CT Energy Consumption Savings From a Rapid-Reactivation Power-Save Mode for Interexamination Idle Periods

BACKGROUND. Strategies to reduce CT scanner energy consumption have focused on powering down systems during extended idle periods. This approach is impractical for short interexamination periods. OBJECTIVE. The purpose of this study was to evaluate energy consumption savings associated with a rapid-reactivation CT scanner power-save mode designed for short interexamination idle intervals. METHODS. A single CT scanner (Somatom X.ceed, Siemens Healthineers) was equipped with a new power-save mode that automatically activates 5 minutes after examination completion and allows instantaneous scanner reactivation. Power measurements were extracted at 1-second intervals over a 28-week period (November 27, 2024, to June 10, 2025) and segmented into active, idle, and power-save states; idle and power-save states collectively constituted nonproductive time. Correlation was determined between daily proportions of nonproductive and power-save times. Energy consumption was computed. Savings from the power-save mode were estimated for the study scanner and for hypothetical practices with varying examination volumes. CT technologists were surveyed to assess workflow impact. RESULTS. Power measurement data were evaluated for 124 workdays. The scanner was on for 1253 hours, including 425, 347, and 481 hours in active, idle, and power-save states, respectively. Thus, nonproductive time accounted for 66.1% of scanner-on time, and the power-save state accounted for 58.1% of nonproductive time. Proportional daily nonproductive and power-save times showed very strong correlation (r = 0.81). The mean power draw was 1.6 ± 0.1 kW for the power-save state versus 2.1 ± 0.1 kW for the idle state. Given this difference, the power-save mode was estimated to facilitate energy consumption savings of 15.6% and 7.2% relative to extrapolated nonproductive and total energy consumption, respectively. For hypothetical practices, the power-save mode yielded estimated energy consumption savings ranging from 3.5% to 20.7% of extrapolated nonproductive energy consumption. Nineteen of 25 technologists completed the survey; none reported workflow disturbance or technical issues from the power-save mode. CONCLUSION. The power-save mode allowed a decrease in nonproductive energy consumption during interexamination idle periods without subjectively reported workflow disruptions. CLINICAL IMPACT. The power-save mode provides a practical sustainability strategy for nonproductive idle periods when complete system shutdowns are operationally infeasible.