ModifiedUnitedHealthcarePolicy CS179ID.B

Radiation Therapy: Fractionation, Image-Guidance, and Special Services (for Idaho Only)

Defines medically necessary radiation therapy fractionation limits, indications for image-guided radiation therapy (IGRT), and coding/special services guidance for members in Idaho (including Idaho Medicaid Plus). Applies to UnitedHealthcare plans in Idaho.

Policy Summary

PayerUnitedHealthcare

PolicyRadiation Therapy: Fractionation, Image-Guidance, and Special Services (for Idaho Only)

Policy CodePolicy CS179ID.B

Change TypeDocumentation requirement added

Effective DateApr 1, 2026

Next Review DateN/A

Key ActionInclude in the patient medical record documentation that fully supports medical necessity (history, exam, relevant diagnostic test results) for radiation therapy requests.

SourceLink

POLICY UPDATE CHANGES

The patient's medical record must contain documentation that fully supports the medical necessity for the requested services.

up to 10palliative bone EBRT fractions

up to 5APBI fractions (breast)

up to 35NSCLC fractions

up to 28prostate standard fractions

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addeddocumentation requirement

Coverage Criteria for Radiation Therapy

inv-01: Bone metastases — palliative EBRT — Covered when at least one of the following applies:

Covered when at least one of the following applies:

Bone metastasis fractionation: Delivery of up to 10 fractions of radiation therapy is medically necessary for palliative EBRT for bone metastasis.<=10 fractions

Prior radiation at site: Delivery of greater than 10 fractions is medically necessary for treatment of a site that has previously received radiation therapy.>10 fractions when prior RT to site

inv-02: Breast adenocarcinoma — EBRT — Covered when ALL of the following fractionation rules are observed:

Covered when ALL of the following fractionation rules are observed:

APBI: Delivery of up to 5 fractions for accelerated partial breast irradiation (APBI) is medically necessary.<=5 fractions

Standard breast fractionation: Delivery of up to 21 fractions (inclusive of a boost to the tumor bed) is medically necessary.<=21 fractions

Extended fractionation up to 33: Delivery of up to 33 fractions (inclusive of a boost to the tumor bed) is medically necessary when any of: treatment of supraclavicular and/or internal mammary lymph nodes; post-mastectomy RT; prior thoracic RT; or connective tissue disorder (e.g., lupus, scleroderma).<=33 fractions with listed criteria

Exclusion: Delivery of greater than 33 fractions (inclusive of a boost to the tumor bed) for breast cancer is not medically necessary.>33 fractions

inv-03: Locally advanced non-small cell lung cancer (NSCLC) — Covered when the following is met:

Covered when the following is met:

NSCLC fractionation: Delivery of up to 35 fractions for locally advanced non-small cell lung cancer (with or without chemotherapy) is medically necessary.<=35 fractions

Delivery of greater than 35 fractions is not medically necessary.

inv-04: Prostate adenocarcinoma — EBRT — Covered when at least one of the following applies depending on clinical scenario:

Covered when at least one of the following applies depending on clinical scenario:

Limited metastatic disease definitive: Delivery of up to 20 fractions for Definitive Treatment in an individual with Limited Metastatic Disease is medically necessary.<=20 fractions

Applicable to limited metastatic prostate cancer only.

Localized prostate standard: Delivery of up to 28 fractions for localized prostate cancer is medically necessary.<=28 fractions

Extended localized prostate: Delivery of up to 45 fractions for localized prostate cancer is medically necessary when any of: high-risk disease with pelvic lymph node radiation; post-prostatectomy RT; history of inflammatory bowel disease (e.g., ulcerative colitis or Crohn disease); or prior pelvic RT.

inv-05: Image-Guided Radiation Therapy (IGRT) — IGRT is medically necessary when ANY of the following are met:

IGRT is medically necessary when ANY of the following are met:

IGRT with IMRT: When used with intensity modulated radiation therapy (IMRT) (e.g., prostate cancer).

IGRT with PBRT: When used with proton beam radiation therapy (PBRT).

Prior or adjacent RT: When the target has received prior radiation therapy or abuts a previously irradiated area.

Implanted fiducials: When implanted fiducial markers are being used for target localization.

