Departments of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Departments of Cleveland Clinic Medical School, University of Wisconsin-Madison, Madison, Wisconsin, USA.
J Appl Clin Med Phys. 2024 May;25(5):e14335. doi: 10.1002/acm2.14335. Epub 2024 Mar 27.
We address the misconception that the typical physician dose is higher for CT fluoroscopy (CTF) procedures compared to C-Arm procedures.
We compare physician scatter doses using two methods: a literature review of reported doses and a model based on a modified form of the dose area product (DAP). We define this modified form of DAP, "cumulative absorbed DAP," as the product of the area of the x-ray beam striking the patient, the dose rate per unit area, and the exposure time.
The patient entrance dose rate for C-Arm fluoroscopy (0.2 mGy/s) was found to be 15 times lower than for CT fluoroscopy (3 mGy/s). A typical beam entrance area for C-Arm fluoroscopy reported in the literature was found to be 10.6 × 10.6 cm (112 cm), whereas for CTF was 0.75 × 32 cm (24 cm). The absorbed DAP rate for C-Arm fluoroscopy (22 mGycm/s) was found to be 3.3 times lower than for CTF (72 mGycm/s). The mean fluoroscopy time for C-Arm procedures (710 s) was found to be 21 times higher than for CT fluoroscopy procedures (23 s). The cumulative absorbed DAP for C-Arm procedures was found to be 9.4 times higher when compared to CT procedures (1.59 mGym vs. 0.17 mGym).
The higher fluoroscopy time in C-Arm procedures leads to a much lower cumulative DAP (i.e., physician scatter dose) in CTF procedures. This result can inform interventional physicians deciding on whether to perform inter-procedural imaging inside the room as opposed to retreating from the room.
我们纠正了一种误解，即认为 CT 透视（CTF）检查的典型医师剂量高于 C 臂检查。
我们使用两种方法比较医师散射剂量：文献中报告剂量的回顾和基于剂量面积乘积（DAP）的修正形式的模型。我们将这种 DAP 的修正形式定义为“累积吸收 DAP”，即照射到患者的射线束的面积、单位面积剂量率和曝光时间的乘积。
发现 C 臂透视的患者入射剂量率（0.2 mGy/s）比 CTF 低 15 倍（3 mGy/s）。文献中报道的 C 臂透视的典型光束入射面积被发现为 10.6×10.6 cm（112 cm），而 CTF 为 0.75×32 cm（24 cm）。C 臂透视的吸收 DAP 率（22 mGycm/s）比 CTF 低 3.3 倍（72 mGycm/s）。发现 C 臂手术的透视时间（710 s）比 CTF 手术高 21 倍（23 s）。与 CTF 程序相比，C 臂程序的累积吸收 DAP 被发现高 9.4 倍（1.59 mGym 比 0.17 mGym）。
C 臂手术中的透视时间较长，导致 CTF 手术中的累积 DAP（即医师散射剂量）要低得多。这一结果可以为决定是否在室内进行介入性成像的介入医师提供信息，而不是从室内撤退。
