A new study found head CT scans do not put younger patients at risk of developing cataracts.
The study included 410,997 children and young adults who underwent CT in the UK between 1985 and 2014. Their cumulative number of head-region CT examinations was calculated. A sample of images from these head examinations (n = 668) were reviewed to determine the level of eye inclusion. Lens dose per scan was estimated using NCICT V1.0.
A total of 284,878 patients underwent 448,108 head-region CT examinations. Most patients (72%) had a single recorded head-region examination; only a small subset (∼1%, n = 2,494) underwent ≥10 examinations and 0.1% (n = 387) underwent ≥20 examinations. Lenses were included in the head CT scan 57% of the time.
Results showed that estimated lens doses ranged from 20 to 75 milligray (mGy) and the mean lens dose per scan was 47 mGy. Potential cumulative lens doses ranged from ∼3 mGy to ∼4,700 mGy, with 2,335 patients potentially receiving >500 mGy. Because most patients will receive cumulative lens doses below 500 mGy, the risk of causing cataracts is very small.
Harbron RW, Ainsbury EA, Barnard SGR, et al. Radiation dose to the lens from CT of the head in young people. Clin Radiol. 2019;74(10):816.e9-816.e17. doi: 10.1016/j.crad.2019.06.029.