Oncology & Hematology Coding Alert

Question: We think our oncologist may have performed special dosimetry on a patient recently, which was a first for our office. Unfortunately, we're unsure if it actually qualifies as special dosimetry. When does basic dosimetry become special, and what should we include on our claim to ensure coding success?

Alaska Subscriber

Answer: If there are no special circumstances, oncology offices typically report dosimetry calculations with 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).

Exception: However, if the oncologist decides that radiation must be measured to a specific area in order to gauge the success of a current treatment plan, you may be able to report 77331 (Special dosimetry [e.g., TLD, microdosimetry [specify], only when prescribed by the treating physician).

Warning: You must prove medical necessity on your special dosimetry claim; otherwise, it's likely to be denied. On your special dosimetry claim, be sure to include:

1. Information on the method of measurement the physician used during the procedure (i.e., thermoluminescent dosimetry, microdosimetry, film dosimetry, solid-state diode, etc.).

2. Documentation on any radiation measuring/monitoring devices used, such as solid-state diode probes.

3. A hard copy of all notes related to the measurements, which must bear the signature of both the physicist and the radiation oncologist.

4. The radiation oncologist's written request for the special dosimetry, including medical necessity.

Remember: Special dosimetry claims are not common, so don't start reporting them frequently. Reserve the special dosimetry code for patients who need complex treatment planning in which it is important to measure the amount of radiation a patient has received.

(The ASTRO/ACR Radiation Oncology Coding User's Guide, 2002 indicates that code 77331 is not used for routine quality assurance.)