Radiation-shielding technologies protect interventionalists

New composite radiation shields and flat-panel x-ray detectors significantly reduce interventional radiologists' exposure to radiation, according to studies presented at the 2005 Society of Interventional Radiology meeting.

The benefits of IR procedures generally outweigh the risks of radiation in slender patients. Obese patients, however, require a longer time at the fluoro suite, and their numbers are growing. They subject IRs to potentially higher risk for continuous exposure during fluoroscopy-guided procedures. Standard shields for scatter radiation can be ineffective.

Dr. Gary D. Hartwell and colleagues at the University of Virginia Health System evaluated lead-equivalent shielding materials' ability to reduce scatter radiation during interventional procedures. They found that, when used appropriately, composite shields could reduce IRs' radiation exposure by more than 80%.

The investigators conducted radiation-exposure tests using an anthropomorphic phantom and a fluoro C-arm configured with its x-ray tube under the angiography table. They gauged exposure with a dosimeter at different body levels and C-arm position degrees with and without composite shields. Exposures to the eye, chest, waist, and knee levels at 30° with and without shields provided mrems/second readings of 2.1 versus 15.6, 2.9 versus 20, 3.1 versus 26.4, and 2.9 versus 30.2, respectively.

Another study from the same conference compared a conventional image-intensifier fluoroscopy system with a digital flat-panel angiography system on 44 patients. Dr. Hal L. Folander and colleagues at St. Luke's Hospital in Bethlehem, PA, found the digital system reduced operator radiation exposure up to 54%. Flat-panel technology provided improved fluoroscopic capabilities with a lower amount of contrast.

The investigators assessed operator radiation dose, contrast media concentration, fluoro time, and fluoro image quality on diagnostic abdominal aortograms and inferior vena cava filter placements performed randomly during 2004. They used standardized protocols to ensure consistency in terms of patient selection, procedure types, and contrast volumes on both systems. Dosimeters were attached to operators' aprons at midchest level to record exposure.

Compared with a conventional image intensifier, the digital flat-panel system delivered several statistically significant differences:

• operator radiation dose: 1.07 mrems versus 0.49 mrems

• fluoro image quality ratings: five versus six on a seven-point Leikert scale

• contrast agent concentration: 240 mgI/mL versus 213 mgI/mL

The flat-panel angio system also reduced fluoro time, but the difference was not statistically significant.

For more information from the Diagnostic Imaging archives:

Cumulative exposure to x-rays and gamma rays causes cancer

IR radiation dose comes under scrutiny

Going digital can help lower radiation dose

Meeting touts minimally invasive therapy, practice building