Radiation Therapy: Fractionation, Image-Guidance, and Special Services (for Idaho Only)
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Clinical policy governing medically necessary fractionation limits, use of image-guided radiation therapy (IGRT), and special radiation services for members in Idaho, including Idaho Medicaid Plus plans; applies to radiation oncologists and billing staff.
Added criterion requiring delivery of up to 10 fractions for accelerated partial-breast irradiation with 3D technique.
Replaced criterion to require delivery of up to five fractions for accelerated partial breast irradiation with intensity-modulated radiation therapy.
Clarified connective tissue disorder examples to 'systemic lupus erythematosus or scleroderma' for allowing up to 33 fractions inclusive of boost.
Added detailed notation on CPT code 77331 special dosimetry use, typical measurement ranges (one to six), and documentation expectations for requests beyond the standard range.
Notated that CPT codes 77436–77439 are not on the State of Idaho Medicaid Fee Schedule and therefore may not be covered by Idaho Medicaid.
Updated guidance that megavoltage planning, imaging, and treatment delivery codes should not be reported during superficial, surface, or orthovoltage radiation therapy; CPT codes 77436–77439 should be reported for those therapies.
Coverage Criteria for Radiation Therapy
inv-01: Bone metastases — palliative EBRT — Medically necessary when ONE of the following is met
Medically necessary when ONE of the following is met
Reirradiation exception per policy
inv-02: Breast adenocarcinoma — EBRT fractionation — Medically necessary when ONE of the following fractionation regimens applies
Medically necessary when ONE of the following fractionation regimens applies
Per policy revision: IMRT-specified APBI
Added in 06/01/2026 policy revision
Standard whole-breast/chest wall fractionation limit
Connective tissue disorder exception clarified in policy history
inv-03: Locally advanced non-small cell lung cancer — Medically necessary when ALL of the following are met
Medically necessary when ALL of the following are met
Escalation to 74 Gy with concurrent chemotherapy was not superior and may be harmful (RTOG trial)
inv-04: Prostate adenocarcinoma — EBRT fractionation — Medically necessary when ONE of the following applies
Medically necessary when ONE of the following applies
For limited metastatic prostate disease per policy
Conventional and moderate hypofractionation options described in guidelines
Greater than 45 fractions is not medically necessary
inv-05: Image-guided radiation therapy (IGRT) coverage — IGRT is medically necessary when ANY of the following conditions are met
IGRT is medically necessary when ANY of the following conditions are met
Examples include prostate IMRT/PBRT
Supports safe reirradiation and narrow-margin treatments
Fiducial-based localization indications
See policy for full list and subconditions
Case-by-case documented rationale permitted
inv-06: Palliative bone metastases — recommended fractionation — Covered when one of the guideline-recommended palliative fractionation schemes is used and clinically indicated
Covered when one of the guideline-recommended palliative fractionation schemes is used and clinically indicated:
Guideline-backed regimens summarized from ASTRO, ACR, ESTRO, NCCN
inv-07: Comparative effectiveness and harms — Clinical considerations and comparative outcomes to inform coverage decisions
Clinical considerations and comparative outcomes to inform coverage decisions:
Data include AHRQ review, Hartsell trial, and meta-analyses
inv-08: Early-stage breast cancer — hypofractionation and PBI — Covered when used in populations supported by trials demonstrating noninferiority or guideline endorsement
Covered when used in populations supported by trials demonstrating noninferiority or guideline endorsement:
Brunt et al. and guideline endorsement cited
NSABP B-39/RTOG 0413 and Meattini et al.; technique- and patient-selection dependent
inv-09: Breast RT dose-fractionation and PBI — Covered when consistent with evidence-based guideline regimens and technique documentation
Covered when consistent with evidence-based guideline regimens and technique documentation
ASTRO and NCCN endorse these regimens
Technique- and schedule-specific documentation required
inv-10: Locally advanced (stage III) NSCLC definitive RT — Covered when delivered according to standard-dose concurrent chemoradiation practice
