Radiation exposure measurements in the 8-15 kVp X-ray range.

Abstract

Exposure measurements are described for a typical Grenz-ray-ray machine operating in the 8–15 kVp energy range. The previously acknowledged energy dependence and sensitivity limitation of available instrumentation compromised the precision of such exposure measurements. Thus, users of Grenz-ray-ray machines, X-ray diffraction instruments, and other low-energy X-ray devices were often deluded into assuming the absence of ionizing radiations, as determined by use of conventional survey meters which were calibrated for higher energies. Although the first centimeter of tissue almost completely absorbs X-ray photons of this energy, their effects to such superficial sites, as the lens of the eye, are of concern. Commercially available detectors, of known energy dependence and sensitivity were used to measure primary and secondary levels of exposure to occupancy points. 10 mR/hr exposure rates were measured as far as 6 ft away from a scattering phantom irradiated by a 15 kVp primary beam.