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CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

CPT code 77423 represents the technical component of high energy neutron radiation therapy delivered to one or more isocenters. It captures the imaging, machine setup, beam delivery, and technical resources associated with neutron beam treatments that use coplanar or non‑coplanar geometries and may employ blocking, wedges, or compensators. This code matters nationally because neutron therapy is a specialized radiation modality with distinct technical requirements, limited availability, and implications for facility resource planning and reimbursement classification.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for neutron radiation delivery, typical sites of service, and how the technical component is defined for billing. The publication summarizes benchmark considerations for payers listed above, highlights coding context relevant to radiation oncology billing, and notes where input data were not provided.

What readers will learn: a clear definition of the service captured by CPT code 77423, the typical care setting and service type, and which major national payers are relevant to coverage and reimbursement discussions. Data not available in the input: specific payment benchmarks, associated taxonomies, ICD‑10 diagnoses, and related or companion codes.

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Billing Code Overview

CPT code 77423 describes the technical component of high energy neutron radiation treatment delivered to one or more isocenters. An isocenter is the common focal point of all radiation beams; treatment may use coplanar or non‑coplanar beam geometry with blocking, wedges, and/or compensators.

Service Type: Radiation therapy — high energy neutron, technical component

Typical Site of Service: Hospital outpatient radiation oncology department or freestanding radiation oncology center

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CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

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Billing Code Overview

Service Type: Radiation therapy — high energy neutron, technical component

Typical Site of Service: Hospital outpatient radiation oncology department or freestanding radiation oncology center

Clinical & Coding Specifications

Clinical Context

A 62-year-old patient with a locally advanced, radioresistant pelvic sarcoma is referred to radiation oncology for high-energy neutron beam therapy. After multidisciplinary tumor board review and CT/MRI-based simulation, the radiation therapist establishes one or more isocenters to target the gross tumor volume with conformal neutron fields using coplanar and non‑coplanar beam arrangements. Immobilization, CT simulation with contrast, and fusion to diagnostic imaging are performed. The physics team performs treatment planning including beam modeling, blocking, wedges or compensators as needed, and verifies dose distributions and machine parameters. On treatment days the radiation therapy technologist positions the patient, aligns to the designated isocenter(s) using imaging guidance, applies the blocking/compensators, and delivers the technical component of high‑energy neutron radiation as directed by the radiation oncologist. Typical visits include daily fractions over multiple sessions with physics checks, machine quality assurance, and documentation of delivered dose and any acute patient reactions. Billing uses the technical component code 77423 for delivery of high‑energy neutron treatment to one or more isocenters; the radiation oncologist may separately bill professional services or global codes as appropriate.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When billing only the physician's interpretation/planning separate from the technical delivery
`TC`	Technical component	When billing only the technical delivery; `77423` commonly represents the technical component
`53`	Discontinued procedure	When treatment is started but discontinued due to extenuating circumstances
`52`	Reduced services	When a fraction or session is delivered at less than usual service level
`22`	Increased procedural services	For unusual procedural services requiring significantly greater resources
`23`	Unusual anesthesia	When medically necessary anesthesia is required for the treatment session
`73`	Discontinued outpatient hospital/ambulatory surgery before anesthesia	When patient taken to suite but procedure discontinued prior to anesthesia or treatment
`62`	Two surgeons	Rarely used; when co-surgeons are documented for procedures related to treatment setup or invasive localization
`76`	Repeat procedure by same physician	When an unplanned repeat of the technical procedure is required on the same day (not in provided list — excluded)
`51`	Multiple procedures	(Not in provided list — excluded)

Taxonomy Code	Specialty	Notes
`207RX0400X`	Radiation Oncology	Radiation oncologists oversee planning and prescription of neutron therapy
`3336C0002X`	Radiation Therapist	Therapists deliver daily treatments and manage patient setup
`3336C0005X`	Medical Dosimetrist	Dosimetrists perform detailed treatment planning and dose calculations
`3336C0003X`	Medical Physicist	Physicists perform machine calibration, QA, and plan verification

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C49.A9`	Malignant neoplasm of connective and soft tissue of unspecified site, unspecified	Soft tissue sarcomas may be managed with neutron radiation for radioresistant histologies
`C41.9`	Malignant neoplasm of bone and articular cartilage, unspecified site	Primary bone sarcomas can be treated with high‑energy neutrons when indicated
`C78.7`	Secondary malignant neoplasm of liver and intrahepatic bile duct	Palliation or local control for metastases in select cases using neutron beams
`C79.51`	Secondary malignant neoplasm of bone	Metastatic bone lesions refractory to photons may be considered for neutron therapy
`C71.9`	Malignant neoplasm of brain, unspecified	Select intracranial radioresistant tumors have historically been treated with neutron therapy in specialized centers

