Medical applications of opaque scintillator radiation detectors

该项目旨在开发一种用于医学成像的新型辐射探测器技术，该技术将以更具成本效益的方式大大提高设备的性能。在医学上，为了成像的目的，放射性示踪剂通常被注射到血液中。最常用的一种是基于葡萄糖的，它优先被癌症肿瘤或身体的其他活跃部位吸收，从而集中了放射性。通过发射正电子而衰变的放射性同位素被使用，因为与电子的湮灭会产生两个0.51 MeV的伽马射线，它们以相反的方向（背对背）发射，通常会从身体中逸出。通过记录数千次，甚至数百万次放射性衰变的伽马的位置和时间，可以形成图像。这是正电子发射断层扫描（PET）扫描仪中使用的技术。这些扫描仪的需求不断增长，但其高昂的价格（通常每台扫描仪150万英镑）是限制其可用性的一个因素。用于探测伽马射线的闪烁晶体占成本的很大一部分。该项目的目标是开发一种新的不透明闪烁体探测器，以更经济有效的方式制造更大、更高性能的扫描仪。许多辐射探测器使用闪烁体，闪烁体是一种当伽马射线等辐射击中它们时会发光的材料。传统上，闪烁体一直是透明的，这对于探测光是必要的。在这个项目中应用的新概念是使用不透明闪烁体和光纤电缆晶格的组合。这种不透明性导致光线在产生光线的地方附近反弹，然后纤维将光线提取出来。这样的配置可以以较低的成本实现高分辨率成像功能。在这个项目的前半部分，我们将研究不透明形式的多个闪烁体，以确定它们与不同配置的波长移动光纤电缆结合的性能。这些调查的结果将为我们设计用于医学成像的原型辐射探测器提供信息，该探测器将在项目的后半段建造。

This project is to develop a novel radiation detector technology for medical imaging that will allow devices with substantially improved performance to be built in a more cost-effective way. In medicine radioactive tracers are routinely injected into the blood stream for imaging purposes. The most commonly used one is based on glucose, which is preferentially taken up by cancer tumours or other active parts of the body thus concentrating the radioactivity. Radioisotopes that decay by emitting positrons are used since the annihilation with electrons gives rise to two 0.51 MeV gamma rays that are emitted in opposite directions (back-to-back) and typically escape from the body. Images can be formed by recording the positions and times of the gammas from thousands, or even millions, of radioactive decays. This is the technique used in a Positron Emission Tomography (PET) scanner. These scanners are growing in demand yet their high price (typically £1.5 million per scanner) is a factor that limits their availability. The scintillation crystals used to detect the gamma rays are a substantial fraction of the cost. The objective of this project is to develop a new opaque scintillator detector that will allow larger, higher performance scanners to be built in a more cost-effective way.Many radiation detectors use scintillators, which are materials that give off light when radiation such as gamma rays hits them. Traditionally, scintillators have always been transparent, and this was necessary to allow detection of the light. The new concept that will be applied in this project is to use the combination of an opaque scintillator and a lattice of fibre optic cables. The opacity causes the light to bounce around close to where it is produced and then the fibres extract the light. Such a configuration enables high-resolution imaging capabilities at a lower cost. In the first half of this project we will investigate multiple scintillators in opaque form to establish their performance in combination with different configurations of wavelength shifting fibre optic cables. The results from those investigations will inform our design of a prototype radiation detector for medical imaging that will be built in the second half of the project.