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.

Our expertise is the result of over 25 years of clinical experience, including treatment planning, TPS modeling, developing quality assurance protocols, data collection, and testing.

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.

With our collaborative approach, we customize our services to meet your unique needs.

  • Rigorous, thorough commissioning methodology
  • Clear communication at every stage of the project
  • Flexibility in scheduling, no downtime for your physicists
  • Extensive experience with all major vendors
  • Complete documentation of results

Over the last 20+ 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.

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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)