Stereotactic Radiotherapy

This chapter focuses on plan quality in stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT), whereby precision is vital due to high doses per fraction, steep gradients, and limited treatment opportunities. It outlines key components of the stereotactic workflow and offers practical strategies for evaluating and maintaining plan quality. Plan quality must reflect not only the dose distribution but also accurate alignment between planned and delivered dose. The chapter reviews key evaluation metrics – conformity and gradient indices (CI, HI, R50, D2cm), tissue-specific dose constraints (e.g., HyTEC), and cumulative dose analysis using BED or EQD2. Readers are encouraged to assess multiple isodose levels and consider the spatial dose distribution, not just summary values. Practical quality assurance tips include reviewing MLC apertures for stray voxels or margin errors, using scripts to flag contouring issues, and referencing DICOM metadata to catch motion management mismatches. For multi-target plans, careful collimator rotation helps avoid island blocking. Common pitfalls such as incorrect templates or prescription errors are addressed with standardized forms and peer-review checkpoints. The chapter underscores that high-quality plans require both technical accuracy and coordinated team oversight.