An energy- and depth-dependent model for x-ray imaging
- NIBIB/CDRH Laboratory for the Assessment of Medical Imaging Systems, 12720 Twinbrook Parkway, Rockville, Maryland 20857 (United States)
In this paper, we model an x-ray imaging system, paying special attention to the energy- and depth-dependent characteristics of the inputs and interactions: x rays are polychromatic, interaction depth and conversion to optical photons is energy-dependent, optical scattering and the collection efficiency depend on the depth of interaction. The model we construct is a random function of the point process that begins with the distribution of x rays incident on the phosphor and ends with optical photons being detected by the active area of detector pixels to form an image. We show how the point-process representation can be used to calculate the characteristic statistics of the model. We then simulate a Gd{sub 2}O{sub 2}S:Tb phosphor, estimate its characteristic statistics, and proceed with a signal-detection experiment to investigate the impact of the pixel fill factor on detecting spherical calcifications (the signal). The two extremes possible from this experiment are that SNR{sup 2} does not change with fill factor or changes in proportion to fill factor. In our results, the impact of fill factor is between these extremes, and depends on the diameter of the signal.
- OSTI ID:
- 20634435
- Journal Information:
- Medical Physics, Vol. 31, Issue 11; Other Information: DOI: 10.1118/1.1806293; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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