The oncologist writes your prescription for radiation therapy, including the type and dose. The dosimetrist fills the prescription by creating a treatment plan and calculating how much radiation is needed to deliver the dose. But it’s the medical physicist who works behind the scenes to ensure you get exactly what is prescribed in the exact spot that you need it and nowhere else.
“In a nutshell, a medical physicist is a unique combination of scientist, clinician, engineer, artist, computer programmer and technician,” says Yijian Cao, PhD, chief of physics in the Department of Radiation Medicine at Northwell Health Center for Advanced Medicine, who has been doing this type of work for more than 25 years.
The medical physicist ensures that the complex treatments are tailored exactly for each patient, develops the protocols designed to maintain that the treatments are safe, effective, and with pinpoint accuracy. Radiation can be delivered with surgical precision in a space that’s smaller than a quarter inch by a quarter inch. Designing effective treatment plans that affect the cancer involves complex math, physics and highly sophisticated computer software. The medical physicist tests the equipment—linear accelerators, CT scanners and radioactive isotopes periodically—to make sure they are calibrated accurately to deliver the prescribed therapy to the exact place in the body. They are also in compliance with the state and international agencies that oversee radioactive materials and radiation safety. The quality and safety protocols for the technicians operating the machines are developed to avoid any unnecessary radiation exposure to staff and public.
“Our job is to maximize the radiation’s effect on the tumor while minimizing the effect on any nearby or surrounding normal tissue,” Dr. Cao explains. “We want to save lives and preserve quality of life. Those are equally important to us.”