We are committed to providing our clients with expertise, accuracy, and confidence.

LinearPhysics, LLC is a national provider of medical physics consulting services to the radiation oncology market, partnering with hospitals and clinics.

We partner with you to commission and provide QA for your linear accelerators. Our American Board of Radiology-certified team, with over 100 commissioned linear accelerators, will help you:

  • Design vault shielding and perform final survey
  • Commission all aspect of your accelerator
  • Perform Annual Quality Assurance
  • Provide reports to your hospital administrators and accrediting bodies

When you work with LinearPhysics, we will:

  • Commission your accelerator with thorough and rigorous methodology
  • Provide Board-Certified Physicists each with 20+ years of experience and over 100 linacs commissioned
  • Clearly communicate with you and your medical physicist at every stage of the project
  • Work with your schedule: we work evenings and weekends so your patients are not impacted
  • Provide flexibility to meet your timeline
  • Use state-of-the art equipment to provide accurate testing and measurements
  • Two medical physicist’s review of results prior to review by your medical physicist
  • Comprehensive data acquisition based on AAPM recommendations and compliant with ACR requirements for quality patient treatment
  • Deliver complete detailed documentation of results

We are dedicated to delivering the highest quality, most accurate, and thorough Commissioning and Quality Assurance services to the radiation oncology clinic.  Our physicists are highly trained, board certified experts who take pride in communicating well and delivering confidence to the clinical physicist and physicians.

Over the last 25+ years we have commissioned more than 100 linear accelerators, including all Varian, Siemens, and Elekta models. In the collection of data, we have utilized IBA, Sun Nuclear, and PTW scanning systems. We have measured data for Eclipse, Monaco, RayStation, and Pinnacle treatment planning systems.

LinearPhysics works globally, focused primarily in North America.  We hold the additional required state licenses for Florida, Texas, New York, Virginia, and Ohio (CRE).

Clinicians can trust their equipment performance backed by the quality and value provided by our ABR board certified physicists.

Contact us online

Leadership and Expertise

Wm. Gary Shields, MSc DABR
President and Senior Physicist

As President and Senior Physicist at LinearPhysics LLC, entrepreneurial-minded Gary Shields leverages his years of experience to provide personalized attention to what has been missing in comprehensive commissioning.  His consultative approach allows LinearPhysics to customize services to better meet the needs of the customer.

Over his 25 year career, Gary has commissioned over 85 linear accelerators including TrueBeam and  Elekta Versa HD, and the first clinical Halcyon in the United States.  Gary has worked internationally, commissioning linear accelerators in Russia, Myanmar, and Columbia.

Gary is a board-certified physicist with experience that includes all aspects of clinical physics, including dosimetry, patient and machine quality assurance, and regulatory compliance. He obtained his Master Degree from the University of Cincinnati, and is ABR Board Certified in Therapeutic Radiologic Physics.

LinearPhysics is made up of a team of experts from not only industry but academic institutions to assure we are providing the best possible services. Additionally, we consult with medical and industry professionals to keep up-to-date on the latest technology, issues, and trends.


Michael Lamba, PhD, DABR
Medical Physicist

Carl Shields, PhD
Medical Physicist

Dan Ionascu, PhD, DABR
Medical Physicist

Brian Zeppuhar
Director of Sales

“LinearPhysics was easy to work with from the start.
Their personal attention and flexibility gave us the perfect commissioning experience.
Our project from shielding, acceptance, commissioning, model validation, and finally end to end testing, gave us the 'first day treatment' confidence that we needed. “

- Lisa DiBernardi, DVM, Diplomate ACVIM (Oncology), Diplomate ACVR (Radiation Oncology)