A picture of an open-beam analytical device.

The Division of Radiation Safety (DRS) is a resource for scientists who use open beam analytical x-ray devices at NIH. These instruments can range from low keV x-ray energy to very high energy x-ray generation. Manufacturers of these devices must provide appropriate safety guidance, and the x-ray device must contain interlocks and warning lights to operators, so that radiation exposures can be controlled and hazards minimized.

DRS provides dosimetry for x-ray operators to wear while conducting experiments with analytical x-ray devices with an open beam geometry. No dosimeters are required for closed system (cabinet) x-ray devices, also known as x-ray irradiators. However, in an open beam x-ray system, it is possible for operators to receive a radiation dose as a result of the x-ray beam’s scatter radiation, especially if personnel are near the beam path.

To keep radiation doses as low as reasonably achievable (ALARA), operators should pay attention to others who may be near the beam path and ensure that adequate shielding is surrounding the beam. Operators should ensure that the control panel lights (and audible speakers, if applicable) are working to indicate when the beam is on, and do not defeat any interlock meant to prevent an operator from placing a part of the body into the beam path. Utilize good radiation safety technique by remembering the basic principles of time, distance and shielding.

Radiation dose limits from x-ray equipment are set by the Occupational Safety and Health Administration. Limits are set at:

• 1,250 millirem per calendar quarter to the whole body including the lens of the eye
• 7,500 millirem per quarter to skin
• 18,750 millirem per quarter to any extremity (hand, forearm)

Radiation injuries may occur if operators place portions of their body into the direct beam path and may consist of acute dermal injuries as well as opacities to the lens of the eye. This can be especially harmful if the x-ray energy is high and the hand or eye is in the direct x-ray beam. Extreme caution needs to be taken when operators manipulate their sample to position it in alignment with the x-ray beam. Accidents have been known to occur when this sample positioning was done while the beam was still unknowingly “on.”

Please contact DRS at (301) 496-5774 to speak with a health physicist about registering your analytical x-ray device, to request a safety consultation or dosimetry, and for any additional questions or concerns. Remember, safety first!