Radiation exposure dose of fluoroscopy-guided gastrointestinal procedures: A single-center retrospective study

Managing radiation safety and protection in gastroenterology in Japan: insights from the REX-GI study

Fluoroscopy-guided gastrointestinal procedures, including gastrointestinal stenting, balloon-assisted endoscopy (BAE), endoscopic retrograde cholangiopancreatography (ERCP), and endoscopic ultrasound (EUS), are essential for diagnosis and treatment in gastroenterology. Such procedures involve radiation exposure that necessitates strict safety measures to protect patients, doctors, and medical staff. The April 2020 update to Japan's Ionizing Radiation Injury Prevention Regulations for occupational exposure reduced the lens exposure dose limit to approximately one-seventh of its previous level. This change highlights the need for improved safety protocols. Without adaptation, the sustainability of fluoroscopy-based endoscopic techniques could be at risk due to the potential to exceed these new limits. This review examines the current state of medical radiation exposure in the field of gastroenterology in Japan and discusses the findings of the REX-GI study.

Dedicated Echoendoscope for Interventional Endoscopic Ultrasound: Comparison with a Conventional Echoendoscope

Background/Objective: Interventional endoscopic ultrasound (I-EUS) is technically difficult and has risks of severe adverse events due to the scarcity of dedicated endoscopes and tools. A new EUS scope was developed for I-EUS and was modified to increase the puncture range, reduce the blind area, and overcome guidewire difficulties. We evaluated the usefulness and safety of a new EUS scope compared to a conventional EUS scope. Methods: All I-EUS procedures were performed at Juntendo University Hospital from April 2020 to April 2022. The primary outcomes included the procedure time and fluoroscopy time. The secondary outcomes included the technical success rate and the rates of procedure-related adverse events. Clinical data were retrospectively reviewed and statistically analyzed between the new and conventional EUS scopes. Results: In total, 143 procedures in 120 patients were analyzed. The procedure time was significantly shorter with the new EUS scope, but the fluoroscopy time was not different. Among the patients only undergoing EUS-guided biliary drainage (EUS-BD), 79 procedures in 74 patients were analyzed. Both the procedure time and fluoroscopy time were significantly shorter with the new EUS scope. Multivariate analysis revealed that a new EUS scope and use of covered metal stents could reduce the fluoroscopy time. The technical success rate and the adverse event rate were not significantly different between the total I-EUS and the EUS-BD only groups. However, the conventional scope showed stent deviation during stent placement, which did not happen with the new scope. Conclusions: The new EUS scope reduced procedure time for total I-EUS and fluoroscopy time for EUS-BD compared to a conventional EUS scope because of the improvement suitable for I-EUS.

Impact of equipment technology on reference levels in fluoroscopy-guided gastrointestinal procedures

OBJECTIVES

To evaluate the effect of equipment technology on reference point air kerma (Ka,r), air kerma-area product (PKA), and fluoroscopic time for fluoroscopically-guided gastrointestinal endoscopic procedures and establish benchmark levels.

METHODS

This retrospective study included the consecutive patients who underwent fluoroscopically-guided gastrointestinal endoscopic procedures from May 2016 to August 2023 at a tertiary care hospital in the U.S. Fluoroscopic systems included (a) Omega CS-50 e-View, (b) GE Precision 500D, and (c) Siemens Cios Alpha. Radiation dose was analyzed for four procedure types of endoscopic retrograde biliary, pancreas, biliary and pancreas combined, and other guidance. Median and 75th percentile values were computed using software package R (version 4.0.5, R Foundation).

RESULTS

This large study analyzed 9,459 gastrointestinal endoscopic procedures. Among four procedure types, median Ka,r was 108.8-433.2 mGy (a), 70-272 mGy (b), and 22-55.1 mGy (c). Median PKA was 20.9-49.5 Gy∙cm2 (a), 13.4-39.7 Gy∙cm2 (b), and 8.91-20.9 Gy∙cm2 (c). Median fluoroscopic time was 2.8-8.1 min (a), 3.6-9.2 min (b), and 2.9-9.4 min (c). Their median value ratio (a:b:c) was 8.5:4.8:1 (Ka,r), 2.7:2.1:1 (PKA), and 1.0:1.1:1 (fluoroscopic time). Median value and 75th percentile are presented for Ka,r, PKA, and fluoroscopic time for each procedure type, which can function as benchmark for comparison for dose optimization studies.

