Department of Radiology, Keck School of Medicine of USC, 1441 Eastlake Avenue, Suite 2315B, Los Angeles, CA, 90033-0377, USA.
J Digit Imaging. 2013 Jun;26(3):406-11. doi: 10.1007/s10278-012-9525-z.
Most CT dose data aggregation methods do not currently adjust dose values for patient size. This work proposes a simple heuristic for reliably computing an effective diameter of a patient from an abdominal CT image. Evaluation of this method on 106 patients scanned on Philips Brilliance 64 and Brilliance Big Bore scanners demonstrates close correspondence between computed and manually measured patient effective diameters, with a mean absolute error of 1.0 cm (error range +2.2 to -0.4 cm). This level of correspondence was also demonstrated for 60 patients on Siemens, General Electric, and Toshiba scanners. A calculated effective diameter in the middle slice of an abdominal CT study was found to be a close approximation of the mean calculated effective diameter for the study, with a mean absolute error of approximately 1.0 cm (error range +3.5 to -2.2 cm). Furthermore, the mean absolute error for an adjusted mean volume computed tomography dose index (CTDIvol) using a mid-study calculated effective diameter, versus a mean per-slice adjusted CTDIvol based on the calculated effective diameter of each slice, was 0.59 mGy (error range 1.64 to -3.12 mGy). These results are used to calculate approximate normalized dose length product values in an abdominal CT dose database of 12,506 studies.
大多数 CT 剂量数据聚合方法目前都不能调整患者体型的剂量值。本研究提出了一种从腹部 CT 图像中可靠计算患者有效直径的简单启发式方法。在飞利浦 Brilliance 64 和 Brilliance Big Bore 扫描仪上对 106 名患者进行的评估表明，计算出的和手动测量的患者有效直径之间具有紧密的对应关系，平均绝对误差为 1.0cm（误差范围+2.2 至-0.4cm）。在西门子、通用电气和东芝扫描仪上的 60 名患者中也表现出了相同的对应关系。在腹部 CT 研究的中间切片中计算出的有效直径，与整个研究的平均计算有效直径非常接近，平均绝对误差约为 1.0cm（误差范围+3.5 至-2.2cm）。此外，使用中间切片计算出的有效直径计算出的平均调整后体 CT 剂量指数（CTDIvol）与基于每个切片计算出的有效直径的平均每片调整后 CTDIvol 相比，平均绝对误差为 0.59mGy（误差范围 1.64 至-3.12mGy）。这些结果用于计算 12506 项腹部 CT 剂量数据库中近似的归一化剂量长度乘积值。