3D-CRT definitive treatment:

inv-06: Covered regimens and clinical considerations — Coverage supported when radiation regimens align with evidence-based fractionation options and guideline recommendations for the indicated scenarios.

Coverage supported when radiation regimens align with evidence-based fractionation options and guideline recommendations for the indicated clinical scenario.

Palliative bone metastases fractionation: Permissible regimens include single-fraction 8 Gy or multifraction schedules such as 20 Gy in 5 fractions, 24 Gy in 6 fractions, or 30 Gy in 10 fractions; selection should consider prognosis, prior radiation, normal tissue risks, and patient goals.

Supported by randomized trials and ACR/ASTRO guideline statements.

Reirradiation to same bone site: For reirradiation to the same site, single-fraction (8 Gy) or multifraction conventional palliative RT regimens (e.g., 2,000 cGy in 5 fractions, 2,400 cGy in 6 fractions, or 2,000 cGy in 8 fractions) are appropriate; reirradiation achieves pain response in ~58% of patients.

Supported by systematic reviews and ASTRO recommendations.

Spine metastases with cord compression not eligible for surgery: Conventional palliative RT regimens recommended include 800 cGy in 1 fraction, 1,600 cGy in 2 fractions, 2,000 cGy in 5 fractions, or 3,000 cGy in 10 fractions.

inv-07: Site-specific coverage principles — Coverage aligned with high-quality evidence and specialty society guidelines for common disease sites:

Coverage aligned with high-quality evidence and specialty society guidelines for common disease sites:

Breast cancer - early stage WBI: Hypofractionated whole-breast irradiation (e.g., 40 Gy in 15 fractions or 42.5 Gy in 16 fractions) is supported as safe and effective after breast-conserving surgery; APBI regimens such as 30 Gy in 5 fractions are supported for selected patients.

Supported by START trials, ASTRO, NCCN, and NICE guidance.

Breast cancer - technical considerations: Use of DIBH for left-sided disease to reduce heart dose and use of IGRT as appropriate; weekly or more frequent imaging recommended per NCCN.

ASTRO/NCCN/NICE guidance.

Locally advanced NSCLC: Definitive chemoradiation should use ~60 Gy in 2 Gy fractions (once daily) with concurrent chemotherapy; dose escalation to 74 Gy is not supported because of worse survival and increased toxicity.

Based on RTOG/NRG trial and ASTRO/NCCN guidance.

inv-08: Covered when guideline-based IGRT/motion-management and hypofractionation criteria are met — Guideline-based recommendations relevant to coverage decisions

Guideline-based recommendations relevant to coverage decisions

Prostate moderate hypofractionation: Moderate hypofractionated EBRT (defined in document as ~2.4–3.4 Gy per fraction) is recommended for low-risk and intermediate-risk prostate cancer patients opting for active treatment and may be used for high-risk when pelvic nodes are not treated; example regimens include 3 Gy × 20 (6000 cGy) and 2.5 Gy × 28 (7000 cGy). Counsel patients about a small increased risk of acute GI toxicity; late GI/GU toxicities are similar to conventional fractionation.

ASTRO/AUA and NCCN guidance referenced.

IGRT indicated scenarios: IGRT is indicated for targets near critical structures, subject to daily internal variation, previously irradiated adjacent areas, volumes requiring narrow margins, or when dose escalation/highly conformal techniques (IMRT, 3D-CRT, PBRT, APBI) are used.

ACR-ASTRO and ASTRO resources referenced.

Daily IGRT recommendation for specific contexts: Daily image guidance is recommended or strongly recommended in multiple site-specific ASTRO guidelines (e.g., dose-escalated liver RT, oligometastatic NSCLC, conventionally fractionated pancreatic RT, preoperative RT for extremity/truncal soft tissue sarcoma).

inv-09: Clinical indications and guideline-based recommendations — IGRT is supported/recommended in scenarios where accuracy and motion management are critical; common clinical indications include:

IGRT is supported/recommended in scenarios where accuracy and motion management are critical; common clinical indications include:

Common indications for IGRT: Any target volume located near or within critical structures; targets in tissue with inherent setup variation; volumes requiring narrow margins to protect adjacent structures; targets subject to daily variation due to internal motion; targets adjacent to previously irradiated areas requiring precise abutting fields; scenarios planning dose escalation beyond usual doses for similar tumors.

