Answer to Question #12472 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I had two arm x rays and I think my head was within 50–100 centimeters from the x-ray tube. Is my head at risk?
No, your head is not at risk.
On an overhead radiographic unit there are two major components (1) the x-ray tube and protective housing, and (2) the variable-aperture collimator. The protective housing has a window through which the x rays are emitted. In all other directions, the protective housing is constructed with radiation absorbing material (e.g., lead).
Affixed to the window of the x-ray tube protective housing is the variable-aperture collimator. This device allows the technologist to adjust the actual size of the x-ray beam to only the area of interest by manipulating two pair of shutters in two dimensions (the length and width of the x-ray beam).
These devices are designed to shape and direct the x-ray beam to one direction as it comes out the bottom of the collimator. The amount that "escapes" through the shielding of the protective housing and the collimator (called leakage radiation) is a very small fraction of the useful beam. The permissible amount of leakage radiation is regulated by U.S. Food and Drug Administration and State regulations. It is checked during equipment inspections performed by diagnostic imaging physicists and State inspectors.
The bottom line is that any radiation that your head received would be very small and completely inconsequential.
Certified Health Physicist
Fellow, Health Physics Society