优势，因为通过布拉格峰的能量沉积是确定的。这个博士项目是epsrc资助的一个大型合作项目的一部分，该项目旨在开发具有适合未来治疗用途的激光产生离子束，并测试在正常细胞和肿瘤细胞中暴露于这些离子束的后果。与传统来源相比，激光产生的离子束以极高的剂量率提供辐射剂量，除了探索这种体制的放射生物学外，博士研究的一个关键目标将是确定在这些极端条件下质子和碳剂量测定的有效方法。由于未来临床应用的潜力，目前使用激光驱动源的实验活动致力于开发一种在激光等离子体环境中进行有意义的生物分析的方法，在这种环境中，单次照射可以提供几个Gys的剂量。发展合适的剂量测定方法是本研究过程中面临的一个关键挑战。由于激光驱动离子源的稳定性和可重复性仍然不理想，为了正确估计辐照条件，必须在每次辐照事件过程中可靠地测量剂量，最好是采用非侵入性方式。因此，我们将致力于在与激光驱动离子源相关的特定能量和剂量范围内适当校准薄膜剂量计。这将包括验证定制的无线电铬膜，以及丙氨酸颗粒和CR39粒子轨迹探测器的使用。除了这些相对剂量测定方法之外，该项目还将测试在激光等离子体环境下绝对剂量测定工具（如法拉第杯和离子量热计）的有效性。

Laser-generated ion beams have the potential to be used for future cancer therapies as they may provide compact, less expensive alternative sources to those currently used for proton and carbon-ion therapies. Ion-beam therapies have considerable advantages for treating tumours relative to high energy X-rays due to the defined deposition of energy via a Bragg Peak. This PhD project forms part of a large, EPSRC-funded collaborative effort aimed to develop laser-generated ion beams with properties suitable for future use in therapy, and test the consequences of exposure to these beams in normal and tumour cells. Laser produced ion beams deliver radiation dose at extremely high dose-rates in comparison to conventional sources and, in addition to exploring the radiobiology of this regime, a key goal of the PhD research will be to define effective approaches for proton and carbon dosimetry under these extreme conditions. Motivated by the potential for future clinical applications, current experimental activities employing laser-driven sources are devoted to developing a methodology for carrying out meaningful biological assays in a laser-plasma environment , where doses of the order of several Gys can be delivered in a single irradiation. The development of appropriate approaches to dosimetry is a key challenge to be faced in the course of this research. Since the stability and reproducibility of laser-driven ion sources is still not ideal, for a correct estimate of the irradiation conditions, the dose must be measured reliably in the course of every irradiation event, ideally in a non-invasive manner. We will therefore devote effort to the appropriate calibration of film dosimeters in the specific energy and dose range of relevance to the laser-driven ion sources. This will include the validation of customised radio chromic films, as well as the use of alanine pellets and CR39 particle track detectors. In addition to these approaches to relative dosimetry, the project will aim to test the effectiveness in a laser-plasma environment of tools for absolute dosimetry such as Faraday cups and ion calorimeters.