Radiology Coding Alert

Know your carrier's requirement and restrictions

If you're reporting CPT 77300 multiple times on a single claim, you'd better know your carrier's requirements and restrictions for this code. To speed reimbursement and reduce denials, check with your insurer before you report 77300 more than once per port per volume, for each treatment setup.

Some carriers will reimburse 77300(Basic radiation dosimetry calculation, central axis depth dose calculation, TDF, NSD, gap calculation, off-axis factor, tissue inhomo-geneity factors, calculation of nonionizing radiation surface and depth dose, as required during course of treatment, only when prescribed by the treating physician) each time you perform a basic dosimetry calculation, as long as the medical record documentation includes a specific order for the service and the calculation is considered medically necessary.

Basic dosimetric calculations may include central axis depth dose, time dose factor, nominal standard dose, gap calculation, off-axis factor, tissue inhomogeneity factors, monitor unit calculation(s) for photon or electron fields, breast angle, point calculations, etc.

For example, if your radiation oncologist orders monitor units for breast tangents while treating breast cancer (174.x), that volume will result in two dosimetry calculations - one for each tangent or portal. Your carrier should accept 77300 x 2 for the two monitor units, using the ICD-9 code of 174.x each time, says Deborah I. Churchill, RTT, president of Churchill Consulting Inc., a Killingworth, Conn., consulting firm.

Reassess if Tumor Volumes Change

Most carriers will pay only once per port, per treatment setup, says James E. Hugh III, MHA, vice president of AMAC, a consulting, coding and billing firm in Atlanta. If your radiation oncologist treats a brain tumor patient (191.x) with six ports requiring dosimetry calculations, you should report six units of 77300, with 191.x as the diagnosis code. If the patient's condition changes, however, your carrier should allow you to report additional units of 77300.

For instance, if the patient requires further treatment after the tumor's volume changes such as occurs in a boost situation, and your radiation oncologist treats the patient with six new ports, you can bill for six additional calculations, Hugh says.

But an exception would arise if your radiation oncologist performed dosimetry calculations with two ports on a patient with prostate cancer (185) and the ports represented mirror images, such as anterior and posterior. In this case, you could report 77300 only once because the images are calculations of the same size, field, shape and depth.

As of July 1, the National Correct Coding Initiative, version 9.2, allows you to report 77300 and 77301 (Intensity modulated radiotherapy plan, including dose-volume histograms for target and critical structure partial tolerance specifications) on the same date of service. An example of when you might report both codes is if your radiation oncologist treated a patient for a five-field prostate cancer IMRT.

You should report 77301 for the intensity modulated radiotherapy (IMRT) isodose plan, which generates five dosimetry calculations. To report the basic dosimetry calculations with IMRT, you must also perform a second algorithmic calculation, Churchill says. "This can only be performed by using separate specialized computer software, as the monitor units cannot be hand-calculated with IMRT," she says. "You cannot separately report the computer-generated monitor units, but you can bill for a separate basic dosimetry (77300) for each separate algorithmic calculation. That number should match the number of full portals treated using IMRT."