70 year old female patient had head and chest ct scan in february. last week dental x-rays. and coming week both knee x-ray for arthritis check up. should the knee x-ray be safe given so many ct scan and x-ray in one year. ?

You use special imaging as often as needed to solve clinical questions that would otherwise go unanswered or require exploratory surgery. In proper hands the physicians who know the full history have the best chance of answering such a question.

Perfectly safe. Diagnostic radiographs result in a very low exposure. Don't give it a second thought.

First, today's digital exposures are nothing like yesterday's film exposures. They are minuscule by comparison. Also to attempt diagnosis without proper imaging is to guess. It means asking your practitioner to work blind. Of course discuss your trepidation with your practitioner, but go with his/her recommendation.