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`77290`	Simulation of the treatment area (three-dimensional)	CT simulation and image-based localization performed before `77423` planning and delivery
`77301`	Special radiation physics consultation, treatment plan, complex	Dosimetry and complex treatment planning typically required prior to neutron therapy delivery
`77431`	Radiation therapy; complex treatment technique, protracted or multiple fields (professional component)	Professional management of complex or protracted radiation therapy that may accompany technical delivery `77423`
`77336`	Continuing medical physics consultation, review and assessment of treatment progress	Ongoing physics review and chart checks during a course of neutron therapy
`77334`	Special medical radiation physics consultation, review and reporting of treatment plan radiation parameters	Additional physics services that support accurate delivery of `77423`

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

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Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When billing only the physician's interpretation/planning separate from the technical delivery
`TC`	Technical component	When billing only the technical delivery; `77423` commonly represents the technical component
`53`	Discontinued procedure	When treatment is started but discontinued due to extenuating circumstances
`52`	Reduced services	When a fraction or session is delivered at less than usual service level
`22`	Increased procedural services	For unusual procedural services requiring significantly greater resources
`23`	Unusual anesthesia	When medically necessary anesthesia is required for the treatment session
`73`	Discontinued outpatient hospital/ambulatory surgery before anesthesia	When patient taken to suite but procedure discontinued prior to anesthesia or treatment
`62`	Two surgeons	Rarely used; when co-surgeons are documented for procedures related to treatment setup or invasive localization
`76`	Repeat procedure by same physician	When an unplanned repeat of the technical procedure is required on the same day (not in provided list — excluded)
`51`	Multiple procedures	(Not in provided list — excluded)

Taxonomy Code	Specialty	Notes
`207RX0400X`	Radiation Oncology	Radiation oncologists oversee planning and prescription of neutron therapy
`3336C0002X`	Radiation Therapist	Therapists deliver daily treatments and manage patient setup
`3336C0005X`	Medical Dosimetrist	Dosimetrists perform detailed treatment planning and dose calculations
`3336C0003X`	Medical Physicist	Physicists perform machine calibration, QA, and plan verification

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C49.A9`	Malignant neoplasm of connective and soft tissue of unspecified site, unspecified	Soft tissue sarcomas may be managed with neutron radiation for radioresistant histologies
`C41.9`	Malignant neoplasm of bone and articular cartilage, unspecified site	Primary bone sarcomas can be treated with high‑energy neutrons when indicated
`C78.7`	Secondary malignant neoplasm of liver and intrahepatic bile duct	Palliation or local control for metastases in select cases using neutron beams
`C79.51`	Secondary malignant neoplasm of bone	Metastatic bone lesions refractory to photons may be considered for neutron therapy
`C71.9`	Malignant neoplasm of brain, unspecified	Select intracranial radioresistant tumors have historically been treated with neutron therapy in specialized centers

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`77290`	Simulation of the treatment area (three-dimensional)	CT simulation and image-based localization performed before `77423` planning and delivery
`77301`	Special radiation physics consultation, treatment plan, complex	Dosimetry and complex treatment planning typically required prior to neutron therapy delivery
`77431`	Radiation therapy; complex treatment technique, protracted or multiple fields (professional component)	Professional management of complex or protracted radiation therapy that may accompany technical delivery `77423`
`77336`	Continuing medical physics consultation, review and assessment of treatment progress	Ongoing physics review and chart checks during a course of neutron therapy
`77334`	Special medical radiation physics consultation, review and reporting of treatment plan radiation parameters	Additional physics services that support accurate delivery of `77423`

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

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CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

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Billing Code Overview

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CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

References

CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

Sign up for cpt 77423 policy alerts

Billing Code Overview

CPT 77423: High Energy Neutron Radiation Therapy, Technical Component

Sign up for cpt 77423 policy alerts

Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

What service does CPT 77423 represent?

Which modifiers are commonly used with 77423 and when should they be applied?

What related CPT codes are commonly billed alongside 77423?

Where is high‑energy neutron therapy (77423) typically delivered and what clinical processes support it?

Which payers are referenced for coverage or reimbursement analysis of 77423, and are payment rates provided?

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

What service does CPT 77423 represent?

Which modifiers are commonly used with 77423 and when should they be applied?

What related CPT codes are commonly billed alongside 77423?

Where is high‑energy neutron therapy (77423) typically delivered and what clinical processes support it?

Which payers are referenced for coverage or reimbursement analysis of 77423, and are payment rates provided?

References