Comparison of the calculated object X-ray pattern with its radiographic image energy flux density distribution

The effective relative X-ray pattern is obtained from a microdensitometric trace of radiographic exposures of simple aluminium cylinder phantoms recorded on film. The densitometric trace of the photographic image is converted into a relative energy flux density profile with the application of calibration data obtained with an inverse square sensitometer. The effective relative X-ray pattern differs from the actual X-ray pattern due to the interposition of the quantum sensitivity of the recording emulsion. Calculations employing measured spectra and the attenuation properties of the phantom demonstrate reasonably close agreement with experimental determinations derived from microdensitometric scans of images. Differences between the calculated X-ray pattern, the emulsion quantum sensitivity modulated pattern and the experimental profile were intercompared in the spatial frequency domain and were found to be correspondingly small.