CPT code 77387: IGRT guidance billing, modifiers, and 2026 reimbursement

Key Takeaways

CPT code 77387 describes guidance for localization of target volume during radiation treatment delivery (IGRT), reported once per session.

77387 is a companion code: it cannot be billed alone and must be reported alongside a radiation treatment delivery code such as 77385 or 77386.

Missing per-session documentation or pairing 77387 with the wrong delivery code are the two most common denial triggers for this code.

Pabau’s claims management software tracks modifier requirements, payer rules, and session documentation so radiation oncology billing staff can reduce claim errors before submission.

According to the American Medical Association (AMA) CPT code set, CPT code 77387 is officially described as: Guidance for localization of target volume for delivery of radiation treatment delivery, intratreatment. The code covers the imaging guidance used to confirm patient positioning and target alignment immediately before or during a radiation fraction, which is the clinical workflow known as IGRT.

Think of it as real-time verification that the treatment beam will hit the intended target, not surrounding healthy tissue. Good medical billing workflows depend on understanding exactly what clinical service each code captures before writing the claim.

When is CPT code 77387 used?

CPT code 77387 applies whenever a radiation oncology practice uses imaging guidance to localize the treatment target volume immediately before or during a radiation session. The imaging modality can vary: cone-beam CT (CBCT), 2D kV or MV imaging, ultrasound localization, or electromagnetic tracking all qualify, provided the imaging is used for intratreatment target confirmation.

Per guidance from the American Society for Radiation Oncology (ASTRO), the following clinical situations support reporting 77387:

• Stereotactic body radiation therapy (SBRT) requiring daily image guidance for tumor localization
• IMRT delivery (77385, 77386) where imaging confirms setup before each fraction
• Prostate cancer treatment using CBCT or ultrasound to account for daily organ motion
• Head and neck IMRT where patient repositioning is verified with kV imaging
• Any radiation session where a physician reviews and approves the localization image prior to treatment delivery

One rule that trips up billing staff: CPT code 77387 is reported once per session, not once per field or treatment fraction. A patient receiving two fields in a single session still generates one unit of 77387, not two. This per-session reporting rule is confirmed by both ASTRO coding guidance and CMS LCD documentation.

CPT code 77387 modifiers

Modifier use for CPT code 77387 depends on how the technical and professional components of the IGRT service are split between the facility and the interpreting physician. The table below covers the most common scenarios.

Payer-specific modifier rules vary. Verify modifier requirements against your MAC’s local coverage articles before submitting, particularly for Modifier 59 in NCCI edit contexts. Check your insurance eligibility verification process to confirm payer-specific modifier acceptance before the date of service.

Medicare reimbursement for CPT code 77387

Medicare reimburses CPT code 77387 under the CMS Physician Fee Schedule (PFS). Specific 2026 payment amounts vary by geographic locality and should be confirmed directly through the CMS Physician Fee Schedule lookup tool using your practice’s MAC jurisdiction. The FastRVU 2026 RVU lookup provides Work, Practice Expense, and Malpractice RVU breakdowns by code and locality.

CMS implemented significant changes to radiation oncology reimbursement for 2026, according to confirmed ASCO and ASTRO policy summaries. Practices should check updated RVU values annually, as these change with each PFS final rule.

Effective revenue cycle management for radiation oncology depends on tracking these annual updates before January 1 each year. Routing electronic claims through the Claim.MD clearinghouse integration gives practices real-time eligibility checks and automated ERA reconciliation, reducing the lag between service delivery and payment posting.

Note: The 2026 national payment amount for CPT code 77387 must be verified through the CMS PFS tool or your MAC’s fee schedule. Do not rely on third-party estimates for claim submission. RVU values change annually and should be rechecked each October when the PFS proposed rule publishes.

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Pabau’s claims management tools help billing staff track CPT 77387 documentation, apply correct modifiers, and route clean claims through Claim.MD before common denial triggers hit your account.

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Documentation requirements for CPT 77387

Inadequate documentation is the single fastest path to a denied or recouped 77387 claim. CMS and MAC-level LCD policies require specific evidence that IGRT guidance was clinically indicated, performed, and reviewed by a physician. Medical billing compliance in radiation oncology depends on building documentation habits into every session, not retrofitting them after a payer audit.