Sources: ACR-ASTRO practice parameter and ASTRO coding resource.

Motion management and image guidance recommended: For hepatocellular carcinoma or intrahepatic cholangiocarcinoma receiving dose-escalated hypofractionated EBRT, respiratory motion management and daily image guidance are recommended.

ASTRO guideline (Apisarnthanarax et al., 2022).

Highly conformal RT and motion management: For oligometastatic NSCLC and highly conformal RT using inverse planning, appropriate motion management strategies and image-guided RT delivery are recommended.

When the documented IGRT criteria are not met, the use of image‑guided radiation therapy is considered not medically necessary. Examples include IGRT for superficial treatment of skin cancer (including superficial radiation therapy or electronic brachytherapy) and use of IGRT solely to align bony landmarks without implanted fiducial markers (for example, during palliative radiation therapy). Refer to coding clarifications for appropriate reporting with brachytherapy, SRS, and SBRT.

Within the portions of the document addressing EBRT, SBRT, accelerated partial breast irradiation (APBI), and hypofractionated whole‑breast irradiation (HF‑WBI), there are no additional explicit modality exclusions beyond the IGRT coding and reporting clarifications already noted. Coverage and fractionation limits are specified per disease site and clinical context rather than by blanket exclusion of these modalities.

High‑dose escalation to 74 Gy (given in 2 Gy daily fractions) with concurrent chemotherapy for inoperable stage III non‑small cell lung cancer was evaluated in a randomized trial and was not superior to standard‑dose therapy; it was associated with worse overall survival and increased severe toxic effects. Thus, escalation beyond the guideline‑recommended definitive dose (e.g., 60 Gy in 2 Gy fractions) is not supported by the evidence and is associated with potential harm.

ASTRO guidance states that IGRT is not indicated for superficial skin treatments and is not appropriate when used solely to align external bony landmarks in the absence of implanted fiducial markers. These scenarios are specifically cited as examples where IGRT would not generally be considered medically necessary.

ASTRO coding guidance clarifies that IGRT should not be reported for imaging performed during brachytherapy (verification of applicator position should be reported using CPT code 77280) and that IGRT is not indicated for superficial skin treatments or solely to align bony landmarks without fiducials. Additionally, IGRT may not be reported separately with SBRT or SRS per ASTRO coding guidance.

The policy specifies maximum fractionation limits by disease site; delivery beyond those maximums is considered not medically necessary. Examples include: for breast cancer, >33 fractions (inclusive of boost) is not medically necessary; for locally advanced NSCLC, >35 fractions is not medically necessary; and for localized prostate cancer, >45 fractions is not medically necessary except where site‑specific criteria allow extended fractions.

The excerpts do not label specific treatment modalities (for example, SBRT versus conventional EBRT or particular PBI techniques) as uniformly not medically necessary. Instead, limitations are described and the document notes areas where evidence is limited and further research is needed to compare some modalities and techniques.

Reiterating guidance from ASTRO and the policy: using IGRT solely to align bony landmarks without implanted fiducials or for superficial skin cancer alignment is not generally appropriate and may be denied when used in those circumstances. Appropriate use of IGRT requires a clinical rationale (e.g., target motion, proximity to critical structures, fiducial localization).

Applicable Procedure and Billing Codes

Applicable CPT/G-codes for radiation therapy servicesmixed

77014	Computed tomography guidance for placement of radiation therapy fields.
77301	IMRT planning (includes special dosimetry).
77331	Special dosimetry (e.g., TLD, microdosimetry).
77370	Special medical radiation physics consultation.
77385	IMRT delivery; simple.
77386	IMRT delivery; complex.
77387	Guidance for localization of target volume, includes intrafraction tracking.
77399	Unlisted procedure, medical radiation physics, dosimetry and special services.
77401	Radiation treatment delivery, superficial and/or orthovoltage, per day.
77402	Radiation treatment delivery, >=1 MeV; simple.

