Department of Vascular Surgery, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
J Vasc Surg. 2011 Apr;53(4):885-894.e1; discussion 894. doi: 10.1016/j.jvs.2010.10.106. Epub 2011 Feb 2.
A great deal of attention has been directed at the necessity and potential for deleterious outcomes as a result of radiation exposure during diagnostic evaluations and interventional procedures. We embarked on this study in an attempt to accurately determine the amount of radiation exposure given to patients undergoing complex endovascular aortic repair. These measured doses were then correlated with radiation dose estimates provided by the imaging equipment manufacturers that are typically used for documentation and analysis of radiation-induced risk.
Consecutive patients undergoing endovascular thoracoabdominal aneurysm (eTAAA) repair were prospectively studied with respect to radiation dose. Indirect parameters as cumulative air kerma (CAK), kerma area product (KAP), and fluoroscopy time (FT) were recorded concurrently with direct measurements of dose (peak skin dose [PSD]) and radiation exposure patterns using radiochromatic film placed in the back of the patient during the procedure. Simultaneously, operator exposure was determined using high-sensitivity electronic dosimeters. Correlation between the indirect and direct parameters was calculated. The observed radiation exposure pattern was reproduced in phantoms with over 200 dosimeters located in mock organs, and effective dose has been calculated in an in vitro study. Scatter plots were used to evaluate the relationship between continuous variables and Pearson coefficients.
eTAAA repair was performed in 54 patients over 5 months, of which 47 had the repair limited to the thoracoabdominal segment. Clinical follow-up was complete in 98% of the patients. No patients had evidence of radiation-induced skin injury. CAK exceeded 15 Gy in 3 patients (the Joint Commission on Accreditation of Healthcare Organizations [JCAHO] threshold for sentinel events); however, the direct measurements were well below 15 Gy in all patients. PSD was measured by quantifying the exposure of the radiochromatic film. PSD correlated weakly with FT but better with CAK and KAP (r = 0.55, 0.80, and 0.76, respectively). The following formula provides the best estimate of actual PSD = 0.677 + 0.257 CAK. The average effective dose was 119.68 mSv (for type II or III eTAAA) and 76.46 mSv (type IV eTAAA). The operator effective dose averaged 0.17 mSv/case and correlated best with the KAP (r = 0.82, P < .0001).
FT cannot be used to estimate PSD, and CAK and KAP represent poor surrogate markers for JCAHO-defined sentinel events. Even when directly measured PSDs were used, there was a poor correlation with clinical event (no skin injuries with an average PSD >2 Gy). The effective radiation dose of an eTAAA is equivalent to two preoperative computed tomography scans. The maximal operator exposure is 50 mSv/year, thus, a single operator could perform up to 294 eTAAA procedures annually before reaching the recommended maximum operator dose.
在诊断评估和介入手术中，由于辐射暴露而导致有害后果的必要性和潜在风险引起了广泛关注。我们开展这项研究的目的是准确确定接受复杂血管内主动脉修复术的患者所接受的辐射剂量。然后，将这些测量的剂量与成像设备制造商提供的辐射剂量估计值进行比较，这些估计值通常用于记录和分析辐射诱发风险。
连续接受血管内胸腹主动脉瘤（eTAAA）修复的患者进行前瞻性辐射剂量研究。同时记录累积空气比释动能（CAK）、比释动能面积乘积（KAP）和透视时间（FT）等间接参数，以及在手术过程中在患者背部放置放射色胶片直接测量的剂量（峰值皮肤剂量[PSD]）和辐射暴露模式。同时，使用高灵敏度电子剂量计测量操作人员的暴露量。计算间接参数与直接参数之间的相关性。在模拟器官中放置超过 200 个剂量计的体模中再现观察到的辐射暴露模式，并在体外研究中计算有效剂量。散点图用于评估连续变量之间的关系和 Pearson 系数。
在 5 个月内对 54 名患者进行了 eTAAA 修复，其中 47 例仅进行了胸腹段修复。98%的患者完成了临床随访。没有患者出现辐射诱导的皮肤损伤。3 名患者的 CAK 超过 15 Gy（医疗机构联合委员会 [JCAHO] 规定的警戒事件阈值）；然而，所有患者的直接测量值均远低于 15 Gy。通过量化放射色胶片的曝光量来测量 PSD。PSD 与 FT 呈弱相关，但与 CAK 和 KAP 相关性更好（r = 0.55、0.80 和 0.76）。以下公式提供了实际 PSD 的最佳估计值= 0.677 + 0.257 CAK。平均有效剂量为 119.68 mSv（II 型或 III 型 eTAAA）和 76.46 mSv（IV 型 eTAAA）。操作人员的有效剂量平均为 0.17 mSv/例，与 KAP 相关性最好（r = 0.82，P <.0001）。
FT 不能用于估计 PSD，CAK 和 KAP 是 JCAHO 定义的警戒事件的不良替代标志物。即使使用直接测量的 PSD，与临床事件（无皮肤损伤，平均 PSD >2 Gy）的相关性也很差。eTAAA 的有效辐射剂量相当于两次术前计算机断层扫描。操作人员的最大暴露量为 50 mSv/年，因此，单个操作人员每年可以进行多达 294 次 eTAAA 手术，直到达到推荐的最大操作人员剂量。
