Estimation of organ-absorbed radiation doses during 64-detector CT coronary angiography using different acquisition techniques and heart rates: a phantom study
Estimation of organ-absorbed radiation doses during 64-detector CT coronary angiography using different acquisition techniques and heart rates: a phantom study
复制标题
使用不同采集技术和心率估算 64 探测器 CT 冠状动脉造影过程中器官吸收的辐射剂量：一项模型研究
作者：
K. Matsubara;K. Koshida;K. Noto;T. Takata;T. Shimono;H. Kawashima;Tomoyuki Yamamoto;O. Matsui
背景：虽然在最新的双源CT上，合适的图像采集参数可以使有效剂量低于1mSv的CT冠状动脉成像，但单源探测器CT由于其技术限制，会导致较大的辐射剂量。因此，估算探测器CTCA中器官吸收的辐射剂量是非常重要的。目的采用不同的采集技术和心率，估算探测器经皮冠状动脉腔内成形术(CTCA)时胸部器官的辐射剂量。材料与方法用人体体模和放射光致发光玻璃剂量计(RPLD)评价乳房、心脏、肺、红骨髓、胸腺和皮肤的吸收剂量。在将RPLD放置在每个器官的解剖位置后，通过施加60次/分钟的模拟心率(Bpm)来执行心电门控螺旋采集和心电触发的非螺旋采集，并通过在每个器官的解剖位置放置RPLD后应用40、60和90 bpm的模拟心率来执行使用管电流的心电调制(ECGM)的心电门控螺旋采集。将校准后的RPLD平均剂量值乘以质量能量系数比，计算出各器官的吸收剂量。结果在所有采集中，心脏的吸收剂量最高。当模拟心率为60次/分进行螺旋和非螺旋采集时，螺旋采集、带ECGM的螺旋采集和非螺旋采集的心脏吸收剂量分别为215.5、202.2和66.8mGy.在模拟心率为40、60和90次/分的情况下，使用ECGM进行螺旋采集时，心脏的吸收剂量分别为178.6、139.1和159.3 mGy.结论为减少辐射剂量，建议采用心电触发非螺旋采集法。此外，在使用ECGM的心电门控螺旋采集过程中适当控制患者的心率也是至关重要的。
Background Though appropriate image acquisition parameters allow an effective dose below 1 mSv for CT coronary angiography (CTCA) performed with the latest dual-source CT scanners, a single-source 64-detector CT procedure results in a significant radiation dose due to its technical limitations. Therefore, estimating the radiation doses absorbed by an organ during 64-detector CTCA is important. Purpose To estimate the radiation doses absorbed by organs located in the chest region during 64-detector CTCA using different acquisition techniques and heart rates. Material and Methods Absorbed doses for breast, heart, lung, red bone marrow, thymus, and skin were evaluated using an anthropomorphic phantom and radiophotoluminescence glass dosimeters (RPLDs). Electrocardiogram (ECG)-gated helical and ECG-triggered non-helical acquisitions were performed by applying a simulated heart rate of 60 beats per minute (bpm) and ECG-gated helical acquisitions using ECG modulation (ECGM) of the tube current were performed by applying simulated heart rates of 40, 60, and 90 bpm after placing RPLDs on the anatomic location of each organ. The absorbed dose for each organ was calculated by multiplying the calibrated mean dose values of RPLDs with the mass energy coefficient ratio. Results For all acquisitions, the highest absorbed dose was observed for the heart. When the helical and non-helical acquisitions were performed by applying a simulated heart rate of 60 bpm, the absorbed doses for heart were 215.5, 202.2, and 66.8 mGy for helical, helical with ECGM, and non-helical acquisitions, respectively. When the helical acquisitions using ECGM were performed by applying simulated heart rates of 40, 60, and 90 bpm, the absorbed doses for heart were 178.6, 139.1, and 159.3 mGy, respectively. Conclusion ECG-triggered non-helical acquisition is recommended to reduce the radiation dose. Also, controlling the patients’ heart rate appropriately during ECG-gated helical acquisition with ECGM is crucial.