Links: Radiation Safety
Radiation Exposure in X-ray examinations: RadiologyInfo is a site which answers questions about X-rays. This site is maintained by the American College of Radiology (ACR) and the Radiology Society of North America. This site provides a good chart on effective doses for various radiologic procedures and comparable natural background radiation.
Image Gently is a site dedicted to issues in pediatric imaging, maintained by the Alliance for Radiation Safety in Pediatric Imaging.
Radiology Safety Resources: This ACR page is a more comprehensive catalog on the subject, including both patient-oriented educational sites, as well as white papers and guidelines for the medical community.
Response to NEJM on Radiation Safety: ACR's response to an article in the New England Journal of Medicine regarding radiation risk in CT imaging.