CPT code 77439 describes ultrasound imaging used to guide placement of surface radiation therapy (SRT) fields for cutaneous tumors. It is reported once per course of treatment and only in addition to the primary SRT delivery code. Nationally, this code captures a targeted imaging service that supports precision in localized radiation for skin cancers and superficial lesions, with implications for billing consistency and documentation standards across payers.

Key payers included in this analysis are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what the code represents, expected sites of service, and the clinical context for use. The publication provides benchmark framing and payer coverage considerations where available, notes on how the code is typically reported in relation to primary SRT delivery services, and pointers to policy language and documentation elements that commonly affect reimbursement decisions. The content highlights the role of ultrasound-guided positioning in improving field accuracy and treatment reproducibility for cutaneous radiation therapy. Data not available in the input is explicitly identified, and readers are directed to payer policy sources for plan-specific coverage rules and billing instructions.