Patients' radiation doses during thoracic stent-graft implantation: the problem of long-lasting procedures.

BACKGROUND: This article investigates patient radiation doses during implantation of thoracic stent-graft. Aortic stengraft implantation can be disturbed by many factors, which, in turn, lead to prolongation of the procedure time and, as a consequence, increase the radiation dose.

METHODS: Measurements of radiation length (fluoroscopy and exposure), air kerma (AK) in grays, and dose-area product in grays·square centimeters were conducted simultaneously in 100 patients. The patients were analyzed retrospectively, regarding their body mass index (BMI), type of aneurysms, number of stent-graft parts, angulation of aorta, and coverage of the left subclavian artery.

RESULTS: Mean total dose-area product value for this kind of treatment was 361 Gy·cm2. This was caused by the fact that total mean AK was high for the cohort analyzed and reached 797 mGy. For 23 patients total AK was between 1 and 2 Gy, and for 3 it exceeded 2 Gy. In the remaining group, the maximal radiation dose was very high and exceeded 3 Gy. The total AK of patients with BMI within the range of 25 to 29.9 kg/m2 and with BMI greater than 30 kg/m2 significantly increased in comparison with the group of patients with BMI between 18 and 24.9 kg/m2 (p=0.00005 and 0.000001, respectively). During the study, a good correlation between AK and fluoroscopy time (r=0.6) and for AK (or dose-area product) and exposure time (r=0.66 or 0.81, respectively) was observed.

CONCLUSIONS: The main factors contributing to a high radiation dose being acquired by patients during thoracic stent-graft were BMI greater than 25 kg/m2, number of parts of the stent-graft, and angulation of the neck of aneurysm exceeding 60 degrees.