Guidelines for Radiation Shield Use Can Optimize Operator Protection

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Several types of radiation shields can provide substantial protection in the cath lab during invasive cardiology procedures, but proper positioning of the shields is essential to minimize physician radiation risk, according to a study published in the October 2011 issue of JACC: Cardiovascular Interventions.

Researchers led by Kenneth A. Fetterly, PhD, of the Mayo Clinic (Rochester, MN), measured protection from scatter radiation by various radiation shield devices that are widely available in cardiac interventional laboratories. Protection was analyzed with shields vs. no shields at various elevations from the floor as well as the 3 most commonly used patient access points for cardiology procedures:

• Right jugular vein
• Right femoral artery
• Left anterior chest

The precise placement of the ceiling-mounted upper body shield was of particular interest to the researchers as this shield requires the most movement during a procedure. They also investigated protection via positioning of a lower body shield with a detachable vertical extension and radiation-absorbing disposable pads.

Placement Matters

Protection from scatter radiation varied widely among access points and elevations. For the femoral artery access location, they found that the combination of shields can provide at least 80% protection from scatter radiation at all elevations; however this depends greatly on the positioning of the upper body shield.

Contrary to how the majority of physicians position the upper body shield during a procedure, the researchers found that the optimal placement for this shield is tight on the patient’s body and positioned just cephalad from the femoral access. According to the authors, when this shield is offset from the patient’s body by even 5 cm and 20 cm cephalad from the femoral access point, upper and middle body protection for the operator is compromised. This finding conflicts with the conventional thought that this shield should be placed close to the radiation source to maximize the size of the protective radiation shadow of the shield.

The lower body shield was found to provide at least 90% protection for the physician’s lower body, while the accessory vertical extension provided additional middle body protection of 25% to 90%. In addition, Dr. Fetterly and colleagues conclude that used properly, the disposable pad can provide moderate upper body protection (35%-70%) during procedures in which the upper body shield cannot be used effectively. But the authors stress that physicians need to be aware of recommended use practices so as not to compromise the efficacy of radiation shields or impede the efficacy of the procedure (table 1).

Table 1. Recommended Use of Radiation Shields

 
Protection Over Inconvenience

Dr. Fetterly said he was surprised to find maximum effectiveness of the upper body shield in a position divergent from how the majority of physicians use it. If physicians take away anything from this study, it should be to change the way they use this particular shield, he said in a telephone interview with TCTMD.

The degree to which physicians will see increased benefits by following the paper’s best practices “depends on how poor their habits are right now,” Dr. Fetterly said. “They could recognize a substantial decrease in their badge dose readings and the actual amount of radiation that gets to them. So it could be that more physicians will see a substantial change in the amount of radiation they receive over the course of a year.”

Referencing other similar studies, Stephen Balter, PhD, of Columbia University Medical Center (New York, NY), told TCTMD in an interview that physicians should be increasingly worried about protecting their eyes during procedures with radiation. He said that in addition to wearing leaded eyeglasses, physicians should recognize the necessity of the radiation shields in providing another layer of protection.

Dr. Balter also said despite any inconvenience experienced by the operator by using the radiation shields during certain procedures, the importance of the shields should not be underestimated.

“The protection is there,” he said. “[Physicians] should use it and learn how to use it properly in a way that minimizes loss of efficiency.”

The Future of Radiation Shielding 

Although the study was designed to specifically analyze radiation risk for the physician only, Dr. Balter said future research should look at radiation risk for others in the laboratory.

“My technical objection to this paper is that [it is] too focused on the operator and not the other people in the room,” he said. “Things that will maximize safety for the operator won’t necessarily provide as much safety for everyone else.”

Drs. Balter and Fetterly both mentioned ongoing research regarding a more automated laboratory setting. Because of the “active management” required for the effective operation of many of these shields, the operator and other lab technicians could see reduced radiation risk if this technology becomes available, Dr. Fetterly said.

In an editorial accompanying the study, Lloyd W. Klein, MD and Justin Maroney, MD, of Advocate Illinois Masonic Medical Center (Chicago, IL), say that the study suggests applicable guidelines for how physicians should be using the radiation shields. The best practices outlined in this paper should be put in place in every laboratory where invasive cardiology procedures are performed, they add.

“That the most advantageous shield positioning can have a greater than 4-fold relative reduction in scatter radiation exposure supports its use even when inconvenient, and suggests that learning to coordinate multiple shields should be among the fundamental principles taught in every interventional cardiology training program,” the editorial states. “Moreover, the future interventional laboratory must be designed so that radiation safety is not predicated on the voluntary cooperation, sensitivity, and education of the operators, but rather is constructed into the design of the laboratory.”

 

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Sources:
1. Fetterly, KA, Magnuson, DJ, Tannahill GM, et al. Effective use of radiation shields to minimize operator dose during invasive cardiology procedures. J Am Coll Cardiol Intv. 2011;4:1133-1139.

2. Klein LW, Maroney J. Optimizing operator protection by proper radiation shield positioning in the interventional cardiology suite. J Am Coll Cardiol Intv. 2011;4:1140-1141.

 

 

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