Design of a flood source for calibration of gamma cameras used in nuclear medicine imaging

全世界每天进行超过4000万例核医学手术，其中约200万例在加拿大。 一般来说，这些测试产生用于诊断的心脏，肺和癌症的图像。 这些图像是用伽马相机产生的，需要每天校准。 重要的是，摄像机应进行校准，以便在图像中的所有点均匀记录，这样医生在寻找图像中的细微变化时就不会被摄像机伪影所迷惑。 目前，确保相机响应均匀性的校准是用放射性盘形“泛源”完成的，该辐射源照亮整个相机视场。 这些放射源工作正常，但必须经常更换，而且放射性很强，因此必须使用特殊程序和屏蔽，以尽量减少技术人员的辐射暴露。 这个Engage提案测试了一个有前途的新设计概念的可行性，该概念可以远程打开和关闭洪水源。 与目前使用的单一放射源不同，新设计将采用三种元素。 第一个会发射α粒子，第二个会吸收这些α粒子并发射中子，第三个会捕获中子并发射用于校准相机的伽马射线。 该概念的优点在于，可以通过简单地分离第一元件和第二元件来关闭伽马;这可以机械地完成，因此可以关闭泛源。 在关闭状态下的残余放射性可以忽略不计，因此不需要特殊的屏蔽或处理程序。 卡尔顿正在与加拿大最佳医疗公司合作，该公司在辐射测量和校准设备方面拥有经验，并可以进入目前美国每年价值4000万美元的洪水源市场。

Over 40 million nuclear medicine procedures are carried out daily around the world, with approximately 2 million of these in Canada. Generally, these tests produce images of the heart, lung and cancers that are used for diagnoses. These images are produced with gamma cameras that need daily calibration. It is important that the camera be calibrated to record uniformly at all points in the image so that physicians will not be confused by camera artefacts when looking for subtle changes in the images. Currently, calibration to ensure uniformity in the camera response is done with a radioactive disk-shaped 'flood source' that illuminates the entire camera field of view. These sources work well, but they must be replaced frequently, and are highly radioactive so that special procedures and shielding must be used to minimize radiation exposure to technical staff. This Engage proposal tests the feasibility of a promising new design concept for a flood source that can be turned on and off remotely. Instead of a single radioactive source as is currently used, the new design would employ three elements. The first would emit alpha particles, the second would absorb these alphas and emit neutrons, and the third would capture the neutrons and emit the gamma rays used to calibrate the cameras. The advantage of this concept is that the gammas can be turned off by simply separating the first and second elements; this can be done mechanically, hence the flood source can be turned off. The residual radioactivity in the off state is negligible, hence no special shielding or handling procedures are required. Carleton is partnering with Best Medical Canada who has experience with radiation measurement and calibration devices and access to the current US market for flood sources valued at $40M annually.