Radiology: Dose to interventional rads low in hemodialysis procedures, but concerns remain
Because operators are positioned close to the primary radiation beam during percutaneous interventions with fluoroscopic guidance, study authors Sam Heye, MD, and colleagues from University Hospitals Leuven in Leuven, Belgium, sought to evaluate operator radiation exposure during interventions for hemodialysis arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs).
Dose measurements were taken during 77 procedures performed in 57 patients. The interventional radiologist wore two ring dosimeters, two thermoluminescent dosimeters on the lower legs and a thermoluminescent dosimeter on the forehead.
Based on the results, the authors found that for hemodialysis procedures, dose-area product is not indicative of operator radiation dose to extremities, though the position of the hands relative to the x-ray tube is the main determinant for dose to the hand. Radiation exposure to the hands was significantly higher compared with that to the legs, according to the authors. Mean operator radiation doses for the left and right hand were both 0.28 mSv, while does to the left and right legs were 0.11 and 0.12 mSv, respectively.
In recanalization procedures, fluoroscopy time, total procedure time and the average number of angiographic runs were higher than for percutaneous transluminal angioplasty, according to Heye et al. Radiation exposures to the hands and left leg were higher as well. Interventions with left-sided access resulted in higher doses to the right hand and leg, while the opposite was true for right-sided access interventions.
Overall mean operator radiation dose to the eye lens was low at 0.03 mSv. However, eye lens radiation dose was significantly higher for procedures performed with a flat-panel detector than those performed in a conventional angiography suite with an image intensifier.
“We hypothesize that the flat-panel detector, with larger dimensions than the image-intensifier (50 × 40–cm rectangle vs 40-cm-diameter circle), could not be positioned as close to the patient’s arm since it was limited by the patient’s chest and that, therefore, scattering dose to the eye was higher,” wrote the authors.
Heye and colleagues concluded that more studies on eye lens dose are warranted, particularly in light of new recommendations from the International Commission on Radiological Protection which advise lowering the annual dose limit to the lens of the eye to 20 mSv. Under this guideline and with the doses observed in the study, the maximum number of procedures would be about 667 per year before exceeding the recommendations.
While there was an increase in dose to the eye with a flat-panel detector, there was no significant different between systems with regard to operator radiation doses to the hands and legs.