Ringelstein Adrian, Lechel Ursula, Fahrendorf Delia M, Altenbernd Jens C, Forsting Michael, Schlamann Marc
From the *Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen; and †Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Neuherberg, Germany.
J Comput Assist Tomogr. 2014 Jan-Feb;38(1):25-8. doi: 10.1097/RCT.0b013e3182a3f9a0.
This study aimed to show the simulation of the radiation exposure of the brain during perfusion measurements multi-detector-CT.
The effective dose and different organ doses were measured with thermoluminescent dosimeters in an Alderson-Rando phantom and compared with the data of a simulation program (CT-Expo V1.6) for varying scan protocols with different tube voltages (in kilovolts) and constant parameters for tube current (270 mAs), scan length (28.8 mm), scan time (40 seconds), slice thickness (24 × 1.2 mm), and number of scans (40) for multi-detector-CT perfusion measurements of the brain.
The thermoluminescent dosimeter measurements yielded effective doses of 3.8 mSv (80 kV), 8.6 mSv (100 kV), 14.1 mSv (120 kV), and 22.2 mSv (140 kV). These values were in line with the data from the simulation program CT-Expo V1.6. The organ doses varied between 97 and 556 mGy (brain), 10.7 and 80.9 mGy (eye lens), 9.6 and 46 mGy (bone marrow), 1.2 and 6.7 mGy (thyroid gland), and 4.1 to 22.3 mGy (skin). The maximum local skin dose ranged from 355 mGy (80 kV) to 1855 mGy (140 kV) in the directly exposed part of the skin.
The radiation exposure during perfusion measurements of the brain is strongly dependent on the tube voltage and can vary widely even if the other exposure parameters remain constant. Maximum organ doses up to 556 mGy (brain) can be measured. Even if we never reached local organ doses that can cause a direct radiation injury, the review of the tube voltages implemented by the vendor is mandatory beside the limitation of the scanned area by clinical examination and the reduction of the number of scans. Simulation programs are a valuable tool for dose measurements.
本研究旨在展示多探测器CT灌注测量期间脑部辐射暴露的模拟情况。
在Alderson-Rando体模中使用热释光剂量计测量有效剂量和不同器官剂量，并将其与模拟程序（CT-Expo V1.6）的数据进行比较，该模拟程序针对不同管电压（千伏）的扫描方案以及脑部多探测器CT灌注测量中管电流（270 mAs）、扫描长度（28.8 mm）、扫描时间（40秒）、层厚（24×1.2 mm）和扫描次数（40次）的恒定参数。
热释光剂量计测量得出的有效剂量分别为3.8 mSv（80 kV）、8.6 mSv（100 kV）、14.1 mSv（120 kV）和22.2 mSv（140 kV）。这些值与模拟程序CT-Expo V1.6的数据一致。器官剂量在97至556 mGy（脑）、10.7至80.9 mGy（晶状体）、9.6至46 mGy（骨髓）、1.2至6.7 mGy（甲状腺）以及4.1至22.3 mGy（皮肤）之间变化。在皮肤直接暴露部位，最大局部皮肤剂量范围为355 mGy（80 kV）至1855 mGy（140 kV）。
脑部灌注测量期间的辐射暴露强烈依赖于管电压，即使其他暴露参数保持恒定，也可能有很大差异。可测量到高达556 mGy（脑）的最大器官剂量。即使我们从未达到可导致直接辐射损伤的局部器官剂量，但除了通过临床检查限制扫描区域以及减少扫描次数外，对设备供应商所采用的管电压进行审查也是必要的。模拟程序是剂量测量的宝贵工具。
