This paper provides a comprehensive review of the fundamental theories, clinical practices, technological advancements, current status, and future prospects of FLASH radiation therapy (FLASH-RT). As an emerging technique, FLASH-RT offers the potential to enhance therapeutic efficacy while minimizing damage to healthy tissues. We elaborate on the physical principles of the "FLASH effect" in radiation biology and its dose-distribution characteristics, describe clinical applications in tumor treatment, and evaluate protective effects on normal tissues. Furthermore, the review discusses technical advancements in equipment, dosimetry, and imaging, while analyzing current research hotspots and technical bottlenecks. We also examine pathological mechanisms, future applications, and prevailing controversies regarding safety, efficacy uncertainty, and ethics. This comprehensive discussion provides a valuable reference for deepening the understanding of FLASH-RT's translational journey.

Hepatocellular carcinoma (HCC) presents significant challenges in modern surgical and radiation oncology, primarily due to biological heterogeneity and the complexities of underlying liver cirrhosis. This review evaluates stereotactic body radiation therapy (SBRT) as a mature, curative-intent modality within the multidisciplinary management of primary hepatic malignancies. Drawing parallels with high-dose-per-fraction successes in early-stage non-small cell lung cancer, pancreatic adenocarcinoma, and spinal metastases, we analyze the physical evolution, radiobiological principles, and functional dosimetric constraints specific to the hepatic microenvironment. Specifically, we examine advanced motion management, distinguishing pre-treatment setup from real-time intrafractional monitoring via kilovoltage projection streaming images (kV-PSI) and MR-guidance. We evaluate the prognostic value of metabolic imaging parameters, specifically SUL _peak and radiomic signatures, alongside the therapeutic synergy between SBRT and systemic agents, including tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs). Additionally, the review explores the emerging role of artificial intelligence (AI) in automating planning and executing real-time online adaptive radiotherapy (ART). Finally, by synthesizing pathological evidence of complete necrosis in explanted specimens following conversion therapy, this work provides a roadmap for optimizing SBRT across the clinical spectrum of HCC.

Background: Oligometastases, an intermediate stage of metastatic cancer, are increasingly managed with Stereotactic Ablative Radiotherapy (SABR), a highly precise local therapy representing a pivotal paradigm shift for improving patient outcomes. This study aimed to comprehensively map the research landscape of SABR for oligometastases. Methods: We conducted a cross-sectional bibliometric analysis of 1,066 publications from the Web of Science Core Collection and PubMed from January 1, 2006, to December 31, 2025. Publication trends, key contributors, and collaboration networks were quantified and visualized using bibliometrix, VOSviewer, and CiteSpace. Results: Our results indicate significant and consistent growth in this field since 2006, with the United States, Italy, and Canada as leading countries, and Humanitas University among the most productive institutions, alongside key authors like Marta Scorsetti. Influential research appeared in leading oncology journals, and keyword analysis identified hotspots in cancer types, metastatic sites, treatment strategies, and the integration of immunotherapy and AI. Landmark clinical trials (e.g., SABR-COMET, ORIOLE) were highly cited. Conclusion: This comprehensive overview underscores the rapid development, international collaboration, and critical research directions within the field, highlighting SABR’s translational potential and providing a foundation for identifying future research priorities.