dose assessment and evaluation of cancer risk due to prevalent ct scan procedures

Introduction: the use of ct scan in diagnosis is increasing significantly. the purpose of this study is evaluating the normal brain and chest computed tomography (ct) scans at six medical imaging departments in tehran and evaluate the radiation dose and estimate the cancer risk associated with these normal ct scans.materials and methods:  the data of 1080 patients between 20 to 50 years old referred to the six medical imaging centers in tehran hospitals (1st january to 30th march) were collected. patients were categorized into six groups according to their ages. in this study, a radiologist helped us in interpreting the ct scan images. the drl was assessed and the beir vii model was used to estimate the radiation cancer.results: among the 1080 patients, 642 (59%) were males and the average age of the patients was 45.05 ± 22.60 years. brain ct scans in 65% cases and chest ct scan in 52% were reported normal. the third quartile of ctdivol, dlp, and ed values in the brain and chest scans were calculated and introduced as local drl values. these values were determined as 22.13, 428.58, and 0.65 for ctdivol, dlp, and ed values in the brain scan, and 5, 187.35, and 3.71 in the chest scan. the highest risk of cancer incidence in the brain scan was related to leukemia with a value of 0.73 per 100000 exposures, followed by thyroid with a value of 0.62 in women aged 20-25 years. and in the chest scan, the highest risk of cancer incidence was related to breast cancer with a value of 22.4 per 100000 followed by lung cancer with a value of 19.02 in the same age group.conclusion: as the age decreases, the risk of cancer increases, therefore, by optimizing the radiation dose and avoiding ct scans without indications, the risk of cancer can be significantly reduced.