Nickoloff E L, Khandji A, Dutta A
Department of Radiology, Columbia University P&S and New York-Presbyterian Hospital, New York 10032-3784, USA.
Health Phys. 2000 Dec;79(6):675-81. doi: 10.1097/00004032-200012000-00013.
CT fluoroscopy (CTF) is a relatively new imaging modality that is particularly useful for performing complex biopsy procedures. Despite the obvious benefits, the potential exists to deliver considerable radiation doses to both the patients and medical staff. The purpose of our study was to quantify the radiation levels based upon typical clinical procedures. To assess the potential radiation risks, the patient radiation doses via the CT dose index (CTDI) method were measured during CTF for a GE Pro-Speed CT scanner using standardized head and body phantoms and a CT ionization chamber. The measurements were performed for a variety of kVp, mA, and slice thickness settings. To determine patient radiation doses, the CT kVp, mA, and total CTF scan times were recorded for various biopsy procedures. To determine the radiation doses to the hands of the radiologists, a radiation survey meter was used to measure the scattered radiation from standard phantoms. The effectiveness of various types of leaded gloves and shields were also determined. The measured CTDI values ranged from 20.4 cGy min(-1) to 63.1 cGy min(-1) of CTF. For a group of 78 patients, the clinically utilized imaging times varied from 13.0 to 407 s with an mean time of 96.6 s +/- 78.9 s (1 standard deviation). The scattered x-ray radiation at the position of the radiologists hands performing the biopsy procedures was measured to be 0.6 to 1.5 mGy min(-1). The thin leaded gloves provided a relatively minimal reduction in the scattered radiation to the hands between 11% and 44% dependent upon the kVp and the type of glove. However, floor mounted radiation shields reduced the scattered radiation levels to the body by 94% to 99%. In comparison to standard x-ray fluoroscopy, CTF employs much higher radiation dose rates due to the higher kVp, mA, and rotating geometry. It is important to minimize the radiation dose to patients and staff by limiting the imaging times, employing lower mA settings, and using appropriate radiation protection measures.
CT透视（CTF）是一种相对较新的成像方式，对进行复杂活检程序特别有用。尽管有明显益处，但存在向患者和医护人员传递大量辐射剂量的可能性。我们研究的目的是根据典型临床程序量化辐射水平。为评估潜在辐射风险，在使用GE Pro-Speed CT扫描仪进行CTF时，通过CT剂量指数（CTDI）方法，使用标准化头部和身体模型以及CT电离室测量患者辐射剂量。针对各种千伏峰值（kVp）、毫安（mA）和切片厚度设置进行测量。为确定患者辐射剂量，记录各种活检程序的CT kVp、mA和总CTF扫描时间。为确定放射科医生手部的辐射剂量，使用辐射测量仪测量来自标准模型的散射辐射。还确定了各种类型铅手套和防护屏的有效性。测量的CTF的CTDI值范围为20.4 cGy min⁻¹至63.1 cGy min⁻¹。对于一组78名患者，临床使用的成像时间从13.0秒至407秒不等，平均时间为96.6秒±78.9秒（1个标准差）。在进行活检程序时，放射科医生手部位置的散射X射线辐射测量值为0.6至1.5 mGy min⁻¹。薄铅手套对传递到手上的散射辐射减少相对较小，减少幅度在11%至44%之间，这取决于kVp和手套类型。然而，落地式辐射防护屏将身体的散射辐射水平降低了94%至99%。与标准X射线透视相比，由于更高的kVp、mA和旋转几何结构，CTF采用的辐射剂量率要高得多。通过限制成像时间、采用较低的mA设置以及使用适当的辐射防护措施，将患者和工作人员的辐射剂量降至最低很重要。
