William Dieter
William Dieter is a Radiation Oncology Physician in Chicago, IL, registered under NPI 1891572533. This provider registers 2 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 1520 W HARRISON ST, Chicago, IL 60607. 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 |
|---|---|---|
| 125.086179 | IL | Student in an Organized Health Care… |
| 125086179 | IL | Radiation Oncology Physician primary |
This provider holds licence 125.086179 issued in IL. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Order And Referring Only - Radiation Oncology
- PAC ID
- 1850837998
- Enrollment ID
- I20240724003829
Medicare enrolment is recorded as approved under the provider type Order And Referring Only - Radiation Oncology. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Radiation Oncology covers
A radiologist who deals with the therapeutic applications of radiant energy and its modifiers and the study and management of disease, especially malignant tumors. NUCC Health Care Provider Taxonomy, code 2085R0001X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 390200000X | Student in an Organized Health Care Education/Training Program | 125.086179 | IL | |
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | 125086179 | IL | primary |
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 | 1891572533 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Sep 14, 2023 |
| Last updated | Aug 5, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Male |
| Practice address |
1520 W HARRISON ST Chicago, IL 60607 (312) 942-0712 |
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 | 9 | 1 | 5 | 7 | 2 | 5 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 8 | 9 | 1 | 1 | 7 | 4 | 5 | 6 |
Sum = 67 · next multiple of 10 = 70 · check digit = 3 · actual last digit = 3
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.