NPI registry status
Active
2026 NPPES data Radiation Oncology Physician NPI 1043211360 M.D.
Verify on CMS → Gregory Sibley, M.D.
Radiation Oncology Physician in Fairfax, Virginia.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 6,018 in Radiation Oncology Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
107
Medicare Part D claims · 37 beneficiaries · Radiation Oncology Physician avg: 186
Generic prescribing
81%
generic claims · 19% brand-name · higher generic rates reduce patient out-of-pocket costs
MIPS score
92/100
▲ 9 pts above national avg 83.1 · Exceptional
Industry payments
$190.17
3 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
Compiled from official public sources by the PlainDoctor editorial team.
What the federal data shows
Gregory Sibley, M.D. reported a CMS MIPS final score of 92/100 - above the 83.1 national average - and filed 107 Medicare Part D claims in 2023.
- 92/100
- MIPS score · +9 vs avg
- 107
- Part D claims, 2023
- 81%
- generic prescribing
- Likely
- board-certified (heuristic)
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Gregory Sibley, M.D.'s MIPS score vs every scored U.S. clinician
CMS Merit-based Incentive Payment System (MIPS) final score, 2023, the federal quality measure
92 Top 37% higher than 63% of 477,587 scored providers
Each bar is a band; taller bars hold more scored providers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source CMS Merit-based Incentive Payment System (MIPS) · 2023
Where Gregory Sibley, M.D. sits
This provider among radiation oncology physician peers
Across the 1,988 radiation oncology physician providers who report both Medicare Part D prescribing and a MIPS quality score, Gregory Sibley, M.D. writes more Part D claims than 54% of them and scores higher on MIPS quality than 66% - placing this provider in the high-volume, high-quality quadrant. Volume reflects patient-panel size and specialty, not quality; the two axes are independent.
Part D claim volume vs MIPS quality, by specialty percentile
Each dot is one radiation oncology physician peer from a representative sample of 60; the gold marker is Gregory Sibley, M.D.. Source: CMS Medicare Part D Prescriber data and the CMS Merit-based Incentive Payment System, 2023.
✓
Board certification likely (heuristic, not verified)
Gregory Sibley, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + MIPS quality reporting + 1 hospital affiliation - signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Gregory Sibley, M.D.?
High performer (top quartile)Primary specialty
Radiation Oncology Physician
Medicare Part D claims
107 42% vs specialty avg
MIPS final score
92/100 8.9 pts vs avg
Specialty distribution in Virginia
How Radiation Oncology Physician compares to other specialties among Virginia providers
Medicare quality performance, MIPS
Gregory Sibley, M.D.'s 2023 MIPS final score plotted against the Radiation Oncology Physician national average
- MIPS Final Score
- 92/100
- vs 83.1 national avg · 2023 performance year
MIPS final score (Radiation Oncology Physician) - 92/100 vs national avg 83.1
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Gregory Sibley, M.D. appears in the CMS NPPES registry as a Radiation Oncology Physician provider holding M.D. credentials at 8613 ROUTE 29 STE 100N, Fairfax, VA, 22031, with a listed phone of (571) 350-8400. NPI 1043211360 was issued on 08/09/2005.
Medicare Part D records for calendar year 2023 show 107 prescription claims written by this provider, covering 37 Medicare beneficiaries and totaling roughly $37K in drug spend, split 19% brand-name and 81% generic by claim count. On the CMS Merit-based Incentive Payment System, this provider earned a Final Score of 92/100 for the 2023 performance year (Quality 81.4), compared with the national average of 83.1.
Radiation Oncology Physician is a mid-sized specialty nationwide, with 6,018 enrolled providers across 52 states and an average of 186 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline.
Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist, always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.
Practice Address
Provider Details
| NPI | 1043211360 |
|---|---|
| Specialty | Radiation Oncology Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 08/09/2005 |
CMS Quality Score (MIPS)
Merit-based Incentive Payment System (MIPS) scores from CMS, 2023 performance year.
91.9614
Final Score
Avg: 83.1
81.4039
Quality
100
Promoting Interoperability
Reporting: Alternative Payment Model
Hospital and facility affiliations
Facilities where Gregory Sibley, M.D. bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" - a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.
Virginia Cancer Specialists, P.C.
Fairfax, VA
Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).
Industry payments received (2024) - CMS Open Payments transparency data
The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for Gregory Sibley, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$190
Largest payer
Myriad Genetic Laboratories, Inc.
Most common payment type
Food and Beverage
Industry payments are not necessarily indicators of bias, they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.
