The three parameter equivalent spectra as an index of beam quality.

A parametric spectral model based on the work of Birch and Marshall is used to characterize the x-ray spectra of a specific x-ray system. Using least-squares comparison between measured and calculated attenuation data, an equivalent spectrum (EQSPEC) is iteratively found which very closely matches the measured attenuation characteristics of the x-ray system. The resulting parametric spectrum is a function of the anode angle (theta), equivalent kilovoltage (kVeq), and the equivalent aluminum filtration (Aleq), and these three parameters can serve as very concise yet very accurate indices of beam quality. The utility of the EQSPEC for characterization and reporting of x-ray spectra (and thus beam quality) may have numerous applications in diagnostic imaging procedures where spectral quality is an important consideration.