Radiation Oncologist Salary. Radiation oncologists employed in the United States typically earn salaries in the range from $197,763 to $579,743 a year including bonuses according to the salary information reported by Payscale.adiation oncologists based in Alaska earn a median salary of $157,000 a year, those working in New Mexico and Colorado are paid $178,000 a year on average, and doctors based in Connecticut earn around $226,000 a year.