Turning off CT scanners during low-use times can result in substantial conservation of carbon, energy, and financial resources, researchers have reported.
The findings could offer a relatively easy way to "go green" in the radiology suite, according to a study led by Nicholas Marks of the NSW Health Net Zero Clinical Leads Program of Australia's Ministry of Health in New South Wales. The group's results were published September 21 in the Journal of Medical Radiation Sciences.
"[Our study] showed that the simple measure of switching off CT scanners that are not clinically required can lead to considerable power savings with associated carbon and financial savings," the investigators wrote.
Medical imaging has been identified as a "carbon hotspot" in health care, and demand for imaging services is increasing – as is concern regarding the impact that "human activities have on climate change and planetary health," the group noted. Medical imaging contributes 1% of global carbon emissions, in part because MRI and CT scanners use high amounts of electrical power at all hours, whether or not they are in use.
"One department with five MRI scanners and three CT scanners uses the equivalent electrical power of 85 four-person households," the team explained. "The total energy used by a CT scanner in an idle state can be between 14 and 30 times higher than the energy used for active scans."
Marks and colleagues conducted a quality improvement study that introduced a "switch it off" intervention for which radiologic technologist (RT) staff turned off a surplus CT scanner after hours (5:00 pm to 8:00 am for seven days in July of 2023). The team tracked energy consumption (kilowatt hours, KWh) during the intervention period and compared the results to a seven-day control period during which the intervention was not used, and calculated financial and carbon emission impacts based on these energy consumption results. During the intervention period, 49 CT scans were performed, while during the control period, 64 CT scans were performed. The investigators invited the 22 RTs who participated in the study to complete a pre- and postintervention survey; 10 completed it.
The researchers found the following:
Energy use pre- and post-CT scanner "switch off" intervention | |||
Measure | Preintervention | Postintervention | Percent reduction |
| Kilowatt hours (kWh) | 433.96 | 294.17 | 32% |
They reported that extrapolating these results over a 12-month timeframe could lead to savings of 7280 kWh in energy use, $1,381 Australian dollars ($911 U.S.) to the hospital budget, and 5.5 tons of carbon dioxide. The pre- and postintervention survey found that the proportion of radiographers who reported switching off the scanner when not in use increased by 70% (p = 0.002), from 10% preintervention to 80% postintervention.
As make and model of CT scanners differ by vendor, power consumption can vary widely, the group noted, also acknowledging that "not all sites and scanners will have the capacity to operate within this system … [as] CT is an on-demand emergency service where timely scans and results are essential, particularly in trauma and stroke imaging."
But it's worth the effort to determine whether an initiative such as this could work in the radiology department, according to the team.
"Regardless, scanners should be investigated to ensure that low power modes are activated wherever possible so that the least power consumption is occurring whenever possible," it concluded. "Further research may also explore facilitators and barriers to sustaining this practice change as well as possible expansion into switching of scanners of other modalities and ancillary equipment."
The complete study can be found here.
