Overall risk of cancer incidence attributable to adult body CT examinations: impact of a seven-year continuous quality improvement program.

OBJECTIVES

To estimate the impact of a continuous dose reduction and quality improvement program on radiation-induced cancer risk in adult computed tomography (CT).

METHODS

Between 2016 and 2022, the retrospective cohort study involved four phases: phase (P1) focused on harmonizing protocols and three subsequent phases (P2, P3, P4) aimed at progressive dose reduction and quality improvement across nine centers in a Swiss private radiology network. P2 optimized exposure parameters, P3 introduced new-generation CT scanners, and P4 implemented deep learning image reconstruction techniques. Patient-specific data, including organ doses, age, and sex, were extracted from the dose monitoring system for body CT examinations (chest and abdomen only). Based on the BEIR VII model, the risk index (RI) of developing cancer was estimated using RadRAT (version 4.2.1). Mean RIs from each phase were compared using One-way ANOVA with a significance threshold of p < 0.05. Data were further stratified by anatomical region and clinical indication. The study also assessed local clinical Diagnostic Reference Levels (DRLs) changes across the four phases.

RESULTS

A total of 11,970 exams were collected across P1/P2/P3/P4 (1010/961/5348/4651), with 60 excluded. 47.5% were male and 52.5% female (average age 60 years). A 53.1% RI reduction was observed from P1 to P4, with 52.5% and 53.7% reductions for the chest and abdomen, respectively. The highest risk reductions were seen for emphysema (59.1%) and diverticulitis (61.2%), while the lowest were observed for pneumonia (30.0%) and renal tumor (37.3%).

CONCLUSIONS

Radiation-induced cancer cases can be reduced through continuous quality improvement in CT imaging.

ADVANCES IN KNOWLEDGE: This study is the first to quantify the impact of a seven-year continuous quality improvement program focused on radiation-induced cancer risk in adult CT imaging, demonstrating a 53.1% risk reduction and emphasizing the effectiveness of integrating advanced imaging technologies and protocol harmonization in clinical practice.