Reduction of radiation dose and contrast volume in CT pulmonary angiography: A systematic review and meta-analysis

Introduction CT Pulmonary Angiography (CTPA) is the reference standard for detecting pulmonary embolism. Yet, it is associated with substantial radiation exposure and using iodinated contrast media, which carry inherent patient risks. With growing emphasis on patient safety and adherence to the ALARA (As Low as Reasonably Achievable) principle, optimizing CTPA protocols to minimize radiation dose and contrast volume has become a critical focus in clinical imaging. This systematic review and meta-analysis aimed to evaluate the impact of low tube voltage and reduced contrast volume protocols in CTPA on radiation dose, contrast media usage, image quality, and diagnostic accuracy, and to identify evidence-based strategies for optimizing these parameters in clinical practice. Method This review followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. A systematic search of PubMed, Embase, Scopus, Web of Science, and CINHAL was conducted to identify studies investigating dose-reduction and contrast-sparing techniques in CTPA. Eligible studies reported quantitative outcomes on radiation exposure, contrast media volume, and image quality. Two reviewers independently screened titles, abstracts, and full texts, performed data extraction, and assessed methodological quality using validated risk of bias tools (QUADS-2). Meta-analytical synthesis was conducted when data were sufficiently homogenous, with subgroup analyses performed to explore sources of heterogeneity. Results The search identified 148 records, of which 35 studies were included for data extraction, including 11 that provided complete data on radiation dose, contrast volume, and image quality. Studies consistently demonstrated that protocols using low tube voltage (≤80 kVp) and reduced contrast volume (≤60 ml), particularly when combined with iterative reconstruction techniques (e.g., SAFIRE, iDose4), achieved significant reductions in computed tomography dose index (CTDIvol) and effective dose ranging from 50 % to over 80 % while preserving diagnostic image quality. Image parameters such as attenuation, signal-to-noise ratio, and contrast-to-noise ratio remained within acceptable diagnostic limits, supporting the efficacy of low-dose protocols. Conclusion Low-kVp CTPA protocols with reduced contrast volume and iterative reconstruction significantly decrease radiation and contrast exposure without compromising diagnostic performance. These findings support their integration into routine practice, especially for patients at risk of contrast-induced nephropathy or radiation sensitivity. Implications for practice Using low tube voltage CTPA protocols with reduced contrast volume, particularly when combined with iterative reconstruction, enhances patient safety by minimizing radiation exposure and contrast-induced risks.