Operator Radiation Dose Still Higher with Radial Access Despite Patient Shielding

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Use of a pelvic lead shield is highly effective in reducing operator radiation exposure during coronary angiography via both radial and femoral access, according to a study published in the April 2012 issue of JACC: Cardiovascular Interventions. Despite the added protection, however, radial procedures are still associated with higher radiation doses.

Helmut W. Lange, MD, of Herzzentrum Bremen, and Heiner von Boetticher, PhD, of Klinikum Links der Weser (both Bremen, Germany), randomized 210 patients undergoing elective coronary angiography by the same operator to radial (n = 107) or femoral (n = 103) access with or without pelvic lead shielding of the patient. All procedures were performed by Dr. Lange, who has extensive radial experience.

In all cases, standard protection consisted of an overhead-suspended lead acrylic shield with a patient contour cutout pulled down to the patient’s abdomen. A leaded side shield was mounted to the side of the table and the upper shield flap was folded down in all cases. An additional table-to-floor flap extended along the table.

Pelvic shielding of the patient consisted of a custom-made lead blanket extending from the diaphragm to the knees. The upper portion was shaped diagonally to permit caudal projections, with 1 or 2 cutouts for the femoral puncture sites.

Extra Shielding Works for Operators

The radiation dose for the operator was recorded at the beginning and end of each procedure by a dosimeter attached to the outside breast pocket of the lead apron.

With pelvic lead shielding, the operator dose was lower for both radial and femoral procedures compared with standard protection, although radial procedures still imparted operator doses that were about 3 times higher than with femoral procedures. Pelvic lead shielding decreased the dose-area product-normalized operator dose (operator dose divided by the dose-area product) by similar amounts for both access routes (table 1).

Table 1. Reductions in Operator Radiation Dose

 

Standard Protection

Pelvic Lead Shield

P Value

Operator Dose, µSv
Femoral
Radial


15.3 ± 10.4
20.9 ± 13.8


2.9 ± 2.7
9.0 ± 5.4


< 0.0001
< 0.0001

Dose-Area Product-Normalized, µSv x Gy-1 x cm-2
Femoral
Radial




0.70 ± 0.26
0.94 ± 0.28

 


0.16 ± 0.13
0.39 ± 0.19




< 0.0001
< 0.0001


Fluoroscopy time was higher for radial cases than for femoral cases (2.7 ± 1.4 min vs. 2.1 ± 1.1 min; P < 0.001). Patient radiation dose was similar across all radial and all femoral cases, and there were no differences in exposure regardless of whether or not pelvic shielding was added to standard protection.

In further analysis, only pelvic shield and route of access were shown to affect operator radiation dose and dose area product-normalized operator dose.

Radial Procedures Require More Protection

According to the authors, both procedure-related and operator-related factors are responsible for the increased radiation directed at the operator in radial procedures. For example, technical challenges of maneuvering the catheters into the coronary ostia often lead to longer fluoroscopy time, which diminishes with increasing operator expertise.

“Most important for the need of improved radiation protection, the closer position of the operator relative to the X-ray tube is inherent to the radial procedure,” they write. In a previous study they found that the operator dose was doubled for diagnostic procedures and 50% higher for interventions performed via radial access.

Importantly, the current study also found significant scatter radiation from the pelvic bones emerging from the angle between the ceiling-mounted shield and the side shield, “which can be nearly abolished by a shield covering the patient’s pelvis and thighs,” they add.

“The main message is that if you carefully add shielding, you get better protection,” Stephen Balter, PhD, of Columbia University Medical Center (New York, NY), told TCTMD in a telephone interview. “I think it’s worthwhile, particularly as the operator stands closer to the heart during a radial procedure. You need the extra protection.”

More Needed to Close the Radial-Femoral Gap

But pelvic shielding alone is not enough to close the “radiation gap” for the operator that exists between radial and femoral access, the authors say. They suggest that further reductions in radiation exposure for radial operators “are possible and should be aimed for, such as a combination of the pelvic lead shield and the protection board. These measures may eventually eliminate the difference in operator radiation exposure associated with the radial approach.”

Dr. Balter said that while the protection board is a good start, more needs to be done to make radiation doses as low as possible, which is particularly crucial for high-volume radial operators. More to the point, although the pelvic shield used in the study was highly effective, it is not available in the United States.

“We have disposable [drapes with built-in radiation protection shields], but they run up the money, whereas the pelvic shield is reusable and serves the same niche,” Dr. Balter said. “The basic message is if you are going to be doing radial procedures, you need more protection than if you are going to do femorals and [the pelvic shield] is a good example of how we can implement protection devices effectively.”

Dr. Balter added that worldwide, there is an effort to lower the maximum allowable operator dose during procedures.

“That means operators have got to use everything that’s available to be able to stay within those limits,” he said. “This paper describes the German limits, which probably will become the US limits in the next few years, so it’s definitely something we need to pay more attention to.”

 


Source:
Lange HW, von Boetticher H. Reduction of operator radiation dose by a pelvic lead shield during cardiac catheterization by radial access: Comparison with femoral access. J Am Coll Cardiol Intv. 2012;5:445-449.

 

 

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Disclosures
  • Drs. Lange, von Boetticher, and Balter report no relevant conflicts of interest.

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