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

<b>BACKGROUND.</b> 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. <b>OBJECTIVE.</b> 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. <b>METHODS.</b> 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. <b>RESULTS.</b> 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. <b>CONCLUSION.</b> The power-save mode allowed a decrease in nonproductive energy consumption during interexamination idle periods without subjectively reported workflow disruptions. <b>CLINICAL IMPACT.</b> The power-save mode provides a practical sustainability strategy for nonproductive idle periods when complete system shutdowns are operationally infeasible.