IEEE Trans Med Imaging. 2020 Mar;39(3):588-600. doi: 10.1109/TMI.2019.2932333. Epub 2019 Aug 1.
This study investigated the feasibility of a highly specific multiplexed image-guided small animal radiation therapy (SART) platform based on triple imaging from on-board single-photon emission computed tomography (SPECT), spectral-CT, and cone-beam CT (CBCT) guidance in radiotherapy treatment. As a proof-of-concept, the SART system was built with the capability of triple on-board image guidance by utilizing an x-ray tube and a single cadmium zinc telluride (CZT) semiconductor photon-counting imager via a Monte Carlo simulation study. The x-ray tube can be set at a low tube current for imaging mode and a high tube current for radiation therapy mode, respectively. In the imaging mode, both x-ray and gamma-ray projection data were collected by the imager to reconstruct CBCT, SPECT and spectral CT images of small animals being treated. The modulation transfer function (MTF) of the pixelated CZT imager measured was 8.6 lp/mm. The overall performances of the CBCT and SPECT imaging of the system were evaluated with sufficient spatial resolution and imaging quality to be fitted into the SART platform. The material differentiation and decomposition capacities of spectral CT within the system were verified using K-edge imaging, image-based optimal energy weighted imaging, and image-based linear material decomposition methods. The triple imaging capability of the system was demonstrated using a PMMA phantom containing gadolinium, iodine and radioisotope Tc inserts. All the probes were clearly identified in the registered image. The results demonstrated that a novel SART platform with high-quality on-board CBCT, spectral-CT, SPECT image guidance is technically feasible by using a single semiconductor imager, thus affording comprehensive image guidance from anatomical, functional, and molecular levels for radiation treatment beam delivery.
本研究探讨了基于 onboard 单光子发射计算机断层扫描（SPECT）、能谱 CT 和锥形束 CT（CBCT）引导的三重成像的高度特异性的小动物放射治疗（SART）平台在放射治疗中的可行性。作为概念验证，该 SART 系统通过蒙特卡罗模拟研究，利用 X 射线管和单个碲锌镉（CZT）半导体光子计数成像仪，具备三重 onboard 图像引导功能。X 射线管可分别设置为成像模式下的低管电流和放射治疗模式下的高管电流。在成像模式下，成像仪同时采集 X 射线和伽马射线投影数据，以重建正在治疗的小动物的 CBCT、SPECT 和能谱 CT 图像。测量的像素化 CZT 成像仪的调制传递函数（MTF）为 8.6 lp/mm。系统的 CBCT 和 SPECT 成像的整体性能具有足够的空间分辨率和成像质量，可适用于 SART 平台。通过 K-edge 成像、基于图像的最佳能量加权成像和基于图像的线性材料分解方法，验证了系统内能谱 CT 的物质区分和分解能力。使用包含钆、碘和放射性同位素 Tc 插塞的 PMMA 体模演示了系统的三重成像能力。所有探针在注册图像中均清晰可辨。结果表明，通过使用单个半导体成像仪，具有高质量 onboard CBCT、能谱 CT、SPECT 图像引导功能的新型 SART 平台在技术上是可行的，从而为放射治疗束传输提供了从解剖学、功能和分子水平的全面图像引导。
