RT Answers: This is a website run by the American Society for Therapeutic Radiation and Oncology (ASTRO) that provides a wealth of information about the general aspects of what radiation therapy is and what it entails, specific types of radiation such as brachytherapy, and brief discussion of information about RT for specific cancers along with anticipated side effects.

NIH Radiation Therapy site: Questions and answers from the NIH website about radiation for cancer.  Topics are general, but answers are provided in pretty good detail.

CancerlinksUSA.com Radiation Therapy: Compiled information from a variety of web sources to provide general information about radiation therapy.  Unfortunately, several of the links are no longer active, and I don’t think this site is updated often.

MD Anderson Radiation Therapy Information: Answers to common questions about radiation therapy for cancer, provided by MD Anderson Cancer Center in Houston, TX.

Fox Chase Radiation Therapy FAQ: A similar offering from Fox Chase Cancer Center in Philadelphia, PA, this site provides discussion of concerns about radiation therapy and also a link to a patient educator for more specific questions. 

DrJohnG.com: Dr. John Gwozdz is a radiation oncologist at Texas Oncology in Amarillo who has provided a website with answers to common questions about radiation for cancer.