Wang Qiang, Fu Qiang, Pang Cong
Department of Occupational Disease Prevention, Changzhou Center for Disease Control and Prevention, Changzhou, Jiangsu 213022, China.
The First People's Hospital of Changzhou, Changzhou, Jiangsu 213022, China.
Radiat Prot Dosimetry. 2022 Apr 26;198(5):281-289. doi: 10.1093/rpd/ncac026.
This work investigates the impact of iodinated contrast medium (ICM) on radiation dose in computed tomography (CT) scans using linear models established through a phantom study. Thermoluminescence dosemeters (TLDs) were calibrated using semi-conductor X-ray dosemeters. An electron density phantom, with a vial containing TLDs and different concentrations of iodinated blood, were scanned at different tube voltages. Irradiated TLD outputs were measured and absorbed dose to iodinated blood calculated. CT numbers (tissue attenuation as measured by Hounsfield units) were plotted against absorbed doses to obtain linear models. Data from 49 real patient scans were used to validate the linear models. At each X-ray energy, CT numbers were linearly correlated with the absorbed doses, that is with the increase of blood iodine concentration, the CT number increased and the absorbed dose increased accordingly. ICM can cause an increase of organ dose; the average dose increases were 31.8 ± 8.9% for thyroid, 37.1 ± 9.2% for cardiac muscle, 77.7 ± 14.0% for cardiac chamber, 7.1 ± 2.3% for breast, 26.1 ± 7.3% for liver, 39.8 ± 11.8% for spleen, 96.3 ± 12.2% for renal cortex and 82.4 ± 11.6% for medulla nephrica. ICM used in enhanced CT scan resulted in increased organ doses. Our models for estimating organ dose based on CT number were established by experiment and verified in clinical use.
本研究通过体模研究建立线性模型，探讨了碘化造影剂（ICM）对计算机断层扫描（CT）辐射剂量的影响。使用半导体X射线剂量计对热释光剂量计（TLD）进行校准。在不同管电压下，对含有TLD和不同浓度碘化血液的小瓶的电子密度体模进行扫描。测量辐照后TLD的输出，并计算碘化血液的吸收剂量。绘制CT值（以亨氏单位测量的组织衰减）与吸收剂量的关系图，以获得线性模型。使用49例真实患者的CT扫描数据验证线性模型。在每个X射线能量下，CT值与吸收剂量呈线性相关，即随着血液碘浓度的增加，CT值增加，吸收剂量也相应增加。ICM可导致器官剂量增加；甲状腺平均剂量增加31.8±8.9%，心肌增加37.1±9.2%，心腔增加77.7±14.0%，乳腺增加7.1±2.3%，肝脏增加26.1±7.3%，脾脏增加39.8±11.8%，肾皮质增加96.3±12.2%，肾髓质增加82.4±11.6%。增强CT扫描中使用的ICM导致器官剂量增加。我们基于CT值估算器官剂量的模型通过实验建立，并在临床应用中得到验证。
