Isotopes for New Modalities of PET/SPECT Imaging: Experimentation and Evaluation

传统的PET和SPECT医学成像依赖于反向投影技术，由于伽马射线的散射和吸收，其缺点是产生伪影，导致假阴性和/或假阳性诊断。用不同同位素进行双能成像被认为是提高成像质量的可能手段。它们总是需要额外的设备，更高的剂量和更长的暴露时间等。我们尝试了一种将PET/SPECT成像与单一同位素相结合的新方法，该同位素在不到几纳秒的时间滞后内发射正电子和伽马射线。在实现时，我们可以采用标准的核粒子物理实验三维顶点重建技术。除了增强对比度外，该方法还提供了基于不同软件切割的多幅图像，并使用传统的反向投影来严格评估图像伪影并最大限度地减少错误诊断。在确定候选同位素时，我们主要关注同位素对人类的生物相容性、衰减校正的双重能量需求、经济可行性和生产便宜性、材料的稳定性等。候选同位素是43-Sc、73-Se、123-Xe、85-Y、77-Kr和75-Br，这些元素已经在医学上使用和摄入。

The conventional medical imaging by PET and SPECT relies on back projection techniques and it has drawbacks of artifacts due to scattering and absorption of gamma rays, contributing to false negative and/or false positive diagnostics. Dual energy imaging with separate isotopes has been suggested as possible means of improving the image qualities. They invariably involve additional equipment, higher doses and longer exposures etc. We attempt a novel approach of combining PET/SPECT imaging with single isotopes which emit positrons and gamma rays within less than a few nano second time lags. When implemented, we can employ standard 3D- vertex reconstruction technique of nuclear and particle physics experiments. In addition to enhanced contrast, this method provides multiple images based on different software cuts with conventional back projection to evaluate the image artifacts critically and minimize false diagnostics. In identifying candidate isotopes, we focussed on biological compatibility of isotopes to humans, dual energy requirement for attenuation corrections, economic viability and ease of production, stability of materials etc. The candidate isotopes are 43-Sc, 73-Se, 123-Xe, 85-Y, 77-Kr and 75-Br, the elements of which are already in medical use and ingestion.