Radiation dose to the lens from computed tomography scanning in a neuroradiology department

The radiation dose to the lens was measured by thermoluminescent dosimetry on 194 patients undergoing routine head and neck computed tomography scanning in a neuroradiology department. The results are lower than previously reported: brain scans, mean value 5.1 mGy; orbital scans, mean value 18.5 mGy; and direct coronal pituitary scans, mean value 1.9 mGy. These lower values in axial brain scans are due to use of the supraorbital meatal baseline for radiographic positioning.