In view of the rapid expansion of diagnostic nuclear medicine procedures in Iran, this study was undertaken to examine trends of nuclear medicine practice in the country and to determine the mean effective dose equivalent per patient and per capita.

Comprehensive national data covering 93% of all nuclear medicine centers in 1985-1989 were obtained.

The total number of nuclear medicine examinations increased by 42% during these years.

The relative frequency of thyroid investigations was 84% followed by liver/spleen and bone procedures (7% and 6%, respectively). 99mTc was the radionuclide of choice for 86% of investigation while 131I alone accounted for 59% of collective effective dose equivalent.

The annual average number of nuclear medicine procedures per 1,000 people was 1.9. For the thyroid, the highest number (48%) of patients investigated was in the 15-29 y age group and the lowest (3%) was in the>64 y age group.

The male to female ratio of thyroid and cardiac patient was 0.18 and 3.64, respectively.

The numbers of males and females studied for the remaining eight procedures were less frequent and about the same.

The mean effective dose equivalent per patient and per capita was about 4.3 mSv and 8 muSv, respectively. 131I was responsible for most of collective effective dose equivalent produced by nuclear medicine.

Therefore, future efforts should be concentrated on dose reduction for diagnostic 131I tests.