CPT 77338Radiology

Design mlc device for imrt

CPT 77338 covers the design and creation of a custom multi-leaf collimator (MLC) device used in intensity-modulated radiation therapy (IMRT), a highly precise cancer treatment that shapes radiation beams to match the tumor's exact contours.

Showing rates for

National Average

Base Medicare rate

$461.58

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

4.29

PE RVU (NF)

9.73

MP RVU

0.25

Total RVU

14.27

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

NCCI bundling edits

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Billing tips

Bill 77338 only once per IMRT treatment plan, not per fraction or per beam angle; it represents the entire MLC device design for the treatment course
Impact: Prevents automatic denials for duplicate billing; overbilling this code can result in $461.58+ in takebacks per inappropriate claim
Ensure clear documentation distinguishes the MLC device design (77338) from the basic IMRT treatment plan (77301) and dosimetry calculations (77300); these are separate services that may be billed together
Impact: Proper documentation supports billing all appropriate planning codes together, potentially adding $800-1,200 in additional reimbursement beyond the 77338 base
Document the number of MLC leaf positions, complexity of beam modulation, and specific software/hardware used in the design process to support medical necessity
Impact: Strengthens defense against audits and medical necessity denials; audit recovery rate increases 60-75% with detailed technical documentation
Verify that IMRT delivery codes (77385-77386) are also being billed appropriately, as 77338 should correlate with actual IMRT treatment delivery, not 3D-CRT or other modalities
Impact: Ensures consistency in billing pattern; mismatches between planning codes and delivery codes trigger automated audits in 85% of cases
When adaptive re-planning occurs mid-treatment requiring new MLC design, append modifier 76 and document specific clinical changes (tumor shrinkage, weight loss, anatomical variation) justifying the need
Impact: Enables additional $461.58 payment for medically necessary re-planning; without modifier 76 and documentation, second billing will deny as duplicate

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Frequently asked questions

What is the Medicare reimbursement rate for CPT 77338 in 2025?

The 2025 Medicare national average reimbursement rate for CPT 77338 is $461.58 for both facility and non-facility settings. This is based on 14.27 total RVUs (4.29 work RVU, 9.73 PE RVU, 0.25 MP RVU) multiplied by the 2025 conversion factor of 32.3465.

How many times can you bill CPT 77338 for a single patient?

CPT 77338 should be billed only once per complete IMRT treatment plan. If adaptive re-planning is medically necessary during the course of treatment due to significant tumor or anatomical changes, it may be billed again with modifier 76 and detailed documentation justifying the need for a new MLC device design.

What is the difference between CPT 77338 and 77301?

CPT 77301 represents the basic IMRT treatment planning and dose calculation, while CPT 77338 specifically covers the design of the multi-leaf collimator (MLC) device that shapes and modulates the radiation beams. Both codes can be billed together for comprehensive IMRT planning as they represent distinct components of the planning process.

Can CPT 77338 be billed with CPT 77385 or 77386 on the same date?

CPT 77338 (MLC device design) and CPT 77385-77386 (IMRT treatment delivery) should not typically be billed on the same date of service. The MLC device design (77338) occurs during the treatment planning phase, while treatment delivery codes are used when the patient receives actual radiation therapy, which happens days or weeks later.

What documentation is required to support billing CPT 77338?

Documentation must include: physician prescription for IMRT, medical physics treatment plan showing MLC leaf sequences and beam modulation specifications, number of beam angles, optimization objectives, quality assurance verification, physicist signature and credentials, and clear evidence that the planning was specifically for IMRT delivery rather than other radiation modalities.

Does CPT 77338 require modifier 26 or TC?

CPT 77338 includes both professional and technical components in its global fee of $461.58. Modifier 26 should be appended only when billing the professional component separately, and modifier TC when billing only the technical component, typically in split billing arrangements between different entities.

Is CPT 77338 bundled with other radiation oncology codes?

CPT 77338 is not bundled with IMRT treatment delivery codes (77385-77386) according to NCCI edits and is separately reportable. However, it should not be confused with basic treatment planning codes; proper documentation must clearly distinguish the specific MLC device design work from other planning components to avoid bundling denials.