This website contains educational materials from a Massachusetts Institute of Technology (MIT) Principles of Radiation Interactions course offered in the fall semester of 2004. This site is part of the MIT OpenCourseWare project, which was developed to share MIT undergraduate and graduate course resources with the Internet community. This course "is intended to provide a broad understanding of how different types of radiation deposit energy, including the creation and behavior of secondary radiations; of how radiation affects cells and why the different types of radiation have very different biological effects." The course addresses the effects of radiation on biological systems, in vivo mammalian systems, in vitro cell survival models, radiation therapy, and more. The course website contains downloadable lecture notes, six problem sets, and two exams. The site also lists reading assignments, and includes a 30-page downloadable Overview of Cell Biology document.