Summary & Overview
CPT 77293: Respiration-Correlated (4D) CT Simulation for Radiation Planning
CPT code 77293 denotes a respiration-correlated (4D) CT simulation study performed in addition to a 3D radiotherapy or intensity-modulated radiation therapy (IMRT) plan. The code captures advanced imaging used to quantify tumor and organ motion with respiration so that radiation treatment planning can incorporate motion management strategies. Nationally, use of respiration-correlated CT is important for improving targeting accuracy and reducing normal-tissue exposure in thoracic and upper abdominal radiotherapy.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for 4D CT simulation, common billing considerations, and national benchmarking themes where available. The publication summarizes service definitions, typical sites of service, and commonly associated modifiers and payment considerations. It also outlines how CPT code 77293 fits into modern radiotherapy workflows including 3D planning and IMRT.
This summary is intended to inform revenue cycle, coding, and clinical teams about the clinical purpose and billing context for CPT code 77293, and to provide a national perspective on operational and policy-relevant aspects of respiration-correlated CT simulation.
Billing Code Overview
CPT code 77293 describes a respiration-correlated or 4D CT simulation study performed in addition to a 3D radiotherapy plan or intensity-modulated radiation therapy (IMRT) plan. This service documents acquisition of four-dimensional imaging to account for respiratory motion when developing a radiation treatment plan.
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Service type: Advanced radiation therapy simulation (4D CT / respiration-correlated CT) performed as an adjunct to a 3D or IMRT planning study.
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Typical site of service: Radiation oncology departments or hospital-based radiation therapy centers where CT simulation and treatment planning for radiotherapy are performed.
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Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with a newly diagnosed, centrally located non–small cell lung cancer is referred for definitive radiation therapy. The radiation oncology team plans an intensity–modulated radiation therapy (IMRT) course. Because the tumor exhibits significant motion with respiration on diagnostic imaging and the treatment target is in the thorax, a respiration–correlated (4D) CT simulation is performed in addition to the standard 3D/IMRT planning CT. During the visit the radiation therapist acquires a 4DCT while the patient breathes normally using an external respiratory monitoring device; images are reconstructed into multiple breathing-phase datasets and an internal target volume (ITV) is delineated by the radiation oncologist. The physics team uses the 4D dataset to account for motion during contouring and dose calculation, and the dosimetrist generates an IMRT plan that incorporates the motion information. The 4DCT simulation is billed in conjunction with the 3D/IMRT planning services to document that respiration–correlated imaging was performed to guide planning and motion management.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
11 | Office or other outpatient visit | Use when service is provided in an outpatient radiation oncology setting by the reporting practitioner. |
22 |