Answer to Question #11148 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
Is it possible for any amount of scatter x-radiation to travel as far as behind a medical diagnostic x-ray tube? If the x-ray tube was horizontally orientated and tightly collimated, and then exposed at 109 kVp and 3.2 mAs, can any x ray reach behind the direction of x ray (and thus behind the tube)?
Yes, the scatter from the patient goes out in all directions with the highest percentage being toward the x-ray tube. However, the x-ray tube will absorb most of the scatter that it intercepts due to the thick lead lining inside of the tube. That said, the x rays that are not absorbed by the tube will continue in the same direction. If one is standing behind the tube there will still be exposure from the x rays that are not absorbed by the tube, i.e., above and below the tube.
The best place to stand during an x-ray exposure is outside of the room (in a control booth) or behind a lead shield.
Joel Gray, PhD