Patient BMI and physician radiation dose in coronary angiography

Obesity has become more common among patients undergoing cardiac catheterization, as it has in the population as a whole. Heavier patients need more radiation for a usable image, and the patient is where the scatter that reaches staff comes from. One study measured what that means for the physician.

What the study measured

Madder and colleagues collected real-time radiation data from 1,119 consecutive coronary angiography procedures. They estimated the patient’s dose from the dose area product and recorded the physician’s dose with a dosimeter the physician wore. Patients were grouped by body mass index (BMI): under 25, 25 to 29.9, 30 to 34.9, 35 to 39.9, and 40 or more.¹

What it found

Both the patient’s dose and the physician’s dose rose significantly across the BMI groups. Compared with patients whose BMI was under 25, patients with a BMI of 40 or more had:

• 2.1 times the patient dose, a median dose area product of 91.8 against 44.5 Gy·cm².
• 7.0 times the physician dose, a median of 1.4 against 0.2 µSv per case.

Allowing for other factors, each one-point rise in BMI came with a 5.2% rise in physician dose (95% confidence interval 3.0% to 7.5%). The authors call for further studies of whether patient obesity has adverse effects on physicians through these higher doses.¹

Shielding that does not depend on the patient

Scatter rises with the patient, so shielding matters more as caseloads get heavier. In a phantom study of EggNest^® Complete, average scatter across six staff positions was 92.5% lower than with standard cath lab shielding. The study was sponsored by Egg Medical, and its authors note the results need confirming in clinical studies.² See the study on the Evidence page.