Medical Radiology and Radiation Safety. 2026. Vol. 71. № 4

DOI:10.33266/1024-6177-2026-71-4-120-126

M.V. Osipov

LOW DOSES OF DIAGNOSTIC RADIATION IN CANCER PATIENTS UNDERWENT COMPUTED TOMOGRAPHY AND THE RISK OF DEATH FROM CANCER

Southern Urals Federal Research and Clinical Center for Medical Biophysics, Ozyorsk, Russia

Contact person: M.V. Osipov, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

ABSTRACT

Purpose: Assessment of subdistribution of hazard death from cancer among oncological patients exposed to low doses of diagnostic radiation during computed tomography (CT), adjusted for non-radiation risk factors taking into account competing causes of death. 

Material and methods: The source of data analyzed was the information on the population of the nuclear city of Ozersk who underwent CT scans at several medical units of the Chelyabinsk region during the period since 1989 to 2019. The analysis of time-to-event data has been performed using cohort design. The study cohort included 1,333 men and women of various ages with different stages of cancer, diagnosed before the 1st CT scan. One-third of the study cohort were the employees at the Mayak Production Association. The average cumulative radiation dose from CT scans was 15.7±0.8 mSv (max 316.6 mSv). The subdistribution hazard of cancer death, taking into account competing causes, was analyzed using the Fine-Gray method in a multivariate model adjusted for several radiation and non-radiation risk factors. The cumulative probability of death from cancer among oncological patients was estimated using the cumulative incidence function. 

Results: A statistically significant linear association was found between the diagnostic radiation dose from CT and the relative hazard of cancer death among oncological patients. Main non-radiation risk factors influencing the risk were patient gender, age at 1st cancer diagnosis, and stage of malignancy. On average, for every 1 mSv of CT diagnostic radiation dose, the sub-distribution hazard ratio of cancer death increased by 1.1% (95% CI 1.001–1.021). A multiplicative effect was found between the diagnostic radiation dose and occupational radiation, as well as stage of malignancy. Exposure to occupational radiation among oncological patients was found not to be a linear predictor of cancer death.

Discussion: The obtained results indicate an increased subdistribution hazard ratio of cancer death among oncological patients examined using computed tomography, adjusted for several radiation and non-radiation risk factors. The effect of diagnostic radiation dose is significantly susceptible to confounding by indication due to multiple diagnostic CT scans administered to oncological patients, which can largely determine the linear dose-effect relationship. 

Conclusions: Low dose of exposure to diagnostic radiation due to CT scans in oncological patients was found to be a significant predictor of cancer-related death, along with the influence of gender, age and stage of malignancy. These results support the need for individualized CT protocols for cancer patients based on gender, age, and cancer stage to minimize the diagnostic radiation dose. Confounding by indication should be controlled using a randomized controlled trial using a subgroup of oncological patients not exposed to diagnostic radiation from CT scans.

Keywords:  computed tomography, low dose, oncology, cancer patients, diagnostic exposure, cancer risk

For citation:  Osipov MV. Low Doses of Diagnostic Radiation in Cancer Patients Underwent Computed Tomography and the Risk of Death from Cancer. Medical Radiology and Radiation Safety. 2026;71(4):120–126. DOI:10.33266/1024-6177-2026-71-4-120-126

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Conflict of interest.The authors declare no conflict of interest.

Financing.   The study was conducted using funds from the Federal Budget of the Russian Federation within the framework of contract No. 11.314.25.2 for the implementation of applied research work “Analysis of the consequences of exposure to ionizing radiation on the health of the population and descendants living near nuclear facilities of «Rosatom» (“Consequences 25–27”).

Contribution. Osipov M.V. – concept and design of the study, research methodology, literature overview, statistical processing and data analyses.

Article received: 20.01.2026. Accepted for publication: 25.04.2026.