Transitioning to Environmentally Sustainable, Climate-Smart Radiation Oncology Care

Planetary Health: Should We Care?

The delivery of radiologic services and other health care produces a large amount of environmental pollution, which increases human morbidity and mortality. Planetary health looks for sustainable strategies to deliver high-quality health care and reduce environmental impact. Radiologists should consider the sustainability and resilience of their practice in the face of limited natural resources and increasing extreme weather events. Additionally, there is a strong business case for including planetary health in radiology given the financial benefits of sustainability efforts. The extent of radiology's environmental impact and the central role radiologists play in patient care should encourage radiologists to lead these efforts in health care.

The impact of transportation mode, socioeconomic deprivation and rurality on travel times to radiotherapy and surgical services for patients with prostate cancer: A national population-based evaluation

BACKGROUND

The distances that patients have to travel can influence their access to cancer treatment. We investigated the determinants of travel time, separately for journeys by car and public transport, to centres providing radical surgery or radiotherapy for prostate cancer.

METHODS

Using national cancer registry records linked to administrative hospital data, we identified patients who had radical surgery or radiotherapy for prostate cancer between January 2017 and December 2018 in the English National Health Service. Estimated travel times from the patients' residential area to the nearest specialist surgical or radiotherapy centre were estimated for journeys by car and by public transport.

RESULTS

We included 13,186 men who had surgery and 26,581 who had radiotherapy. Estimated travel times by public transport (74.4 mins for surgery and 69.4 mins for radiotherapy) were more than twice as long as by car (33.4 mins and 29.1mins, respectively). Patients living in more socially deprived neighbourhoods in rural areas had the longest travel times to the nearest cancer treatment centres by car (62.0 mins for surgery and 52.1 mins for radiotherapy). Conversely patients living in more affluent neighbourhoods in urban conurbations had the shortest (18.7 mins for surgery and 17.9 mins for radiotherapy).

CONCLUSION

Travel times to cancer centres vary widely according to mode of transport, socioeconomic deprivation, and rurality. Policies changing the geographical configuration of cancer services should consider the impact on the expected travel times both by car and by public transport to avoid enhancing existing inequalities in access to treatment and patient outcomes.

Robust optimization of a radiotherapy pretreatment preparation workflow

Objective. Increasing cancer incidence, staff shortage and high burnout rate among radiation oncologists, medical physicists and radiation technicians are putting many departments under strain. Operations research (OR) tools could optimize radiotherapy processes, however, clinical implementation of OR-tools in radiotherapy is scarce since most investigated optimization methods lack robustness against patient-to-patient variation in duration of tasks. By combining OR-tools, a method was developed that optimized deployment of radiotherapy resources by generating robust pretreatment preparation schedules that balance the expected average patient preparation time (Fmean) with the risk of working overtime (RoO). The method was evaluated for various settings of an one-stop shop (OSS) outpatient clinic for palliative radiotherapy.Approach. The OSS at our institute sees, scans and treats 3-5 patients within one day. The OSS pretreatment preparation workflow consists of a fixed sequence of tasks, which was manually optimized for radiation oncologist and CT availability. To find more optimal sequences, with shorterFmeanand lowerRoO, a genetic algorithm was developed which regards these sequences as DNA-strands. The genetic algorithm applied natural selection principles to produce new sequences. A decoder translated sequences to schedules to find the conflicting fitness parametersFmeanandRoO. For every generation, fitness of sequences was determined by the distance to the estimated Pareto front ofFmeanandRoO. Experiments were run in various OSS-settings.Main results. According to our approach, the expectedFmeanof the current clinical schedule could be reduced with 37%, without increasingRoO. Additional experiments provided insights in trade-offs betweenFmean,RoO, working shift length, number of patients treated on a single day and staff composition.Significance. Our approach demonstrated that OR-tools could optimize radiotherapy resources by robust pretreatment workflow scheduling. The results strongly support further exploration of scheduling optimization for treatment preparation also outside a one-stop shop or radiotherapy setting.

Evaluating the Environmental Impact of Radiation Therapy Using Life Cycle Assessments: A Critical Review

Concurrent increases in global cancer burden and the climate crisis pose an unprecedented threat to public health and human well-being. Today, the health care sector greatly contributes to greenhouse gas emissions, with the future demand for health care services expected to rise. Life cycle assessment (LCA) is an internationally standardized tool that analyzes the inputs and outputs of products, processes, and systems to quantify associated environmental impacts. This critical review explains the use of LCA methodology and outlines its application to external beam radiation therapy (EBRT) with the aim of providing a robust methodology to quantify the environmental impact of radiation therapy care practices today. The steps of an LCA are outlined and explained as defined by the International Organization for Standardization (ISO 14040 and 14044) guidelines: (1) definition of the goal and scope of the LCA, (2) inventory analysis, (3) impact assessment, and (4) interpretation. The existing LCA framework and its methodology is described and applied to the field of radiation oncology. The goal and scope of its application to EBRT is the evaluation of the environmental impact of a single EBRT treatment course within a radiation oncology department. The methodology for data collection via mapping of the resources used (inputs) and the end-of-life processes (outputs) associated with EBRT is explained, with subsequent explanation of the LCA analysis steps. Finally, the importance of appropriate sensitivity analysis and the interpretations that can be drawn from LCA results are reviewed. This critical review of LCA protocol provides and evaluates a methodological framework to scientifically establish baseline environmental performance measurements within a health care setting and assists in identifying targets for emissions mitigation. Future LCAs in the field of radiation oncology and across medical specialties will be crucial in informing best practices for equitable and sustainable care in a changing climate.

