Method and device for determining the attenuation function of an object with respect to the transmission of a reference material thickness
First Claim
1. A method to determine an object'"'"'s attenuation function,characterized in that it comprises the following stages:
- A. expressing the object'"'"'s transmission function as a finite power expansion of the transmission u of a reference-material reference thickness, each power of u being assigned a coefficient, the expansion powers being equal to a ratio between previously determined thicknesses of the reference material to the reference thickness,B. determining the expansion coefficients;
(a) by measuring the intensity of a test beam for different energy spectra,(b) by measuring, for each of said energy spectra, the intensity of the beam transmitted by each of considered reference-material reference thicknesses,(c) by measuring, for each of said energy spectra, the object'"'"'s transmitted beam intensity,(d) by resolving, for each of said energy spectra, the object'"'"'s transmitted beam intensity into a sum of the intensities measured in the stage B-b relative to the spectrum under consideration, these intensities being assigned the looked-for coefficients,(e) by resolving the system of equations derived in the stage B-d,C. deriving the object'"'"'s attenuation function in terms of u from the stages 1 and B.
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Abstract
The object'"'"'s transmission function is expressed as a finite power expansion of a reference-material reference thickness, each expansion power being equal to a ratio of a reference-material thickness to the reference thickness; the expansion coefficients are determined from the measurements of the intensities transmitted by the selected various thicknesses, including zero thickness, of the reference material exposed to a test beam evincing consecutively several energy spectra and from the measurements of the intensity transmitted by the object exposed to this same variable-spectrum test beam; the attenuation function is derived from the determination of the transmission function.
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Citations
18 Claims
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1. A method to determine an object'"'"'s attenuation function,
characterized in that it comprises the following stages: -
A. expressing the object'"'"'s transmission function as a finite power expansion of the transmission u of a reference-material reference thickness, each power of u being assigned a coefficient, the expansion powers being equal to a ratio between previously determined thicknesses of the reference material to the reference thickness, B. determining the expansion coefficients; (a) by measuring the intensity of a test beam for different energy spectra, (b) by measuring, for each of said energy spectra, the intensity of the beam transmitted by each of considered reference-material reference thicknesses, (c) by measuring, for each of said energy spectra, the object'"'"'s transmitted beam intensity, (d) by resolving, for each of said energy spectra, the object'"'"'s transmitted beam intensity into a sum of the intensities measured in the stage B-b relative to the spectrum under consideration, these intensities being assigned the looked-for coefficients, (e) by resolving the system of equations derived in the stage B-d, C. deriving the object'"'"'s attenuation function in terms of u from the stages 1 and B. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification