Table 3.

Summary of radiological examinations of the cohort and case groups

Variable	Whole database	Cohort group (n=1,848)	Case group (n=13)
No. of patients (dose data available)	69,640	1,741	13
No. of CT studies (dose data available)	283,158	26,546	282
No. of CT studies per patient	4.1	14.4	21.7*
No. of abdominal angiographies per patient	NA	0.43†	1.69
No. of radioactive scans per patient	NA	0.15†	1.07*
Cumulative CTDI per patient (mGy)	144	1,031	1,680*
Cumulative effective dose per patient (mSv)	65	351	560*
Follow-up period (mo.)	NA	33.6	50*

CT: Computed tomography, CTDI: Computed tomography dose index, NA: Not available. *Statistically significant before and statistically nonsignificant after family-wise correction compared with the cohort group (P=0.02-0.03). ^†Average of randomly chosen data from 112 subjects