Novel detectors for medical isotopes: Securing theranostics for Canada

医用同位素构成了核成像(例如，用于单光子发射计算机断层扫描(SPECT)的Tc-99m，用于正电子发射断层扫描(PET)的F-18和Ga-68)和治疗癌症治疗(例如，Ac-225、Hg-197)的主干。虽然这些同位素中的一些可以通过发电机获得，但这些同位素或其母同位素通常可以在粒子加速器上生产，特别是回旋加速器。需要进行必要核反应的起始材料可以是固体、气体或液体，通常被安置在金属靶体中；在辐射过程中，大量的能量被沉积在相对较小的体积中。除了核转化之外，人们对靶子内部发生的物理和化学过程的了解还很少；这些过程包括局部加热、物质相变、对流、吸附以及辐射分解和热原子化学等化学反应。所有这些过程都可能导致显著不同的总体目标性能，这可能会影响机器和人员的安全，以及放射性生产产量。这些效应的模拟工作是存在的，但往往限于宏观观测，因为在这些极端环境条件下进行精细和局部测量是困难的，这些极端环境条件包括高温、高压和辐射场。为了改进模拟，以便更充分地了解这些高度相互关联的过程和反应，并推动优化加速器目标以获得更好的性能和追求新的同位素，有必要对内部条件和过程进行更详细的测量，并跟踪辐照条件。这对通过Ra-226或Th-232质子照射的Ac-225等新兴治疗性同位素尤其重要，因为这两种靶材料本身都是放射性的，大规模靶失败可能会产生严重后果，特别是在城市环境中。为了支持我们目前的实验和建模工作，这项建议旨在推进一项研究计划，重点是进一步开发新型和创新的诊断方法，以测量这些极端恶劣环境中的温度、压力、束流沉积和辐射，这些环境中现有的诊断方法在可用性和功能性方面都非常有限。为了实现这一目标，我们将采用和探索包括光纤在内的技术的可行性，并开发定制解决方案。这项研究属于核工程、医学物理、原子和光学物理以及亚原子物理的交叉学科。这项工作的结果将是在设计新的生产硬件方面具有开创性，以获得最大的同位素产量，并为加拿大及其他地区的成像和治疗生产新的同位素。

Medical isotopes form the backbone of nuclear imaging (e.g., Tc-99m for Single Photon Emission Computed Tomography (SPECT), F-18 and Ga-68 for Positron Emission Tomography (PET)) and therapeutic cancer treatments (e.g., Ac-225, Hg-197). While some of these isotopes are available via generators, the isotopes or their parent isotopes, can often be produced on particle accelerators, particularly cyclotrons. The starting material that needs to undergo the necessary nuclear reaction can be solid, gaseous, or liquid and is typically housed in a metal target body; during irradiation, large amounts of power are deposited in a relatively small volume. Beyond the nuclear transformation, the understanding of the physical and chemical processes taking place inside the target are poorly understood; they include local heating, matter phase changes, convection currents, adsorption, and chemical reactions like radiolysis and hot-atom chemistry. All of these processes can lead to a dramatically different overall target performance that can affect both machine and personnel safety, as well as radioactive production yields. Modelling efforts of these effects exist but are often limited to macroscopic observables due to the difficulty in performing fine and localized measurements in these extreme environmental conditions which include high temperatures, pressures, and radiation fields. For improved modelling to more fully understand these highly interconnected processes and reactions, and to push the envelope to optimize accelerator targets for better performance and pursue novel isotopes, more detailed measurement of internal conditions and processes and tracking of irradiation conditions is necessary. This is especially important for the emerging therapeutic isotopes such as Ac-225 via the proton irradiation of Ra-226 or Th-232, as both target materials are themselves radioactive and large-scale target failure could have significant consequences, especially in an urban environment. In support of our current experimental and modelling efforts, this proposal aims to advance a research program focused on the further development of novel and innovative diagnostics to measure temperature, pressure, beam deposition and radiation in these extremely hostile environments, where existing diagnostics are highly limited in both availability and functionality. To achieve this, we will employ and explore the feasibility of technology including optical fibres as well as develop custom solutions. This research falls at the intersection of nuclear engineering, medical physics, atomic and optical physics, and subatomic physics. The result of this work will be ground-breaking in the design of new production hardware for maximal isotope yields, and for the production of novel isotopes for imaging and therapy in Canada and beyond.