Qualified medical physicists work directly with the radiation oncologist during treatment planning and delivery. They oversee the work of the dosimetrist, and help ensure that complex treatments are properly tailored for each patient. Medical physicists are responsible for developing and directing quality control programs for equipment and procedures. Their responsibility also includes making sure the equipment works properly by taking precise measurements of the radiation beam and performing other safety tests on a regular basis.

Qualified medical physicists have a PhD or a master's degree. They have completed at least four years of college, and then generally two- to four-years of graduate school. They also typically have one- to two-years of clinical physics training. Medical physicists are certified by the American Board of Radiology or the American Board of Medical Physics.