The relationship between pixel value and beam quality in photostimulable phosphor imaging.
Direct digital capture systems are relatively new in diagnostic imaging. Full utilization of these devices requires a thorough understanding of the image formation process. The conversion of x-ray photon energy to a digital pixel value in a commercially available photostimulable phosphor (PSP) imaging system is investigated in this paper. Pixel values measured at 16 different combinations of 4 x-ray beam peak voltages (60, 80, 100, and 120 kVp) and 4 beam qualities are reported. At 60 and 80 kVp exposures were made at 2.58 x 10(-7) C/kg (1 mR); at 100 and 120 kVp exposures were made at 5.16 x 10(-7) C/kg (2 mR). Analysis of variance was used to determine the statistical significance of the relationship between pixel value and beam quality for a given kVp and exposure. A computer model accounting for x-ray spectral effects that accurately predicts pixel value is presented. Calculated pixel value agree within 5.0% of measured values over the range of beam energies, exposures, and qualities.
Tucker
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Department of Radiology, University of Alabama School of Medicine, Birmingham 35233, USA. dtucker@rpimail.mdacc.tmc.edu
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D000704:Analysis of Variance; D055592:Biophysical Phenomena; D001703:Biophysics; D003198:Computer Simulation; D006801:Humans; D008163:Luminescent Measurements; D017785:Photons; D011856:Radiographic Image Enhancement / Q000379:methods*; D014965:X-Rays