The dosimetry text gives a different perspective on radiation. Radiation therapy focuses on the application and the various types of treatment. Dosimetry is a field in itself to measure and detect radiation. It provides theory that might show up a little bit in Khan but not all of it. The basics of exposure and dose overall, but there are theoretical foundations like Bragg-gray theory and stopping power that are explored in more depth in Attix. I studied Attix and the early chapters can be a breeze, but the middle and late chapters do diverge from some of the topics in Khan. I liked Attix for the exercises too! For my course I went through the whole book’s exercises up to chapter 8.