Instrumentation physics of a novel positron-emission based motion and shape tracking technique for medicine

跟踪物体和设备的三维运动在医学物理、工业工程、生物医学工程和医疗保健等领域有着广泛的应用。本计画旨在探讨正电子发射运动追踪技术的基本仪器物理。当前可用的运动跟踪技术包括光学跟踪、电磁跟踪和利用X射线成像的跟踪。然而，每种技术都有其局限性。光学方法无法跟踪腔内的物体。由于干扰的存在，当发射机或接收机靠近金属物体时，电磁跟踪会产生很大的跟踪误差。X射线成像引入显著的辐射剂量。这些技术通常需要最小尺寸的标记物来提供用于精确跟踪的足够的信噪比，这进一步限制了这些技术的应用。所提出的技术用正电子发射同位素标记目标对象。发射出的正电子与周围的电子湮灭，产生成对的背靠背伽马射线。通过检测这些湮灭伽马射线，可以以亚毫米的精度实时重建物体的形状、位置和方向。正电子同位素可以以任何形式嵌入或沉积在靶中，点源标记，线标记，甚至可以“涂”在靶装置的表面上。用于标记的同位素的活性非常低（小于3 MBq），并且对患者和操作者的辐射剂量并不显著：与加拿大人平均接受的4 mSv年剂量相比，操作者在50 cm距离处的辐射剂量小于1 uSv/hr。所提出的技术可以克服上述限制，并可以跟踪对象，目前的技术太小。它的灵活性将导致新的医疗程序的出现。将资助的工作是：1）开发目标运动和形状的跟踪算法。2)开发用于5自由度跟踪的同位素标记技术3）开发专用检测器系统以促进该技术的广泛应用。4)探索在医学和工程中的可能应用。

Tracking the 3D motion of objects and devices has wide application in medical physics, industrial engineering, biomedical engineering and health care. This proposal is to investigate the fundamental instrumentation physics of a positron emission based motion tracking technique. Currently available motion tracking techniques include optical tracking, electromagnetic tracking and tracking with x-ray imaging. However, each technique has its limitations. The optical method cannot track an object inside a cavity. Due to interference, electromagnetic tracking can produce large tracking error when the transmitter or receiver is placed close to a metallic object. X-ray imaging introduces significant radiation dose. These techniques usually require a minimum size of the markers to provide adequate signal to noise ratios for accurate tracking, which further limits the application of these techniques. The proposed technique labels the target object with positron-emitting isotopes. The emitted positrons annihilate with surrounding electrons and produce pairs of back-to-back gamma rays. By detecting these annihilation gamma rays, the shape, location and orientation of the object can be reconstructed in real-time with sub-millimeter accuracy. The positron isotope can be embedded into or deposited on the target in any form, point source marker, line marker and can even be "painted" on the surface of the target device. The activity of isotope for labeling is very low (less than 3MBq) and the radiation dose to the patient and operator is not significant: less than 1 uSv/hr for an operator at 50 cm distance, as compared with 4 mSv annual dose received by an average Canadian. The proposed technique can overcome the above limitations and can track objects that are too small for current techniques. Its flexibility will lead to the emergence of new medical treatment procedures. The work to be funded is to: 1) Develop tracking algorithms for both target motion and shape. 2) Develop isotope labeling techniques for 5 degrees-of-freedom tracking 3) Develop dedicated detector systems to prompt wide application of this technique. 4) Explore possible applications in medicine and engineering.