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.