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Applicable G-codes for radiation therapy delivery and guidancemixed

G6001	Ultrasonic guidance for placement of radiation therapy fields.
G6002	Stereoscopic x-ray guidance for localization of target volume for the delivery of radiation therapy.
G6003	Radiation treatment delivery, single treatment area, up to 5 MeV.
G6004	Radiation treatment delivery, single treatment area, 6-10 MeV.
G6005	Radiation treatment delivery, single treatment area, 11-19 MeV.
G6006	Radiation treatment delivery, single treatment area, 20 MeV or greater.
G6007	Radiation treatment delivery, two separate treatment areas, up to 5 MeV.
G6008	Radiation treatment delivery, two separate treatment areas, 6-10 MeV.
G6009	Radiation treatment delivery, two separate treatment areas, 11-19 MeV.
G6010	Radiation treatment delivery, two separate treatment areas, 20 MeV or greater.

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Imaging/verification notemixed

verification imaging required for each fraction in five-fraction schedule (no specific CPT/HCPCS codes listed in these chunks)

Referenced modalities (no explicit codes in this excerpt)mixed

not specified

ASTRO coding resource references IGRT use with 3D-CRT, IMRT, PBRT and external beam-based APBI but does not provide explicit CPT/HCPCS codes in this section.

Hypofractionation fraction size

Defined hypofractionation range240–340 cGy per fraction (hypofractionation defined as EBRT with fraction size between 240 and 340 cGy).

Lower bound240 cGy per fraction.

Upper bound340 cGy per fraction.

Definition contextHypofractionated radiotherapy = fewer and larger (>200 cGy) doses; guideline uses 240–340 cGy to define moderate/typical hypofractionation.

Prostate hypofractionation regimens

Example regimen — 3.0 Gy × 20

Provider Requirements, Prior Authorization, and Documentation

Billing Rule

Code listing and coverage note

The following list(s) of procedure and/or diagnosis codes is provided for reference only and may not be all inclusive. Inclusion of a code does not guarantee coverage or payment; benefit coverage is determined by federal, state, contractual requirements, and applicable laws. Providers should verify coverage and prior authorization requirements before billing.

Listing of codes is for reference only
Inclusion does not imply reimbursement or guarantee claim payment

Prior Authorization

Prior authorization: verification imaging note

Prior authorization or clinical protocols that adopt five‑fraction whole‑breast schedules (as in the Brunt et al. trial) should require verification imaging for each fraction, with documentation that measured displacements were corrected as recommended by the trial.

Background and Evidence Summary

External beam radiation therapy (EBRT) encompasses techniques such as 3D‑CRT, IMRT, and proton beam therapy and is frequently used for treatment across cancer types. IGRT—the use of imaging (for example, cone‑beam CT or MVCT) at the time of treatment to verify and, if needed, correct patient/target positioning—is described as an important adjunct when high targeting accuracy, motion management, or dose escalation are required; guideline documents and systematic reviews support daily or frequent image guidance in many clinical contexts to improve accuracy and reduce toxicity risk.

Definitions and Terminology

Definitive Treatment

DefinitionRadiation treatments delivered with curative intent (Definitive Treatment).

Typical settingUsed for curative-intent management of primary tumors or disease sites where definitive local control is intended.

TeamDelivered by a multidisciplinary radiation oncology team including radiation oncologist, medical physicist, dosimetrist, therapists and nursing staff.

Limited Metastatic Disease (prostate)

Definition (prostate)Absence of visceral metastasis or fewer than four bone metastases with no metastasis outside the vertebral bodies or pelvis (Limited Metastatic Disease).

ApplicabilityUsed to define patients eligible for definitive treatment approaches in limited metastatic prostate cancer scenarios.

Policy Revision History

Policy Summary

PayerUnitedHealthcare

PolicyRadiation Therapy: Fractionation, Image-Guidance, and Special Services (for Idaho Only)

Policy CodePolicy CS179ID.B

Change TypeDocumentation requirement added

Effective DateApr 1, 2026

Next Review DateN/A

Key ActionInclude in the patient medical record documentation that fully supports medical necessity (history, exam, relevant diagnostic test results) for radiation therapy requests.

SourceLink

On This Page

<=45 fractions with listed criteria

Exclusion: Delivery of greater than 45 fractions for localized prostate cancer is not medically necessary.>45 fractions

During Definitive Treatment using three-dimensional conformal radiation therapy (3D-CRT) for specified sites and scenarios (e.g., breast APBI, breast boost with photons, hypofractionated whole-breast up to 5 fractions, prone positioning, left breast with DIBH; boost for rectal/bladder; esophageal; gastric; head and neck; hepatobiliary; lung; pancreatic; soft tissue sarcoma).

