| Abstract [eng] |
The rising dependency on computed tomography (CT) for diagnostic and monitoring purposes has led to an increase in the total radiation dose among certain patients. While a single CT scan is usually a low-risk procedure that is clinically justified, the repeated imaging can lead to cumulative effective doses (CED) that overreach the thresholds corresponding to the increased cancer risk. Since many of these exposures are occurring over long periods of time—especially in oncology, trauma, and chronic disease management—this thesis is about the request for a systematic assessment of CED accumulation and the risks that are associated with it in recurrent CT imaging. The central idea in this thesis is to study the incidence of cumulative effective dose in patients subjected to recurrent CT procedures, particularly in those being categorized in high-dose subgroups, clinical associated indications driving imaging frequency and the potential for radiation-related harm. The research was constructed around three objectives: (1) to describe and quantify cumulative radiation exposure using data from recent multicentre and national studies, (2) to identify and characterize the clinical contexts most frequently associated with high cumulative dose, and (3) to evaluate associated patient risks, particularly the proportion of individuals exceeding thresholds such as 100 mSv. A structured retrospective analysis of 15 peer-reviewed studies published between 2017 and 2024 was created. These studies included multicentre audits for dose monitoring, analyses of national registries, and clinical cohorts from a single centre. The data collected made it possible to display the sample size, imaging frequency, cumulative dose thresholds, clinical indications, and risk estimation models. Descriptive analysis was conducted to find dose accumulation trends, indication frequency, and patient risks. The results depicted that in the case of most patients having CT imaging, the majority are exposed to moderate cumulative doses; however, there is a subgroup of patients accumulating doses ranging from 0.65% to 6.7% and above 100 mSv. Oncological, trauma, and chronic disease follow-up were the main indications related to the rehiring of the images. Some studies used lifetime cancer risk models based on ICRP and RadRAT that were predicted by some high-dose patients with a share-up to 9.2%. Cumulative exposure from the recurrent CT imaging therefore imposes a measurable and clinically relevant risk for certain groups of patients. The data obtained are a strong endorsement for the importance of the dose tracking systems, the implementation of stricter justification protocols, and optimization strategies directed particularly to the areas of outpatient care with high-frequency visitation and the settings for oncology treatment. |