• Physician order: A written order documenting the clinical indication for IGRT guidance before the course of treatment begins
• Treatment record: Each session’s treatment record must confirm that image guidance was performed, including the imaging modality used (CBCT, kV, ultrasound, etc.)
• Image review documentation: Evidence that a physician reviewed the localization images and approved patient positioning before delivery. A therapist note alone is insufficient.
• Date and time: The date and time of the imaging must align with the radiation treatment delivery date to support the per-session billing unit
• Medical necessity narrative: For SBRT or cases with complex tumor motion, include a brief clinical justification for daily IGRT rather than less frequent image guidance

LCD and payer coverage policies

Medicare coverage for CPT code 77387 is governed at the MAC level. Noridian Healthcare Solutions (JF Part B) and other MACs apply Local Coverage Determinations that define which clinical indications support IGRT billing. Practices should confirm the current LCD number and status with their specific MAC, as LCDs are periodically revised or superseded.

Superbill documentation that includes the treating diagnosis, delivery code, and IGRT imaging modality gives reviewers the information they need to confirm coverage at a glance. Ensuring your documentation supports submitting a clean claim means fewer RAC audit flags and faster payment cycles.

Related CPT codes billed with 77387

CPT code 77387 never stands alone. Understanding the companion and co-billing codes in the radiation oncology family prevents unbundling errors and ensures your claims reflect the full scope of services delivered. The AAPC CPT code lookup is a useful reference for cross-checking code relationships before submission.

77427 and 77387 together: Radiation treatment management (77427) and IGRT guidance (77387) address different services and can be billed on the same date. However, 77427 is reported per five-fraction milestone, while 77387 is reported per session. Never substitute one for the other or combine their units. Managing this correctly is part of any solid revenue cycle management approach for radiation oncology.

Common billing errors and how to avoid them

Billing staff reviewing denial patterns on 77387 tend to see the same errors repeat. Recognising them early prevents revenue leakage across a full course of radiation treatment, which can run 25 to 40 sessions or more.

• Billing per fraction instead of per session: 77387 is one unit per session. Billing two units when a patient received two fields in one sitting generates a medical necessity denial.
• Missing physician image review documentation: Therapist notes confirming that imaging was performed do not satisfy the physician review requirement. Every session needs a dated attestation that a physician reviewed and approved the localization image.
• Incorrect modifier pairing with 77014: Billing 77387 and 77014 on the same date without Modifier 59 triggers NCCI bundle edits. Confirm current NCCI edit status before assuming these codes are unrestricted.
• Billing 77387 without a companion delivery code: This code describes guidance for a delivery service. A claim with 77387 alone has no delivery context and will deny. Always pair it with 77385, 77386, 77412, or another active delivery code.
• Incorrect TC/26 split: In hospital outpatient settings, the facility bills the technical component and the physician group bills the professional component. Billing the global code from both entities creates a duplicate payment alert.

Effective denial management for 77387 starts with pre-submission claim scrubbing. Reviewing claim denial codes at the code level after each remittance cycle helps billing teams identify whether denials are documentation-driven, modifier-driven, or bundling-driven, and fix root causes rather than just resubmitting.

How practice management software supports IGRT billing compliance

Image-guided radiation therapy billing is documentation-intensive. Each session generates a record that must capture the imaging modality, physician review, delivery code pairing, and per-session unit count, and that record must survive payer audit scrutiny. Manual tracking across a 30-fraction course creates real audit exposure.

Pabau’s claims management software gives radiation oncology billing staff a structured workflow for tracking CPT 77387 alongside companion delivery codes, applying the correct modifiers, and flagging documentation gaps before a claim reaches the payer.

Claims route through a medical claims clearinghouse via Claim.MD, which validates each claim against payer rules and NCCI edits in real time, catching bundling issues and modifier errors at the clearinghouse stage rather than after a denial. Electronic remittance advice comes back automatically, so billing staff see denial reason codes and payment amounts without manually downloading 835 files from each payer portal.

For practices managing high-volume radiation courses, that combination of pre-submission scrubbing, clearinghouse validation, and automated ERA processing typically closes the gap between billing date and payment posting significantly.

Conclusion

CPT code 77387 is a high-frequency, high-scrutiny code in radiation oncology billing. Getting the per-session unit, companion delivery code, modifier, and physician documentation right on every claim is what separates practices with clean reimbursement from those managing chronic denial backlogs.

Pabau’s claims management tools give billing teams a structured way to handle 77387 across long treatment courses, from pre-submission modifier checks to real-time clearinghouse validation via Claim.MD. To see how it works for radiation oncology billing workflows, book a demo with the Pabau team.

Continue your research

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Want to reduce billing errors before claims leave your system? Pabau claims management software provides pre-submission scrubbing, modifier tracking, and Claim.MD integration for oncology practices.

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