Definition and requirements for stereotactic radiotherapy: a systematic review

BACKGROUND AND PURPOSE: This systematic review aimed to consolidate current definitions of stereotactic radiotherapy, identify commonly proposed quality standards and address inconsistencies in international practices despite its extensive use. MATERIALS AND METHODS: This systematic literature review followed the PRISMA methodology, conducting searches across PubMed, Embase, Cochrane, Scopus, and Epistemonikos databases between January 2001 and April 2024. Eligible articles included those explicitly defining stereotactic radiotherapy or providing detailed implementation criteria. Data extracted covered definitions, staffing needs, technological considerations, and quality assurance procedures. RESULTS: Analysis of 51 articles revealed significant discrepancies in stereotactic radiotherapy definitions and standards. Commonly proposed characteristics included targeting accuracy within ≤ 1 mm for SRS and ≤ 2 mm for SBRT, and high doses per fraction (≥5 Gy per fraction). Fractionation schemes varied extensively, ranging from ≤ 5 fractions (ACR-ASTRO, AAPM Task Group 101) to ≤ 12 fractions (DEGRO). Essential quality measures consistently emphasized multidisciplinary staffing involving radiation oncologists, medical physicists, radiotherapy technologists, and relevant specialists. Technical recommendations frequently highlighted high-resolution imaging methods (e.g., thin-slice CT, 4D CT), precise immobilization techniques, and daily IGRT (CBCT), alongside rigorous quality assurance protocols, including dosimetric validation and equipment checks. CONCLUSION: Although stereotactic radiotherapy is broadly adopted in daily routine practice, substantial variability exists in its definitions and implementation. This review underscores the need for unified, updated guidelines incorporating contemporary technological advancements and standardized clinical practices to ensure consistent, high-quality patient outcomes.