■计算机断层扫描(CT)系统的诊断准确性和计算的Hounsfield单位(HU)的可靠性对于肿瘤检测和癌症患者的治疗计划至关重要。本研究评估了扫描参数(千伏峰或kVp,毫安秒或MAS重建内核和算法,重建视野,和切片厚度)对图像质量的影响,HUs,和治疗计划系统(TPS)中的计算剂量。
■用16层西门子CT扫描仪对质量剂量验证体模进行了几次扫描。将DOSisoftISO灰色TPS应用于剂量计算。采用SPSS.24软件对结果进行分析,P值<0.05为显著性。
■重建内核和算法显著影响噪声,信噪比(SNR),和对比度噪声比(CNR)。通过提高重建核的清晰度,噪声增加,CNR降低。与滤波反投影算法相比,SNR和CNR在迭代重建时具有相当大的增量。通过提高软组织中的MAS来降低噪声。此外,KVp对HU有显著影响。TPS-纵隔和主链的计算剂量变化小于2%,肋骨的计算剂量变化小于8%。
■尽管HU变化取决于临床上可行范围内的图像采集参数,其剂量学对TPS计算剂量的影响可以忽略。因此,可以得出结论,在癌症患者的治疗计划中,在不影响计算剂量的情况下,可以应用扫描参数的优化值,以获得最大的诊断准确性并更精确地计算HU。
UNASSIGNED: The diagnosis accuracy of computed tomography (CT) systems and the reliability of calculated Hounsfield Units (HUs) are critical in tumor detection and cancer patients\' treatment planning. This
study evaluated the effects of scan parameters (Kilovoltage peak or kVp, milli-Ampere-second or mAS reconstruction kernels and algorithms, reconstruction field of view, and slice thickness) on image quality, HUs, and the calculated dose in the treatment planning system (TPS).
UNASSIGNED: A quality dose verification phantom was scanned several times by a 16-slice Siemens CT scanner. The DOSIsoft ISO gray TPS was applied for dose calculations. The SPSS.24 software was used to analyze the results and the P-value <0.05 was considered significant.
UNASSIGNED: Reconstruction kernels and algorithms significantly affected noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The noise increased and CNR decreased by raising the sharpness of reconstruction kernels. SNR and CNR had considerable increments at iterative reconstruction compared with the filtered back-projection algorithm. The noise decreased by raising mAS in soft tissues. Also, KVp had a significant effect on HUs. TPS--calculated dose variations were less than 2% for mediastinum and backbone and less than 8% for rib.
UNASSIGNED: Although HU variation depends on image acquisition parameters across a clinically feasible range, its dosimetric impact on the calculated dose in TPS can be neglected. Hence, it can be concluded that the optimized values of scan parameters can be applied to obtain the maximum diagnostic accuracy and calculate HUs more precisely without affecting the calculated dose in the treatment planning of cancer patients.