METHODS OF SENSITOMETRY FOR LOW ENERGY RADIOGRAPHY.

Inverse-square sensitometry for low kVp techniques is limited by air attenuation and beam hardening. It is thus difficult to obtain accurage H and D curves for mammographic screen-film combinations at technique factors used clinically. Methods are described for the determination of characteristic curves at low X-ray energies which provide composite intensity-scale curves using small changes in source-to-receptor distance and concomitant changes in either exposure time, beam attenuation, or kVp. H and D curves obtained at low kVp's using various sensitometric approaches are compared with those obtained using inverse-square sensitometry. Relative merits of the different methods are discussed.