CPT code 77789: Surface brachytherapy, low-dose-rate application2026 Medicare rate & RVUs in Missouri
Reports low-dose-rate brachytherapy when a radionuclide source is applied at a superficial treatment site rather than inserted into tissue or a cavity.
Medicare pays $119.97–$128.45 for 77789 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 77789 covers
This service covers applying a low-dose-rate radionuclide source at a superficial treatment site using a surface applicator. A radiation oncologist typically directs the treatment, with radiation therapy staff assisting in a hospital or radiation oncology setting. The source is positioned against the target rather than placed into an interstitial tract or body cavity, distinguishing this approach from interstitial and intracavitary brachytherapy.
Select the code for the surface application method, and document the treatment site, source or applicator placement, and the physician’s work. CMS allows billing for the global service or separately for the professional interpretation with modifier 26 and the technical portion with modifier TC. Same-day preoperative and postoperative care is included in the 0-day global period. Modifier 50 is inappropriate. An assistant at surgery is paid only when medical necessity is documented; co-surgeons and team surgery are not permitted.
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 77789 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
$119.97 to $128.45
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | $127.18 | Unavailable |
| Metropolitan St. Louis, MO | $128.45 | Unavailable |
| Rest of Missouri | $119.97 | Unavailable |
How the 77789 rate is calculated
Each of 77789’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 · 77789
RVUs × geographic indexes × conversion factor
Work1.11
1.11 RVUs× 1.000 GPCI
Practice expense2.80
2.80 RVUs× 1.000 GPCI
Malpractice0.07
0.07 RVUs× 1.000 GPCI
Adjusted RVUs
3.9800
Conversion factor
$33.4009
Medicare rate
$132.94
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 77789
The CMS indicators that decide how 77789 is paid alongside other services.
CMS payment indicators · 77789
Surface brachytherapy, low-dose-rate application
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 000 | Same-day global: pre- and post-op care on the day of the procedure is included. |
| 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
77789 without 26 · national office
$132.94
Surface brachytherapy, low-dose-rate application
77789-26 · Professional component
$59.79
Pays only the interpretation and report.
77789 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 77767Skin brachytherapyOne channel
- 77767 describes high-dose-rate skin surface brachytherapy using one channel. Choose 77789 for low-dose-rate surface source application.
- 77768Skin brachytherapySurface field over 2 cm
- 77768 describes high-dose-rate skin surface brachytherapy using multiple channels. It is not the low-dose-rate surface application reported with 77789.
- 77761Intracavitary brachytherapySimple application
- 77761 applies when a source is placed inside a body cavity for a simple intracavitary treatment; 77789 is for a surface application.
77789 billing questions
How does this differ from the high-dose-rate skin surface codes?
This code is for low-dose-rate surface application. Codes 77767 and 77768 describe high-dose-rate skin surface brachytherapy and are selected according to channel count.
When would an intracavitary code be more appropriate?
Use an intracavitary code when the source is placed within a body cavity, rather than applied at the surface. Codes 77761–77763 distinguish intracavitary applications by complexity.
Can the professional and technical portions be billed separately?
Yes. Modifier 26 identifies the professional interpretation, and modifier TC identifies the technical portion; billing without either modifier represents the global service.
Does the 0-day global period include same-day care?
Yes. Same-day preoperative and postoperative care is included in the service.
Can modifier 50 or an assistant-at-surgery modifier be used?
Modifier 50 is inappropriate for this code. Assistant-at-surgery payment requires documented medical necessity; co-surgeons and team surgery are not permitted.
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
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