Mellenberg D E, Sato Y, Thompson B H, Warnock N G
Department of Radiology, University of Iowa College of Medicine, Iowa City 52241, USA.
Acad Radiol. 1999 Nov;6(11):687-90. doi: 10.1016/S1076-6332(99)80118-4.
Real-time computed tomography (CT) has the potential to expedite and improve CT-guided needle biopsies by allowing cross-sectional images to be viewed in real time as a needle is advanced toward the target lesion. A major concern about this procedure is the scattered and leaked radiation to which the operator is exposed. This study was undertaken to determine the exposure rates around a CT scanner during CT-guided needle biopsies and to identify the areas of greatest personnel exposure.
Pig and human cadavers were used to simulate patients undergoing a CT-guided needle biopsy. Various anatomic biopsy sites were used. The radiologist's exposure was assessed by timing the procedure and measuring the exposure rates around the CT scanner with an ionization-chamber survey meter. Ion-chamber measurements multiplied by the time the radiologist spent performing several mock biopsies were compared with film dosimeter results. Doses to the hands, wrists, and whole body were measured with ring, wrist, body, and collar film dosimeters.
The average time required to perform a single biopsy was about 1 minute. The dose to the radiologist performing the simulated biopsies was calculated to be 123 mR, 68 mR, 14 mR, and less than 0.5 mR to the fingers, wrist, collar, and body, respectively, as calculated from ionization-chamber and time measurements. These exposure rates correlate well with the film dosimeter readings accumulated during the mock procedures.
The dose received by the radiologist performing a CT-guided biopsy was comparable to that of other interventional procedures. In addition, operating from the head of the machine (ie, distal to the bed) appeared to markedly reduce personnel exposure, due to the shielding in the gantry of the CT scanner used in the study.
实时计算机断层扫描（CT）能够在将针朝目标病变推进时实时查看横断面图像，因而有潜力加快并改善CT引导下的穿刺活检。对该操作的一个主要担忧是操作人员会受到散射和泄漏辐射。本研究旨在确定CT引导下穿刺活检期间CT扫描仪周围的辐射暴露率，并识别人员暴露最高的区域。
使用猪和人体尸体模拟接受CT引导下穿刺活检的患者。采用了各种解剖学活检部位。通过记录操作过程的时间，并使用电离室测量仪测量CT扫描仪周围的暴露率，来评估放射科医生的暴露情况。将电离室测量值乘以放射科医生进行几次模拟活检所花费的时间，并与胶片剂量计的结果进行比较。使用指环、手腕、身体和领口胶片剂量计测量手部、手腕和全身的剂量。
进行一次活检所需的平均时间约为1分钟。根据电离室测量值和时间计算，进行模拟活检的放射科医生手指、手腕、领口和身体所接受的剂量分别为123 mR、68 mR、14 mR和小于0.5 mR。这些暴露率与模拟操作期间累积的胶片剂量计读数密切相关。
进行CT引导下活检的放射科医生所接受的剂量与其他介入操作相当。此外，由于本研究中使用的CT扫描仪机架的屏蔽作用，从机器头部（即床的远端）操作似乎可显著减少人员暴露。
