Computed tomography as a risk factor of cancer among the population of the nuclear city of Ozyorsk

Exposure to ionizing radiation resulted from computed tomography (CT) examinations concerns a risk associated with potential radiation-induced cancers. Widespread use of this diagnostic method during the last decades has led to significant increase of collective dose of the world’s population. Minor dose restrictions for diagnostic X-ray procedures involve considerable “beneficial” exposure burden among CT-examined patients. Assessment of possible consequences became necessary in order to manage potential risks in terms of “benefit-harm” control. Retrospective epidemiological study has been performed using the cohort of individuals exposed to diagnostic radiation from CT. The source of information was the “CT Register” database which contains medical and dosimetric data on the population of nuclear city of Ozyorsk, including data on several potential risk factors such as gender, age at exposure, cancer anamnesis and contact with occupational radiation. Risk calculation was performed using conditional logistic regression. A hypothesis on increasing chances of developing of malignant neoplasm depending on the number of recurrent CT during the lifetime, taking into account potential confounders and the impact of reverse causation was tested. The relation between recurrent CT examinations and the subsequent malignant neoplasm (OR 1.01-1.10) can be confirmed at (1-alpha) 90%, which indicates the probable radiogenic component of carcinogenic risk. Further investigation with expanded follow-up period will facilitate accounting possible unrealized cancer cases with long latency period and improve the results of the study.