CPT 77336 in Medical Billing: Continuing Medical Physics Consultation, Per Five Fractions
CPT 77336 is continuing medical physics consultation: the qualified medical physicist’s ongoing review of a radiation course (chart checks, dose verification, equipment and treatment quality assurance), reported once per five fractions as a technical-only service. Its companion, 77370, is the special medical physics consultation, a problem-specific written analysis reported once per course.
If you already count 77427 correctly, you can count 77336 the same way, because both codes follow the same five-fraction count. The differences are in who bills them and in a few edge cases.
Where you see it
| Place | What goes there |
|---|---|
| CMS-1500 box 24D and 24G, freestanding center | 77336 with no modifier, one unit per five fractions; 77370 with no modifier, one unit |
| Medicare Physician Fee Schedule (2026) | PC/TC indicator 3 (technical only), status A, global XXX; 77336 is 2.76 RVUs with 0.00 work RVUs, 77370 is 4.52 |
| OPPS Addendum B (CY 2026) | Both status S, APC 5611, national unadjusted 137.32, billed by the hospital |
| MUE table (effective 10/01/2026) | 77336: 1 per date of service, indicator 2 (policy); 77370: 1 per date of service, indicator 3 (clinical) |
The two codes
| Code | Covers | Reported | Who signs |
|---|---|---|---|
| 77336 | Continuing medical physics consultation: weekly quality assurance of the course, with a report, in support of the radiation oncologist | per five fractions (“per week of therapy”); also once for a course of fewer than five fractions | the medical physicist |
| 77370 | Special medical physics consultation: a physician-requested analysis of a specific problem, with a written report | once per course | the medical physicist, on the physician’s request |
Neither code has a professional component. The Claims Processing Manual, Chapter 13, section 70.5, states that 77336 and 77370 “are technical services only codes that are payable by A/B MACs (B) in settings in which only [the] technical component [is] payable,” and Noridian puts it plainly: technical services only, payable only in freestanding clinic settings.
How the 77336 count follows 77427
Medicare’s rule for 77427 (Chapter 13, section 70.1) is a unit per five fractions regardless of calendar time, with three or four leftover fractions at the end earning a final unit and one or two earning nothing. The NCCI Policy Manual’s rule for 77336 is that it is reported “per week of therapy,” may be reported after every five treatments, and may also be reported if the whole course is fewer than five fractions. Noridian’s code table reads “once per one (1) to five (5) fractions of external beam.”
In a routine course the counts match exactly:
| Course | 77427 units | 77336 units |
|---|---|---|
| 20 fractions | 4 | 4 |
| 3 fractions (palliative) | 0 (the course is 77431) | 1, under the fewer-than-five clause |
| 5-fraction SBRT | 0 (the course is 77435) | 1 |
| 23 fractions | 5 (three leftover fractions earn a unit) | 5 |
The counts can differ at the end of a course. For 22 fractions Medicare pays four units of 77427 and nothing for the two leftover fractions. The CMS manual does not address leftover fractions for 77336, and Noridian’s “once per one to five fractions” wording would allow a fifth unit. Many practices bill the same number of 77336 units as 77427, the conservative reading; ask your MAC before billing the more generous one.
Two places where 77336 cannot simply follow 77427:
- Brachytherapy. NCCI states that brachytherapy includes 77427, 77431 and 77336. If external beam runs at the same time, 77336 is reported for the external beam fractions; for multi-step brachytherapy it may be appropriate with the brachytherapy itself.
- Planning codes on the same date. NCCI edits deny 77336 with 77261 to 77295, 77301 to 77318 and 77332 to 77334 on the same date, because planning normally precedes treatment. When a planning procedure is legitimately repeated mid-course (a replan after weight loss, a new device), modifier 59 or XE, XP, XS or XU on 77336 is allowed.
Who performs and who bills
A qualified medical physicist performs the service: reviews the chart, verifies the dose delivered against the prescription, checks the treatment parameters and signs the weekly report. Noridian’s documentation requirements expect “documentation of dosimetric verification of treatment setup and delivery” signed by the radiation oncologist and the medical physicist, and that signed check is what supports each unit.
