Energy-Efficient Usage of CT Scanners Through Mathematically Optimized Examination Scheduling

Medical imaging devices are large consumers of electricity. This study aims to estimate potential energy savings through optimized CT examination scheduling using an ideal (hypothetical) lower-bound and a clinically realistic model. Examination timestamps and power consumption data of all CT examinations (n = 13,153) performed on three CT scanners in a tertiary care radiology department across 261 workdays in 2015 were retrospectively analyzed. CT examination scheduling was optimized using binary linear programming to minimize total scanner energy consumption. Two models were evaluated: a lower-bound model (LB model) allowing shutdown of all nonemergency scanners and a realistic model (R model) keeping one additional routine scanner continuously available during operating hours. Optimization problems were solved within seconds for each workday. Compared with observed clinical operation, the LB model achieved a reduction in daily energy consumption of 34.8% (34.2-35.5%), whereas the R model yielded an 11.0% (10.7-11.3%) reduction. These corresponded to estimated annual energy savings of 10,933 kWh and 3,460 kWh, respectively. For the R model, this translated to approximately $692 in annual cost savings and a reduction of 998 kgCO₂-equivalent emissions, while preserving clinically feasible scanner availability. Optimization-based CT examination scheduling can substantially reduce energy consumption without additional hardware. Even under realistic workflow constraints, meaningful sustainability and cost benefits were observed. Automated, optimization-guided CT scheduling may represent a practical strategy to reduce the environmental footprint of radiology departments.