About ROC

ROC is the state’s largest private practice radiation oncology group. They are experienced in the delivery of:

  • 3-D conformal radiation therapy (3DCRT)
  • Intensity modulated radiation therapy (IMRT)
  • Gamma Knife radiosurgery (stereotactic radiosurgery)
  • Stereotactic radiotherapy, TomoTherapy
  • High dose-rate (HDR) brachytherapy
  • Low dose-rate (LDR) brachytherapy
  • Proton therapy

William F. Hartsell, MD, FACR, FACRO

Chicago Proton Center

William F. Hartsell, MD, FACR, FACRO
Medical Director, Chicago Proton Center
Radiation Oncology Consultants

Education & Training

Undergraduate: University of Oklahoma, Norman, OK

Medical Degree: University of Oklahoma, Oklahoma City, OK

Internship: Presbyterian-St. Luke’s, Denver, CO

Residency: Rush-Presbyterian St. Luke’s, Chicago, IL

Board Certification: American Board of Radiology in Radiation Oncology

Dr. Hartsell is the president of Radiation Oncology Consultants (ROC) and the medical director of the Northwestern Medicine Chicago Proton Center. He previously served as the medical director of radiation oncology at Good Samaritan Cancer Center and Lutheran General Cancer Care Center. Dr. Hartsell joined ROC in 1997 after completing his residency at Rush-Presbyterian St. Luke’s Medical Center in Chicago, where he spent six years as an assistant professor and three years as director of the residency program.

John Han-Chih Chang, MD

Chicago Proton Center

John Han-Chih Chang, MD
Director of Education, Chicago Proton Center
Radiation Oncology Consultants

Education & Training

Undergraduate: University of Michigan, Ann Arbor, MI

Medical Degree: University of Michigan Medical School, Ann Arbor, MI

Internship: St. Joseph Medical Center, Ann Arbor, MI

Residency: Hospital of the University of Pennsylvania, Philadelphia, PA

Board Certification: American Board of Radiology in Radiation Oncology

Vinai Gondi, MD

Chicago Proton Center

Vinai Gondi, MD
Director of Research, Chicago Proton Center
Radiation Oncology Consultants

Education & Training

Undergraduate: University of Wisconsin, Madison, WI

Medical Degree: Columbia University College of Physicians & Surgeons, New York, NY

Internship: Columbia University College of Physicians & Surgeons
St. Luke’s/Roosevelt Hospital, New York, NY

Residency: University of Wisconsin, Madison, WI

Board Certification: American Board of Radiology in Radiation Oncology

Christy M. Kesslering, MD

Chicago Proton Center

Christy M. Kesslering, MD
Medical Director, Radiation Oncology for CDH and Delnor
Radiation Oncology Consultants

Education & Training

Undergraduate: University of California, Los Angeles, CA

Medical Degree: Stritch School of Medicine, Loyola University, Maywood, IL

Internship: MacNeal Hospital, Berwyn, IL

Residency: University of Wisconsin, Madison, WI

Board Certification: American Board of Radiology in Radiation Oncology

Stephen A. Mihalcik, MD, PhD

Stephen Mihalcik, MD, PhD

Stephen A. Mihalcik, MD, PhD
Radiation Oncology Consultants

Education & Training

Undergraduate: University of Maryland, College Park

Medical Degree: Mayo Medical School

Internship & Residencies: Massachusetts General Hospital, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Beth Israel Deaconess Medical Center. Boston Children's Hospital, Boston Medical Center

Board Certification: American Board of Radiology in Radiation Oncology

Nasiruddin Mohammed, MD, MBA

Chicago Proton Center

Nasiruddin Mohammed, MD, MBA
Radiation Oncology Consultants

Education & Training

Undergraduate: University of Illinois, Chicago, IL

Medical Degree: Loyola University Stritch School of Medicine, Maywood, IL

Internship & Residency: William Beaumont Hospital, Royal Oak, MI

Board Certification: American Board of Radiology in Radiation Oncology