The owner of the technical component bills it. In a freestanding center that is the center, on the CMS-1500 with no modifier. In a hospital department it is the hospital, under OPPS in APC 5611, and the radiation oncologist’s claim carries no physics code at all.
The special physics consultation, 77370
77370 is the physicist’s answer to a specific question the physician asked in writing: the composite spinal cord dose in re-irradiation, the dose to a pacemaker, fetal dose in pregnancy, total body irradiation, or an SBRT or SRS course. It takes a documented request from the physician and a written report from the physicist; a note that the physicist “reviewed the plan” is 77336 work, not 77370.
Noridian lists 77370 as once per treatment course, and its 2026 MUE is one per date of service. A second unit in the same course needs a distinct new problem with its own request and report, and whether a payer accepts it is a payer-by-payer question.
Worked example: 20 fractions and 23 fractions
A freestanding center, 2026 national amounts before geographic adjustment (RVUs from the CMS October 2026 RVU file times the 33.4009 conversion factor). Illustrative figures.
| Course | 77427 | 77336 | 77370 |
|---|---|---|---|
| 20 fractions, standard | 4 x 195.40 = 781.60 | 4 x 92.19 = 368.76 | none requested |
| 23 fractions, re-irradiation | 5 x 195.40 = 977.00 | 5 x 92.19 = 460.95 | 1 x 150.97, for the composite dose analysis |
In a hospital department the hospital bills each physics unit at the APC 5611 rate (137.32 national unadjusted) and the radiation oncologist bills 77427 alone.
What to do
- Post 77336 from the fraction count, after the fifth fraction, never from the calendar.
- Hold the last unit until the course closes, and count leftover fractions the same way you do for 77427 unless your MAC has told you otherwise.
- No modifiers. 26 and TC are invalid on a PC/TC indicator 3 code. Use 59 or an X modifier only on the date a planning procedure was genuinely repeated.
- Post 77370 once, with the request and report in hand, and only from the entity that owns the technical component.
- Denials to recognize: CARC 151 with RARC N362 when a unit posts before its fifth fraction or beyond the fraction count, a correction once the log agrees; CARC 97 or CARC 236 when 77336 lands on the same date as a planning code or with a brachytherapy code, a correction unless the planning was repeated (then resubmit with the modifier); CARC 4 with RARC N519 when 26 or TC is appended, a correction.
- Iridium Suite’s Record & Verify import from Aria and Mosaiq brings charges in from the treatment system, and 77427 and 77336 can be created automatically from the fraction count, with a billing note.
Related terms
- CPT 77427
- Hyperfractionation billing
- Brachytherapy CPT codes
- SBRT billing codes
- Modifier 26 and TC
- Facility versus non-facility
Further reading: CMS Medicare Claims Processing Manual, Chapter 13, sections 70.1 and 70.5; NCCI Policy Manual for Medicare Services (chapter 9, Radiology); Noridian JF Part B, Radiation Oncology; CMS PFS Relative Value Files.
Frequently asked
What is CPT 77336?
CPT 77336 is continuing medical physics consultation: the qualified medical physicist's ongoing quality assurance of a radiation course, including chart checks, dose verification and review of treatment parameters, with a written report. It is reported once per five fractions, or once for a course of fewer than five fractions, and it is a technical-only code with no professional component.
How does the 77336 count relate to 77427?
Both codes run on a five-fraction cadence, so in a routine course they post together: 20 fractions is four units of each. 77336 is a technical service billed by the center or hospital, while 77427 is the physician's management, but the same fraction log sets the count for both.
Can a physician bill 77336 or 77370 for a hospital patient?
No. Both codes carry PC/TC indicator 3 in the Medicare Physician Fee Schedule, meaning they are technical-only services. The Claims Processing Manual says they are payable by the Part B contractor only in settings where only the technical component is payable, which means a freestanding center. For hospital patients the hospital bills them under OPPS.
What is CPT 77370?
CPT 77370 is the special medical physics consultation: a physician-requested, problem-specific analysis by the physicist with a written report, for situations such as stereotactic treatment, total body irradiation, a pacemaker or defibrillator in the field, pregnancy or re-irradiation dose reconstruction. Medicare contractors list it as once per course of treatment.