Real-time Monitoring Device Lowers Radiation to PCI Operators

Marlene Busko

December 01, 2014

CHICAGO, IL — By wearing a novel radiation-monitoring device that beeps faster and faster as radiation exposure increases, interventional cardiologists working in a cardiac catheterization laboratory were able to lessen their radiation exposure by a third, in the RadiCure study[1].

This was the first prospective randomized trial to evaluate the use of a real-time radiation monitoring device—the Bleeper SV (Vertec Scientific, Berkshire, UK)—during diagnostic angiography and PCI.

Conventional radiation-detection badges detect cumulative radiation doses and are read monthly. However, by wearing this real-time monitoring device, the interventional cardiologists knew they were being exposed to more radiation and could make immediate changes during a procedure, Dr Georgios Christopoulos (University of Texas Southwestern Medical Center, Dallas), told heartwire at a poster presentation at the American Heart Association (AHA) 2014 Scientific Sessions.

"Real-time monitoring is a pretty novel finding, and people don't really know about it," he added. Operators "can . . . adjust the position of the shield, or [they] can distance [themselves] from the patient and the radiation source" to limit radiation exposure when they hear an increased rate of beeping, he said.

"We were looking for a long time to find a device that would provide live feedback on operator radiation exposure; when we finally found one (after searching the internet) we were so excited we wanted to study how good it actually is in reducing radiation exposure," senior author Dr Emmanouil S Brilakis (University of Texas Southwestern Medical Center) told heartwire in an email.

The RadiCure study was published online November 25, 2014 in Circulation: Cardiovascular Interventions[2].

Does the Warning Device Work?

The researchers randomized 18 operators (16 fellow and two attending physicians) to use the Bleeper SV or a silent radiation dosimeter during cardiac catheterization procedures at their center between January 2012 and May 2014.

Almost all the patients undergoing the procedures (99%) were men. They had an average age of 65, and 30% had previous CABG.

Most patients had diagnostic coronary angiograms (64%), and the rest had angiograms plus PCI (25%) or PCI alone (11%).

The operators used radial access in 18% of cases, and 7% of the procedures were chronic total-occlusion (CTO) PCIs.

Overall, the procedures lasted a median of 27 minutes. Diagnostic angiography procedures lasted a median of 17 minutes and PCI lasted a median of 42 minutes.

The Bleeper device produces a "bleep" sound every 15 minutes in response to normal background radiation, and the beeping rate increases as radiation exposure increases until it becomes a continuous sound in high radiation fields. The device, which is about 6 inches by 1 inch, is worn clipped to a pocket. It also has a digital display showing radiation exposure during the procedure.

By using the radiation-monitoring device, operators closest to the patient (first operators) were able to lessen their radiation exposure by 36%. Assistants who were farther from the patient (second operators) were able to lessen their radiation exposure by 29%.

The improvement in radiation safety appeared to be independent of operator experience. Thus, the study supports the "expanded use of [real-time monitoring] devices in the cardiac catheterization laboratory," the researchers conclude.

Which Factors Predict High Radiation Exposure?

In the study presented at the AHA meeting, Christopoulos and colleagues analyzed data from RadiCure to identify which factors predicted high operator radiation exposure (above the median or >1.0 mrem) during cardiac catheterization.

Multivariable analysis identified that radial access and CTO intervention were associated with high first-operator radiation exposure. Real-time radiation monitoring and the use of a radioabsorbent drape were independently associated with lower operator radiation exposure.

Predictors of High Radiation Exposure by Operators During PCI and/or Angiography

Predictor OR (95% CI)
Radial access 6.62 (3.13–14.76)
CTO intervention 5.53 (1.73–20.71)
Real-time monitoring 0.33 (0.19–0.57)
Radioabsorbent drape 0.38 (0.18–0.77)

Radioabsorbent drapes are part of standard protective equipment in the cardiac catheterization laboratory, and this study reinforces their value. It also points to the value of providing operators with real-time radiation-exposure monitoring devices, Christopoulos said.

In the US, Fluke Biomedical sells the device for about $900, Brilakis said.

"Real-Time Radiation Devices Are Useful"

Asked to comment, Dr Sanjit Jolly (McMaster University, Hamilton, ON)—who conducted the RADIATION-PROTECT study that found that operators in the catheterization lab who wore a novel protective surgical cap had lower radiation exposure to the brain—said that he was not familiar with this real-time radiation monitoring device, although he knew of others.

"This shows that real-time radiation-monitoring devices are useful [and that] making operators aware of dose will make them more careful for each case and reduce doses," he said. Although he was unaware of the added value of a warning sound, he said he would use this device if it were available.

The researchers hope to receive funding to conduct a larger RadiCure II study that is powered to detect a reduction in patients' exposure to radiation in the cardiac catheterization lab.

Christopoulos has no relevant financial relationships. Brilakis received honoraria/speaker fees from St Jude Medical, Terumo, Asahi, Abbott Vascular, Somahlution, Elsevier, and Boston Scientific and a research grant from Guerbet; his spouse is an employee of Medtronic. Disclosures for the coauthors are listed in the article.

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