Variations in tumor size and position due to irregular breathing in 4D-CT: A simulation study
Variations in tumor size and position due to irregular breathing in 4D-CT: A simulation study
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DOI：
10.1118/1.3298007
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发表时间：
2010-03-01
期刊：
影响因子：
3.8
通讯作者：
Sharp, Gregory C.
中科院分区：
文献类型：
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作者：
Sarker, Joyatee;Chu, Alan;Sharp, Gregory C.
方法：设计一台虚拟4D-CT扫描仪，采用回顾性检索的方法再现轴位扫描。该虚拟扫描仪根据用户的规格创建人造球形肿瘤，并使用患者呼吸波形重建可能由4D-CT扫描仪产生的图像。对155例患者的呼吸波形进行4D-CT扫描变异性检验。将每个呼吸波形标准化并缩放到1、2和3 cm峰-峰运动，并针对每个缩放波形模拟半径为2和4 cm的人工肿瘤。计算重新排序的4D-CT图像的质心和体积，并与人工肿瘤的质心和体积的预期值进行比较。受试者内的变异性进行了调查，通过运行虚拟扫描仪在不同的子间隔，每个病人的呼吸waveform.Results：人工肿瘤的质心位置的平均误差小于2毫米的标准偏差为2厘米的运动。相应的体积平均误差小于4%。在最坏的情况下，一个中心的质量误差为1.0厘米的标准差和体积误差30%-60%at inflation. Systematic误差中观察到的一个子集的患者由于不规则的呼吸，这些错误是更明显的肿瘤体积时，较小的结论：不规则的呼吸过程中4D-CT模拟造成系统误差的体积和质量中心的测量。这些误差很小，但取决于肿瘤的大小，运动幅度和呼吸不规则的程度。
Methods: A virtual 4D-CT scanner was designed to reproduce axial mode scans with retrospective resorting. This virtual scanner creates an artificial spherical tumor based on the specifications of the user, and recreates images that might be produced by a 4D-CT scanner using a patient breathing waveform. 155 respiratory waveforms of patients were used to test the variability of 4D-CT scans. Each breathing waveform was normalized and scaled to 1, 2, and 3 cm peak-to-peak motion, and artificial tumors with 2 and 4 cm radius were simulated for each scaled waveform. The center of mass and volume of resorted 4D-CT images were calculated and compared to the expected values of center of mass and volume for the artificial tumor. Intrasubject variability was investigated by running the virtual scanner over different subintervals of each patient's breathing waveform.Results: The average error in the center of mass location of an artificial tumor was less than 2 mm standard deviation for 2 cm motion. The corresponding average error in volume was less than 4%. In the worst-case scenarios, a center of mass error of 1.0 cm standard deviation and volume errors of 30%-60% at inhale were found. Systematic errors were observed in a subset of patients due to irregular breathing, and these errors were more pronounced when the tumor volume is smaller.Conclusions: Irregular breathing during 4D-CT simulation causes systematic errors in volume and center of mass measurements. These errors are small but depend on the tumor size, motion amplitude, and degree of breathing irregularity.