Covered when delivered according to standard-dose concurrent chemoradiation practice
RTOG trial found 74 Gy with concurrent chemo was not superior and may be harmful
inv-11: Prostate RT fractionation and pelvic nodal coverage — Covered regimens reflect trial-proven schedules and indications
Covered regimens reflect trial-proven schedules and indications
Cochrane review, Catton, Dearnaley trials support
Murthy et al. RCT supports improved BFFS and DFS
inv-12: Covered with criteria — Hypofractionation and IGRT — Relevant clinical trial outcomes and guideline recommendations supporting use of moderate hypofractionation and IGRT
Relevant clinical trial outcomes and guideline recommendations supporting use of moderate hypofractionation and IGRT:
ASTRO, Cochrane, Catton, Dearnaley trials cited
HYPRO trial concerns
Wang et al. 2022 meta-analysis and guideline recommendations
inv-13: Indications where IGRT is recommended — IGRT is recommended or strongly recommended in the following clinical scenarios per professional society and guideline statements
IGRT is recommended or strongly recommended in the following clinical scenarios per professional society and guideline statements:
Based on ACR-ASTRO, ASTRO, NCCN guidance
inv-14: Evidence-based benefits and motion-management considerations — Clinical evidence and studies report the following effects informing coverage decisions and clinical practice
Clinical evidence and studies report the following effects informing coverage decisions and clinical practice:
Korreman et al. 2012
Kotte et al. 2007
Lin et al. 2012
Chen et al. 2007
inv-15: Quality assurance and operational requirements — Safe and effective IGRT requires institutional processes
Safe and effective IGRT requires institutional processes:
AAPM and ASTRO guidance cited
inv-16: Breast adenocarcinoma - accelerated partial breast irradiation (APBI) fractionation — Revised coverage criteria for fractionation in APBI
Revised coverage criteria for fractionation in APBI
Policy history 06/01/2026 revised APBI fractionation; note that some APBI trials did not meet equivalence to WBI and patient selection/technique matter
inv-17: Connective tissue disorder exception for fractionation — Exception permitting extended fractionation when connective tissue disorder present
Exception permitting extended fractionation when connective tissue disorder present
Clarified connective tissue disorder examples in policy history
Image-guided radiation therapy (IGRT) is considered not medically necessary when the policy’s specified IGRT coverage criteria are not met. This includes use of IGRT solely to align bony landmarks without the presence of implanted fiducial markers (for example, during palliative radiation therapy) or when none of the listed clinical indications (such as use with IMRT/PBRT, prior/adjacent radiation, implanted fiducials, or documented motion/immobilization issues) are documented.
For breast cancer treatment, delivery of radiation exceeding 33 fractions (inclusive of any tumor‑bed boost) is not medically necessary except where the policy explicitly allows up to 33 fractions for the listed conditions (treatment of supraclavicular/internal mammary nodes, postmastectomy radiation, prior thoracic RT, or specified connective tissue disorders).
For locally advanced non‑small cell lung cancer treated with EBRT (with or without chemotherapy), delivery of radiation beyond 35 fractions is designated not medically necessary by this policy. The medically necessary limit is up to 35 fractions.
For localized prostate cancer, the policy limits EBRT to a maximum of 45 fractions only when one or more specific circumstances apply (e.g., pelvic nodal radiation for high‑risk disease, post‑prostatectomy treatment, history of inflammatory bowel disease, or prior pelvic RT). Delivery of greater than 45 fractions for localized prostate cancer is not medically necessary.
The large randomized NSABP B‑39/RTOG 0413 trial did not meet equivalence criteria for accelerated partial breast irradiation (APBI) compared with whole‑breast irradiation (WBI) for local tumor control, so APBI should not be assumed equivalent to WBI outside the specific patient populations, techniques, and schedules tested in trials. Coverage and indication for APBI are therefore limited to the populations and techniques supported by trial evidence and guideline endorsement.
