Quantitative Assessment of Computed Tomography Energy Use and Cost Savings Through Overnight and Weekend Power Down in a Radiology Department.

To assess energy and cost savings when a CT scanner is powered down during overnight non-operational times compared with the CT scanner left on full power or partial shutdown mode. Temporary portable power data loggers were placed on the power supply to the CT scanner to measure the energy consumption of the CT scanner in 3 power modes over 9 weeks: system ON (computer on, gantry on), computer ON (computer on/gantry off), and system shutdown (computer off/gantry off). Energy was separated into daily average consumption during normal operating hours and consumption after hours for three different day types: weekdays, Saturdays, and Sundays/Holidays. To estimate savings, the average after hours energy use per day during the system ON was compared to each of the two power saving modes. 95% confidence intervals were calculated for each mode and savings result. Overnight and Sunday system shutdown compared to system ON mode is shown to save approximately 14 000 kWh over one year with a 95% confidence interval of (13 899 kWh, 14 464 kWh) as calculated by the electricity provider. Energy consumed by a CT scanner can be significantly reduced through system shutdown when the unit is non-operational, saving emissions and cost. In addition to cost and energy savings, this study emphasizes the importance of clinician leadership in convening interdisciplinary teams outside of usual healthcare silos to rethink how we purposefully use energy and reduce waste.