IGRT with 3D-CRT may also be necessary for other conditions when documentation shows DVH/plan differences, immobilization intolerance, significant target motion, or need for smaller CTV margins.

ASTRO guideline recommendations.

Early-stage breast cancer — partial breast irradiation (PBI): PBI modalities (3D-CRT, IMRT, brachytherapy) are supported for appropriately selected patients, with similar ipsilateral breast recurrence and survival compared to whole-breast irradiation in trials; intraoperative RT (IORT) had higher ipsilateral recurrence in some studies.

AHRQ systematic review and trials summarized.

Hypofractionated whole-breast regimens: Five-fraction adjuvant regimens such as 26 Gy in 5 fractions over one week may be non-inferior to longer regimens for selected patients; verification imaging per fraction was used in the trial setting.

UK FAST-Forward and related trials cited.

Prostate cancer - localized: Moderate hypofractionated EBRT (e.g., 60 Gy in 20 fractions) is an acceptable standard for low- and intermediate-risk patients; whole-pelvic radiotherapy with ADT is supported for selected high-risk patients with estimated nodal risk ≥20%.

Supported by large RCTs and ASTRO/AUA guidance.

ASTRO guideline citations in excerpt.

Motion management and 4D imaging: For tumors affected by respiratory motion (e.g., lung), planning with 4D-CT and 4D image guidance and beam gating can reduce required margins substantially.

Korreman et al. multicenter series.

ASTRO guideline (Iyengar et al., 2023).

Conventionally fractionated RT for pancreatic cancer: Daily image guidance is strongly recommended.

ASTRO guideline (Palta et al., 2019).

Soft tissue sarcoma: Daily IGRT with at least weekly volumetric image guidance is strongly recommended for primary localized extremity/truncal soft tissue sarcomas and for preoperative RT for retroperitoneal sarcomas.

ASTRO guideline (Salerno et al., 2021).

NCCN recommendations: NCCN recommends or strongly recommends IGRT for biliary tract, hepatocellular, head and neck, non-small cell lung, and soft tissue sarcoma RT when steep gradients, nearby OARs, or complex motion management techniques are present.

NCCN guideline citations (2024).

60 Gy total delivered as 3.0 Gy per fraction for 20 fractions (6000 cGy); supported by ASTRO as a moderate hypofractionation option.

Example regimen — 2.5 Gy × 2870 Gy total delivered as 2.5 Gy per fraction for 28 fractions (7000 cGy); cited as an example in guideline discussion.

Example regimen — 60 Gy in 20 fractions (trial evidence)Randomized trials (e.g., Dearnaley et al.) demonstrated 60 Gy in 20 fractions is non-inferior to conventional schedules for localized prostate cancer.

Context noteModerate hypofractionation (~2.4–3.4 Gy/fraction) recommended for low- and intermediate-risk patients and some high-risk when pelvic nodes are not treated.

Five‑fraction whole‑breast schedules require verification imaging for each fraction
Documentation should show measured displacements and corrective actions

Prior Authorization

Prior authorization for hypofractionation and IGRT

When utilizing moderate or ultra‑hypofractionation, SBRT, highly conformal treatments, or when daily/near‑daily IGRT is planned, prior authorization may be required to document rationale, imaging frequency, motion management, and QA processes to support safe delivery.

Prior authorization considerations apply for hypofractionation and IGRT/highly conformal RT
Provide treatment intent, fractionation, imaging plan, motion management, and QA documentation

Documentation Required

Medical necessity documentation for reviews

The patient's medical record must contain documentation that fully supports the medical necessity for the requested services. This includes relevant medical history, physical examination, diagnostic test results, treatment intent, prior therapies, and any imaging/planning comparisons used to justify the requested approach. Records must be legible, maintained in the medical record, and available upon request.

Include history, physical exam, and pertinent diagnostic test/procedure results
Include documentation of prior irradiation or adjacent previously irradiated areas when relevant
Maintain legible records and make available upon request

Denial Risk

IGRT denial triggers

IGRT is not medically necessary when the documented clinical criteria are not met. Examples that may trigger denial include superficial treatment of skin cancer (including superficial radiation therapy/electronic brachytherapy) and use solely to align bony landmarks without implanted fiducials (such as routine palliative setups).

