Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany.
Authors contributed equally.
Phys Med Biol. 2020 Dec 22;65(24):245045. doi: 10.1088/1361-6560/abc832.
A deeper understanding of biological mechanisms to promote more efficient treatment strategies in proton therapy demands advances in preclinical radiation research. However this is often limited by insufficient availability of adequate infrastructures for precision image guided small animal proton irradiation. The project SIRMIO aims at filling this gap by developing a portable image-guided research platform for small animal irradiation, to be used at clinical facilities and allowing for a precision similar to a clinical treatment, when scaled down to the small animal size. This work investigates the achievable dosimetric properties of different lowest energy clinical proton therapy beams, manipulated by a dedicated portable beamline including active focusing after initial beam energy degradation and collimation. By measuring the lateral beam size in air close to the beam nozzle exit and the laterally integrated depth dose in water, an analytical beam model based on the beam parameters of the clinical beam at the Rinecker Proton Therapy Center was created for the lowest available clinical beam energy. The same approach was then applied to estimate the lowest energy beam model of different proton therapy facilities, Paul Scherrer Institute, Centre Antoine Lacassagne, Trento Proton Therapy Centre and the Danish Centre for Particle Therapy, based on their available beam commissioning data. This comparison indicated similar beam properties for all investigated sites, with emittance values of a few tens of mm·mrad. Finally, starting from these beam models, we simulated propagation through a novel beamline designed to manipulate the beam energy and size for precise small animal irradiation, and evaluated the resulting dosimetric properties in water. For all investigated initial clinical beams, similar dosimetric results suitable for small animal irradiation were found. This work supports the feasibility of the proposed SIRMIO beamline, promising suitable beam characteristics to allow for precise preclinical irradiation at clinical treatment facilities.
为了深入了解促进质子治疗更有效治疗策略的生物学机制，需要在临床前辐射研究方面取得进展。然而，这通常受到临床设施中用于小动物质子辐照的精确图像引导的基础设施不足的限制。SIRMIO 项目旨在通过开发一种用于小动物辐照的便携式图像引导研究平台来填补这一空白，该平台可在临床设施中使用，并在缩小到小动物尺寸时达到与临床治疗相似的精度。这项工作研究了不同最低能量临床质子治疗束的可实现剂量学特性，这些特性通过专用的便携式束线进行操纵，包括初始束能量降低后的主动聚焦和准直。通过测量靠近束喷嘴出口的空气中的横向束尺寸和水中的横向积分深度剂量，为 Rinecker 质子治疗中心的临床束的束参数创建了基于分析的束模型，用于最低可用的临床束能量。然后，我们应用相同的方法来根据 Paul Scherrer 研究所、Antoine Lacassagne 中心、特伦托质子治疗中心和丹麦粒子治疗中心的可用束调试数据来估算不同质子治疗设施的最低能量束模型。该比较表明，所有研究地点的束特性相似，发射度值为几十毫米·毫拉德。最后，从这些束模型出发，我们模拟了通过一种新型束线的传播，该束线旨在操纵束能量和大小以进行精确的小动物辐照，并评估了水的结果剂量学特性。对于所有研究的初始临床束，都发现了适合小动物辐照的类似剂量学结果。这项工作支持了拟议的 SIRMIO 束线的可行性，有望提供适合的束特性，以允许在临床治疗设施中进行精确的临床前辐照。
