Reducing the fluoroscopy pulse rate from 7.5 to 1.0 pulses per second during endoscopic retrograde cholangiopancreatography for common bile duct stone removal significantly decreases total patient radiation exposure without altering procedure times or adverse event rates, following recent clinical findings.
This retrospective before-and-after study examined 173 total cases at Sendai Kousei Hospital in Sendai, Japan. Led by Daichi Togo from the Department of Gastroenterology, the evaluation compared a standard-rate group treated between November 2021 and April 2022 with a super-low-rate cohort treated from June 2022 to October 2022.
Lower Pulse Rates Reduce Radiation Without Affecting Safety
- Radiation Dose Reduction: Lowering the machine’s pulse rate sharply drops the total X-ray exposure a patient receives during the procedure, falling from a median of 7.80 mGy down to 2.13 mGy.
- Unchanged Procedure Duration: Dropping the pulse rate does not lengthen the time required to complete the operation or extend active fluoroscopy time.
- Identical Safety Profile: The frequency of postoperative complications, residual stones, and overall procedural success remained stable between both groups.
Sendai Kousei Hospital Tests Pulse Frequency in ERCP
Endoscopic retrograde cholangiopancreatography, commonly known as ERCP, uses fluoroscopy—an X-ray imaging technique—to guide clinicians through the biliary tree. To address this risk, researchers at Sendai Kousei Hospital evaluated whether adjusting pulse frequency could curb radiation output without compromising visualization or safety.
The investigation split 173 patient cases into two distinct cohorts. The standard-rate group comprised 91 patients with a mean age of 75.2 years who underwent ERCP at 7.5 pulses per second. The super-low-rate group included 82 patients with a mean age of 74.9 years treated at 1.0 pulse per second. Imaging across the study utilized a low-dose setting operating at 35% of normal radiation parameters alongside adjustable pulse rate options.
| Parameter | Standard-Rate Group (7.5 pps) | Super-Low-Rate Group (1.0 pps) | Statistical Significance |
|---|---|---|---|
| Patient Cohort (n) | 91 | 82 | – |
| Mean Age (Years) | 75.2 | 74.9 | – |
| Total Radiation Dose (Median mGy) | 7.80 | 2.13 | P < .001 |
| Fluoroscopy Time (Median Minutes) | Not significantly different | Not significantly different | – |
| Adverse Event Rates | No significant difference | No significant difference | – |
Multivariable Regression Analysis of Fluoroscopic Variables
Data collection quantified the total fluoroscopy dose using air kerma measured at the patient entrance reference point. Investigators also tracked fluoroscopy duration, overall procedure length, procedural success rates, and the percentage of cases requiring repeat intervention for residual stones. Multivariable regression analysis confirmed that super-low-rate pulsed fluoroscopy was independently associated with a marked decrease in total radiation dose, yielding a beta coefficient of -11.90 with a P-value under .001.
The analysis also identified patient body mass index and active fluoroscopy time as independent predictors of total radiation dose. Despite these influencing factors, dropping the pulse rate successfully restricted overall radiation absorption.
Study authors noted clear parameters regarding generalizability and measurement scope. Radiation measurements relied exclusively on air kerma to reflect patient dose, meaning operator and staff exposure levels were not evaluated. Image quality was not systematically assessed, and the low incidence of adverse events limited the statistical power required to identify differences in rare clinical complications.
Future Directions in Biliary Endoscopy Safety
Published online in Techniques and Innovations in Gastrointestinal Endoscopy, the study received no specific funding, and the authors reported no conflicts of interest.
References
- Togo, D., et al. Low-Pulse Fluoroscopy Tied to Reduced Radiation Dose in ERCP. Techniques and Innovations in Gastrointestinal Endoscopy.
