title: The risk of cataract associated with repeated head and neck CT studies: a nationwide population-based study.
abstract: OBJECTIVE
  Medical radiation-induced cataracts, especially those resulting from head and neck CT studies, are an issue of concern. The current study aimed to determine the risk of cataract associated with repeated radiation exposure from head and neck CT.
  
  
  METHODS
  This study used information from a random sample of 2 million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database. Exposed cases consisted of patients with head and neck tumor 10-50 years old who underwent at least one CT between 2000 and 2009. The nonexposed control group was composed of subjects who were never exposed to CT studies but who were matched by time of enrollment, age, sex, history of coronary artery disease, hypertension, and diabetes.
  
  
  RESULTS
  There were 2776 patients in the exposed group and 27,761 matched subjects in the nonexposed group. The exposed group had higher overall incidence of cataracts (0.97% vs 0.72%; adjusted hazard ratio [HR], 1.76; 95% CI, 1.18-2.63). Further stratifying the number of CT studies in the exposed group into one or two, three or four, and five or more revealed that cataract incidence increased gradually with increasing frequency of CT studies (0.79%, 0.93%, and 1.45%, respectively) (p=0.001, adjusted for trend). Radiation exposure due to repeated head and neck CT studies was independently associated with an increased risk of developing cataracts when the cumulative CT exposure frequency involved more than four studies (adjusted HR, 2.12; 95% CI, 1.09-4.14).
  
  
  CONCLUSIONS
  Repeated exposure to head and neck CT is significantly associated with increased risk of cataract.
authors: Department of Radiology, National Yang-Ming University Hospital, Yi-Lan, Taiwan.
authors: Mei-Kang
authors: MK
authors: Yuan
authors: Der-Chong
authors: DC
authors: Tsai
authors: Shih-Chieh
authors: SC
authors: Chang
authors: Mei-Chun
authors: MC
authors: Yuan
authors: Shu-Ju
authors: SJ
authors: Chang
authors: Huan-Wu
authors: HW
authors: Chen
authors: Hsin-Bang
authors: HB
authors: Leu
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002386:Cataract / Q000453:epidemiology / Q000209:etiology*; D002648:Child; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012306:Risk; D013624:Taiwan / Q000453:epidemiology; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*