APBI delivered with techniques or schedules that do not meet the dose‑volume requirements tested in randomized trials or professional guidelines—or delivered on twice‑daily schedules that have been associated with increased late toxicity and worse cosmetic outcomes—are discouraged unless the provider documents a clear rationale and that dose‑volume constraints and technique mitigate the known risks.
The HYPRO trial evaluated a hypofractionated prostate regimen of 19 fractions of 3.4 Gy and did not establish that schedule as superior; it showed higher acute GU/GI toxicity without clear superiority in efficacy. Therefore the HYPRO regimen cannot be regarded as the new standard of care for intermediate‑ or high‑risk prostate cancer and should not be adopted routinely without explicit justification and documentation.
IGRT is not indicated for superficial treatment of skin cancer, and is not medically necessary when used solely to align bony landmarks without implanted fiducials. The policy and ASTRO guidance specify that surface/superficial treatments generally do not require IGRT unless other specified clinical indications are present.
Megavoltage planning, imaging, and treatment delivery CPT codes should not be reported for superficial, surface, or orthovoltage radiation therapy. Instead, the policy clarifies that CPT codes for superficial/surface/orthovoltage therapy (CPT codes 77436–77439) should be reported for those treatments; billing of megavoltage codes in that context is inconsistent with the policy’s coding guidance.
For breast cancer, delivery of radiation in excess of 33 fractions (inclusive of a boost) is identified as not medically necessary. The policy allows up to 33 fractions only under specified conditions (for example, nodal treatment, postmastectomy RT, prior thoracic RT, or defined connective tissue disorders).
For locally advanced (stage III) non‑small cell lung cancer, the policy states that delivery of more than 35 fractions is not medically necessary; the medically necessary regimen is limited to up to 35 fractions.
For localized prostate cancer, delivery of greater than 45 fractions is considered not medically necessary. Up to 45 fractions are permitted only when the documented clinical criteria described in the policy are met (eg, pelvic nodal irradiation, post‑prostatectomy, inflammatory bowel disease, prior pelvic RT).
Some palliative regimens present trade‑offs between efficacy and toxicity (for example, single‑fraction 8 Gy versus multifraction regimens such as 20 Gy/5); the evidence indicates similar overall pain response but differing retreatment rates and toxicity profiles. The policy does not convert these trade‑offs into blanket 'not medically necessary' statements—both approaches remain clinically acceptable options when chosen with appropriate documentation and clinical rationale.
Escalation of thoracic radiotherapy to 74 Gy with concurrent chemotherapy for stage III NSCLC was not superior and was associated with potential harm compared with standard‑dose chemoradiation (60 Gy), based on RTOG trial results; such dose escalation is therefore not supported by the trial evidence and is discouraged without compelling justification.
Hypofractionated prostate regimens that demonstrably increase acute genitourinary or gastrointestinal toxicity without established superiority in efficacy—such as the 19 × 3.4 Gy HYPRO schedule evaluated in trials—should be regarded as non‑preferred and require clear justification, counseling, and documentation if considered for individual patients.
Coding notes in the policy identify state‑specific coverage limitations: CPT codes 77436, 77437, 77438, and 77439 are noted as not appearing on the State of Idaho Medicaid Fee Schedule and therefore may not be covered for Idaho Medicaid members; providers should consult the Idaho Medicaid Provider Handbook for exclusions and fee‑schedule details.
