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Compare the published Medicare service mix of Gregory S Willis, M.D. with clinicians in the same registry specialty: Radiation Oncology (CMS).

TUALATIN, OR · 10 milesEdit location
Within 10 miles · Approximate ZIP-area distance

Approximate straight-line distances between ZIP-area centers; a city search starts from the average of its ZIP centers. Uses the primary reported practice ZIP, not an exact office address or driving distance. Records without matched coordinates are excluded. How distance works

2024 published service data · 19 eligible profiles compared. Similarity describes billing patterns, not quality, outcomes, or suitability for your care.

Casey Williamson, M.D.

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
94%Service-mix similarity~9.4 milesView profile →

Re-I Chin, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
89%Service-mix similarity~8.7 milesView profile →

Eric Keith Hansen, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
88%Service-mix similarity~8.7 milesView profile →

Bradley Ackerson, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
87%Service-mix similarity~8.7 milesView profile →

Howard M Sandler, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
85%Service-mix similarity~9.4 milesView profile →

Carl Martin Post, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Calculation of radiation therapy dose (77300)
  • Design and construction of complex radiation treatment device (77334)
83%Service-mix similarity~9.4 milesView profile →

Joshua M Walker, MD/PHD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
81%Service-mix similarity~9.4 milesView profile →

Lubna Abdel Rahman Hammoudeh, MD

Specialty details in registry · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Calculation of radiation therapy dose (77300)
  • Design and construction of complex radiation treatment device (77334)
80%Service-mix similarity~9.4 milesView profile →

Arthur Y Hung, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)
  • Calculation of radiation therapy dose (77300)
80%Service-mix similarity~9.4 milesView profile →

Sophia Bornstein, M.D. PH.D.

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Calculation of radiation therapy dose (77300)
  • Design and construction of complex radiation treatment device (77334)
79%Service-mix similarity~8.7 milesView profile →

Lanceford M Chong, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Calculation of radiation therapy dose (77300)
  • Design and construction of complex radiation treatment device (77334)
76%Service-mix similarity~9.4 milesView profile →

Nima Nabavizadeh, MD

Radiation Oncology (CMS) · Portland, OR

Shared published services
3 shared services · view billing descriptions
  • Ct guidance for insertion of radiation therapy fields (77014)
  • Calculation of radiation therapy dose (77300)
  • Design and construction of complex radiation treatment device (77334)
75%Service-mix similarity~9.4 milesView profile →
How this comparison works

We use the same calendar year of CMS Medicare Physician & Other Practitioners data for both providers. Published non-drug service counts are combined by HCPCS code across places of service. We apply log(1 + count), normalize the vectors, and compare them using cosine similarity.

Candidates share the reference provider’s current NPPES primary taxonomy and match the location you enter. We examine up to 500 candidates in approximate distance order, then show up to 12 with the highest positive similarity within that set. The score is not a percentile, medical recommendation, or prediction. Suppressed services are not estimated. Medicare fee-for-service data does not describe a provider’s entire practice.

Source: CMS Medicare Physician & Other Practitioners - by Provider and Service : 2024-12-01 · Published May 21, 2026.