Department of Electrophysiology-Cardiology, University Hospital Gasthuisberg, 49, Herestraat, 3000-Leuven, Belgium.
Phys Med Biol. 2010 Feb 7;55(3):563-79. doi: 10.1088/0031-9155/55/3/001. Epub 2010 Jan 7.
There is increasing use of three-dimensional rotational angiography (3DRA) during cardiac ablation procedures. As compared with 2D angiography, a large series of images are acquired, creating the potential for high radiation doses. The aim of the present study was to quantify patient-specific effective doses. In this study, we developed a computer model to accurately calculate organ doses and the effective dose incurred during 3DRA image acquisition. The computer model simulates the exposure geometry and uses the actual exposure parameters, including the variation in tube voltage and current that is realized through the automatic exposure control (AEC). We performed 3DRA dose calculations in 42 patients referred for ablation on the Siemens Axiom Artis DynaCT system (Erlangen, Germany). Organ doses and effective dose were calculated separately for all projections in the course of the C-arm rotation. The influence of patient body mass index (BMI), dose-area product (DAP), collimation and dose per frame (DPF) rate setting on the calculated doses was also analysed. The effective dose was found to be 5.5 +/- 1.4 mSv according to ICRP 60 and 6.6 +/- 1.8 mSv according to ICRP 103. Effective dose showed an inversely proportional relationship to BMI, while DAP was nearly BMI independent. No simple conversion coefficient between DAP and effective dose could be derived. DPF reduction did not result in a proportional effective dose decrease. These paradoxical findings were explained by the settings of the AEC and the limitations of the x-ray tube. Collimation reduced the effective dose by more than 20%. Three-dimensional rotational angiography is associated with a definite but acceptable radiation dose that can be calculated for all patients separately. Their BMI is a predictor of the effective dose. The dose reduction achieved with collimation suggests that its use is imperative during the 3DRA procedure.
越来越多的心脏消融手术中使用三维旋转血管造影（3DRA）。与二维血管造影相比，采集的图像数量众多，因此存在潜在的高辐射剂量。本研究旨在定量测量患者特定有效剂量。在这项研究中，我们开发了一种计算机模型，可准确计算 3DRA 图像采集过程中器官剂量和有效剂量。该计算机模型模拟曝光几何形状，并使用实际的曝光参数，包括通过自动曝光控制（AEC）实现的管电压和管电流的变化。我们在西门子 Axiom Artis DynaCT 系统（德国埃尔兰根）对 42 例接受消融治疗的患者进行了 3DRA 剂量计算。分别为 C 臂旋转过程中的所有投影计算了器官剂量和有效剂量。还分析了患者体重指数（BMI）、剂量面积乘积（DAP）、准直和每帧剂量（DPF）率设置对计算剂量的影响。根据 ICRP 60，有效剂量为 5.5 +/- 1.4 mSv，根据 ICRP 103，有效剂量为 6.6 +/- 1.8 mSv。有效剂量与 BMI 呈反比关系，而 DAP 与 BMI 几乎无关。无法得出 DAP 与有效剂量之间的简单转换系数。DPF 减少并未导致有效剂量成比例减少。这些矛盾的发现可以通过 AEC 的设置和 X 射线管的局限性来解释。准直可使有效剂量降低 20%以上。三维旋转血管造影具有明确但可接受的辐射剂量，可分别为所有患者计算。他们的 BMI 是有效剂量的预测因子。准直可降低剂量，因此在 3DRA 手术过程中必须使用。
