Institute of Medical Physics, University Erlangen-Nürnberg, Henkestr. 91, Erlangen, Germany.
Radiology. 2010 Oct;257(1):158-66. doi: 10.1148/radiol.10100047.
To determine conversion factors for the new International Commission on Radiological Protection (ICRP) publication 103 recommendations for adult and pediatric patients and to compare the effective doses derived from Monte Carlo calculations with those derived from dose-length product (DLP) for different body regions and computed tomographic (CT) scanning protocols.
Effective dose values for the Oak Ridge National Laboratory phantom series, including phantoms for newborns; 1-, 5-, and 10-year-old children; and adults were determined by using Monte Carlo methods for a 64-section multidetector CT scanner. For each phantom, five anatomic regions (head, neck, chest, abdomen, and pelvis) were considered. Monte Carlo simulations were performed for spiral scanning protocols with different voltages. Effective dose was computed by using ICRP publication 60 and publication 103 recommendations. The calculated effective doses were compared with those derived from the DLP by using previously published conversion factors.
In general, conversion factors determined on the basis of Monte Carlo calculations led to lower values for adults with both ICRP publications. Values up to 33% and 32% lower than previously published data were found for ICRP publication 60 and ICRP publication 103, respectively. For pediatric individuals, effective doses based on the Monte Carlo calculations were higher than those obtained from DLP and previously published conversion factors (eg, for chest CT scanning in 5-year-old children, an increase of about 76% would be expected). For children, a variation in conversion factors of up to 15% was observed when the tube voltage was varied. For adult individuals, no dependence on voltage was observed.
Conversion factors from DLP to effective dose should be specified separately for both sexes and should reflect the new ICRP recommendations. For pediatric patients, new conversion factors specific for the spectrum used should be established.
确定新的国际辐射防护委员会（ICRP）出版物 103 对成人和儿科患者的建议的转换系数，并比较来自不同身体部位和计算机断层扫描（CT）扫描协议的蒙特卡罗计算得出的有效剂量与剂量长度乘积（DLP）得出的有效剂量。
使用蒙特卡罗方法为 64 层多排 CT 扫描仪确定包括新生儿在内的橡树岭国家实验室体模系列的有效剂量值；1 岁、5 岁和 10 岁的儿童；和成年人。对于每个体模，考虑了五个解剖区域（头部、颈部、胸部、腹部和骨盆）。针对不同电压的螺旋扫描协议进行了蒙特卡罗模拟。使用 ICRP 出版物 60 和出版物 103 的建议计算有效剂量。将计算出的有效剂量与先前发表的转换系数从 DLP 得出的有效剂量进行比较。
一般来说，基于蒙特卡罗计算确定的转换系数导致 ICRP 发布的两种出版物的成人值都降低。与先前发表的数据相比，ICRP 出版物 60 和 ICRP 出版物 103 的值分别低了 33%和 32%。对于儿科个体，基于蒙特卡罗计算的有效剂量高于从 DLP 和先前发表的转换系数获得的有效剂量（例如，在 5 岁儿童的胸部 CT 扫描中，预计会增加约 76%）。对于儿童，当管电压变化时，转换系数的变化高达 15%。对于成年个体，没有观察到对电压的依赖性。
从 DLP 到有效剂量的转换系数应分别针对男女指定，并应反映新的 ICRP 建议。对于儿科患者，应建立特定于所用光谱的新转换系数。
