Ethan Ludmir, M.D., grew up watching Star Wars. But unlike other fans, his favorite character wasn’t Luke Skywalker or Han Solo. Instead, Ludmir favored a character who got much less screen time: the man tasked with controlling the Death Star’s laser beams.

Today, Ludmir’s work as a radiation oncologist in Gastrointestinal Radiation Oncology has certain similarities to the movies he grew up watching. But instead of using lasers...