CPT 77318Radiology

Brachytx isodose complex

CPT 77318 covers the complex computer planning required for brachytherapy, a type of internal radiation treatment where radioactive sources are placed directly in or near a tumor. This code represents the technical work of creating detailed radiation dose maps to ensure the tumor receives the right amount of radiation while protecting healthy tissue.

Showing rates for

National Average

Base Medicare rate

$450.26

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

2.9

PE RVU (NF)

10.81

MP RVU

0.21

Total RVU

13.92

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

Loading bundling edits…

Billing tips

Document the number of dwell positions, channels, and catheters included in the isodose plan to demonstrate complexity and justify use of 77318 over simpler planning codes
Impact: Prevents downcoding to 77316 (simple planning at ~$200 less reimbursement); proper documentation supports the full $450.26 payment
Bill 77318 only once per complete treatment course unless significant replanning is required due to clinical changes (tumor response, catheter repositioning, or treatment modification)
Impact: Multiple billings without justification trigger audits; legitimate replanning with modifier 76 can capture additional $450.26 when medically necessary
Ensure dose-volume histograms (DVHs) for target and critical structures are documented in the treatment plan as this is a key element distinguishing complex from intermediate planning
Impact: DVH documentation is audited frequently; absence may result in denial or downgrade to 77316, losing approximately $200-250 per case
Bill on the date the complex planning is completed and approved, not the date of implant or treatment delivery, and link to the appropriate diagnosis code for the cancer being treated
Impact: Incorrect dating causes claim rejections and payment delays; proper timing ensures clean claims processing and 14-21 day faster payment
For hospital-employed physicians, verify whether billing globally or split billing with modifiers 26/TC to avoid duplicate billing conflicts with facility technical charges
Impact: Duplicate billing results in 100% denial of one claim; proper modifier use ensures both professional ($225-270) and technical ($180-225) components are paid correctly

Live Field Datano reports yet

Real billers contribute denial patterns and appeal strategies for this code. Once 5+ reports come in, you’ll see live aggregated data here — the only place this exists, free.

Working with CPT 77318?

Get the free Revenue Protection Toolkit — the denial triggers, modifier pitfalls, and bundling conflicts that quietly cost you reimbursement. Instant download.

Help build the field knowledge

MedPayIQ gets smarter as billers contribute. If you've had this code denied, share what happened so others learn from it. Anonymous, no patient info.

Related actions

Frequently asked questions

What is the Medicare reimbursement rate for CPT 77318 in 2025?

The 2025 Medicare national average reimbursement for CPT 77318 is $450.26 for both facility and non-facility settings. This rate is based on 13.92 total RVUs multiplied by the 2025 conversion factor of 32.3465.

How many times can I bill CPT 77318 during a brachytherapy treatment course?

Typically, CPT 77318 should be billed once per complete treatment course. Additional billings are appropriate only when significant replanning is medically necessary due to clinical changes such as tumor response, catheter repositioning, or treatment modification. Use modifier 76 for repeat planning and document the medical necessity thoroughly.

What is the difference between CPT codes 77316, 77317, and 77318?

These codes represent increasing complexity of brachytherapy planning: 77316 is simple planning (1-4 sources/ribbons), 77317 is intermediate (5-10 sources), and 77318 is complex planning involving advanced dose calculations, optimization algorithms, multiple dwell positions, and dose-volume histogram analysis for target and critical structures.

Can I bill CPT 77318 with external beam radiation planning codes on the same date?

Yes, you can bill 77318 with external beam planning codes (such as 77295 or 77301) when both brachytherapy and external beam treatments are planned as part of a combined modality approach. Append modifier 59 to 77318 to indicate it is a distinct procedural service and prevent bundling denials.

What RVU value does CPT 77318 have for 2025?

CPT 77318 has a total RVU value of 13.92 for 2025, consisting of 2.9 work RVUs, 10.81 practice expense RVUs (both facility and non-facility), and 0.21 malpractice RVUs. This relatively high RVU value reflects the technical complexity and time required for advanced brachytherapy treatment planning.

Do I need to use modifier 26 or TC when billing CPT 77318?

Use modifier 26 (professional component) if you are billing only for physician supervision and interpretation without providing equipment or technical staff. Use modifier TC (technical component) if billing only for equipment, supplies, and technical personnel. In most integrated radiation oncology practices, 77318 is billed globally without modifiers when the same entity provides both components.

What documentation is required to support medical necessity for CPT 77318?

Required documentation includes dose-volume histograms for target and critical structures, isodose curves in multiple planes, optimization reports, source loading patterns with dwell times and positions, critical structure dose constraints, medical physicist's planning report, and physician approval signature. The documentation must demonstrate complexity beyond intermediate planning to justify 77318 over 77317.