Parallax error in long-axial field-of-view PET scanners-a simulation study.
Parallax error in long-axial field-of-view PET scanners-a simulation study.
复制标题
DOI：
10.1088/0031-9155/61/14/5443
复制
发表时间：
2016-07-21
影响因子：
3.5
通讯作者：
Surti S
中科院分区：
文献类型：
--
作者：
Schmall JP;Karp JS;Werner M;Surti S
在具有非常长的轴向范围的PET扫描器的设计和构造中存在日益增长的兴趣。一个关键的设计挑战是长轴向范围对扫描仪空间分辨率特性的影响。在这项工作中，我们的特点视差PET系统设计具有轴向FOV为198厘米（全身PET扫描仪），使用全三维蒙特卡罗模拟的影响。研究了两种不同的闪烁材料：LSO和LaBr 3。两种情况下的晶体尺寸均为4×4×20 mm 3。研究了几种不同的相互作用深度（DOI）编码技术，以表征使用具有DOI能力的检测器时空间分辨率的提高。为了测量空间分辨率，我们在成像FOV中心的温暖背景中模拟了点源，其中轴向视差的影响最大，并且在从中心径向偏移的几个位置处。使用基于响应线的OSEM重建算法，我们发现当将轴向接收角（α）从±12°延伸时，LSO扫描器中的轴向分辨率在成像FOV中心处从4.8 mm（FWHM）降低到5.7 mm（FWHM（对应于18 cm的轴向FOV）最大为±67°-使用LaBr 3获得了类似的结果，其中，轴向分辨率从5.3 mm下降到6.1 mm。为了比较，我们还测量了由于横向成像FOV中的径向视差误差引起的退化; LSO扫描仪的横向分辨率（平均径向和切向）从4.9 mm降低到7.7 mm，对于扫描仪中心处的测量，与具有23 cm径向偏移的测量相比。DOI检测器设计的模拟在所有维度上提高了空间分辨率。在基于LSO的扫描仪中，α = ±67°的轴向分辨率通过结合双层DOI探测器从5.7 mm提高到5.0 mm。这些结果表征了完全开放的2 m长PET扫描仪的最大轴向模糊，并证明了当使用当前的临床探测器技术（无DOI功能）时，可以在分辨率适度降低的情况下获得较大的灵敏度增益。
There is a growing interest in the design and construction of a PET scanner with a very long axial extent. One critical design challenge is the impact of the long axial extent on the scanner spatial resolution properties. In this work, we characterize the effect of parallax error in PET system designs having an axial FOV of 198 cm (total-body PET scanner) using fully-3D Monte Carlo simulations. Two different scintillation materials were studied: LSO and LaBr3. The crystal size in both cases was 4×4×20 mm3. Several different depth-of-interaction (DOI) encoding techniques were investigated to characterize the improvement in spatial resolution when using a DOI capable detector. To measure spatial resolution we simulated point sources in a warm background in the center of the imaging FOV, where the effects of axial parallax are largest, and at several positions radially offset from the center. Using a line-of-response based OSEM reconstruction algorithm we found that the axial resolution in an LSO scanner degrades from 4.8 mm to 5.7 mm (FWHM) at the center of the imaging FOV when extending the axial acceptance angle (α) from ±12° (corresponding to an axial FOV of 18 cm) to the maximum of ±67°—a similar result was obtained with LaBr3, in which the axial resolution degraded from 5.3 mm to 6.1 mm. For comparison we also measured the degradation due to radial parallax error in the transverse imaging FOV; the transverse resolution, averaging radial and tangential directions, of an LSO scanner was degraded from 4.9 mm to 7.7 mm, for a measurement at the center of the scanner compared to a measurement with a radial offset of 23 cm. Simulations of a DOI detector design improved the spatial resolution in all dimensions. The axial resolution in the LSO-based scanner, with α = ±67°, was improved from 5.7 mm to 5.0 mm by incorporating a two-layer DOI detector. These results characterize the maximum axial blurring for a fully open 2 m long PET scanner and demonstrate that large sensitivity gains are possible with a modest reduction in resolution when using current clinical detector technology with no DOI capability.
登录
查看更多内容
影响因子：
1.8
作者：
Matej, S;Lewitt, RM
通讯作者：
Lewitt, RM
影响因子：
3.5
作者：
MacDonald, L. R.;Harrison, R. L.;Kinahan, P. E.
通讯作者：
Kinahan, P. E.
影响因子：
3.5
作者：
Schmall, Jeffrey P.;Roncali, Emilie;Cherry, Simon R.
通讯作者：
Cherry, Simon R.
影响因子：
1.8
作者：
Watanabe, M;Shimizu, K;Tanaka, E
通讯作者：
Tanaka, E
影响因子：
1.8
作者：
Eriksson, L.;Conti, M.;Bendriem, B.
通讯作者：
Bendriem, B.