CONCLUSION

This study shows manifold variation in doses (Ka,r and PKA) among three fluoroscopic equipment types and provides local reference levels (50th and 75th percentiles) for four gastrointestinal endoscopic procedure types. Besides procedure type, imaging technology should be considered for establishing diagnostic reference level.

SUMMARY

With manifold (2 to 12 times) variation in doses observed in this study among 3 machines, we recommend development of technology-based diagnostic reference levels for gastrointestinal endoscopic procedures.

Is there a role for routine intraoperative cholangiogram in diagnosing CBD stones in patients with normal liver function tests? A prospective study

Objectives

Cholecystectomy with or without intraoperative cholangiogram (IOC) is an accepted treatment for cholelithiasis. Up to 11.6 % of cholecystectomies have incidental common bile duct (CBD) stones on IOC and 25.3 % of undiagnosed CBD stones will develop life-threatening complications. These will require additional intervention after primary cholecystectomy, further straining the healthcare system. We seek to examine the role of IOC in patients with normal LFTs by evaluating its predictive values, intending to treat undiagnosed CBD stones and therefore ameliorate these issues.

Methods

All patients who underwent cholecystectomies with normal LFTs from October 2019 to December 2020 were prospectively enrolled. IOC was done, ERCPs were performed for filling defects and documented as "true positive" if ERCP was congruent with the IOC. "False positives" were recorded if ERCP was negative. "True negative" was assigned to normal IOC and LFT after 2 weeks of follow-up. Those with abnormal LFTs were subjected to ERCP and documented as "false negative". Sensitivity, specificity, and predictive values were calculated.

Results

A total of 180 patients were analysed. IOC showed a specificity of 85.5 % and a NPV of 88.1 % with an AUC of 73.7 %. The positive predictive value and sensitivity were 56.5 and 61.9 % respectively.

Conclusions

Routine IOC is a specific diagnostic tool with good negative predictive value. It is useful to exclude the presence of CBD stones when LFT is normal. It does not significantly prolong the length of hospitalization or duration of the cholecystectomy hence reducing the incidence of undetected retained stones and preventing its complications effectively.

Medical radiation exposure during gastrointestinal enteral metallic stent placement: Post hoc analysis of the REX-GI study

Background and Aim

Recently, the use of various endoscopic procedures performed under X-ray fluoroscopy guidance has increased. With the popularization of such procedures, diagnostic reference levels (DRLs) have been widely accepted as the global standard for various procedures with ionizing radiation. The Radiation Exposure from Gastrointestinal Fluoroscopic Procedures (REX-GI) study aimed to prospectively collect actual radiation exposure (RE) data and establish DRLs in gastrointestinal endoscopy units. In this post hoc analysis of the REX-GI study, we established DRLs for each disease site by analyzing cases of gastrointestinal enteral metallic stent placement.

Methods

The REX-GI study was a multicenter, prospective observational study conducted to collect actual RE data during gastrointestinal enteral metallic stent placement. To establish DRL values for three disease sites, namely the esophagus, gastroduodenum, and colon, we examined fluoroscopy time (FT; min), number of X-ray images, air kerma at the patient entrance reference point (K a,r; mGy), and the air kerma-area product (P KA; Gy cm2) during enteral metallic stent placement.

Results

Five-hundred and twenty-three stenting procedures were performed. The DRL values of FT (min) and the number of X-ray images for the esophagus/gastroduodenum/colon were 9/16/18 min and 9/15/11 min, respectively. Furthermore, the DRL values of K a,r and P KA for each disease site were 43.3/120/124 mGy and 10.3/36.6/48.4 Gy cm2, respectively. Among the procedures, esophageal stents were significantly associated with the lowest values (P < 0.001).

Conclusion

The characteristics of RE vary according to disease site among gastrointestinal enteral metallic stent placements. Thus, it is desirable to set DRL values based on the disease site.

