Radiation exposure of the ocular lens and thyroid gland during digital subtraction angiography of arteries supplying the brain.

Purpose: To find out the individual level of radiation exposure of the ocular lens and thyroid gland during DSA of arteries supplying the brain, considering the indication. Material and Method: The study was conducted on 72 patients during aortic arch and cerebral artery angiographies using thermoluminescent dosimetry. Results: During 20 aortic arch angiographies the measured values were within non-critical limits, whereas during carotid, Vertebral or cerebral four-vessel angiography of the left ocular lens exposure values of more than 500 mGy (max. 782 mGy) were stated in two of 52 cases. The highest measured exposure relating to the right ocular lens was 126 mGy, to the thyroid gland 88 mGy. However, in 51 of 52 cases thyroid gland doses of below 51 mGy were measured. In 71 of 72 cases there was a lateral difference between right and left lens exposure up to twice the measured dose for the right ocular lens during aortic arch angiographies and up to sixteenfold in respect of the left lens during cerebral angiographies. Conclusion: In addition to the fluoroscopic time, number of images, fade-in and zoom some other dose-influencing factors, radiation geometry is especially decisive for organ exposure. The risk of cataracts or thyroid gland carcinomas/hypothyrosis can be neglected with median Values of 40 and 70 mGy relating to the ocular lens and 17 mGy for the thyroid gland during cerebral angiographies.