Oncology & Hematology Coding Alert

Question: Are there clear-cut rules established as to how many of code 77300 (basic radiation dosimetry calculation, central axis depth dose, TDF, NSD, gap calculation, off axis factor, tissue inhomogeneity factors, as required during course of treatment, only when prescribed by the treating physician) can be billed with a simulation? Can you bill for each field of interest?

Iowa Reader

Answer: According to CPT Assistant, October 1997, this service may be coded and billed as many times as medically necessary during the course of treatment. Each service should be documented in the patient chart, including physician sign-off and date, to support the billing of a professional component for the service. According to Medicare guidelines � and most third-party payers � the radiation oncologist is responsible for ordering the dosimetry services and approving the calculations.

In my experience, most payers allow code 77300 to be billed once per port each time calculations are ordered and performed. For example, if the patient is receiving four-field pelvis radiation that requires four calculations, the charge is billed 77300, four units, for the initial set of calculations.

If the field size changes due to tumor shrinkage or alteration of patient body habitus and the calculations have to be repeated, then 77300, four units, would be coded and billed again based upon the second order for calculations. The date of service billed for the calculations is generally the date listed on the computer printout, which also should be the date the radiation oncologist approves the calculations. Not all payers subscribe to this payment methodology, however, and it is important that coding and billing criteria be obtained from each of the practice�s major insurers to ensure compliance. According to insurance payers, an average of 2.84 calculations are billed per case, with an overall range of one to 12 dosimetry calculations per patient chart.

Calculations that are completed but not used for some reason (incorrect field size, etc.) should be marked �not used� when they are maintained in the patient�s chart. Of course, calculations not used also are not coded and billed. In addition, calculations checked during the weekly chart review are not assigned code 77300 but are included in the continuing medical physics consultation (code 77336). As a result, when 77300 and 77336 are billed on the same date of service, providers typically will receive a denial of code 77300. Medicare had installed this edit among the �black box� unbundling edits last year, due to the possibility that dosimetry codes may have been improperly billed.

� Cindy Parman, CPC, CPC-H, principal of Coding Strategies Inc, a coding consulting firm based in Dallas, Ga., answered this question.