Simple Measures Can Reduce Radiation to Patients, Operators in Cath Lab

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Institution of fairly simple radiation-reduction measures in the cath lab can have considerable impact on the radiation exposure of patients and lab personnel during angiography, according to a single-center report published online August 5, 2014, in Circulation: Cardiovascular Interventions.

Methods
Researchers led by Samir R. Kapadia, MD, of the Cleveland Clinic (Cleveland, OH), compared patients at their institution who underwent diagnostic catheterization (n = 2,838) or PCI (n = 209) in 2012 with propensity-matched patients who had the same procedures in 2013 after the start of a radiation safety program.
The initiative included:
  • Reduction of default fluoroscopic frame rate from 10 to 7.5 frames per second
  • Greater emphasis on the use of low-dose acquisition in all cath labs
  • Greater emphasis on optimal radiation practices including use of less extreme angulations, maximal collimation, reduction in source-to-detector distance, increased field of view, and decreased geometric magnification by decreasing source-to-object distance
  • Review and critical appraisal of monthly radiation dosimetry of each interventional cardiology fellow by the cath lab director
 
The equipment and operators were the same for the 2 study periods.


Significant Reductions in Air Kerma

When radiation burdens were compared between 2012 and 2013, there was a 22% reduction in total air kerma for diagnostic catheterization and a 32% reduction for PCI, as well as decreases in fluoroscopy- and acquisition-based total air kerma rates for both procedures (table 1).

Table 1. Median Air Kerma Values, 2013 vs 2012

 

2012

2013

P Value

Diagnostic Catheterization

Total Air Kerma, mGy

798

625

< .001

Fluoroscopy-Based Air Kerma, mGy

338

196

< .001

Fluoroscopy-Based Air Kerma Rate, mGy/s

0.76

0.43

< .001

Acquisition-Based Air Kerma, mGy

423

384

< .001

Acquisition-Based Air Kerma Rate, mGy/s

7.85

7.15

< .001

PCI

Total Air Kerma, mGy

2,463

1,675

< .001

Fluoroscopy-Based Air Kerma, mGy

1,713

1,047

< .001

Fluoroscopy-Based Air Kerma Rate, mGy/s

1.14

0.68

< .001

Acquisition-Based Air Kerma, mGy

574

430

< .001

Acquisition-Based Air Kerma Rate, mGy/s

8.81

7.11

.001

 

Comparison of procedures performed with low-dose acquisition in 2013 vs normal-dose acquisition in 2012 found lower fluoroscopy- and acquisition-based air kerma and air kerma rates. Additionally, procedures using normal-dose acquisition in 2013 had significantly lower radiation values vs matched procedures in 2012.

Using comparative 3D spatial maps for fluoroscopy- and acquisition-based air kerma, the researchers also found a reduction for various projections (right anterior oblique-left anterior oblique and cranial-caudal) after reduction in the default fluoroscopic frame rate.

“Contrary to the existing belief, our study clearly demonstrates that the use of lower fluoroscopic frame rate and low-dose acquisition can lead to marked reduction in the total air kerma, even for projections involving steep angulations,” Dr. Kapadia and colleagues write.

More Operator Education Stressed

But the researchers note that despite the availability of multiple tools for reducing radiation dose without hampering image quality, many operators may be unaware of “technical intricacies” required to use newer digital imaging technology and flat-bed panel detectors to their fullest potential.

Although radiation dose during cardiac catheterization is affected by several factors that may be considered unalterable—eg, body surface area, procedural complexity, operator experience, equipment— it is also “highly dependent on factors that may be controlled by the operator, thereby providing avenues to minimizing radiation doses by substantial amounts,” they say.

Stephen Balter, PhD, of Columbia University Medical Center (New York, NY), agreed, telling TCTMD in a telephone interview that successful radiation reduction requires both proper technology use and physician education.

“What studies like this show is if you choose different settings, you can do your cases with less radiation to the patient and by inference, less radiation to yourself,” he added. “There’s always the opportunity to turn it up if you can’t see. If you use the technology optimally, you can make do with less and still get your job done. That’s the bottom line.”

Dr. Balter, who will be conducting 8 hours of training in radiation safety at the upcoming TCT meeting in Washington, DC, also noted that less radiation also means less risk of radiation-induced skin injury, which is of particular importance for PCI patients with longer exposures.  

Overall, he said, the investigators should be congratulated on significantly reducing radiation at their center and incorporating key elements of good radiation practice into their protocol, especially feedback to clinicians about their radiation use.

 


Source:
Agarwal S, Parashar A, Ellis SG, et al. Measures to reduce radiation in a modern cardiac catheterization laboratory. Circ Cardiovasc Interv. 2014;Epub ahead of print. 

Disclosures:
Drs. Kapadia and Balter report no relevant conflicts of interest. 

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