ATTENUATION CORRECTION IN PET USING SINGLE-PHOTON TRANSMISSION MEASUREMENT
ATTENUATION CORRECTION IN PET USING SINGLE-PHOTON TRANSMISSION MEASUREMENT
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DOI：
10.1118/1.597394
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发表时间：
1994-06-01
期刊：
影响因子：
3.8
通讯作者：
NAHMIAS, C
中科院分区：
文献类型：
--
作者：
DEKEMP, RA;NAHMIAS, C
用旋转棒源测量单光子透过率来测量正电子发射断层扫描(PET)中的衰减校正因子。使用探测器位置和棒源位置将单束投影重新采样到符合几何图形中。针对McMaster PET扫描仪中的块探测器，提出了一种非瘫痪死区时间校正算法。这使得能够使用用于传输扫描的广泛的震源强度来计算准确的衰减校正系数(ACF)。横向分辨率约为6 mm，可与发射扫描性能相媲美。轴向分辨率约为25 mm，仅有粗源准直。与符合传输精度相比，由于跨平面散射增加，ACF被低估了高达10%。当比较单次透射率测量和电流符合透射率测量时，校正因子对物体密度的响应在15%以内。使用单次传输测量的主要优势是显著提高了计数率。使用2-MCI传输棒源，计数率比符合扫描提高7倍是可能的。在这种声源强度和2分钟的采集时间下，传输图像中2%的均匀度是可能的。在单次传输扫描中没有统计随机数，这使得测量的计数率随源活动而线性变化。在与2-MCI棒源相对的探测器中，单探测器死区时间损失约为6%。
The use of single photon transmission measurement with a rotating rod source has been evaluated to measure the attenuation correction factors in positron emission tomography (PET). The singles projections are resampled into the coincidence geometry using the detector positions and the rod source location. A nonparalyzable dead time correction algorithm was developed for the block detectors used in the McMaster PET scanner. This enables accurate attenuation correction factors (ACFs) to be computed using a wide range of source strengths for transmission scanning. Transaxial resolution is approximately 6 mm, which is comparable to emission scanning performance. Axial resolution is about 25 mm, with only crude source collimation. ACFs are underestimated by as much as 10% due to increased cross-plane scatter, compared to coincidence transmission accuracy. The response of the correction factors to object density is within 15%, when comparing singles transmission measurement to current coincidence transmission measurement. The major advantage of using singles transmission measurement is a dramatically increased count rate. A factor of 7 increase in count rate over coincidence scanning is possible with a 2-mCi transmission rod source. Uniformity of 2% in the transmission images is possible with this source strength and a 2-min acquisition. There are no randoms counted in singles transmission scans, which makes the measured count rate vary linearly with source activity. Singles detector dead time losses are approximately 6% in the detectors opposite a 2-mCi rod source.