Abstract No 209: CT Fluoroscopy: Physician Radiation Dose Reduction Using Partial Angle Scanning
Physicians may be able to decrease their radiation exposure during CT-fluoroscopic (CTF) procedures by 12%–35% by utilizing a new partial angle scanning technique, a new study suggests.
Emily A. Knott
According to Emily A. Knott, a student at Cleveland Clinic Lerner College of Medicine, and presenting author of SIR 2025 Featured Abstract, CT Fluoroscopy: Physician Radiation Dose Reduction Using Partial Angle Scanning, minimizing radiation doses during CTF-guided interventions may be as simple as taking advantage of dose-reduction strategies employed during fluoroscopic C-arm procedures—and may increase overall CTF utilization.
CTF guidance for percutaneous procedures has been available since the late 1980s, Knott said, and has brought many advantages to the IR suite, such as decreased procedure times, fewer complications, and the ability to rapidly obtain multiple incremental images and finely adjust the needle trajectory in near real time.
“Based on a nonscientific sampling of academic radiology departments on the East Coast, we realized that despite the known advantages of CTF, many centers were not using it, in part due to concerns about radiation exposure to the operating physician,” Knott said.
Instead, their team learned that many physicians were performing CTF-guided procedures using a technique described in 1976 that involved walking in and out of the room between each needle movement.
“This is time consuming and can lead to large needle movements to increase efficiency, but also results in no radiation exposure to the physician,” Knott said.
As a result, Knott and her team felt there was a need to both quantify actual exposure dosage and propose a way to reduce the dose in order to increase utilization rates while decreasing safety fears. The first part of this investigation is detailed in an SIR 2025 Poster, 81 - CT Fluoroscopy-Guided Percutaneous Procedures: What is the actual physician radiation dose vs. C-arm fluoroscopic procedures?
“When first investigating this topic, we realized that quite a bit was known about operator radiation during fluoroscopic C-arm procedures, including numerous dose reduction strategies,” Knott said. “One well-known method is to position the X-ray tube away from the physician with the patient in between to decrease exposure to scatter radiation.”
Two medical physicists at her institution realized that with the advent of CT scanners, they could reconstruct an image with less than a 360° scan rotation. Physicians may be able to similarly decrease the “on-time” of the X-ray tube during CTF, Knott said.
“This would have the effect of moving the radiation source away from the physician with the patient in between, similar to conventional fluoroscopy,” she said. “We hypothesized that this technique could be leveraged to reduce operator dose during CTF-guided interventions, and we named it partial angle CTF (PACT).”
The team’s data showed that while full and partial rotation scans resulted in equivalent patient dose, the physician dose decreased when the partial angle scans were angled at 180, 225 and 275 degrees. Compared to full rotation scans, the dosage decreased by 2.3%, 12.3% and 8.8%, respectively. Other prior work suggested this could be increased up to 35% with further optimization of scan parameters.
“The results of this work demonstrate that operators using PACT can reduce their personal radiation dose by 12–35% with minimal adjustments to the scanner,” Knott said. This dose reduction is essentially “free” with no cost in terms of image quality or patient dose.
However, there are minor adjustments to scanner settings that need to be made to realize this dose reduction on current commercial scanners, she said, and precise placement is crucial. “If the physician or technologist inadvertently sets an incorrect angle so that the tube radiates when close to the physician, the operator dose can actually increase.”
As a result, Knott and her team are planning to work with manufacturers to implement the PACT system into commercial scanners as a default, with safeguards in place to avoid overexposure of the operator.
“Ultimately, we envision this as a default setting during CTF that reduces physician dose by up to 35% without the operator having to change parameters or noticing any change in image quality,” she said.
Knott encouraged all IRs who may be hesitant due to radiation concerns to keep in mind that CTF radiation dose for common percutaneous procedures with existing scanners and settings is much lower compared to most conventional fluoroscopic procedures.
“If you are avoiding doing CTF at all because of concerns about personal exposure, don’t!” Knott said.
Knott will present her findings at SIR 2025 on Tuesday, April 1, at 3 p.m. during the General IR 2 session.
Team member Adrienne Kisting will present her poster 81 - CT Fluoroscopy-Guided Percutaneous Procedures: What is the actual physician radiation dose vs. C-arm fluoroscopic procedures? on Monday, March 31, at 12:10 p.m. in the Expo Poster Area.
