"Off is not off" - how radiology reduces energy consumption in everyday life

What methods have you developed to investigate energy consumption in imaging?

Tobias Heye: We measured the energy consumption of each of our four MRIs and three CTs every half second for a year. We also took data from the radiology information system and the devices about what action the device is currently performing.

"We wanted to improve the_{carbon footprint} in radiology."

Thanks to a collaboration with the University of Applied Sciences Northwestern Switzerland, which developed software for us, we were able to combine these three sources with the support of our device manufacturer. This took us from 2012 to 2015 - although we were very well supported at the USB, especially by the energy technology department. So our commitment has a long history. We were driven by the desire for sustainability. It wasn't a lack of electricity and cost savings that drove us to find a quick solution - we wanted to improve the_{carbon footprint} of our department.

How high is the energy consumption of radiology equipment?

Tobias Heye: We now know that an average CT device operating at full capacity consumes up to 25,000 kWh per year. That's as much as five households with four people need in a year. With an MRI machine it is more. It can be up to 140,000 kWh. That corresponds to the electricity consumption of 26 households with four people each. These are enormous amounts. However, what shocked us most after the evaluation was the high non-productive share of these devices. This is where we are trying to start.

"Off is not just off."

Elmar Merkle: With CT, 70 percent of the electricity was unproductive - there is no standby mode. With the MRI, it was 30 percent. It is also cooled extensively at night - off is not off, even if we were able to achieve some improvements.

You became involved with the topic of sustainability in radiology at an early stage. Why?

Elmar Merkle: Twelve years ago, we asked ourselves which large radiology device consumes how much energy. Whether the magnetic resonance tomograph (MRT) or the computer tomograph (CT) is the bigger power guzzler, whether these quantities are negligible or gigantic. That was in 2011 at Duke University in the USA. Tobias Heye and I got to know each other there.

Since then, we have developed methods to measure consumption. At that time, the topic of sustainability was only slowly becoming a topic of social interest. Even Google did not yet deliver any useful results for the keyword "sustainability" in connection with "medical imaging".

"There are devices that we now switch off between examinations."

Manfred Meyer: Jan Vosshenrich had the idea of checking the power consumption of all radiology equipment. Our angiography system for imaging blood vessels also consumes a lot of electricity: about twice as much as a CT. However, compared to CT, the system is rarely used to capacity. As it requires significantly less energy when it is shut down, we switch the equipment off between examinations whenever possible.

Have you focused primarily on the power consumption of large appliances?

Jan Vosshenrich: Not only that. We now only run 17 PCs and workstations at night instead of 32. We have also reduced the activity of 28 of our 55 printers - this alone has enabled us to save 3600 kWh. Saving energy is also worthwhile on a small scale.