CPT code 61799 designates an add-on procedure for destruction of each additional complex cranial target using externally generated ionizing radiation performed in the same session after treatment of a first complex lesion. It applies to stereotactic radiosurgery or focused radiation procedures where the treated lesions are typically larger than 3.5 cm, and it captures incremental work and resources required when multiple complex intracranial targets are addressed in one encounter. Nationally, accurate use of this code affects billing specificity for high-complexity neuro-oncology and functional neurosurgical cases and supports appropriate resource measurement for payers and providers.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will learn clinical context for when the add-on applies, typical sites of service for these procedures, and the implications for coding and reimbursement workflows. The publication provides benchmarks and policy context relevant to payers and providers, clarifies clinical scenarios that align with the code definition, and highlights common billing considerations and documentation elements needed to support use of the add-on code. Data not available in the input for specific associated taxonomies, ICD-10 diagnoses, related codes, and payer-specific policy language will be noted where relevant.