Coding and Billing Guidance
| 77331 | Special dosimetry (e.g., TLD, microdosimetry) (specify) |
| 77370 | Special medical radiation physics consultation |
| 77387 | Guidance for localization of target volume for delivery of radiation treatment, includes intrafraction tracking, when performed |
| 77399 | Unlisted procedure, medical radiation physics, dosimetry and treatment devices, and special services |
| 77402 | Radiation treatment delivery; Level 1 |
| 77407 | Radiation treatment delivery; Level 2, single-isocenter |
| 77412 | Radiation treatment delivery; Level 3, multiple isocenters or single-isocenter with active motion management |
| 77436 | Surface radiation therapy; superficial or orthovoltage, treatment planning and simulation-aided field setting |
| 77437 | Surface radiation therapy; superficial, delivery, 150 kV, per fraction |
| 77438 | Surface radiation therapy; orthovoltage, delivery, > 150-500 kV, per fraction |
| 77331 | Special dosimetry — considered for coverage only when primary radiation procedure is proven and medically necessary |
| 77370 | Special medical radiation physics consultation — report once under specified complex circumstances |
| 77470 | Special treatment procedure — report once under specified complex circumstances |
| 77399 | Unlisted procedure — only if no other code appropriately describes the procedure |
| No codes listed |
| No codes listed |
| CPT (referenced) | CPT codes are referenced through AMA CPT 2026 Professional Edition (document lists CPT as source but does not enumerate specific CPT codes in this section). |
| FDA product codes LHN, MUJ, IYE (informational) | Device product codes referenced for informational device approvals related to radiation therapy equipment. |
| 77331 | Special dosimetry |
| 77301 | IMRT planning |
Provider Actions, Authorization, and Documentation
Applicable codes and coverage note
The following codes are provided for reference only; inclusion does not guarantee coverage or payment. Providers must bill the appropriate procedure code reflecting the documented level of complexity and clinical services rendered. Note that CPT codes 77436–77439 are not on the State of Idaho Medicaid Fee Schedule and therefore may not be covered by Idaho Medicaid.
- Report radiation treatment delivery at the documented complexity level (77402 = Level 1, 77407 = Level 2, 77412 = Level 3) and include supporting documentation when 77412 is used.
- IGRT technical components are typically included in 77402/77407/77412; report professional IGRT component with 77387-26 when appropriate.
- Special dosimetry (77331), medical radiation physics consultation (77370), special treatment procedure (77470), and unlisted services (77399) are considered for coverage only when the primary radiation procedure is proven and medically necessary; document clinical justification for use.
- CPT 77331: special dosimetry is intended for 1–6 measurements typically; requests beyond that range require justification and will be reviewed case-by-case.
Prior authorization: guideline‑backed regimens
Prior authorization is recommended for palliative bone RT regimens and for other guideline-backed altered-fractionation regimens where the requested schedule deviates from common standards or state-specific coverage rules. When seeking authorization, submit documentation of prognosis, prior RT doses, normal tissue constraints, and patient-centered goals to support the chosen regimen.
- Accepted conventional palliative regimens include: 800 cGy ×1; 2000 cGy ×5; 2400 cGy ×6; 3000 cGy ×10. Spine compression regimens include 800 cGy ×1, 1600 cGy ×2, 2000 cGy ×5, or 3000 cGy ×10.
- No mandated step therapy: multiple acceptable fractionation options exist and no single regimen is required prior to another.
Document fractionation and IGRT frequency
Document the total fractionation schedule requested and the planned IGRT frequency (daily vs nondaily) in the medical record and in any prior‑authorization request. For altered or shortened fractionation, include clinical rationale and references to guideline support.
- For prostate EBRT, state the specific fractionation (e.g., 60 Gy/20 fx) and whether daily localization (preferred) or nondaily IGRT is planned.
- For hypofractionated breast and APBI regimens, specify verification-imaging frequency (trial evidence required verification each fraction for 5‑fraction schedules) and planned corrective thresholds.
Clinical indications for IGRT
IGRT is commonly indicated when targets are adjacent to critical structures, when narrow PTV margins are used, or when targets are subject to daily internal motion. Indications also include previously irradiated adjacent areas, planned dose escalation, and situations requiring tight geometric accuracy (e.g., SBRT, IMRT, proton therapy).
- Examples: head and neck, lung, pancreas, hepatobiliary, liver, prostate, pelvic sarcoma, and accelerated/ultra‑hypofractionated treatments.
