Yes, it is definitely possible to transition from an x ray tech to a radiation therapist.
Here is how you can go about doing it:
Education and Professional Development: The first step would be to pursue formal education and professional development in radiation therapy. This includes either a certificate or degree program from a college or university. You could also get specialized training at a professional institute.
Look for a Radiation Therapist Job: Once you have sufficient training, you can then look for a job as a radiation therapist. Often, radiation therapy is part of a team approach at treatment centers. You may also want to network with other radiation therapists and other healthcare professionals in the field.
Obtain State Licensure: Depending on the state you live in, you may need to obtain licensure in order to practice as a radiation therapist. Most states require a certain amount of clinical rotation hours and a passing score on an exam in order to obtain licensure.
For more information and details on switching to a career as a radiation therapist, please refer to this helpful article from the American Society for Radiation Oncology: https://www.astro.org/Education-Careers/Career-Progression-Options/Career-Changes-in-Radiation-Oncology