Experimental characterization and system simulations of depth of interaction PET detectors using 0.5 mm and 0.7 mm LSO arrays.
Experimental characterization and system simulations of depth of interaction PET detectors using 0.5 mm and 0.7 mm LSO arrays.
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DOI：
10.1088/0031-9155/54/14/015
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发表时间：
2009-07-21
影响因子：
3.5
通讯作者：
Cherry SR
中科院分区：
文献类型：
--
作者：
James SS;Yang Y;Wu Y;Farrell R;Dokhale P;Shah KS;Cherry SR
小动物PET扫描仪可以通过提高灵敏度、提高空间分辨率和提高视场内空间分辨率的均匀性来改进。这可以通过使用基于晶体元件的PET探测器来实现，所述晶体元件在轴向和横轴方向上薄而在径向方向上长，并且通过采用相互作用深度（DOI）编码来最小化视差误差。利用DOI检测器，PET扫描器的环的直径也可以减小。这最小化了实现与具有较大环直径的扫描器相同的立体角覆盖所需的检测器的数量，并且最小化了由于湮灭光子的非共线性引起的误差。在这项研究中，我们表征了原型PET探测器，这些探测器具有0.5 mm × 0.5 mm × 20 mm和0.7 mm × 0.7 mm × 20 mm的单个LSO晶体元件尺寸，通过位置敏感雪崩光电二极管（PSAPDs）在两端读出。对镜面反射器和漫反射器两者进行评估。探测器的特征在于能够清楚地分辨各个晶体元素、DOI分辨率和能量分辨率。我们的研究结果表明，扫描仪的基础上的任何四个探测器的设计将提供更好的空间分辨率和更均匀的空间分辨率相比，目前的小动物PET扫描仪。当探测器采用0.5mm × 0.5mm × 20mm晶体时，空间分辨率将得到最大的提高。进行蒙特卡罗模拟以证明2 mm DOI分辨率足以确保使用这些探测器的小动物PET扫描仪几何结构的均匀空间分辨率。这种扫描仪的灵敏度也使用Monte Carlo模拟进行了模拟，并且对于内径为6cm的四环扫描仪，每个扫描仪环采用20个检测器，其灵敏度大于10%。
Small animal PET scanners may be improved by increasing the sensitivity, improving the spatial resolution and improving the uniformity of the spatial resolution across the field of view. This may be achieved by using PET detectors based on crystal elements that are thin in the axial and transaxial directions and long in the radial direction, and by employing depth of interaction (DOI) encoding to minimize the parallax error. With DOI detectors, the diameter of the ring of the PET scanner may also be decreased. This minimizes the number of detectors required to achieve the same solid angle coverage as a scanner with a larger ring diameter and minimizes errors due to non-collinearity of the annihilation photons. In this study, we characterize prototype PET detectors that are finely pixelated with individual LSO crystal element sizes of 0.5 mm × 0.5 mm × 20 mm and 0.7 mm × 0.7 mm × 20 mm, read out at both ends by position sensitive avalanche photodiodes (PSAPDs). Both a specular reflector and a diffuse reflector were evaluated. The detectors were characterized based on the ability to clearly resolve the individual crystal elements, the DOI resolution and the energy resolution. Our results indicate that a scanner based on any of the four detector designs would offer improved spatial resolution and more uniform spatial resolution compared to present day small animal PET scanners. The greatest improvements to spatial resolution will be achieved when the detectors employing the 0.5 mm × 0.5 mm × 20 mm crystals are used. Monte Carlo simulations were performed to demonstrate that 2 mm DOI resolution is adequate to ensure uniform spatial resolution for a small animal PET scanner geometry using these detectors. The sensitivity of such a scanner was also simulated using Monte Carlo simulations and was shown to be greater than 10 % for a four ring scanner with an inner diameter of 6 cm, employing 20 detectors per scanner ring.
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通讯作者：
Orita, N
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