- IGRT is not medically necessary solely to align bony landmarks without implanted fiducials (for example, during palliative RT) unless other IGRT criteria are met.
Prior authorization recommended for revised fractionation and special dosimetry
Prior authorization is recommended when requesting revised fractionation schedules or special dosimetry (CPT 77331, 77370, 77470, 77399). Requests must include clinical justification, prior‑treatment history, and a clear description of why routine planning/dosimetry is insufficient.
- If requesting CPT 77331, document the clinical scenario requiring point dose measurements and the anticipated number of measurements (typically 1–6).
- Requests for CPT 77370 or 77470 should list the specific complexity (e.g., pediatric daily anesthesia, complex photon/electron interrelationships, specialized brachytherapy) and be supported by documentation.
- Unlisted code 77399: provide detailed operative description and rationale that no other code applies.
Not applicable / administrative notes
Not all provider actions in this policy create automatic authorization or denial triggers. Providers should follow payer-specific submission instructions; absence of a mandated step therapy for certain palliative regimens does not negate the need for documentation to support medical necessity.
- No mandated step therapy is specified for palliative bone metastasis regimens — multiple acceptable options exist.
- Providers must still meet usual prior‑authorization or medical‑necessity documentation requirements per payer.
High‑dose thoracic RT may be disfavored
High‑dose thoracic chemoradiation (e.g., 74 Gy with concurrent chemotherapy for stage III NSCLC) may be disfavored based on trial data showing no survival benefit and higher toxicity compared with standard‑dose regimens (e.g., 60 Gy). Document rationale if higher thoracic doses are requested.
- When requesting doses above commonly recommended ranges, provide clinical justification, prior treatment history, and toxicity mitigation strategies (e.g., IGRT, motion management).
Daily prostate localization using IGRT is essential
Daily prostate localization using IGRT is considered essential for margin reduction and treatment accuracy per guidelines. When daily IGRT is planned, document modality, verification method, and how image guidance will inform setup corrections.
- State whether daily volumetric imaging (CBCT/MVCT) or other daily localization (fiducials, kV imaging) will be used.
- If nondaily IGRT is chosen, include evidence-based rationale; daily IGRT has been associated with improved biochemical control compared with nondaily schedules.
Patient medical record must contain documentation supporting medical necessity
The patient's medical record must contain documentation that fully supports medical necessity for the requested services. Required items include relevant history, physical exam findings, prior radiation doses, imaging and diagnostic test results, and a clear treatment plan describing fractionation, dose constraints, IGRT modality/frequency, and motion‑management techniques.
- Make all documentation legible, available upon request, and submitted with prior‑authorization materials as applicable.
- Include dose‑volume histograms and comparative plans when claiming differences in normal tissue sparing or when justifying IGRT/use of special dosimetry.
Verification imaging for hypofractionated breast RT
Verification imaging is required for certain hypofractionated breast regimens and APBI; trial evidence for 5‑fraction whole‑breast schedules mandated verification imaging for each fraction with correction of measured displacements. At minimum, document the planned verification frequency and corrective action thresholds.
- For external‑beam PBI (e.g., 30 Gy in 5 fx) and 5‑fraction whole‑breast regimens, indicate whether imaging will be performed each fraction and the planned action for measured shifts.
- Use DVHs to evaluate normal tissue constraints (heart, lung) and document use of techniques such as DIBH when applicable.
Imaging and dosimetric documentation
Use dose‑volume histograms and imaging records to document dosimetric reproducibility and to justify reductions in margins or dose escalation. Maintain records of image verification, IGRT modality, and any adaptive/replanning actions taken during the course of treatment.
- When requesting special dosimetry or advanced physics consultation, include DVHs, plan comparisons, and a description of measurements to be performed.
- Document the frequency and type of verification imaging (daily, weekly, on‑line vs off‑line) and the method used to determine and apply setup corrections.
