I believe you are referring to a radiation therapy technology position. (RTT). An RTT degree is one of the best kept secrets out there. It only takes 3 years out of high school. They start at salaries more than almost any 4 year bachelors degree will start at. In the NYC metropolitan area, starting salaries for RTT's out of training range from 60,000 to 75,000 dollars a year. A chief tech will earn in the $80,000 to $100,000 range. The techs at the center where I work are in their early to late 20's and most are driving BMW's.
As with anything else its supply and demand. Three years ago we were giving signing bonuses, and the salaries peaked. We no longer give out signing bonuses, but demand is still steady. Career advancement means becoming a chief tech or becoming a dosimetrist (someone who knows how to use the computerized planning system) An experienced dosimetrist can make more than 100,000 per year.