CPT code 77338: MLC design, per IMRT plan2026 Medicare rate & RVUs in Michigan
Reports design of multileaf collimator devices that shape radiation fields for intensity-modulated radiation therapy, counted per IMRT plan.
Medicare pays $447.59–$469.24 for 77338 in the office in Michigan, from Rest of Michigan to Detroit, MI. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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On this page 9 sections
What 77338 covers
This service covers planning the multileaf collimator (MLC) leaf positions needed to shape and modulate radiation fields for an intensity-modulated radiation therapy (IMRT) plan. A medical physicist or dosimetrist typically performs the technical design work as part of radiation treatment planning, with the radiation oncologist directing the treatment approach. The work supports delivery of the planned dose to the target while shaping radiation around nearby normal tissues.
Report the service per IMRT plan, not per treatment fraction. Documentation should connect the MLC design to the specific IMRT plan and identify the design work performed. CMS recognizes professional and technical components: modifier 26 identifies the professional component, modifier TC identifies the technical component, and an unmodified claim represents the global service. The IMRT dose plan itself is reported separately when supported; MLC device design is distinct from dose calculation and from design of other treatment aids.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 77338 pays more and less in Michigan
| Payment locality | Office | Facility |
|---|---|---|
| Detroit, MI | $469.24 | Unavailable |
| Rest of Michigan | $447.59 | Unavailable |
How the 77338 rate is calculated
Each of 77338’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 77338
RVUs × geographic indexes × conversion factor
Work4.18
4.18 RVUs× 1.000 GPCI
Practice expense9.79
9.79 RVUs× 1.000 GPCI
Malpractice0.25
0.25 RVUs× 1.000 GPCI
Adjusted RVUs
14.2200
Conversion factor
$33.4009
Medicare rate
$474.96
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 77338
The CMS indicators that decide how 77338 is paid alongside other services.
CMS payment indicators · 77338
MLC design, per IMRT plan
| Rule | CMS value | What it means |
|---|---|---|
| Global period | XXX | The global surgery concept doesn’t apply. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic test with separate professional (26) and technical (TC) components. |
What modifiers do to the payment
Modifier 26 · payment effect
With and without the modifier
77338 without 26 · national office
$474.96
MLC design, per IMRT plan
77338-26 · Professional component
$225.12
Pays only the interpretation and report.
77338 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 77301IMRT planningDose optimization and volume analysis
- Choose 77301 for the IMRT treatment dose plan; 77338 represents the MLC device design associated with that plan.
- 77300Dosimetry calculationBasic, per calculation
- 77300 represents a radiation dose calculation, not design of the MLC leaf pattern for an IMRT plan.
- 77332Treatment aidSimple device
- 77332 concerns a simple radiation treatment aid. 77338 is specific to MLC design for IMRT, rather than a general treatment aid.
77338 billing questions
How is 77338 distinguished from 77301?
77338 represents the MLC device design for an IMRT plan. 77301 represents the IMRT treatment planning work, including the dose plan; the services describe different parts of planning.
Is 77338 reported per treatment fraction or per plan?
Report it per IMRT plan, rather than once for each delivered fraction.
Which modifier identifies each component?
Use modifier 26 for the professional component and modifier TC for the technical component. Submit without a component modifier for the global service.
Does 77338 include the IMRT dose calculation?
No. It describes MLC device design; the dose-planning work is represented separately when applicable and documented.
What documentation supports 77338?
The record should identify the IMRT plan and show the MLC design work performed for that plan. It should support the per-plan unit reported.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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