A NOVEL TISSUE EQUIVALENT PHANTOM FOR HADRON THERAPY

薄硅传感器将集成在机械系统中，用于扫描组织等效液体模体，以提供关于强子治疗光束沉积剂量的极其精确的信息，作为进入模体深度的函数和垂直于光束轴的平面上的位置。这将允许以前所未有的空间分辨率和速度精确了解给患者的剂量（3d剂量测绘）。强子治疗光束在人体内深度沉积的剂量遵循一个典型的分布，在旅行结束时终止于称为布拉格峰的高能量释放。这种高能量沉积被用来最大化对癌症的影响，同时对周围的健康组织造成有限的损害。准确了解光束沉积的能量是对个别患者进行治疗计划的关键。此外，在治疗过程中对布拉格峰位置稳定性的在线监测对于治疗的成功至关重要。由于硅探测器的快速响应，布拉格峰扫描将向操作员提供有关治疗束在目标和周围组织中释放的剂量的实时信息。这个幻影利用了一个薄硅探测器来提高扫描的精度。重建配置文件的精度可以选择精确到10微米（这种精度不需要成本或硬件复杂性损失）。该仪器利用一个单一的敏感元件（硅探测器），由一个精密电机与治疗光束在轴上移动。当光束从模体入口点移动到后端时，传感器连续测量光束的能量沉积。光束在幻影体积内停止，扫描以极高的准确性和实时性提供能量沉积剖面。由于该仪器具有高空间分辨率和实时响应能力，因此与现有的幽灵相比，它将是一个重大改进。在治疗的计划阶段，精度和实时反馈的速度将被证明是非常有价值的。它可以单独用于任何强子治疗中心，也可以与其他现有的光束监测设备结合使用。

A thin silicon sensor will be integrated in a mechanical system for scanning through a tissue equivalent liquid phantom for providing extremely accurate information on the dose deposited by a hadron therapy beam as a function of depth into the phantom and on the position in the plane perpendicular to the beam axis. This will allow a precise knowledge of the dose delivered to the patient (3d dose mapping) with unprecedented spatial resolution and speed. The dose deposited in depth by a hadron therapy beam in the human body follows a typical distribution that terminates with the high energy release called Bragg peak at the end of travel. This high energy deposition is exploited to maximise the effect to the cancer while giving limited amage to the surrounding helthy tissue. The accurate knowledge of the energy deposited by the beam is key to planning the treatment on individual patients. Also, the online monitoring of the Bragg peak position stability during treatment is essential for the success of the treatment.Thanks to the fast response of silicon detectors, the Bragg peak scan will provide real-time information to the operators on the dose to be released by the therapy beam in the target and surrounding tissue. This phantom makes use of a thinned silicon detector to enhance the accuracy of the scan. The precision of the reconstructed profiles can be selected to be as fine as 10 microns (this accuracy comes without cost or hardware complexity penalties). This instrument makes use of a single sensitive element (the silicon detector) moved by a precision motor in axis with the therapy beam. The energy deposition of the beam is continuously measured by the sensor while moved from the entrance point of the phantom to the back end. The beam is stopped within the phantom volume and the scan delivers the energy deposition profile with great accuracy and in real time. This instrument would represent a significant improvement with respect to existing phantoms because of its high spatial resolution and real time response. The precision would prove very valuable at the planning stage of the treatment and the speed for real-time feedback. It could be used at any hadron therapy centre alone or in combination with other existing beam monitoring equipment.