Technical note: A comparison of physician doses in C‐Arm and CT fluoroscopy procedures

Purpose We address the misconception that the typical physician dose is higher for CT fluoroscopy (CTF) procedures compared to C‐Arm procedures. Methods 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. Results 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 cm2), whereas for CTF was 0.75 × 32 cm (24 cm2). The absorbed DAP rate for C‐Arm fluoroscopy (22 mGy*cm2/s) was found to be 3.3 times lower than for CTF (72 mGy*cm2/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 mGy*m2 vs. 0.17 mGy*m2). Conclusions 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.