It depends where you practice. For example, in Canada ( where I'm from), radiation therapist actually performes the dosimetric portion of treatment. On the other hand, in the United STates, radiation thearpy and dosimetry are two different professions, even though they are related obviously. Currently I am at the University of Toronto studying radiation therapy, and we are being prepared to do the dosimetry portion of cancer treatment. So as a radiation therapist with few years experience in Canada ( doing dosimetry of course), I will be able to work in the United states as a dosimetrist ( provided I pass the certification exam). With regards to salary potential, in therapy you will start out around 45-65 K depending on where you are in the states. Max out, I dont think you will go over 100k as a general therapist. With regards to dosimetry, if you choose to specialize, starting salary is 75K+ again depending on where you are. On average it is around mid 80's however. As already explained, to become a dosimetrist ( in the U.S), you first must become a radiation therapist, get few years in clinical practice, then either get on the job training (2-3 yrs), or go to a dosimetry school (1-2 yrs... however these are few). If you in Canada, you would go to therapy school ( 2-3 yrs..Diploma or BSc and you get trained in dosimetry also). Therefore, once you are ready for clinical practice, you can go straight into Dosimetry if you perfer. However, in Canada dosimetrist will not make as much as they would in the USA. Being a Canadain graduate is saught after in the STates because of wide range of exposure students get in school ( IMRT, Brachytherapy, Tomotherapy, Dosimetry)