Substantial radiation exposure for patients with subarachnoid hemorrhage.

Increasing attention is being paid to the cancer risk conferred by imaging modalities such as computed tomography (CT). Patients with subarachnoid hemorrhage (SAH) often are critically ill and require numerous imaging studies. A nonradiating diagnostic modality, transcranial Doppler (TCD), effectively screens for cerebral vasospasm. But when TCD is not available, CT angiography or conventional angiography may be ordered, increasing a patient's total radiation dose. This study investigated the total amount of radiation to which patients with SAH are exposed, and whether that amount was decreased by the availability of TCD. Patients with nontraumatic SAH who were admitted to an intensive care unit within 48 hours of symptom onset and who survived and remained hospitalized for at least 7 days were eligible. TCD was available for one group (TCD group) but not for the other group (no-TCD group). The total radiation dose for each patient was tallied. There were no differences in demographic variables or significant difference in radiation exposure between the 2 groups. Average total radiation exposure was 82.03 mSv in the TCD group and 89.79 mSv in the no-TCD group (P=.60). Head imaging accounted for 97.2% of the total radiation exposure in the TCD group and 90% of that in the no-TCD group. Patients with SAH are exposed to a substantial amount of radiation, almost all of which is centered on the head. Using Biological Effects of Ionizing Radiation VII cancer risk estimates, the average lifetime attributable risk from SAH management was approximately 1 in 125. Methods for decreasing radiation exposure are needed.