Method for transforming CT images for attenuation correction in PET/CT imaging
Method for transforming CT images for attenuation correction in PET/CT imaging
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DOI：
10.1118/1.2174132
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发表时间：
2006-04-01
期刊：
影响因子：
3.8
通讯作者：
Bendriem, B
中科院分区：
文献类型：
--
作者：
Carney, JPJ;Townsend, DW;Bendriem, B
在正电子发射断层扫描（PET）数据重建中，提出了一种将不同计算机断层扫描（CT）在不同x射线管电压（kVp）下测量的Hounsfield单位（HU）转换为511 keV线性衰减值的管电压依赖方案，用于衰减校正。Gammex 467电子密度CT幻影成像采用西门子Sensation 16层CT、西门子Emotion 6层CT、GE Lightspeed 16层CT、Hitachi CXR 4层CT和Toshiba Aquilion 16层CT， kVp范围为80 ~ 140 kVp。所有这些CT扫描仪也可以与PET扫描仪结合使用，作为PET/CT断层扫描。在511 keV下，将得到的各种参考组织替代物的HU与已知的线性衰减值进行比较。这种转化适用于肺、软组织和骨骼，其功能为9.6 x 10（-5）。（HU+1000）低于类似于50hu的阈值，a（。）（HU+1000） +b高于阈值，其中a和b是依赖于kVp设置的固定参数。使用依赖于kVp的缩放程序可以显著改善幻像测量中重建的PET活性水平，解决了80 kVp下致密骨幻像的近40%的误差。在不同kVp设置下进行多次CT扫描的患者研究也给出了结果，这些结果都应该导致相同的511 keV线性衰减值。对140 kVp CT图像获得的值进行线性拟合，使用kVp相关缩放作为80 kVp CT图像获得的相应值的函数绘制，得到y=1.003 X -0.001， R-2值为0.999，表明获得相同的值具有很高的精度。(c) 2006年美国医学物理学家协会。
A tube-voltage-dependent scheme is presented for transforming Hounsfield units (HU) measured by different computed tomography (CT) scanners at different x-ray tube voltages (kVp) to 511 keV linear attenuation values for attenuation correction in positron emission tomography (PET) data reconstruction. A Gammex 467 electron density CT phantom was imaged using a Siemens Sensation 16-slice CT, a Siemens Emotion 6-slice CT, a GE Lightspeed 16-slice CT, a Hitachi CXR 4-slice CT, and a Toshiba Aquilion 16-slice CT at kVp ranging from 80 to 140 kVp. All of these CT scanners are also available in combination with a PET scanner as a PET/CT tomograph. HU obtained for various reference tissue substitutes in the phantom were compared with the known linear attenuation values at 511 keV. The transformation, appropriate for lung, soft tissue, and bone, yields the function 9.6 x 10(-5) (.) (HU+1000) below a threshold of similar to 50 HU and a (.) (HU+1000) +b above the threshold, where a and b are fixed parameters that depend on the kVp setting. The use of the kVp-dependent scaling procedure leads to a significant improvement in reconstructed PET activity levels in phantom measurements, resolving errors of almost 40% otherwise seen for the case of dense bone phantoms at 80 kVp. Results are also presented for patient studies involving multiple CT scans at different kVp settings, which should all lead to the same 511 keV linear attenuation values. A linear fit to values obtained from 140 kVp CT images using the kVp-dependent scaling plotted as a function of the corresponding values obtained from 80 kVp CT images yielded y=1.003 X -0.001 with an R-2 value of 0.999, indicating that the same values are obtained to a high degree of accuracy. (c) 2006 American Association of Physicists in Medicine.