CPT code 77300: Dosimetry calculation, basic, per calculation2026 Medicare rate & RVUs in Missouri
A physician-prescribed radiation dose calculation, such as monitor units for a treatment beam, reported for each distinct calculation needed during treatment planning or delivery.
Medicare pays $60.79–$64.94 for 77300 in the office in Missouri, from Rest of Missouri to Metropolitan St. Louis, MO. 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 77300 covers
This service calculates a radiation dose parameter needed to deliver the physician's prescription, such as the monitor units or treatment time for a beam at a specified depth. Other examples include an off-axis factor, tissue inhomogeneity correction, or gap calculation between adjacent fields. A medical dosimetrist or medical physicist typically prepares the calculation in a hospital radiation oncology department or freestanding treatment center; the radiation oncologist reviews and approves the result.
Report a unit for each distinct physician-prescribed calculation, not automatically for each field. A later plan change supports another unit only when it requires a separately prescribed and documented calculation. Retain the prescription, calculation record, and physician approval. Calculations included in a teletherapy isodose plan or an IMRT plan are not separately reported as 77300 for that plan. CMS prices professional and technical components separately: modifier 26 identifies the physician's professional work, modifier TC identifies the equipment and staff component, and an unmodified claim represents both components.
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 77300 pays more and less in Missouri
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
3 payment localities
$60.79 to $64.94
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | $64.31 | Unavailable |
| Metropolitan St. Louis, MO | $64.94 | Unavailable |
| Rest of Missouri | $60.79 | Unavailable |
How the 77300 rate is calculated
Each of 77300’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 · 77300
RVUs × geographic indexes × conversion factor
Work0.60
0.60 RVUs× 1.000 GPCI
Practice expense1.37
1.37 RVUs× 1.000 GPCI
Malpractice0.04
0.04 RVUs× 1.000 GPCI
Adjusted RVUs
2.0100
Conversion factor
$33.4009
Medicare rate
$67.14
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 77300
The CMS indicators that decide how 77300 is paid alongside other services.
CMS payment indicators · 77300
Dosimetry calculation, basic, per calculation
| 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
77300 without 26 · national office
$67.14
Dosimetry calculation, basic, per calculation
77300-26 · Professional component
$32.73
Pays only the interpretation and report.
77300 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 77306Radiation planSimple teletherapy plan
- 77306 covers a simple teletherapy isodose plan, including its basic calculations. Report 77300 for a distinct physician-prescribed calculation rather than separately reporting a calculation included in that plan.
- 77307Isodose planningComplex teletherapy plan
- 77307 covers a complex teletherapy isodose plan, including its basic calculations. Use 77300 for a distinct physician-prescribed calculation outside that plan.
- 77331Radiation dosimetrySpecial measurement
- 77331 covers special dosimetry that measures dose, such as with a diode or thermoluminescent dosimeter. 77300 is a calculation, not a physical measurement.
- 77301IMRT planningDose optimization and volume analysis
- 77301 covers IMRT planning and its included dose calculations. Do not separately report 77300 for calculations included in that IMRT plan.
77300 billing questions
How many units can be reported?
Report one unit per distinct calculation prescribed by the physician, not automatically one per treatment field or beam. A later plan change supports another unit when a new calculation is prescribed and documented.
Can this be billed with an isodose plan such as 77306 or 77307?
Do not separately report calculations included in the teletherapy isodose plan. A calculation outside that plan must be separately prescribed and documented.
Is it separately reportable with IMRT planning?
No, not for calculations included in the IMRT plan reported with 77301. Do not add units of 77300 for that plan's beams.
Which modifier applies when the hospital bills the technical side?
The hospital reports its technical component with modifier TC; the physician reports the professional component with modifier 26. An entity furnishing both components reports the global service without either modifier.
What documentation supports the claim?
Keep the physician's prescription or order, a worksheet or planning-system record identifying each distinct calculation, and the physician's approval of the results.
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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