Not medically necessary for superficial skin treatments (e.g., CPT 77401) including electronic brachytherapy
Not medically necessary solely to align bony landmarks without implanted fiducials (e.g., routine palliative RT)

Note

Not applicable in this document portion

Not applicable: There are no additional provider action items outside those described in this section of the document.

Provider actions limited to documented requirements in this section

Note

IGRT use expectation

Use of IGRT is appropriate and recommended when needed to safely deliver curative radiation therapy, when OARs are close to high‑dose regions, when targets are mobile or variable, with IMRT/3D‑CRT/Proton therapies, and when implanted fiducials are used for localization. Documentation should indicate the clinical indication for IGRT.

IGRT recommended with IMRT, PBRT, for re‑irradiation or abutting prior fields, and when fiducials are used
Indicate clinical reason for IGRT in the record (e.g., motion management, tight margins, OAR proximity)

Denial Risk

Documentation-related denial risk

Lack of adequate documentation to support medical necessity, IGRT indications, imaging frequency, motion management, or QA procedures may result in denial or delay of authorization or payment. Ensure records explicitly tie the requested services to clinical criteria and safety processes.

Denial risk if documentation does not support the requested RT/IGRT services
Include imaging frequency, motion management strategy, and QA evidence to mitigate denial risk

Documentation Required

Imaging frequency and DIBH documentation

NCCN recommends a minimum of weekly imaging to verify breast treatment setup; more frequent or daily imaging may be appropriate for inconsistent reproducibility or when using DIBH. When DIBH is used (e.g., left‑sided breast cancer), document the technique, reproducibility, and DVH comparisons that justify IGRT and OAR sparing.

Minimum weekly imaging recommended per NCCN; increase frequency as clinically indicated
When DIBH is used, document dosimetric benefit (DVH comparisons) and reproducibility

Documentation Required

Record IGRT modality, frequency, and QA

Document the IGRT modality, frequency, and quality assurance procedures in the medical record. Records should state whether volumetric imaging (CBCT/MVCT), planar imaging, or other modalities were used, the verification schedule (daily/weekly/first‑fractions), and that appropriate QA and standard operating procedures were followed as PTV margins are tightened.

Record IGRT modality (e.g., CBCT, MVCT), verification frequency, and whether online vs. off‑line review was used
Document daily QA and geometric accuracy procedures when reduced PTV margins are used

Billing Rule

Special services coding conditions

Special services and physics/dosimetry CPT codes (e.g., 77301, 77331, 77370, 77470, 77399) are considered for coverage only when the primary radiation procedure is proven and medically necessary and when documentation supports the need for these additional services.

77301 (IMRT planning), 77331 (special dosimetry), 77370 (medical physics consultation), 77470 (special treatment procedure), 77399 (unlisted) — considered only when primary RT is medically necessary
Support requests with documentation of the specific clinical or technical circumstance necessitating the service

Note

Clinical evidence for palliative bone regimens

Clinical evidence supports single‑fraction (8 Gy) and multi‑fraction regimens (e.g., 20 Gy/5 fx, 30 Gy/10 fx) for palliative treatment of bone metastases; document indication (palliation), prior treatments, and rationale for fractionation chosen (including expectation of higher retreatment with single fraction).

Single‑fraction 8 Gy is supported for palliative bone metastases (higher retreatment likelihood vs multi‑fraction)
Common multi‑fraction regimens include 20 Gy/5 fx and 30 Gy/10 fx

Note

Pelvic nodal RT expectation

For men with high‑risk prostate cancer and an estimated nodal risk ≥ 20%, contemporary whole‑pelvic radiotherapy (WPRT) with IMRT/IGRT plus a minimum of two years of ADT is supported by randomized data and should be considered; document nodal risk estimate, technique, and ADT duration.

WPRT (e.g., 68 Gy/25# to prostate + 50 Gy/25# to pelvic nodes) with IMRT and IGRT improved biochemical failure‑free survival versus PORT in selected patients
Document estimated nodal risk (≥20%), planned technique (IMRT/IGRT), and ADT plan

Step Therapy

No step therapy requirements described

No step therapy requirements are described in this section.

