1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 25 New Chardon St, 4th Fl, Boston, MA 02114.
AJR Am J Roentgenol. 2015 Jan;204(1):167-76. doi: 10.2214/AJR.13.12191.
Size-specific dose estimates (SSDEs) require manual measurement of torso diameters for individual patients--anteroposterior (hereafter, D(AP)), lateral (hereafter, D(LAT)), and effective (hereafter, D(E))--which can be tedious in clinical settings. We aimed to determine whether body weight can be used as a surrogate for measuring diameter in children.
D(AP) and D(LAT) were measured in 522 consecutive CT examinations (chest, 187 and abdomen-pelvis, 335) performed in 483 (± SD) children (13 ± 7 years). Effective diameter (D(E1)) was calculated as the square root of the product of D(AP) and D(LAT). A second measurement of effective diameter (D(E2)) was obtained using automated software. Correlation coefficients between patient body weight, age, and diameter were measured in addition to 95% prediction interval analysis for diameters corresponding to body weight.
Median body weight was 51 kg, and mean D(AP), D(LAT), D(E1), and D(E2) were 207.1 ± 50.8 mm, 289.8 ± 72.6 mm, 243.3 ± 62.0 mm, and 233.6 ± 55.4 mm, respectively. Overall body weight had a strong correlation with diameter (0.88, 0.85, 0.86, and 0.93 respectively; all p < 0.0001). SSDE measured using body weight was statistically not different than SSDE measured using effective diameters (p = 0.9). Children weighing less than 27 kg and between 46 and 100 kg had statistically significant correlations with torso diameters, whereas only anteroposterior and effective diameters were correlated with children weighing between 27 and 45 kg. Children less than 4 years old had strong correlation with all diameters. Adolescents (15-18 years) did not have statistically significant correlation with any of the diameters.
Body weight, instead of body diameter, can be used as a surrogate to estimate size-specific dose in children, making dose estimation clinically simpler and more rapid.
针对特定大小的剂量估计（SSDE）需要对个体患者的躯干直径进行手动测量——前后径（以下简称 D(AP)）、侧径（以下简称 D(LAT)）和有效径（以下简称 D(E)）——这在临床环境中可能很繁琐。我们旨在确定体重是否可用于替代儿童的直径测量。
对 483 名（±标准差）儿童（13 ± 7 岁）连续进行的 522 次 CT 检查（胸部 187 次，腹部-骨盆 335 次）进行了 D(AP)和 D(LAT)测量。有效直径（D(E1)）计算为 D(AP)和 D(LAT)的乘积的平方根。使用自动软件获得有效直径（D(E2)）的第二次测量。除了对与体重相对应的直径进行 95%预测区间分析外，还测量了患者体重、年龄与直径之间的相关系数。
中位数体重为 51kg，平均 D(AP)、D(LAT)、D(E1)和 D(E2)分别为 207.1 ± 50.8mm、289.8 ± 72.6mm、243.3 ± 62.0mm 和 233.6 ± 55.4mm。总体而言，体重与直径有很强的相关性（分别为 0.88、0.85、0.86 和 0.93；均 p<0.0001）。使用体重测量的 SSDE 在统计学上与使用有效直径测量的 SSDE 无差异（p=0.9）。体重小于 27kg 和 46-100kg 的儿童与躯干直径有统计学显著相关性，而体重在 27-45kg 之间的儿童仅与前后径和有效直径相关。体重小于 4 岁的儿童与所有直径有很强的相关性。15-18 岁的青少年与任何直径均无统计学显著相关性。
体重而不是体径，可以用作儿童特定大小剂量估计的替代指标，使剂量估计在临床上更简单、更快捷。
