GPU-based SPECT Reconstruction Using Reverse Monte Carlo Simulations

项目摘要/摘要 在过去的几年里，人们对放射性药物结合物的应用兴趣显著增加 治疗多种癌症。这些结合物由螯合剂组成，以靶向癌细胞和 放射性核素利用电离辐射的细胞毒性。需要辐射剂量测定来确定 这些治疗的剂量、有效性和安全性，以及活性生物分布的3D定量成像 表示执行剂量测定的最佳工具。对于所使用的大多数放射性核素(非正电子发射体)，SPECT 针对特定患者的剂量测定需要成像。然而，SPECT图像质量受多种物理因素的影响， 例如SPECT扫描中的衰减、散射或响应准直器-探测器系统。说明，说明 其中，蒙特卡罗技术可以使用，因为它们在表示物理过程方面具有显著的准确性 与电离辐射的传输有关。特别是，从所获得的图像中进行3D SPECT重建 可以通过向后传输在伽马相机中检测到的光子来获得二维投影 投影，尽管许多要反向传输的光子需要特殊优化的结构和 模拟。该项目将开发一种用于SPECT重建的新的逆蒙特卡罗软件，该软件是从 在GPU中划痕以加快模拟速度。首先，只会选择相关的反向物理过程 并使用用于辐射传输的特征良好的Topas蒙特卡罗程序的逆过程进行建模。 然后，准直器-探测器系统的特定属性将被集成到我们的代码中以确定角度 探测到的光子的分布。最后，这些开发将被集成到基于GPU的平台中 并与NCI癌症研究计划的信息学技术共享，以获得特定的进一步结果 来自研究界的商业SPECT扫描。

Project Summary/Abstract Interest in applications of radiopharmaceutical conjugates has notably increased in the last few years for the treatment of a variety of cancers. These conjugates are composed of chelators to target cancer cells and radionuclides to employ the cytotoxicity of ionizing radiation. Radiation dosimetry is required to determine the dosages, efficacy, and safety of these treatments, and 3D quantitative imaging of the biodistribution of activity represents the best tool to perform dosimetry. For most radionuclides employed (non-positron-emitters), SPECT imaging is needed for patient-specific dosimetry. However, multiple physical factors affect SPECT image quality, such as attenuation, scattering, or the response collimator-detector system in SPECT scans. To account for them, Monte Carlo techniques can be used due to their remarkable accuracy in representing physical processes relevant to the transport of ionizing radiation. In particular, 3D SPECT reconstruction from the acquired bidimensional projections may be obtained by transporting backward the photons detected in the gamma camera projections, although many photons to be reversely transported require specially optimized architecture and simulations. This project will develop a new reverse Monte Carlo software for SPECT reconstruction, built from scratch in the GPU to speed up simulations. First, only the relevant reverse physical processes will be selected and modeled using inverse processes of the well-characterized TOPAS Monte Carlo code for radiation transport. Then, specific properties of collimator-detector systems will be integrated into our code to determine the angular distributions for the photons detected. Finally, these developments will be integrated into a GPU-based platform and shared with the Informatics Technology for Cancer Research program at NCI for further results of specific commercial SPECT scans from the research community.