The relationship between the radiation doses and the chromosomal aberrations of peripheral lymphocytes was studied in patients under-going catheterization with or without angiocardiography.

The radiation doses were estimated and chromosomal aberration analyses were carried out in 17 cases. They consisted of 10 males and 7 females at the age of 4 to 26 years with an average of 14 years.

Doses in the chest and gonadal regions were measured with calibrated thermoluminescent dosimeters. Peripheral blood samples were taken immediately before and after the diagnostic procedure for chromosome analyses.

Results showed that the average doses in the gonad region during cardiac catheterization with and without angiocardiography were 2.4 and 0.83 kC/kg respectively

while those in the chest region were as high as 0.93 and 0.54kC/kg respectively. The chromosome aberration rate in both groups were significantly higher (2.75—3.33%) than the control value (0.22—0.75%) which was determined before X ray examination. No statistically significant difference of chromosome aberration yield was found between the two groups with and without angiocardiography.