Environmental Sustainability in Radiation Oncology: A Scoping Review

Abstract

<h3>Purpose/Objective(s)</h3> In the United States, the healthcare industry accounts for roughly 10% of greenhouse gas emissions. In recent years, interest in environmental sustainability in relation to the healthcare sector has increased. To date, little research has been conducted to assess the relationship of radiation therapy and its impact on the environment. This scoping review aims to examine and thematically organize literature regarding this subject. <h3>Materials/Methods</h3> An evaluation of evidence was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols extension for Scoping Reviews (PRISMA-ScR). Manuscripts were included that involved environmental sustainability and radiation therapy. Databases Web of Science, MEDLINE, and Scopus were queried, along with gray literature, to identify relevant publications between 1975 and 2022. Data was qualitatively analyzed and categorized. <h3>Results</h3> Of 61 articles identified, 7 met inclusion criteria, including: 5 observational studies, 1 randomized control trial and 1 case report. In relation to radiation therapy, environmental sustainability was classified by: 1) direct carbon emission/energy consumption for radiation therapy delivery; or 2) indirect carbon emission/energy consumption from sources such as patient travel, material utilization and resource lifecycle. Notably, 5 major radiation therapy companies consistently reported material, water, and energy consumption with 3 groups further differentiating between renewable and nonrenewable energy sources. From 2018 to 2021, radiation therapy companies reported decreases in total carbon emissions of 8% to 15% annually, with individual companies' global emissions ranging from 464,917 tons CO₂e to 781,865 tons CO₂e. One randomized control trial was identified which reported that single fraction radiation therapy was associated with decreased CO₂ vehicle emissions compared to conventionally fractionated radiation therapy due to minimizing treatment-related travel. Regarding direct energy usage, one case study demonstrated that with a new sustainably oriented system vs a standard linear accelerator, energy consumption decreased 70% from 4,500 kWh per month to 1,200 kWh per month, while the number of fractions delivered increased from 497 to 610. <h3>Conclusion</h3> This scoping review identified recent technologic advancements from the supplier side, with increasing emphasis on minimizing directly and indirectly related carbon emissions and energy consumption. Several gaps in the literature were identified including comparison of various treatment modalities such as single vs multifraction treatment and photon vs proton vs carbon therapy energy requirements. Further research is needed to elucidate avenues to minimize the environmental impact of radiation therapy while maintaining the highest quality patient care.