ESTRO 2023 - Abstract Book

S759

Monday 15 May 2023

ESTRO 2023

Health Board , South West Wales Cancer Centre, Swansea, United Kingdom; 4 Guy’s and St Thomas’s NHS Foundation Trust , Medical Physics and Engineering, London, United Kingdom; 5 King’s College London, Department of Medical Engineering and Physics, London, United Kingdom; 6 East and North Hertfordshire NHS Trust, Mount Vernon Cancer Centre, Northwood, United Kingdom Purpose or Objective Climate change is a significant threat to our lives and wellbeing. The UK National Health Service (NHS) has recognised this and it’s environmental impact by pledging to become net carbon zero by 2040. Radiotherapy with its extensive use of energy intensive technology and large amount of associated patient travel could contribute significantly to the NHS’s carbon footprint. We aim to find carbon footprint hotspots in the patient pathway to highlight where work is most needed. Here we build on a previous study by the authors estimating the carbon footprint of the radiotherapy pathway in a large academic centre (Centre 1) and assess the generalisability of the results in 3 other centres. Materials and Methods Data for 10 prostate patients (treated with 60 Gy in 20 fractions) were collected in each of the four centres, along with information on technical equipment and patient transport, where available (see Table 1). Each centre collated the patient’s post codes from their records and used an online mapping tool to calculate the distance travelled. The power used to deliver the treatments was measured in 3 centres, with Centre 3 and 4 using the same monitor and analysis to ensure a fair comparison. The number of CT scans was collated from patient records in 3 centres, and MR scans in 2 centres. The number of Personal protective equipment (PPE) items used and amount of SF6 gas leaking from the linacs was also measured at Centre 1. This activity data was then converted into a carbon footprint using government databases for the travel and power consumption, and literature for the CT and MR conversion [1], and PPE [2] A questionnaire of 99 patients and focus group of 11 were conducted at Centres 3 and 1 respectively to determine how patients travelled for treatment and why they had chosen that method.

Results Figure 1 shows the carbon footprint of the parts of the radiotherapy pathway observed at each centre. Among the variables assessed, patient travel is the largest contributor (Figure 1) making up 70-80% of the total radiotherapy carbon footprint. At Centre 3 60% of patients travelled via public transport for treatment whereas at Centre 1 this was only 27% which makes a large difference to the carbon footprint of travel. The linac power used during treatment also varies between centres with two Elekta centres (Centres 1 and 4) using less than the Varian centre (Centre 3).

Conclusion These initial results have shown the carbon footprint of radiotherapy is about 215 kg CO2e and preliminary results of a comparison between four cancer centres shows large variation. Patient travel is the largest contributor to this but if public transport is used by a large fraction of patients this is significantly reduced. However, the lack of standardisation between approaches, low number of patient’s and incomplete datasets across centres illustrates the need for ongoing work in this area.

References: 1. Heye, Radiology, 2020 2. Rizan, J R Soc Med, 2021