CPT 77334 in Medical Billing: Simple, Intermediate and Complex Treatment Devices, and 77338 for IMRT

CPT 77334 is the design and construction of a complex radiation treatment device: a custom immobilization mold, irregular block, special shield or compensator built for one patient’s course. 77332 and 77333 are the simple and intermediate levels, and 77338 is the multileaf collimator device set for an IMRT plan, reported once per plan.

Device charges are small, but they add up over a year, and frequency and bundling edits often deny them. Here are the limits.

Where you see it

Place	What goes there
CMS-1500 box 24D	77332, 77333, 77334 or 77338, one unit per device; global in a freestanding center, with 26 when the physician bills in a facility setting and TC on the facility’s professional-fee claim where applicable
837P electronic claim	Loop 2400, SV1 with the code, modifier if any, and unit count
Medicare Physician Fee Schedule (RVU26D)	PC/TC indicator 1, status A, global XXX; non-facility totals of 1.22, 4.12, 3.78 and 14.22 RVUs
Medicare MUE table (October 1, 2026)	4, 2, 10 and 1 units per date of service
Physician’s device note	Written documentation of the physician’s review and oversight of each device

The three levels and the IMRT device

Noridian’s radiation oncology page describes the levels with examples:

Code	Level	Examples
77332	Simple	Simple block, simple bolus
77333	Intermediate	Multiple blocks, stents, bite blocks, special bolus
77334	Complex	Irregular blocks, special shields, compensators, custom immobilization
77338	MLC device(s) for IMRT	The multileaf collimator configuration for an IMRT plan, reported once per IMRT plan

A thermoplastic head and neck mask and a vacuum-formed body mold are the everyday complex devices. A standard breast board or knee cushion is not a billable device; eviCore’s manual excludes devices used at simulation for patient comfort.

Units and per-course expectations

The NCCI manual sets the Medicare rules for IMRT courses: IMRT planning (77301) “includes many treatment device(s) required for IMRT,” the MLC devices (77338) “may be reported separately once per IMRT plan,” and IMRT delivery “is not normally reported with treatment device design and construction CPT codes 77332-77334.” The exception is a new device “at a later date due to decreased tumor volume or patient weight,” which may be reported with 77332 to 77334. A second rule: 77338 is not reported when the IMRT is compensator based.

Payer manuals add per-course limits. eviCore’s 2026 manual for Cigna allows one unit of 77332, 77333 or 77334 for immobilization per course for the same anatomic area; when a breast board and a custom cradle are both used, only the custom device is billed. A wedge, compensator, bolus and beam-shaping tool used together are one complex device, not four lines. For non-IMRT courses, one device unit is allowed per arc, field or port. Devices are not reported for fiducial markers, gating devices, or during superficial courses (eviCore Radiation Oncology Coding Manual V1.0.2026).

A typical course has few device lines: one immobilization device, one 77338 if IMRT, a bolus or block where one was made, and a replacement only when the chart explains why.

Modifiers 59 and XE

The Medicare Claims Processing Manual, chapter 13, section 70.5, pays the components of 77300 to 77334 “on the same basis as they pay for radiologic services generally,” and for professional billings presumes the physician reviewed or validated the physicist’s work. The bundling questions come from the NCCI procedure-to-procedure edits:

• 77336 with devices. Because planning procedures are generally performed before treatment starts, NCCI edits prevent payment of continuing physics consultation (77336) with 77261 to 77295, 77301 to 77318 and 77332 to 77334 on the same date. When a device is legitimately remade during treatment, the manual allows “modifiers 59 or XE, XP, XS, XU to be appended to CPT code 77336.” The modifier goes on 77336, not on the device.
• Devices with delivery on the same date. The device is usually built at simulation, before the first fraction, so the edit does not apply. When a replacement mask is made on a treatment day, check the current NCCI PTP table for a pair between the device code and 77402, 77407 or 77412. If a pair exists and the device was a distinct service, XE (separate encounter) is the modifier that describes it; 59 is the fallback when no X modifier applies. Without a modifier the device line will deny as a bundled service.
• Devices with 77301. The MLC device for IMRT is 77338, once per plan; a 77332 to 77334 line on the same date as 77301 needs to be a real immobilization device, not a second description of the MLC work.

Worked example: a 28-fraction head and neck IMRT course with a replan

Illustrative figures from the CMS RVU26D file at 33.4009 per RVU, national, before geographic adjustment and sequestration. Global non-facility values: 77334 is 3.78 RVUs, about 126.26 (professional 1.80 RVUs, 60.12; technical 1.98 RVUs, 66.13); 77338 is 14.22 RVUs, about 474.96 (professional 6.74 RVUs, 225.12; technical 7.48 RVUs, 249.84).

Freestanding center, global billing.

Date	Line	Units	Allowed	Note
Simulation day	77334 (thermoplastic mask with indexed bite block)	1	126.26	One complex immobilization device for the course
Plan approval	77338	1	474.96	Once per IMRT plan
Fraction 18	77334 (new mask after 9 kg weight loss)	1	126.26	Documented reason; a treatment day, so check the PTP table and append XE if a pair with 77407 applies
Course total, devices		3	727.48

Had the center billed the mask, the bite block and a shoulder pull as three devices on simulation day, eviCore’s rule would allow only one, and a Medicare reviewer would ask why three immobilization devices were needed for one anatomic area.

Hospital outpatient department, same course. The physician bills 77334-26 twice (60.12 each) and 77338-26 once (225.12), total 345.36; the technical work is paid to the hospital under OPPS. If the replan produced a new IMRT plan, a second 77338 may be supportable because the code is per plan; whether a second 77301 is billable is less clear and is covered in the IMRT planning article.

What to do

• Post one line per device actually built, dated the day it was made and signed off, with the physician’s review documented. Combine wedge, compensator and bolus into one complex device when they were made together.
• Bill 77338 once per IMRT plan and do not report it with compensator-based IMRT.
• For a mid-course replacement, write the reason in the chart first: weight loss, tumor shrinkage, a broken device. That note is what supports an appeal.
• Denials to recognize: CARC 151 with RARC N362 when units exceed the MUE on a date (correct the units); CARC 236 when an NCCI pair was billed without a modifier (add XE or 59 only if the record supports a distinct service, then resubmit); CARC 97 with M15 when a device is bundled into 77301 or IMRT delivery (appeal only if it was a later replacement device); CARC 4 with N519 for an invalid modifier combination.
• Iridium Suite’s claim scrubber checks every service line as it is entered against CCI edits, payer rules and radiation oncology frequency rules.

Related terms

• CPT 77301: IMRT planning
• CPT 77263: treatment planning and Z51.0
• 77407 vs 77412: choosing the delivery level
• MUE: medically unlikely edits
• Modifier 26 and TC
• Global, professional and technical charges

Further reading: Medicare NCCI Policy Manual, Chapter 9, Radiology Services (2026), section F; CMS Medicare NCCI Medically Unlikely Edits (practitioner table effective October 1, 2026); CMS Medicare Claims Processing Manual, Chapter 13, section 70; CMS PFS Relative Value File RVU26D.