No step therapy or prior line‑of‑therapy sequencing required here

SourceDefined in guideline references (Parker et al., 2018) and policy definitions.

Palliative EBRT / Single-fraction 8 Gy

Single-fraction 8 Gy800 cGy in 1 fraction is a commonly used palliative regimen for symptomatic bone metastases and is supported by randomized trials and guideline statements.

Equivalence and tradeoffsSingle-fraction provides similar short-term pain relief but has higher re-irradiation rates compared with multifraction regimens.

Guideline-recommended alternativesMultifraction options include 2,000 cGy in 5 fractions, 2,400 cGy in 6 fractions, or 3,000 cGy in 10 fractions depending on clinical context.

Hypofractionated whole-breast irradiation (HF-WBI)

Short-course example — 26 Gy in 5 fractions26 Gy delivered in five fractions over one week (used in FAST-Forward trial) as an adjuvant whole-breast hypofractionated regimen.

Short-course example — 27 Gy in 5 fractions27 Gy delivered in five fractions over one week; evaluated alongside 26 Gy and 40 Gy/15f in randomized trials.

Standard shorter-course — 40 Gy in 15 fractions40 Gy delivered in 15 fractions over three weeks is a commonly recommended HF-WBI schedule by ASTRO/NCCN/NICE.

HF-WBI / hypofractionated whole-breast irradiation

Preferred HF-WBI doses40 Gy in 15 fractions or 42.5 Gy in 16 fractions are preferred hypofractionated whole-breast irradiation regimens referenced by ASTRO and NCCN.

APBI preferred dosingAPBI preferred dosing per NCCN/ASTRO is 30 Gy in 5 fractions for appropriately selected patients.

Imaging verificationFive-fraction regimens in trials employed verification imaging for each fraction with corrective recommendations for measured displacements.

Moderate hypofractionation (prostate)

Moderate hypofractionation rangeFraction sizes approximately 2.4–3.4 Gy per fraction (document defines moderate hypofractionation for prostate EBRT).

Example — 60 Gy in 20 fractions60 Gy delivered in 20 fractions (3.0 Gy per fraction) supported by randomized trials and recommended as a standard option.

Example — 70 Gy in 28 fractions (as cited)2.5 Gy × 28 fractions (7000 cGy total) listed as a guideline example of a hypofractionated schedule.

DIBH

Technique purposeDeep inspiration breath-hold (DIBH) is used with IGRT to reduce cardiac dose for left-sided breast radiotherapy.

Guideline supportNCCN and NICE recommend DIBH for left-sided breast cancer to reduce heart dose during RT.

Usage noteDIBH is often combined with image guidance and DVH evaluation to ensure OAR protection and acceptable PTV coverage.

IGRT

Definition and examplesIGRT uses imaging (e.g., cone-beam CT [CBCT], megavoltage CT [MVCT]) during treatment to verify and correct patient/target positioning prior to (and sometimes during) each fraction.

Common modalitiesExamples of CT-based volumetric imaging include CBCT and MVCT used for daily image guidance and verification.

Quality assuranceAAPM and professional guidelines emphasize daily QA and geometric accuracy assessment for CT-based IGRT as PTV margins tighten.

4D-IG / 4D-CT

DefinitionFour-dimensional imaging (4D-CT, 4D-IG) accounts for respiratory motion during planning and image guidance to reduce motion-related margins.

Effect on marginsUse of 4D-CT and 4D-IG with gating reduced required treatment margins substantially (median tumor motion 4.4 mm; margin reductions up to ~37%–47% in the cited series).

Clinical useRecommended for tumors affected by respiratory motion (e.g., lung) to enable margin reduction and safer dose delivery.

IGRT (alternate)

IGRT definition summaryImage-guided radiation therapy (IGRT) is the use of imaging during radiation therapy to improve targeting accuracy and precision, commonly used with highly conformal modalities and when targets are near critical structures or subject to motion.

Common contextIGRT is particularly applicable to 3D-CRT, IMRT, PBRT and highly conformal external-beam APBI, and is recommended when dose escalation or narrow margins are planned.

Safety/QA considerationsProfessional societies recommend interdisciplinary teams, documented SOPs, and comprehensive QA programs to ensure safe and effective IGRT implementation.