How should radiation exposure be handled in fluoroscopy-guided endoscopic procedures in the field of gastroenterology?

Fluoroscopy-guided endoscopic procedures (FGEPs) are rapidly gaining popularity in the field of gastroenterology. Radiation is a well-known health hazard. Gastroenterologists who perform FGEPs are required to protect themselves, patients, as well as nurses and radiologists engaged in examinations from radiation exposure. To achieve this, all gastroenterologists must first understand and adhere to the International Commission on Radiological Protection Publication. In particular, it is necessary to understand the three principles of radiation protection (Justification, Optimization, and Dose Limits), the As Low As Reasonably Achievable principle, and the Diagnostic Reference Levels (DRLs) according to them. This review will mainly explain the three principles of radiation exposure protection, DRLs, and occupational radiological protection in interventional procedures while introducing related findings. Gastroenterologists must gain knowledge of radiation exposure protection and keep it updated.

Comparison of Radiation Exposure between Endoscopic Ultrasound-Guided Hepaticogastrostomy and Hepaticogastrostomy with Antegrade Stenting

Fluoroscopy forms an essential part of endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) and hepaticogastrostomy with antegrade stenting (EUS-HGAS). To date, no study has assessed and compared radiation exposure between EUS-HGS and EUS-HGAS. This study aimed to compare the radiation exposure parameters between EUS-HGS and EUS-HGAS. This retrospective single-center cohort study included consecutive patients who underwent EUS-HGS or EUS-HGAS from October 2017 to March 2019. The air kerma (AK: mGy), kerma–area product (KAP: Gycm²), fluoroscopy time (FT: min), and procedure time (PT: min) were assessed and compared between the two procedures. Altogether, 45 and 24 patients underwent EUS-HGS and EUS-HGAS, respectively. The median AK, KAP, FT, and PT were higher in the EUS-HGAS group than in the EUS-HGS group. A comparison revealed no difference in the technical success rate, complications rate, adverse event occurrence rate, and re-intervention rate between both procedures. This is the first report in which radiation exposure was used as a comparative parameter between EUS-HGS and EUS-HGAS. This study revealed that radiation exposure is significantly higher in EUS-HGAS than in EUS-HGS. Increased awareness on radiation exposure is warranted among gastroenterologists so that they choose the procedure with lower radiation exposure in cases where both procedures are indicated.

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study

BACKGROUND

Diagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan.

METHODS

This multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525).

FINDINGS

Overall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely.

INTERPRETATION

This study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values.

FUNDING

This work was supported by a clinical research grant from the Japanese Society of Gastroenterology.

The radiation doses and radiation protection on the endoscopic retrograde cholangiopancreatography procedures

Although many interventions involving radiation exposure have been replaced to endoscopic procedure in the gastrointestinal and hepatobiliary fields, there remains no alternative for enteroscopy and endoscopic retrograde cholangiopancreatography (ERCP), which requires the use of radiation. In this review, we discuss the radiation doses and protective measures of endoscopic procedures, especially for ERCP. For the patient radiation dose, the average dose area product for diagnostic ERCP was 14-26 Gy.cm², while it increased to as high as 67-89 Gy.cm² for therapeutic ERCP. The corresponding entrance skin doses for diagnostic and therapeutic ERCP were 90 and 250 mGy, respectively. The mean effective doses were 3- 6 mSv for diagnostic ERCP and 12-20 mSv for therapeutic ERCP. For the occupational radiation dose, the typical doses were 94 μGy and 75 μGy for the eye and neck, respectively. However, with an over-couch-type X-ray unit, the eye and neck doses reached as high as 550 and 450 μGy, with maximal doses of up to 2.8 and 2.4 mGy/procedure, respectively.A protective lead shield was effective for an over couch X-ray tube unit. It lowered scattered radiation by up to 89.1% in a phantom study. In actual measurements, the radiation exposure of the endoscopist closest to the unit was reduced to approximately 12%. In conclusion, there is a clear need for raising awareness among medical personnel involved endoscopic procedures to minimise radiation risks to both the patients and staff.