Summary & Overview
HCPCS C9794: Complex Therapeutic Radiology Simulation with PET/CT for Radiopharmaceutical Planning
HCPCS Level II code C9794 represents a complex therapeutic radiology simulation and field-setting procedure that includes acquisition of PET and CT imaging data for radiopharmaceutical-directed radiation therapy treatment planning (modeling). This code captures advanced imaging-driven simulation steps used to define treatment volumes and model radiopharmaceutical dose distributions, reflecting growing use of image-guided targeted radiotherapies nationwide. It matters nationally as radiopharmaceutical therapies expand across oncology indications and require standardized reporting for planning resources and reimbursement.
Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the code's clinical context and typical service setting, plus coverage and billing considerations relevant to major commercial payers and Medicare. The publication outlines common modifiers and ancillary billing elements when available, benchmarking topics such as utilization patterns, payer policy alignment, and coding guidance for complex simulation services. It also highlights operational implications for radiation oncology practices and imaging-capable treatment centers that perform PET/CT–based planning for radiopharmaceutical-directed therapies.
Where specific input data is missing, the publication indicates "Data not available in the input."
Billing Code Overview
HCPCS Level II code C9794 describes a therapeutic radiology simulation-aided field setting, complex, with acquisition of PET and CT imaging data required for radiopharmaceutical-directed radiation therapy treatment planning (modeling). The service represents an advanced simulation and planning procedure that integrates multimodality imaging to define radiation fields and parameters for radiopharmaceutical-directed therapies.
Service Type: Therapeutic radiology simulation and treatment planning (complex, imaging-guided, radiopharmaceutical-directed)
Typical Site of Service: Hospital outpatient radiation oncology departments and freestanding radiation oncology centers with PET/CT capability
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient with metastatic castration-resistant prostate cancer is scheduled for radiopharmaceutical-directed radiation therapy targeting multiple oligometastatic lesions identified on prior imaging. The multidisciplinary workflow begins with a consultation by radiation oncology to review prior PET and CT imaging. On the day of simulation, the patient undergoes a complex simulation session that includes immobilization, CT simulation acquisition with thin-slice planning images, and integrated PET imaging (or import of diagnostic PET/CT) to accurately delineate radiopharmaceutical-avid targets. Advanced modeling and field setting are performed to define beam arrangements, dosimetry constraints, and radiopharmaceutical-directed target volumes for subsequent treatment planning. The simulation is performed in a hospital-based radiation oncology department or an outpatient freestanding radiation therapy center with PET/CT capabilities, involving a radiation oncologist, medical physicist, dosimetrist, and radiation therapist. The output from this service is a simulation dataset and modeled field settings used by the treatment planning team to generate the definitive radiopharmaceutical-directed radiation therapy plan.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | When the work or complexity of the simulation and modeling substantially exceeds usual requirements (documentation required). |