Project:

Estimating the carbon footprint of the radiotherapy pathway

Organisation:

The Christie NHS Foundation Trust

What was the issue?

As we move towards the NHS net-zero pledge, it is essential we understand our carbon footprint, and identify key areas of emissions within our health service. Radiotherapy uses high energy radiation to treat about 120,000 cancer patients a year, 50% of all cancer patients. For the radiotherapy pathway, there is little current data or literature to look to for quantification, benchmarking, or indication of potential carbon hotspots.

To improve environmental sustainability within radiotherapy, foundational works for others to develop upon are necessary. Whilst fully understanding the carbon footprint of the radiotherapy pathway will take time and the efforts of many, it is important to begin assessing this UK wide service.

Additionally, the rapid changes in the patient pathway in response to COVID-19 have mostly come due to necessity; the potential adverse environmental effects of these changes are not yet fully appreciated. The effects of the pandemic continue to alter how we work, these changes offer a unique opportunity to compare our working procedures with data from prior to the pandemic, and potentially use this information to further assess our working procedures for a greener future.

What action was taken?

To address these issues, this project has sought to gather primary data alongside available data from literature to quantify the carbon footprint of the radiotherapy pathway for treatment of prostate and breast cancer.

At the initial stage of this project, primary data was recorded for the treatment pathway of a sample of 10 breast and 10 prostate patients from Jan-Mar 2020, and during COVID-19, Jan-Mar 2021.

The data gathered captured the pathways both pre and during COVID, allowing for assessment of potential differences in carbon footprint due to the response to the pandemic. Through this analysis, carbon hotspots have been identified to help focus reductions.

Primary data gathered included:

1. The LINAC (Linear Accelerator) machines direct measurement of the energy use for delivering patient treatments
2. An average measurement of the idle power consumption of the LINACs
3. Sulphur hexafluoride (SF₆) gas leakage from the LINACs
4. Patient data used to assess:
5. travel distances
6. number of appointments at the hospital

Emission conversion factors from literature were used for converting primary activity data into equivalent carbon emissions, and to account for the carbon footprint of PPE, as well as pre-treatment imaging.

The project, methods and preliminary results have been presented to others throughout the project to raise awareness of the work, and the carbon hotspots identified at our centre, and allow others to use similar methods themselves.

What was the Delivering a Net Zero NHS benefit? 

Identified in the Kyoto protocol as a harmful greenhouse gas, SF₆ is a large contributor to global warming. SF₆ is routinely used in our treatment machines and recent measurements have shown that it is steadily leaking into the atmosphere. With 1kg of SF₆ equivalent to 22,800kg of carbon dioxide, even a small leak could have a significant impact.

The project identified several carbon hotspots in our patient pathways, such as patient travel and the idle energy use of treatment machines. These results highlight the benefits of virtual appointments when appropriate and provide further justification for hypofractionation of treatments that for the same clinical outcome reduces the number of visits to hospital for treatment by 75%.

The idle machine energy use highlighted a key area for reductions in centres, potentially opening a dialogue with manufacturers over whether this energy use and SF₆ leakage can be reduced and could bring focus to this as a priority for future machine development.

Figure: Total carbon footprint and breakdown of each treatment site both pre-Covid and during Covid.

What are the wider benefits?

Improving efficiency and reducing costs in the radiotherapy pathway.

If hypofractionated radiotherapy was implemented for more disease sites (where clinically appropriate) this could reduce the carbon footprint of radiotherapy as well as improve patient experience by reducing hospital visits and travel time for treatment.

Link for further information

Interest in the project has sparked discussions with other centres about collaborative investigations. Further data collection has taken place at three sites, the results have been published here;  https://www.sciencedirect.com/science/article/pii/S1120179723001291

Key contact and email:

Dr Robert Chuter- robert.chuter@nhs.net