Radiation hazards of analytical x-ray systems

Because they utilize extremely high intensity x-ray beams, analytical x-ray systems have the potential for posing significant hazards if operated inappropriately. Radiation exposures can result not only from the primary 

The x-rays utilized most commonly in analytical systems have wavelengths in the range of 0.5 to 10 angstroms. These are often referred to as soft x-rays because of the ease by which they are absorbed in matter. While this characteristic enables soft x-rays to be readily shielded (generally requiring only a few millimeters of lead or iron), it also makes them particularly hazardous since they are highly absorbed even by soft tissue. 

The primary beams from analytical x-ray systems are generally well collimated with beam diameters of less than one centimeter. Because of their intensity and their high degree of absorption in tissue, they can produce severe and permanent local injury from exposures of only a fraction of a second. 

Exposure to the primary beam of powder diffraction units is a major concern. In fact, the greatest risk of acute accidental exposures from analytical systems occurs in manipulations of the sample to be irradiated by the direct beam in diffraction studies. Exposure rates on the order of 10,000 R/s ( 4xl0 R/h) can exist at the tube housing port. At these levels, erythema would be produced from exposures of only 0.03 second and permanent injury could be inflicted in only 0.1 second. The fingers, of course, are the part of the body most at risk from such high exposures. 

For x-ray diffraction systems, the diffracted beam is also small and focused with an intensity of up to 80 R/h ( 22 mR/s). Prolonged or repeated exposures to a beam of this intensity could result in an individual exceeding the annual dose limit for the particular tissue irradiated. 

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