Question: How many units can I report when billing 77300? I-m trying to be paid for five units on the same date of service. Arizona Subscriber Answer: Code 77300 (Basic radiation dosimetry calculation, central axis depth dose calculation, TDF, NSD, gap calculation, off axis factor, tissue inhomogeneity factors, calculation of non-ionizing radiation surface and depth dose, as required during course of treatment, only when prescribed by the treating physician) covers a lot of territory, but it's difficult to answer your question without more details. If the patient is under Medicare, for example, this could be a medically unlikely edit (MUE), although being paid for five units for Medicare patients isn't usually a problem. If the rejection came from another payer, however, all bets are off: the denial could stem from anything ranging from a policy issue to a diagnosis coding issue. Verify the documentation with your claim and contact the carrier to determine the best course of action.