Need Insight On Comprehensive X-ray Procedure

This is a question for a dentist to answer please. Yesterday I went to the dentist for a routine cleaning. While there the hygienist said that it was time for some wing bite x-rays. It had been two years since I had my last x-rays done. She proceeded to do them, however, I noticed that she was doing quite a few of them using various mouth pieces to get different views. After at least six different x-rays I asked her why so many were being done and she said that the doctor wanted a comprehensive set of x-rays done since it had been two years since my last x-rays were performed. I then asked the hygienist what comprises a comprehensive set and she said that ever tooth would be x-rayed. She said that they do that because cavities form between teeth and they want to know ahead what teeth might be heading for cavities. I have not had any cavities over the past 15 years and take extremely good care of my teeth, using the water pik twice daily and brushing and flossing regularly. I am concerned about the amount of radiation that we expose ourselves to so this question is important to me to be clear on. I didn't feel I had any real clarification on this and wished for a bit more information. It wasn't forthcoming. So my key question is: what is a comprehensive x-ray procedure, and does it involve filming every tooth in a patient's mouth. I have never heard of this protocol being used before. Any information on this question would be helpful. Thank you.
Linda