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Mathematical method for determining kVp from x‐ray attenuation measurements
Author(s) -
Joseph Peter M.
Publication year - 1975
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.594179
Subject(s) - attenuation , bremsstrahlung , attenuation coefficient , scattering , optics , computational physics , physics , mass attenuation coefficient , photon
A mathematical analysis of the shape of x‐ray attenuation curves is presented that suggests a new method of determining the kVp of bremsstrahlung beams. The main result is a simple analytic formula which gives an excellent approximation to the attenuation curve for large thickness of high‐ Z absorber. From this, a graphical procedure is derived which yields a straight line whose slope is related to the mass attenuation coefficient evaluated at the peak energy. Included are corrections for aluminum filtration, ion‐chamber energy dependence, and coherent scattering. The method is limited to beams generated by a constant potential and with negligible characteristic photons in the filtered spectrum. Numerical data are given for using copper absorber below 70 kVcp and tin above 90 kVcp.