The remarkable evolution of medical imagery and radiotherapy over the last several decades has yielded a panoply of sophisticated machines that provide unprecedented insight into patient physiology and powerful treatments for serious diseases.
Most radiologists, however, are trained to evaluate the product of these sophisticated machines — the images — or to use them to fight disease, not necessarily to understand how the technologies work nor how to ensure that the multimillion-dollar machines are performing optimally. That important task is the purview of the medical physicist, says the director of the master’s degree program in medical physics, George Sgouros.
“Our job is to train medical physicists to be responsible for quality control and maintenance of diagnostic equipment, CT scanners, X-rays, MRI scanners, single-photon emission CT — virtually everything involved in imaging patients,” Sgouros says.
One really big part of the field is supporting external beam radiotherapy, which treats cancerous tumors. It is the medical physicist’s role to ensure exact dosage of radiation to guarantee effective treatment without the potential harm that too much radiation might cause.
“We train medical physicists how to come up with a plan to orient the radiation beams, to specify how long they’re on, how the beam is shaped and so forth,” Sgouros says. “This is very precise work that can have detrimental outcomes if not performed with great skill.”
One of the newest and most exciting areas in medical physics in recent years, Sgouros says, is radiopharmaceutical therapy, in which radiation is delivered not by a beam from outside the body but by attaching radioactive atoms to molecules that are delivered through the bloodstream directly to the tumor deep inside the body.
“This field bridges the diagnostic and therapeutic physics,” Sgouros says. The student, he says, must be well-versed not only in the physics of radiation delivery and the biology and physiology of radioactive molecules delivered through the blood but also in how tumors and normal tissues respond to radiation. If that were not enough, all that knowledge must then be combined with nuclear medicine imaging physics.
The complexity of science explains the fact that Johns Hopkins will be offering the only radiopharmaceutical therapy training program in Maryland. “These students are entering a very promising field at the outset,” says Sgouros.