Brand vs generic prescribing mix · Typical
Gregory Sibley, M.D. - brand share 19.0%
Radiation Oncology Physician average
19% brand-name claims vs 81% generic, on 107 2023 Medicare Part D claims.
The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.
Medicare Part D Prescribing Data
CMS Medicare Part D prescriber-level data for calendar year 2023.
107
Total Claims
$37K
Total Drug Cost
37
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 159
- Total Day Supply
- 3,810
- Brand vs Generic
- 19% brand / 81% generic
- Brand Drug Cost
- $35K
- Generic Drug Cost
- $2K
- Antibiotic Claims
- 11
Patient Demographics
- Average Patient Age
- 75.8 years
- Avg HCC Risk Score
- 2.03
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
| Drug | Claims |
|---|---|
| Tamsulosin Hcl | 39 |
| Orgovyx Relugolix | 13 |
* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.
Radiation Oncology Physician Overview
How Gregory Sibley, M.D. fits within the Radiation Oncology Physician landscape nationally.
6,018
Radiation Oncology Physician Providers in US
52
States with Radiation Oncology Physician
186
Avg Claims per Provider
Gregory Sibley, M.D.'s 107 claims are below the specialty average of 186.
Nearby Radiation Oncology Physician Providers in Virginia
Other clinicians with the same primary specialty enrolled in Virginia, drawn from the same CMS NPPES roster as Sibley.
Dr. Chike Abana
MD, PHD
Norfolk, VA
Dr. Olubunmi Abayomi
M.D.
Richmond, VA
Dr. Harold Agbahiwe
M.D.
Fairfax, VA
Dr. Sanjeev Aggarwal
MD
Gainesville, VA
Dr. M Moinuddin Ali
MD
Richmond, VA
Compare Radiation Oncology Physician nationally: see state-by-state distribution →
Before you book an appointment
Use this federal record as your verification checklist, not as a recommendation.
- Confirm the NPI record is current in the official CMS registry, providers update their own NPPES details, and moves can lag. Verify this NPI
- Check the active license and any disciplinary history with the Virginia medical board, federal registration is not a license check. Credential verification guide
- Weigh a second option: compare this provider with a nearby Radiation Oncology Physician peer on Medicare volume and prescribing patterns. Compare providers
Medicare Part D and MIPS figures describe practice patterns in federal programs only, they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.
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Frequently Asked Questions
What is Gregory Sibley, M.D.'s specialty? ▼
Gregory Sibley, M.D. specializes in Radiation Oncology Physician and practices in Fairfax, Virginia. Credentials: M.D..
How much does Gregory Sibley, M.D. prescribe under Medicare Part D? ▼
In 2023, Gregory Sibley, M.D. wrote 107 Medicare Part D claims totaling $37K in drug costs for 37 beneficiaries.
What is Gregory Sibley, M.D.'s Medicare quality score? ▼
Gregory Sibley, M.D. has a CMS MIPS Final Score of 92/100 (Quality: 81.4). The national average MIPS Final Score is 83.1. Source: CMS Merit-based Incentive Payment System (MIPS) 2023.
Where is Gregory Sibley, M.D. located? ▼
Gregory Sibley, M.D. is located at 8613 ROUTE 29 STE 100N, Fairfax, VA, 22031. Phone: (571) 350-8400.
What is Gregory Sibley, M.D.'s NPI number? ▼
Gregory Sibley, M.D.'s National Provider Identifier (NPI) is 1043211360, issued on 08/09/2005.
Does Gregory Sibley, M.D. prescribe more brand-name or generic drugs? ▼
Gregory Sibley, M.D.'s prescribing is 19% brand-name and 81% generic drugs by claim count, with $35K in brand drug costs.
How many Radiation Oncology Physician providers are there in the US? ▼
There are 6,018 Radiation Oncology Physician providers across 52 states in the US. The average Radiation Oncology Physician provider writes 186 Medicare Part D claims per year.
What drugs does Gregory Sibley, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Gregory Sibley, M.D.'s most frequently prescribed drugs include Tamsulosin Hcl, Orgovyx. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Gregory Sibley, M.D. accept Medicare? ▼
Gregory Sibley, M.D. appears in CMS Medicare data with 107 Part D claims and 37 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Gregory Sibley, M.D.'s credentials? ▼
Gregory Sibley, M.D.'s NPI is 1043211360 with credentials M.D.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Prescribing Data
- CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
- Quality Performance
- CMS Merit-based Incentive Payment System (MIPS) - 2023 performance year.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Compiled from official public sources by the PlainDoctor editorial team.