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在发达的医疗保健系统的县。在这一过程中，一种标记的放射性同位素被注入人体，以照射和杀死肿瘤细胞，同时保护周围的健康器官组织。仅在英国，就有大约200个部门每年进行超过11000次MRT，在大约28个欧盟国家进行约200，000次治疗。新的欧盟指令2013/59要求所有实施任何形式放射治疗的成员国（包括MRT）必须在2018年2月6日之前为每位患者提供剂量测定治疗计划。虽然这听起来像是一个明显的情况，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传递到肿瘤靶点或危险器官的吸收剂量。尽管一般步骤已达成一致，但用于确定剂量的图像的当前采集、质量和处理仍存在很大差异。因此，治疗方案往往是局部性的，基于相对少数患者的经验。尽管这些病人都接受了类似的管理活动，但特定器官所接受的实际剂量可能有很大的差异。由于所涉及的复杂性，放射性核素剂量测定的应用一直局限于具有开发内部技术设施的学术团体。目前，只有极少数治疗中心可以验证剂量计算达到已知的准确度水平，只有少数学术治疗中心可以进行MRT Monte Carlo（MC）计算。我们的团队，建立在曼彻斯特大学和克里斯蒂之间，已经开发出在一个非常大的MRT实践中提供这种能力。我们最近被选中领导欧盟在EMPIR MRT剂量测量项目（2016-19）中验证模拟患者体模和物理3D打印体模的剂量计算工作。该项目将为MRT剂量计划的临床实施提供一个标准化的欧洲框架。在我们的方法中，利用STFC Mini-IPS赠款开发，基于患者CT图像构建3D打印的患者模拟物（phantomy）。这项新技术有明显的潜力为临床服务提供基础，为英国所有临床中心和MRT患者提供改进的活动量化基础。我们在提供这项工作方面处于独特的地位，可以访问科视Christie的MRT患者数据的大型数据库。通过这些数据，我们可以为建立未来的国家临床服务提供基础。科视Christie在MRT剂量学研究以及为国家临床服务（PET/CT）提供MRT剂量学服务所需的培训和支持方面都有丰富的经验。此外，我们的合作与行业有着密切的联系，特别是爱马仕医疗解决方案有限公司，一家领先的核医学工作站软件供应商。通过为临床剂量测定系统开发全面的验证方法，从而证明HERMES剂量测定系统符合该标准，我们的合作将能够为临床剂量测定系统和市场领先的包装提供事实上的验证标准。这些链接提供了一条将技术推广到更广泛的欧盟和国际核医学市场的途径。反过来，这通过允许基于疾病反应的治疗修改来改善患者的结果，并且还通过最大化相同或减少的资源的结果而使医疗保健提供者受益。

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.