07 October 2026

Computerised Tomography (CT) simulation is crucial in developing treatment plans for radiation therapy, but it is also a heavy user of electricity.

Aiming to reduce carbon emissions without out sacrificing optimal patient care, researchers at National Cancer Centre Japan (NCCJ) have tested an experimental 'power save' phase that turned off non-essential systems when not in immediate use.

Soon to be published in the Journal of Medical Radiation Sciences (JMRS), researchers concluded a ‘power save’ mode would create an energy saving of 2.24 Kilowatt Hours (kWh) per day, per machine.

Exactly How Much Energy is That?

In Australia, there are approximately 400 CT machines used in radiation therapy simulation – that’s a saving of 896kWh – per day. Or ~224,000kWh per year.

That means the savings from ONE of these machines is enough to charge your smartphone 110 times, and collectively, an average household for ~2 months.

Importantly, the saving is 157,500kg of carbon dioxide (CO2) per year, based on Australia's National Average of carbon emissions (source, NetNada). That’s the equivalent pollution footprint of a car driven over 2,200,000 kms.

Does Saving Energy Come at a Cost to Workflow?

The authors ran over 100 simulations with more than 20 participants to simulate routine clinical conditions in a typical ten-hour period, recording a baseline and 'power saver' model.

While energy consumption was recorded with power loggers, the impact on practitioner workflow was measured through an anonymous questionnaire to assess patient throughput, technical problems, scanner availability and general issues and delay.

The survey received a 100% engagement rate with only ~5% reporting a delay in workflow and patient throughput, while less than 10% reported impaired immediate scanner availability.

Overall, 95.2% of respondents reported the power saver mode to be generally or otherwise fully acceptable for routine use with zero to minor noticeable impact to workflows.

Is This Realistic? Could We See This Becoming Standardised Across Practices?

You might have noticed 'Eco' modes on modern appliances - all the way from laptop screensavers to start/stop ignitions in cars. They reduce energy use by powering down (often) non-essential systems when not needed, that can come quickly back online on demand.

Applying this theory to medical radiation equipment poses a difficult task, given components like the CT loop require extensive prelim powering before they're ready to use.

As the study outlines however, peripheral components that require electricity - like monitors, scanners and servos that don't require lengthy preliminary powering can be targeted by power saving modes to conserve as much electricity as possible with minimal impact.

With this in mind, manufacturers and vendors could implement more of these functions in future product development, helping practices reduce their impact on the climate.