Tsalafoutas Ioannis A, Tsapaki Virginia, Triantopoulou Charicleia, Gorantonaki Akrivi, Papailiou John
CT Department, Konstantopoulio-Agia Olga Hospital, Athens, Greece.
AJR Am J Roentgenol. 2007 Jun;188(6):1479-84. doi: 10.2214/AJR.06.0705.
The purpose of this study was to determine patient effective dose (E) and peak absorbed dose to the skin of the patient from various CT-guided interventional procedures performed without CT fluoroscopy assistance.
In total, 49 interventions were retrospectively studied: 14 biopsies, 14 radiofrequency ablations, 14 abscess drainages, and seven nephrostomies. CT images were acquired from the department's PACS system and reviewed to record the scan parameters of each slice. Entrance surface dose and E were estimated using the Impactscan database and the related Monte Carlo conversion coefficients.
Median values of E for biopsies, radiofrequency ablations, abscess drainages, and nephrostomies were 23, 35.3, 16.2, and 11.5 mSv, respectively. Respective ranges were 5.8-46.6, 18.4-57.2, 10.9-31.5, and 5.1-32.7 mSv. The corresponding median values and ranges for the peak absorbed dose were 281, 557, 155, and 145 mGy and 133-982, 147-699, 94-315, and 75-297 mGy. The diagnostic scans obtained before the interventions were responsible for 63%, 33% 40%, and 51% of E, respectively. The largest contribution to the peak absorbed dose was due to positioning of the tissue acquisition biopsy gun in biopsies (48%), the radiofrequency needle in ablations (57%), and the catheter in abscess drainages (41%) and nephrostomies (49%).
For the CT interventions studied, and especially for biopsies and radiofrequency ablations, patient effective doses were considerably high. Maximum peak absorbed dose observed was about 1 Gy, considerably lower than the threshold for deterministic effects (2 Gy).
本研究的目的是确定在无CT透视辅助下进行的各种CT引导介入操作中患者的有效剂量（E）以及患者皮肤的峰值吸收剂量。
共回顾性研究了49例介入操作：14例活检、14例射频消融、14例脓肿引流和7例肾造瘘术。从科室的PACS系统获取CT图像并进行审查，以记录每个层面的扫描参数。使用Impactscan数据库和相关的蒙特卡洛转换系数估算体表入射剂量和E。
活检、射频消融、脓肿引流和肾造瘘术的E中位数分别为23、35.3、16.2和11.5 mSv。各自的范围为5.8 - 46.6、18.4 - 57.2、10.9 - 31.5和5.1 - 32.7 mSv。峰值吸收剂量的相应中位数和范围分别为281、557、155和145 mGy以及133 - 982、147 - 699、94 - 315和75 - 297 mGy。介入操作前进行的诊断扫描分别占E的63%、33%、40%和51%。对峰值吸收剂量贡献最大的分别是活检中组织采集活检枪的定位（48%）、射频消融中射频针的定位（57%）、脓肿引流中导管的定位（41%）和肾造瘘术中导管的定位（49%）。
对于所研究的CT介入操作，尤其是活检和射频消融，患者有效剂量相当高。观察到的最大峰值吸收剂量约为1 Gy，远低于确定性效应的阈值（2 Gy）。
