Size Of Specks Research Articles

Optimization of xeroradiographic exposures.

Xeroradiographs were exposed over a range of mAs and kVp in the mammographic energy range. At each kVp, the technique yielding the widest halo also produced the greatest detectability of small aluminum specks in mammographic phantoms. As the kVp increased, the maximum halo width and number of visible specks decreased. At all kVps, the techniques yielding the widest halo furnished almost constant energy deposition in the selenium plate. This constant plate dose was correlated to patient exposure at the entrance of the breast, and the relationships between patient entrance exposure, kVp, and minumum detectable speck size were determined.

Formation and Properties of Sub-Image and Latent-Image Silver Specks. Part I: Thermodynamics of Silver Speck Formation

The formation of latent image specks has been discussed so far as a sequence of steps (Ag1,→Ag2 -→Ag3-→ .) which allegedly leads from precursors (Ag1, Ag2,...) finally to full image centres. This reaction scheme demands that a continuous growth of silver specks by electron capture regardless of the size of the specks takes place as the result of exposure. Sub-image specks obtained by a weak pre-exposure, or reduction sensitization specks are believed to be such precursors of latent image. If silver speck formation is treated as a process of phase formation, calculations suggest that such a continuous growth does not take place: Very small specks (e.g.Ag1, Ag2,) tend to capture holes and are thus destroyed by exposure. Growth by electron capture requires a minimum size of the silver specks which depends on the value of the exposure-induced supersaturation in the crystal.

The Redox Potential of the Latent-Image

AbstractReinders used redox buffers to bleach the latent-image and found that buffers more negative than the silver electrode potential bleached some of it. Refinements in technique haye shown that bleaching in such buffers reaches a limit after a few hours and further bleaching had no more effect. This “limiting value” of bleaching has been used to measure the redox potentials of the latent-image under different exposure conditions. The results confirm deductions by Burton and Berg on the effect of exposure conditions on the size of latent-image specks. The relevance of the findings to the mechanism of development is also discussed.