Development of a quasi-CBCT system for image-guided radiotherapy

描述（由申请人提供）：锥形束计算机断层扫描（CBCT）是图像引导放射治疗（IGRT）以及其他形式的图像引导干预的重要在线成像方式。然而，目前的CBCT图像质量不如诊断扇束CT。目前的CBCT系统是由一个点x射线源和一个二维平板成像仪（FPI）组成的，图像质量问题是其设计中固有的问题。过度的x射线散射、低性能FPI的使用以及大锥角下的重建退化是图像质量退化的三个主要原因。CBCT较差的图像质量限制了这种重要的新型IGRT治疗技术的使用。我们设计了一种新型的准cbct扫描系统，该系统由线性扫描x射线源和线性离散x射线探测器阵列组成。该成像系统将克服基于fpi的CBCT固有的缺陷，从而产生具有诊断质量的在线图像。线性x射线管和探测器阵列分别垂直于旋转平面和在旋转平面内排列。x射线束被狭窄地准直成扇形光束，并在z方向上进行电子扫描。由于其散射抑制机制和高性能离散x射线探测器，该系统将为IGRT提供诊断质量的在线图像。除了提高图像质量外，该系统还由于其纤细的结构而具有更大的间隙。诊断在线图像将促进新的IGRT技术与更好的肿瘤杀伤和正常组织保留。这种创新的设计也将对其他形式的图像引导干预以及诊断成像产生巨大的影响。本研究将建立一个准cbct台式系统。研究了准cbct系统图像质量的可行性和改进方法。将获得临床实施的技术和参数。

DESCRIPTION (provided by applicant): Cone-beam computed tomography (CBCT) is an important online imaging modality for image-guided radiotherapy (IGRT) as well as other forms of image guided interventions. However, current CBCT image quality is inferior to that of the diagnostic fan beam CT. The image quality problem is inherent in the design of the current CBCT system, which is composed of a point x-ray source and a two-dimensional flat panel imager (FPI). Excessive x-ray scatters, the use of low performance FPI, and reconstruction degradation at large cone angles are three major sources of the degradation of image quality. The inferior image quality of CBCT limits the use of this modality for important new IGRT treatment techniques. We have designed a novel quasi-CBCT scanning system comprising a linear scan x-ray source and a linear discrete x-ray detector array. This imaging system will overcome the defects inherent in FPI-based CBCT and thereby produce online images with diagnostic quality. The linear x-ray tube and detector array are aligned perpendicular to and within the rotation plane, respectively. The x-ray beams are narrowly collimated into fan beams and scan in the z-direction electronically. This system will produce diagnostic quality online images for IGRT due to its scatter rejection mechanism and high-performance discrete x-ray detectors. Besides improved image quality, this system also has larger clearance due to its slim structure. Diagnostic online images will facilitate new IGRT techniques with better tumor killing and normal tissue sparing. This innovative design will also have huge impact on other forms of image guided intervention as well as diagnostic imaging. A quasi-CBCT bench-top system will be built in this research. The feasibility and improvement of image quality of the quasi-CBCT system will be studied. Techniques and parameters for clinical implementation will be obtained. NARRATIVE In this project, we will develop a novel quasi cone beam computed tomography (CBCT) system for image guided radiotherapy (IGRT) as well as other forms of image guided interventions. This system will solve the inherent problem of current flat-panel based CBCT and will produce online images with diagnostic quality. Clinical implementation of this innovative online imaging system will facilitate new IGRT techniques that are impossible with the inferior image quality of current CBCT. Once developed, this mobile and diagnostic CT imaging system will have huge impacts on many other forms of medical practice.