K-fluorescence X-rays

Abstract

Therapeutic or industrial X-ray generators can be simply and effectively adapted to the production of K-fluorescence radiation by impinging the primary beam onto an appropriate secondary target. The technique of producing a secondary beam of large diameter with virtually any energy below 100 keV is described. Typical spectra show the beam to be composed almost exclusively of K characteristic radiation, with less than 2% of the total flux attributable to scattering or L-fluorescence if appropriate filtration is used. The essentially monoenergetic beams are extremely valuable for energy depcndence studies of dosimeters and detectors of all types, providing a more intensive study of the response in the 8-100 keVEIl region than is possible with conventional X-ray sources. By use of a radiator with Z near 40, the photon spectrum from 23ePu can be simulated without the necessity of using highly radiotoxic materials. Similar mock spectra can be achieved for 241Am and 243Am. The potential application of this device to radiological standardization is also discussed.

Determination of Photon Conversion Factors Relating Exposure and Dose for Several Extremity Phantom Designs

“…The dependence of the response to photon energy was measured using K-fluorescence x rays (Kathren, Rising and Larson 1971;lOS 1979) ranging from 16 to 76 keV, heavily filtered bremsstrahlung techniques with effective energies of 120 and 211 keV (NBS 1981) and 137 cs and 60 co isotopic sources. Measurements were also performed using three of the bremsstrahlung techniques (M30, S60, and MlSO} specified in ANSI N13.11 (1983}.…”

Standard Sources for Health Physics Instrument Calibration

“…Fluorescent X-rays are secondary X-rays produced by directing a primary X-ray beam of suitable energy at an appropriate element which will absorb a portion of the primary beam and re-emit its characteristic X-rays. The technique has been well described in the literature (LARSON et al, 1955;KATHREN et al, 1971;STORM and SCHLAER, 1965); and a sampling of suitable and conveniently obtainable radiators, kvp of the primary spectrum, and other salient data are given in Table 6. Exposure rates, because of the secondary nature of the X-rays produced, are relatively low; usually no more than a few roentgens per hour can be practically achieved, a range well suited to most health physics applications.…”