Mathematical method for determining kVp from x-ray attenuation measurements.
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.
D008433:Mathematics; D011874:Radiometry / Q000379:methods*; D014965:X-Rays