Green Imaging: Scoping Review of Radiology's Environmental Impact.

Objective: To summarize evidence for the environmental impact of radiology services and identify research gaps.

Methods: A scoping review was conducted following PRISMA-ScR guidelines. Searches were performed in Ovid Medline, Web of Science, Embase, and Scopus from inception to 6/6/2025. Studies were included if they reported environmental outcomes from diagnostic imaging or image-guided procedures in humans. Two reviewers independently screened studies and extracted data. Conference abstracts, narrative reviews, editorials, non-English articles, and studies without primary data were excluded. Data were charted by environmental impact type and summarized using descriptive statistics and narrative synthesis.

Results: Initial searches yielded 2,730 citations, with 115 studies included. Publications spanned 1971-2025, primarily from Europe (44%) and the U.S. (25%). Most were observational; only 8% (9/115) employed life cycle analysis (LCA). Key domains included energy use (27%), nuclear medicine waste (25%), and contrast media waste (14%). Reported annual CO₂ emissions for equipment varied by modality: MRI (53.1±13.2 MT), CT (12.6±2.9 MT), IR (9.6±1.0 MT), fluoroscopy (4.8 MT), radiography (0.7±0.4 MT), workstations (0.7±0.2 MT), and ultrasound (0.3 MT). Per-scan LCA estimates ranged widely: MRI (6.2-76.2 kg), CT (1.1-13.4 kg), ultrasound (0.1-1.2 kg), and radiography (0.7-7.0 kg). Radionuclides and contrast agents were frequently detected in wastewater and ecosystems. Key research gaps include inconsistent methods, limited LCA use, underexplored modalities and informatics, insufficient waste mitigation studies, and lack of cross-specialty carbon assessments.

Conclusion: Among thousands of publications on imaging sustainability, few provide primary data. This review consolidates evidence on radiology's environmental impact and outlines priorities for future research.