By ECRI
Amid increasing electricity prices and increased emphasis on sustainability, health care organizations are looking for ways to reduce their energy consumption. Medical imaging departments are among the larger energy consumers in health care, so substantially reducing power consumption in these areas could result in considerable cost savings.
Health care organizations are large consumers of energy, making them particularly vulnerable to energy supply shortages and price increases, as experienced in recent years. In addition to affecting the financial health of the institution, high energy usage also has a societal impact, making it harder for organizations or communities to meet carbon neutrality goals. Facilities therefore have clear incentives to scrutinize their electricity usage.
“Historically, hospitals have focused on patient care and high-quality service regardless of the energy toll,” notes Francisco Rodriguez-Campos, MSc, Ph.D., MRSO (MRSC), a principal project officer in ECRI’s Device Evaluation group. “But today, we’re seeing interest in finding ways to reduce energy use without compromising care. The imaging suite is a good place to start.”
Looking to the Imaging Suite for Energy Savings
A common target for energy-saving improvements is one of the bigger consumers of electricity within a health care facility: the imaging suite. CT and MR imaging scanners in particular require a great deal of electricity. In addition to the energy demand during scans, a large amount of energy is required to keep these systems cool, even when they are not in active use.
“The climatization requirements of the devices in the imaging suite are a key driver for high energy use,” explains Rodriguez-Campos.
Most imaging systems have dedicated water cooling systems that run independently of the institution’s climate control, while some now use air cooling systems that use the air in the imaging suite for cooling, placing demand on the facility’s heating, ventilating and air conditioning (HVAC) systems.
To help organizations save money and work toward sustainability goals, ECRI summarizes below research showing the amount of energy used by different imaging systems, then offers tips for reducing energy consumption.
Analyzing the Electricity Usage of MR and CT
In a 2015 study, researchers directly monitored the energy usage of three CT scanners, four MR scanners, and their cooling systems at a health care facility in Switzerland for one year (Heye et al. 2020). The total energy consumption of the imaging and cooling systems represented 4% of the facility’s total yearly consumption. Of the energy used for these systems, 44% was to power cooling systems and 56% was for patient imaging exams.
The three CT scanners used 78,679 kWh over the course of the year. Energy usage was broken down into categories based on periods of use: (1) Active periods (includes patient preparation, planning, net scan and reconstruction time): 23,797 kWh. The net scan portion (actual patient scan time during which energy consumption increases) was 10,741 kWh. And (2) Idle periods (time between patients): 42,867 kWh (about four times the amount of power used for scanning patients). During the remaining time, the scanners were off, though ancillary systems continued to consume power.
The four MR scanners – one 3.0-tesla (T) system and three 1.5 T systems – used 467,348 kWh in one year, including 265,334 kWh for active periods and 36,268 kWh for idle periods. In addition, more than a third of the power consumption of the MR scanners was during the off state. Unlike CT scanners, which aren’t associated with significant amounts of energy use when shut down, MR scanners require constant magnet cooling even when the system is off. For CT scanners, nearly two-thirds of electricity was used during idle time, which includes the demand of adjunct cooling systems, and only one-third of power consumption was used during actual imaging exams.
Note that the scanners in this 2015 study did not have certain power-saving technology that is more widely available today. For example, today’s users can take advantage of newer off/standby states that reduce the use of electricity. Also, new technology is downsizing the magnet cooling systems in MR scanners to help reduce electricity usage. MR scanners’ use of electricity is largely driven by the helium cooling heads. Plus, there’s room for new developments. Rodriguez-Campos notes that “novel device designs could be devised to, for example, generate electricity from the moving parts within an imaging device, like the internal tube and detector that keep spinning after a CT scanner exposure.”
10 Tips for Reducing Energy Consumption
- For CT scanners, use optimized schedulers (orchestrators) to maximize time spent performing exams and minimize idle periods.
- For MR scanners, explore the possibility of using waste heat recovery methods that recycle the heat produced by the system rather than spending additional energy to neutralize the excess heat.
- Explore the implementation of a smart cooling system that uses a scanner’s status to adjust the operation of adjunct cooling capabilities.
- Use a modular configuration for cooling systems that allows scalability of ancillary systems instead of each newly installed scanner requiring its own system.
- During the procurement process, request information from the vendor regarding the energy consumed during scanning as well as during the idle and system-off states.
- Replace outdated HVAC systems in the imaging suite with more efficient equipment.
- Monitor energy usage with energy management solutions that can provide granular, real-time information about energy usage. Some applications can give real-time consumption by specific areas of the hospital.
- Ask vendors to modify the scanner’s defaults and other parameters to minimize energy use in idle and system-off states, which is something only manufacturers can do.
- Ask vendors if they take any measures to reduce greenhouse gas (GHG) emissions and if they are implementing features in their equipment to help facilities achieve their GHG goals. A study by Furlan et al. published in February 2023 found that the use of CT and MR is a major contributor to GHG emissions.
- Avoid refurbished devices, which are older and therefore may not have the highest energy efficiency; about 5% of medical imaging devices sold in 2016 were refurbished. There has been a reduction of about 20% in energy usage from 2005 to 2012 in medical devices (COCIR 2018), which indicates that manufacturers are making their devices more energy efficient, and refurbished equipment may not be able to match these improvements.
References
Heye T, Knoerl R, Wehrle T, et al. The energy consumption of radiology: energy- and cost-saving opportunities for CT and MRI operation. Radiology. 2020;295(3):593-605. doi:10.1148/radiol.2020192084
Furlan L, Di Francesco P, Tobaldini E, et al. The environmental cost of unwarranted variation in the use of magnetic resonance imaging and computed tomography scans. Eur J Intern Med. 2023;111:47-53. doi:10.1016/j.ejim.2023.01.016
COCIR. COCIR Self-Regulatory Initiative for the Ecodesign of Medical Equipment. Status Report 2018. COCIR European Coordination Committee of Radiological, Electromedical and Healthcare IT Industry. COCIR Self-Regulatory Initiative for the Ecodesign of Medical Equipment Steering Committee; June 2018. Accessed May 23, 2023. https://www.cocir.org/fileadmin/6_Initiatives_SRI/SRI_Status_Report/COCIR_SRI_Status_Report_2018_-_June_2019.pdf