Effect of Radiation Schedule on Transportation-Related Carbon Emissions: A Case Study in Rectal Cancer

Purpose

The health care sector is a major contributor of worldwide greenhouse gas (GHG) emissions. Indirect emissions, including those associated with transportation, make up 82% of the US health care sector's environmental footprint. Radiation therapy (RT) treatment regimens present an opportunity for environmental health care-based stewardship owing to the high incidence of cancer diagnosis, significant utilization of RT, and myriad treatment days required for curative regimens. Because the use of short-course RT (SCRT) in the treatment of rectal cancer has demonstrated noninferior clinical outcomes compared with conventional, long-course RT (LCRT), we investigate the environmental and health equity-related outcomes.

Methods and Materials

Patients treated with curative, preoperative RT for newly diagnosed rectal cancer at our institution between 2004 and 2022 and living in-state were included. Travel distance was estimated using patients' reported home address. Associated GHG emissions were calculated and reported in carbon dioxide equivalents (CO₂e).

Results

Of 334 patients included, the total distance traveled for the treatment course was significantly greater in patients treated with LCRT versus SCRT (median, 1417 vs 319 miles; P < .001). Total CO₂e emissions for those undergoing LCRT (n = 261) and SCRT (n = 73) were 665.3 kg CO₂e and 149.9 kg CO₂e, respectively, per treatment course (P < .001), with a net difference of 515.4 kg CO₂e. Relatively, this suggests that LCRT is associated with 4.5 times greater GHG emissions from patient transportation.

Conclusions

Using treatment of rectal cancer as proof-of-principle, we advocate for the inclusion of environmental considerations in the creation of climate-resilient oncologic RT practices, especially in the context of equivocal clinical outcomes between RT fractionation schedules.

Evaluating Carbon Footprint of Proton Therapy Based on Power Consumption and Possible Mitigation Strategies

PURPOSE

There is increasing concern about rising carbon dioxide (CO2) emissions and their hazardous effect on human health. This study quantifies the energy utilization of proton therapy, assesses the corresponding carbon footprint, and discusses possible offsetting strategies toward carbon-neutral health care operations.

METHODS AND MATERIALS

Patients treated between July 2020 and June 2021 using the Mevion proton system were evaluated. Current measurements were converted to kilowatts of power consumption. Patients were reviewed for disease, dose, number of fractions, and duration of beam. The Environmental Protection Agency calculator was used to convert power consumption to tons of CO2 equivalent (CO2e) for scope-based carbon footprint accounting.

RESULTS

There were 185 patients treated and a total of 5176 fractions delivered (average, 28). Power consumption was 55.8 kW in standby/night mode and 64.4 kW during BeamOn, for an annual total of 490 MWh. BeamOn time was 149.6 hours, and BeamOn consumption accounted for 2% of the machine total. Power consumption was 52 kWh per patient (breast, highest at 140 kWh; prostate, lowest at 28 kWh). Annual power consumption of the administrative areas was approximately 96 MWh, for a program total of 586 MWh. The carbon footprint for BeamOn time was 4.17 metric tons of CO2e, or 23 kg per patient course (breast cancer, 60 kg; prostate, 12 kg). The annual carbon footprint for the machine was 212.2 tons CO2e, and for the proton program, 253.7 tons CO2e, with an attributed footprint of 1372 kg CO2e per patient. The corresponding CO2e offset for the program could be 4192 new trees planted and grown for 10 years (23 trees per patient).

CONCLUSIONS

The carbon footprint varied by disease treated. On average, the carbon footprint was 23 kg of CO2e per patient and 253.7 tons of CO2e for the proton program. There are a number of reduction, mitigation, and offset strategies possible for radiation oncologists that should be explored, such as waste minimization, less treatment commuting, efficient energy use, and renewable electricity power use.

Towards estimating the carbon footprint of external beam radiotherapy

PURPOSE

The National Health Service (NHS) in the United Kingdom (UK) is aiming to be carbon net zero by 2040 to help limit the dangerous effects of climate change. Radiotherapy contributes to this with potential sources quantified here.

METHOD

Activity data for 42 patients from within the breast IMRT and prostate VMAT pathways were collected. Data for 20 prostate patients was also collected from 3 other centres to enable cross centre comparison. A process-based, bottom-up approach was used to calculate the carbon footprint. Additionally, patients were split into pre-COVID and COVID groups to assess the impact of protocol changes due to the pandemic.

