Your local CMS carrier will have an LCD that will give you definitions on what meets criteria for each code. I am copying the following for you from WPS LCD #L30316 for Nebraska (looks like that's where you are from). There are multiple scenarios in which you might code either, so without an example I can't really tell you.
The level is not solely based on the number of treatment areas.
B.Therapeutic Radiology Simulation - Aided Field Setting (CPT codes 77280-77295)
Radiation oncology simulation is defined as the process of determining and establishing the radiation therapy treatment portals to a specific treatment volume. Ordering and interpreting special tests may be required to assist in the field settings.
Simulation procedures 77280-77290 may be performed if medically necessary to prepare the patient for treatment planning and to ensure accurate treatment.
Following treatment planning, simulation is used to actually direct the treatment beams to the specific volumes of interest. Simulation may be carried out on a dedicated conventional simulator or CT scanner, radiation therapy treatment unit (e.g., linear accelerator), or using diagnostic imaging equipment (e.g., fluoroscopy, Pet scan, CT, MR, ultrasound or virtual reality-based 3D simulation system).
The complexity of simulation is based on the number of ports, volumes of interest, and the inclusion and type of treatment devices. However the number of films taken per treatment, the modality from which images for simulation are obtained, and the use of fluoroscopy are not
determinants of complexity. Portal changes based on unsatisfactory initial simulation(s) are not reported as additional simulations. Additional simulations may be necessary during treatment in order to account for changes in port size, boost dose, or tumor volume.
However, minor changes in port size without changes in beam or without clinical justification do not warrant an additional charge or a higher level of complexity. The inclusion of treatment devices in the simulation process typically increases the complexity. Simulation without the inclusion of devices or with any pre-made devices (e.g., blocks, immobilization) is considered simple. Custom devices elevate complexity when clinically appropriate. Documentation of simulation requires a written record of the procedure and hard copy of a x-ray film or electronic images and evidence of image review by physicians including signature or initials and data review.
The typical course of radiation therapy will require from one to three simulations. However, no more than one simulation may be reported on any given day. Frequency in excess of three simulations should be supported by documentation in the medical record and be made available upon request.
1.CPT code 77280 Set radiation therapy field
Single volume of interest with either a simple port or parallel opposed ports
Simple or no blocking
Block verification simulation
Re-simulation at a later date to verify the accuracy of custom blocks, prior to beginning a treatment is considered a simple simulation (CPT code 77280).
2.CPT code 77285 Set radiation therapy field
Simulation of three or more converging ports, or two separate volumes of interest.
Multiple blocks are covered when clinically necessary.
3.CPT code 77290 Set radiation therapy field
Three or more volumes of interest, or when one or more of the following conditions exists:
■Rotation or arc therapy
■Complex blocking or custom made shielding blocks or compensators, or custom immobilization devices, when clinically necessary.
■Any use of contrast media (e.g. body cavity, GI tract, or intravascular), when clinically necessary to define anatomic structures and volumes of interest.
■Tangential ports with/or without multiple devices.
4.CPT code 77295 Set radiation therapy field
This procedure involves three dimensional computer-generated reconstruction of tumor volume and surrounding critical normal tissue structures from direct CT scan and/or MRI
data in preparation for non-coplanar or coplanar therapy. The simulation uses documented 3-D beam's eye view volume-dose displays of multiple or moving beams. Code 77295 includes those simulation procedures done on the same day in preparation for use of coplanar therapy beams and an additional simulation charge (CPT codes 77280, 77285, and 77290) is not separately payable on the same date. CPT code 77295 also includes the work done for a teletherapy isodose plan (CPT codes 77305-77315) and accordingly CPT codes 77305-77315 must not be separately billed.
Code 77295 may be billed once per treatment course per treatment volume. Documentation in the medical record of 3-D volume reconstruction of target and critical structures and dose distribution is required.
Three dimensional simulation and treatment is clinically warranted when one or more of the following conditions exists:
a.The volume of interest is irregular and in close apposition to normal structures that must be protected.
b.The volume of interest is in such a location that it's parameters can only be defined by MRI or CT
c.The final boost volume of interest must be constructed to the exact tumor volume with its irregular configuration.
d.Multiple conformed portals are necessary to cover the volumes of interest with close margins and protect immediately adjacent normal structures.
e."Beams eye view" of multiple portals must be established for conformal treatment delivery
f.Volume of interest bordering a previously irradiated area
g.3D reconstruction of tumor volume and critical structure volume in brachytherapy cases to develop a DVH
Additional simulations may be required when they are done to verify plan parameters before starting new portals or boosts. In those uncommon circumstances where there is a substantial change in either patient anatomy or tumor conformation where a second CT dataset is required to produce an accurate, efficacious and safe "cone-down" plan, a second 77295 charge may be appropriate. When the physician deems this to be the case, the medical necessity for the second 77295 simulation must be documented.