Providers should document IGRT modality, frequency, and image verification method
Providers should explicitly document the IGRT modality (CBCT, MVCT, kV imaging, fiducials), the image verification method (online vs offline), and the planned imaging frequency in the medical record and in prior‑authorization submissions.
- Specify whether volumetric imaging will be used and the proposed schedule (e.g., daily CBCT for first 5 fractions then mean‑error correction vs daily for entire course).
- If trainees will be involved in verification processes, document supervision and QA procedures.
Quality and safety documentation
Implement and document quality and safety processes for IGRT programs, including standard operating procedures, interdisciplinary team roles, routine QA checks, and documented decision‑making pathways for adaptive replanning or corrective actions.
- Maintain SOPs that address geometric accuracy, daily quality control, and personnel responsibilities.
- Document QA logs, equipment calibration, and incident investigation procedures as part of the medical record and program quality files.
Special dosimetry documentation
When CPT 77331 (special dosimetry) is requested, document the clinical need, the specific measurement technique, and the anticipated number of measurements (typically 1–6). Requests exceeding the typical range require explicit justification and will be reviewed on a case‑by‑case basis.
No mandated step therapy specified
No mandated step therapy is specified for palliative bone metastases; multiple guideline‑endorsed fractionation options are acceptable. Choose the regimen that best matches the clinical situation and patient goals, and document the rationale.
- Acceptable regimens include single‑fraction 8 Gy and multifraction options (2000 cGy/5 fx, 2400 cGy/6 fx, 3000 cGy/10 fx).
- If selecting single‑fraction therapy, note higher retreatment rates may occur and document the discussion with the patient.
Consider WPRT before prostate‑only RT in high‑risk cases
For high‑nodal‑risk prostate cancer (estimated nodal risk ≥20%), consider whole pelvic radiotherapy (WPRT) prior to prostate‑only RT; when WPRT is selected, document nodal risk estimate, planned nodal dose, use of IMRT/IGRT, and duration of ADT.
- Typical WPRT approach example: 68 Gy/25 fx to prostate plus 50 Gy/25 fx to pelvic nodes with IMRT/IGRT and at least 2 years of ADT in high‑risk cases.
- Include rationale and expected benefit (improved biochemical failure‑free survival and disease‑free survival) in authorization materials.
Evidence supports using moderate hypofractionation for localized prostate cancer
Evidence supports moderate hypofractionation (e.g., 60 Gy in 20 fractions) as an appropriate alternative to conventional fractionation for localized prostate cancer; document trial basis and chosen schedule when requesting authorization.
- Preferred moderate hypofractionation examples: 3 Gy ×20 (60 Gy total), 2.7 Gy ×26, 2.5 Gy ×28; conventional regimens typically 1.8–2 Gy ×37–45.
- When using hypofractionation, document IGRT plans and any motion‑management strategies to support margin reduction.
Imaging frequency and verification
Initial verification imaging strategies (for example, imaging during the first 3–5 fractions with mean‑error correction thereafter) can reduce setup error and should be documented. Specify whether verification will be online (immediate correction) or offline (delayed review) and the thresholds that will prompt immediate corrective action or replanning.
- Document planned verification schedule (e.g., daily for first 5 fractions then weekly or mean‑error correction) and the numeric shift thresholds that will trigger correction or repeat imaging.
- For patients with high BMI or known setup variability, consider daily imaging for margin reduction and document this clinical plan.
Background and Evidence Summary
A radiation therapy course comprises several components including consultation, treatment planning, special services (eg, dosimetry, immobilization), treatment delivery across multiple fractions, and follow‑up. Fractionation strategies include conventional, hypofractionated (fraction sizes between 240–340 cGy defined here as hypofractionation), accelerated, and single‑fraction palliative approaches. Understanding these components and fractionation strategies is essential for applying the policy’s coverage criteria and documenting medical necessity.
Definitions and Terminology
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