Bone analogue phantoms: redefining standards in patient specific MRT dosimetry

分子放射治疗（MRT）是一个相对常见的程序与发达国家的医疗保健系统。在这个过程中，一种标记的放射性同位素被施用于身体，以照射和杀死肿瘤细胞，同时保留周围的健康器官组织。仅在英国，就有大约200个科室每年进行超过11000次磁共振成像，在28个欧盟国家进行约20万次治疗。在个性化医疗保健的最新发展中，引入了新的欧盟指令2013/59，要求所有实施任何形式的放射治疗（包括MRT）的成员国必须在2018年2月6日之前为每位患者提供剂量学治疗计划。虽然这听起来似乎是一个显而易见的情况，但MRT实际上已经在临床上使用了大约75年，没有完全建立的剂量学实践来计算肿瘤目标或危险器官的吸收剂量。尽管已经商定了一般步骤，但目前用于确定剂量的图像的获取、质量和处理仍然存在很大差异。因此，治疗方案往往是根据相对少数患者的经验在当地发展起来的。虽然这些病人都接受了类似的给药活动，但对特定器官的实际剂量可能会有很大的差异。由于所涉及的复杂性，放射性核素剂量测定的应用仅限于那些有能力开发内部技术的学术团体。目前很少有治疗中心能够将剂量计算验证到已知的准确性水平，只有少数学术治疗中心可以进行MRT蒙特卡罗（MC）计算。我们的团队是由曼彻斯特大学和克里斯蒂联合成立的，已经开发出了在一个非常大的捷运实践中提供这种服务的能力。我们最近被选中领导欧盟在EMPIR mrtdose metry项目（2016-19）中验证模拟患者幻影和物理3D打印幻影的剂量计算。该项目将为临床实施MRT剂量计划提供一个标准化的欧洲框架。在我们的方法中，由STFC Mini-IPS资助开发，3d打印的患者模拟物（幻影）是基于患者的CTimages构建的。这项新技术具有明确的潜力，为临床服务提供基础，为英国所有临床中心和MRT患者提供改进活动量化的基础。我们在提供这项工作方面具有独特的优势，可以访问克里斯蒂的MRT患者数据的大型数据库。利用这些数据，我们可以为建立未来的国家临床服务提供基础。克里斯蒂在MRT剂量学研究和为提供MRT剂量学服务所需的国家临床服务（PET/CT）提供培训和支持方面都有经验。此外，我们的合作与工业界有着密切的联系，特别是爱马仕医疗解决方案有限公司，核医学工作站软件的领先供应商。通过开发临床剂量测定系统的综合验证方法，从而证明hermes剂量测定系统符合这一标准，我们的合作将能够为临床剂量测定系统提供事实上的验证标准和市场领先的一揽子方案。这些联系为将这些技术推广到更广泛的欧盟和国际核医学市场提供了途径。反过来，这可以根据疾病反应修改治疗方法，从而改善患者的治疗效果，同时也使医疗保健提供者在相同或更少的资源下获得最大的结果，从而受益。

Molecular Radiotherapy (MRT) is a relatively common procedure in counties with developed healthcare systems. In thisprocedure, a labelled radioisotope is administered to the body in order to irradiate and kill tumour cells whilst sparing thesurrounding healthy organ tissue. In the UK alone, there are some 200 departments performing over 11000 MRTs annuallyand ~200,000 therapies in some 28 EU countries.In a recent development towards personalised healthcare, a new EU directive 2013/59 was introduced which requires thatall Member states performing any form of radiotherapeutics (including MRT) must provide dosimetry treatment planning foreach patient by 6th February 2018. Although this may sound like an obvious situation, MRT has in fact been used clinicallyfor around 75 years with no fully established dosimetry practice for calculating the absorbed dose delivered to tumourtargets or to organs at risk. Even though the general steps have been agreed, there still exists a wide variation in thecurrent acquisition, quality and treatment of images used to determine dose. As a result, treatment protocols have oftenevolved locally, based on experience with a relatively small numbers of patients. Although such patients would all havereceived similar administered activities, the actual dose received to particular organs could have large variations.As a consequence of the complexities involved, the application of radionuclide dosimetry has been restricted to thoseacademic groups with the facilities to develop in-house techniques. Very few therapy centres currently can validate dosecalculations to a known level of accuracy and only a few academic therapy centres can perform MRT Monte Carlo (MC)calculations. Our group, established between The University of Manchester and The Christie, has developed the ability todeliver this within a very large MRT practice. We were recently selected to lead the EU work on validating dose calculations from simulated patient phantoms and physical 3D printed phantoms in the EMPIR MRTDosimetry project (2016-19). Theproject will provide a standardised European framework for clinical implementation of MRT dose planning. In our approach,developed with an STFC Mini-IPS grant, 3D-printed patient analogues (phantoms) are constructed based on patient CTimages. This novel technique has clear potential to provide the foundation of a clinical service to provide a basis forimproved activity quantification to all clinical centres and MRT patients in the UK.We are uniquely positioned to deliver this work, having access to a large data base of MRT patient data at The Christie.Working with these data, we can provide the foundation for establishing a future national clinical service. The Christie hasthe experience in both MRT dosimetry research and in providing training and support for a national clinical service(PET/CT) required to provide a MRT dosimetry service. In addition our collaboration has strong links with industry, inparticular Hermes Medical Solutions Ltd, a leading provider of nuclear medicine workstation software. By developing acomprehensive validation methodology for clinical dosimetry systems, and thereby demonstrating that the HERMESdosimetry system meets this standard, our collaboration will be able to provide a de-facto validation standard for clinicaldosimetry systems and a market leading package. These links provide a pathway to distribute the techniques to the widerEU and international nuclear medicine market. In turn, this improves patient outcomes by allowing modification of therapybased on disease response and also benefits the healthcare provider by maximising outcome for the same or reducedresource.