RESULTS

The calculated carbon footprint for prostate and breast pre-COVID were 148 kgCO2e and 101 kgCO2e respectively, and 226 kgCO2e and 75 kgCO2e respectively during COVID. The energy usage by the linac during treatment for a total course of radiotherapy for prostate treatments was 2-3 kWh and about 1 kWh for breast treatments. Patient travel made up the largest proportion (70-80%) of the calculated carbon footprint, with linac idle power second with ∼ 10% and PPE and SF6 leakage were both between 2 and 4%.

CONCLUSION

These initial findings highlight that the biggest contributor to the external beam radiotherapy carbon footprint was patient travel, which may motivate increased used of hypofractionation. Many assumptions and boundaries have been set on the data gathered, which limit the wider application of these results. However, they provide a useful foundation for future more comprehensive life cycle assessments.

Climate toxicity: An increasingly relevant clinical issue in Cancer Care

In recent years the terms time and financial toxicities have entered the vocabulary of cancer care. We would like to introduce another toxicity: climate toxicity. Climate toxicity is a double-edge sword in cancer care. Increasing cancer risk by exposure to carcinogens, and consequently increasing treatment requirements leads to ever growing damage to our environment. This article assesses the impact of climate change on patients, the climate toxicity caused by both healthcare workers and healthcare facilities, and suggests actions that may be taken mitigate them.

Estimating Carbon Dioxide Emissions and Direct Power Consumption of Linear Accelerator-Based External Beam Radiation Therapy

Purpose

Climate change is one of the direst health threats that humanity faces. We aim to estimate the carbon dioxide (CO₂) emissions associated with the energy usage from linear accelerator (LINAC)-based external beam radiation therapy (EBRT) for the most common cancer diagnoses.

Methods and Materials

We identified patients with the 4 most common cancer types treated with curative-intent EBRT. Beam-on time for each fraction was extracted from the treatment planning system and averaged over each site and treatment modality. The power was multiplied by the beam-on time in hours to yield kilowatt hours (kWh). Using the US Environmental Protection Agency Greenhouse Gas Equivalencies calculator, we converted the kWh into estimates of CO₂-equivalent emissions for the average US power grid. Idle time of the LINAC was estimated via Varian Medical Systems.

Results

A total of 10 patients were included for each of the following modalities: conventionally fractionated for prostate cancer (28 fractions [fx]), prostate stereotactic body radiation therapy (SBRT) (5 fx), 15- and 5-fx regimens for early-stage breast cancer, 3- and 5-fx SBRT regimens for early-stage lung cancer, conventional EBRT (30 fx) for locally advanced lung cancer, and short- (5 fx) and long-course (25-28 fx) for rectal cancer. The modality with the lowest and highest carbon emissions per course, on average, was prostate SBRT (2.18 kg CO₂; interquartile range, 1.92-2.30) and conventional treatment for prostate cancer (17.34 kg CO₂; interquartile range, 10.26-23.79), respectively. This corresponds to CO₂-equivalent emissions of driving an average of 5.4 miles and 41.2 miles in a standard vehicle, respectively. "Standby" mode for a LINAC TrueBeam and Clinac IX uses 112 kWh and 64.8 kWh per day, respectively.

Conclusions

We have estimated CO₂ emissions arising from direct energy usage of a LINAC for 4 common cancers treated with EBRT. "Standby" mode of a LINAC uses the most energy per day. Comprehensive studies are warranted to minimize the environmental effects of health and cancer care.

The Impact of Parent and Family Caregiver Roles Among Canadian Radiation Oncologists

PURPOSE

Working parents, and a rising number of adults delivering care for aging relatives, experience numerous challenges in their personal, family, professional, and financial lives owing to multiple responsibilities. This study describes the experiences of Canadian radiation oncologist (RO) parents and family caregivers, reporting challenges that may exist in providing family care with clinical and academic work commitments.

METHODS AND MATERIALS

Canadian ROs, via RO heads of departments in cancer centers across Canada, and physician members of the Canadian Association of Radiation Oncology were invited to participate in an anonymous online survey between November 2021 and January 2022. The survey focused on demographics, experiences of pregnancy and leave, parenting and adult caregiving responsibilities, and self-care.

RESULTS

A total of 103 staff ROs (38%) completed the survey and 78 (75.7%) identified as having a parental (76 [89.7%]) and/or other family caregiver (8 [10.3%]) role; 41% were female and 59% were male, with no difference between genders in the number of children (median, 2; interquartile range, 1-3; P = .17). More female respondents took parental leave for their first child compared with male respondents (mean, 29 vs 6 weeks; P < .001). Of male respondents who started caring for their first child during residency, 27% took parental leave, compared with 77% who started caring for their first child as a staff member (P = .003). The majority of respondents described "always/usually" having collegial support for each pregnancy and parental leave. Both genders described parental responsibilities as negatively affecting attendance at conferences (male, 65%; female, 77%; P = .31) and early or late work-related meetings (male, 76%; female, 79%; P = 1.0). More female respondents described parental responsibilities as negatively affecting their career (50% vs 29%; P = .085). Of female respondents, 52% (vs 26% of male respondents; P = .044) identified a physician mentor or positive role model around parenting issues.

CONCLUSIONS

Parental and other family caregiving responsibilities are not gender unique in Canadian ROs, but competing work and family roles may affect genders differently.