Michael Spak, MD
Michael Spak, MD is a Radiological Physics Physician in Eau Claire, WI, registered under NPI 1831145721. This provider registers 8 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 900 WEST CLAIREMONT AVENUE, Eau Claire, WI 54701. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 20002 | WI | Radiological Physics Physician primary |
| 20002 | WI | Body Imaging Physician |
| 101042 | MN | Body Imaging Physician |
| 20002 | WI | Neuroradiology Physician |
| 101042 | MN | Neuroradiology Physician |
| 20002 | WI | Nuclear Radiology Physician |
| 101042 | MN | Nuclear Radiology Physician |
| 20002 | WI | Pediatric Radiology Physician |
| 101042 | MN | Pediatric Radiology Physician |
| 20002 | WI | Diagnostic Radiology Physician |
| 101042 | MN | Diagnostic Radiology Physician |
| 20002 | WI | Vascular & Interventional Radiology… |
| 101042 | MN | Vascular & Interventional Radiology… |
| 20002 | WI | Diagnostic Ultrasound Physician |
| 101042 | MN | Diagnostic Ultrasound Physician |
Licences are recorded in 2 states: WI, MN. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
Licensed in 2 states
This provider holds licences in 2 states: Minnesota and Wisconsin. The practice address on file is in Eau Claire, WI, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 20002
- Specialty
- Radiological Physics Physician
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Radiological Physics covers
A radiological physicist deals with the diagnostic and therapeutic applications of roentgen rays, gamma rays from sealed sources, ultrasonic radiation and radio-frequency radiation, as well as the equipment associated with their production and use, including radiation safety. NUCC Health Care Provider Taxonomy, code 2085R0205X
All registered taxonomy codes
This provider registers 15 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2085R0205X | Radiological Physics Physician Radiological Physics | 20002 | WI | primary |
| 2085B0100X | Body Imaging Physician Body Imaging | 20002 | WI | |
| 2085B0100X | Body Imaging Physician Body Imaging | 101042 | MN | |
| 2085N0700X | Neuroradiology Physician Neuroradiology | 20002 | WI | |
| 2085N0700X | Neuroradiology Physician Neuroradiology | 101042 | MN | |
| 2085N0904X | Nuclear Radiology Physician Nuclear Radiology | 20002 | WI | |
| 2085N0904X | Nuclear Radiology Physician Nuclear Radiology | 101042 | MN | |
| 2085P0229X | Pediatric Radiology Physician Pediatric Radiology | 20002 | WI | |
| 2085P0229X | Pediatric Radiology Physician Pediatric Radiology | 101042 | MN | |
| 2085R0202X | Diagnostic Radiology Physician Diagnostic Radiology | 20002 | WI | |
| 2085R0202X | Diagnostic Radiology Physician Diagnostic Radiology | 101042 | MN | |
| 2085R0204X | Vascular & Interventional Radiology Physician Vascular & Interventional Radiology | 20002 | WI | |
| 2085R0204X | Vascular & Interventional Radiology Physician Vascular & Interventional Radiology | 101042 | MN | |
| 2085U0001X | Diagnostic Ultrasound Physician Diagnostic Ultrasound | 20002 | WI | |
| 2085U0001X | Diagnostic Ultrasound Physician Diagnostic Ultrasound | 101042 | MN |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1831145721 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 25, 2006 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | MD |
| Practice address |
900 WEST CLAIREMONT AVENUE Eau Claire, WI 54701 (715) 839-4151 |
| Mailing address |
2715 WEST FRANK STREET Eau Claire, WI 54703 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 8 | 3 | 1 | 1 | 4 | 5 | 7 | 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 6 | 1 | 2 | 4 | 1 | 7 | 4 |
Sum = 59 · next multiple of 10 = 60 · check digit = 1 · actual last digit = 1
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.