SQUID magnetometer detection system for real-time tumor tracking

描述（由申请人提供）：放射治疗的目标是向肿瘤输送治疗剂量的放射，同时最大限度地减少对周围正常组织的损伤。目前，肿瘤定位是辐射递送中关于实现治愈性辐射剂量的最重要的问题。为了使递送剂量最大化，必须在空间和时间上准确地知道肿瘤位置，以在运动很重要的治疗期间击中目标。为了解决这种位置不确定性，将肿瘤剂量递送到治疗期间肿瘤可能所在的体积。因此，治疗体积和相应的并发症随着定位不确定性而增加。该项目的长期目标是在放射治疗期间准确定位实时肿瘤位置，同时满足以下限制条件，以提高肿瘤控制：（1）将通过实时跟踪定位肿瘤，其中位置更新将在1秒内获得;（二）肿瘤位置将相对于在治疗室内限定的坐标系以小于1 mm;以及（3）探测器将扩展到2-3米或更大的范围。为该项目提出的定位系统由（1）植入式无源发射器，（2）用于激励发射器的外部偶极天线，以及（3）超导量子干涉器件（SQUID）磁力计检测系统组成。通电的发射器将产生脉冲磁场，该脉冲磁场将由SQUID传感器检测，然后用于实时定位发射器位置。该项目的第一阶段工作将具体涉及探测器系统设计。我们的目标是构建一个矢量磁强计系统，将测量磁场信号的水平为0.1 pT。为了检测这些极低水平的信号，SQUID磁强计将被用作传感器。尽管它们的灵敏度很大，但噪声是一个主要问题，需要特定的滤波和设计才能检测到这些信号。我们将根据本项目中进行的测量和实验设计基本系统。公共卫生相关性：放射治疗中的实时肿瘤跟踪，位置精度小于1 mm，将引导放射到准确的位置。这将减少并发症并将肿瘤控制提高到现有技术无法达到的程度。

DESCRIPTION (provided by applicant): The goal of radiation therapy is to deliver a curative dose of radiation to the tumor while minimizing the damage to the surrounding normal tissue. Currently, tumor localization is the most significant problem in radiation delivery with respect to achieving curative radiation doses. In order to maximize the delivery dose, the tumor position must be accurately known in both space and time to hit the target during treatment where motion is important. To account for this location uncertainty, tumor dose is delivered to the volume where the tumor might be during treatment. Therefore, the treatment volume and corresponding complications increase with positioning uncertainty. The long term goal of this project is to accurately locate the real-time tumor position during radiation treatment with the following constraints necessary for increasing tumor control: (1) the tumor will be located with real-time tracking where position updates will be acquired within one second; (2) the tumor position will be described in three dimensions relative to a coordinate system defined within the treatment room with an accuracy of less than 1 mm; and (3) the detectors will be extended to ranges that are 2-3 meters or greater. The localization system proposed for this project is made of an (1) implantable, passive transmitter, (2) an external dipole antenna for energizing the transmitter, and (3) a superconducting quantum interference device (SQUID) magnetometer detection system. The energized transmitter will generate a pulsed magnetic field that will be detected by the SQUID sensors which will then be used to locate the transmitter position in real-time. This phase I work of this project will specifically address the detector system design. The goal is to construct a vector magnetometer system that will measure the magnetic field signal at a level of 0.1 pT. In order to detect these extremely low level signals, SQUID magnetometers will be used as the sensors. Even though their sensitivity is large, noise is a major problem that requires specific filtering and design in order to detect these signals. We will design the basic system from measurements and experiments conducted within this project. PUBLIC HEALTH RELEVANCE: Real-time tumor tracking in radiation therapy, with positional accuracies less than 1 mm, will guide radiation to the exact location. This will reduce complications and increase tumor control to the extent that has not been possible with existing technologies.