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提供治疗剂量的辐射，同时尽量减少对周围正常组织的损害。目前，肿瘤定位是放射治疗中最重要的问题。为了使给药剂量最大化，必须在空间和时间上准确地知道肿瘤的位置，以便在治疗过程中击中目标，其中运动是重要的。为了解释这种位置的不确定性，在治疗期间，肿瘤剂量被传递到肿瘤可能存在的体积。因此，随着定位的不确定性，治疗量和相应的并发症增加。本项目的长期目标是在放疗过程中精确定位肿瘤的实时位置，并满足以下约束条件，以增加对肿瘤的控制：(1)对肿瘤进行实时跟踪定位，并在1秒内获得位置更新；(2)肿瘤位置将以相对于治疗室内定义的坐标系统的三维空间描述，精度小于1mm；(3)探测器将扩展到2-3米或更大的范围。本项目提出的定位系统由(1)可植入的无源发射机，(2)用于给发射机通电的外部偶极子天线，以及(3)超导量子干涉装置（SQUID）磁强计探测系统组成。通电的发射机将产生脉冲磁场，该磁场将被SQUID传感器检测到，然后用于实时定位发射机的位置。本项目第一阶段的工作将专门针对探测器系统的设计。目标是构建一个测量0.1 pT磁场信号的矢量磁强计系统。为了检测这些极低电平的信号，将使用SQUID磁强计作为传感器。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。我们将根据在本项目中进行的测量和实验来设计基本系统。公共卫生相关性：放射治疗中的实时肿瘤跟踪，定位精度小于1mm，将引导辐射到达准确位置。这将减少并发症，并在一定程度上提高对肿瘤的控制，这是现有技术无法做到的。

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.