Virtual-pinhole PET
Virtual-pinhole PET
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DOI：
10.2967/jnumed.107.043034
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发表时间：
2008-03-01
影响因子：
9.3
通讯作者：
O'Sullivan, Joseph A.
中科院分区：
文献类型：
--
作者：
Tai, Yuan-Chuan;Wu, Heyu;O'Sullivan, Joseph A.
我们提出并测试了一种新的几何形状的PET系统设计类似于针孔SPECT称为虚拟针孔PET（VP-PET）的几何形状，以确定它是否可以提供高分辨率的图像。研究方法：本文分析了光子共线性和探测器尺寸对系统分辨率的影响，并将以往提出的常规PET重建图像分辨率的经验公式推广到预测VP-PET的分辨率。为了测量VP-PET的系统分辨率，我们记录了当（22）Na点源跨过由12 × 12的氧硅酸镥晶体的相同阵列制成的2个探测器之间的响应的符合线时的符合事件（每个测量1.51 x 1.51 x 10 mm（3）），间隔565 mm。为了测量重建图像分辨率，我们使用4种类型的探测器构建了4个VP-PET系统（宽度，1.51- 6.4mm）并成像（64）CU的4个点源（半衰期= 12.7小时以允许长的采集时间）。测量每个源和每个系统的切向和径向分辨率并取平均值。然后，我们成像的聚苯乙烯塑料幻影代表一个2.5厘米厚的横截面孤立的乳房体积。体模中填充了（64）Cu（713 kBq/mL）水溶液，其中嵌入了以下内容：4个内径（ID）范围为1.8至12.6 mm的球形肿瘤，6个微量移液管（0.7或1.1 mm ID，填充有（64）Cu，背景值为5x、20 x或50 x），以及一个外径为10.0 mm的冷损伤。结果：线扩散函数的形状和半高宽的测量值与预测值吻合较好。测量的重建图像分辨率（2.40-3.24 mm）为4个系统中3个系统预测值的+/- 6%。在一种情况下，差异为12.6%，可能是由于低估了低分辨率检测器的块效应。在体模实验中，检测到所有球形肿瘤。如果放射性浓度至少是背景的20倍，则检测到小线源。结论：我们已经开发和表征了一种新的几何PET。遵循VP-PET几何结构的PET系统为系统的高分辨率探测器附近的对象提供高分辨率图像。这种几何形状可能会导致开发专用PET系统或用于常规PET扫描仪的分辨率增强插入装置。
We proposed and tested a novel geometry for PET system design analogous to pinhole SPECT called the virtual-pinhole PET (VP-PET) geometry to determine whether it could provide high-resolution images. Methods: We analyzed the effects of photon acolinearity and detector sizes on system resolution and extended the empiric formula for reconstructed image resolution of conventional PET proposed earlier to predict the resolutions of VP-PET. To measure the system resolution of VP-PET, we recorded coincidence events as a (22)Na point source was stepped across the coincidence line of response between 2 detectors made from identical arrays of 12 x 12 lutetium oxyorthosilicate crystals (each measuring 1.51 x 1.51 x 10 mm(3)) separated by 565 mm. To measure reconstructed image resolution, we built 4 VP-PET systems using 4 types of detectors (width, 1.51-6.4 mm) and imaged 4 point sources of (64)CU (half-life = 12.7 h to allow a long acquisition time). Tangential and radial resolutions were measured and averaged for each source and each system. We then imaged a polystyrene plastic phantom representing a 2.5-cm-thick cross-section of isolated breast volume. The phantom was filled with an aqueous solution of (64)CU (713 kBq/mL) in which the following were imbedded: 4 spheric tumors ranging from 1.8 to 12.6 mm in inner diameter (ID), 6 micropipettes (0.7- or 1.1-mm ID filled with (64)Cu at 5x, 20x, or 50x background), and a 10.0-mm outer-diameter cold lesion. Results: The shape and measured full width at half maximum of the line spread functions agree well with the predicted values. Measured reconstructed image resolution (2.40-3.24 mm) was +/- 6% of the predicted value for 3 of the 4 systems. In one case, the difference was 12.6%, possibly due to underestimation of the block effect from the low-resolution detector. In phantom experiments, all spheric tumors were detected. Small line sources were detected if the activity concentration is at least 20x background. Conclusion: We have developed and characterized a novel geometry for PET. A PET system following the VP-PET geometry provides high-resolution images for objects near the system's high-resolution detectors. This geometry may lead to the development of special-purpose PET systems or resolution-enhancing insert devices for conventional PET scanners.