Design and performance evaluation of a coplanar multimodality scanner for rodent imaging
Design and performance evaluation of a coplanar multimodality scanner for rodent imaging
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DOI：
10.1088/0031-9155/54/18/005
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发表时间：
2009-09-21
影响因子：
3.5
通讯作者：
Desco, M.
中科院分区：
文献类型：
--
作者：
Lage, E.;Vaquero, J. J.;Desco, M.
本文报道了VrPET/CT的发展和性能评估，VrPET/CT是一种新型的多模态共面几何扫描仪，用于啮齿动物体内成像。扫描仪的设计是基于一个部分环形PET系统和一个小动物CT组装在一个旋转的龙门架上，在两个视场（FOV）的几何中心之间没有轴向位移。我们报告了基于NEMA NU-4协议的PET系统性能；本发明不包括CT元件的性能特征。模态间对准的准确性和整个系统的成像能力也在幻影和动物实验中进行了评估。PET图像的切向空间分辨率在视场中心为1.56 mm，在径向偏移3.5 cm处为2.46 mm。同一位置径向分辨率为1.48 mm ~ 1.88 mm，轴向分辨率为2.34 mm ~ 3.38 mm。整个系统的能量分辨率平均为16.5%。对于100-700 keV能量窗和3.8 ns能量窗，绝对符合灵敏度为2.2%。相同设置的散射分数值对于鼠标大小的幻影为11.45%，对于大鼠大小的幻影为23.26%。在0.66 MBq/cc和0.11 MBq/cc条件下，分别获得70.8 kcps和31.5 kcps的峰值噪声等效计数率。模态间对准的精度低于PET分辨率的一半，生物标本的图像质量与测量的性能参数一致。本研究的评估表明，VrPET/CT系统是一种性能良好的小动物成像仪，而与全环PET层析成像相比，部分环检测系统的成本大大降低。
This work reports on the development and performance evaluation of the VrPET/CT, a new multimodality scanner with coplanar geometry for in vivo rodent imaging. The scanner design is based on a partial-ring PET system and a small-animal CT assembled on a rotatory gantry without axial displacement between the geometric centers of both fields of view (FOV). We report on the PET system performance based on the NEMA NU-4 protocol; the performance characteristics of the CT component are not included herein. The accuracy of inter-modality alignment and the imaging capability of the whole system are also evaluated on phantom and animal studies. Tangential spatial resolution of PET images ranged between 1.56 mm at the center of the FOV and 2.46 at a radial offset of 3.5 cm. The radial resolution varies from 1.48 mm to 1.88 mm, and the axial resolution from 2.34 mm to 3.38 mm for the same positions. The energy resolution was 16.5% on average for the entire system. The absolute coincidence sensitivity is 2.2% for a 100-700 keV energy window with a 3.8 ns coincident window. The scatter fraction values for the same settings were 11.45% for a mouse-sized phantom and 23.26% for a rat-sized phantom. The peak noise equivalent count rates were also evaluated for those phantoms obtaining 70.8 kcps at 0.66 MBq/cc and 31.5 kcps at 0.11 MBq/cc, respectively. The accuracy of inter-modality alignment is below half the PET resolution, and the image quality of biological specimens agrees with measured performance parameters. The assessment presented in this study shows that the VrPET/CT system is a good performance small-animal imager, while the cost derived from a partial ring detection system is substantially reduced as compared with a full-ring PET tomograph.