ABSTRACT
Superposable radiographs of lower molar areas were obtained by means of a specially designed film holder and a gnathostat maintained in a constant position with respect to long-cone radiological equipement. A quantitative evaluation of the bone mass in the interradicular area was obtained by scanning the area under a photodensitometer. A photodensitometric scan of the image of an aluminium wedge adapted to each radiograph was also performed. This allowed the transformation, with the aid of a computer, of the photodensitometric recording of bone into a tracing of mm of aluminium equivalents. The reproducibility and precision of the method were verified by comparing magnifications of repeated radiographs, by photodensitometric readings of radiographs developed in different batches and by repeated quantitative readings of the same film. The method allowed one, for instance, to follow quantitatively the healing of a radiographically visible periapical lesion. It was also used to evaluate quantitatively, in the interradicular area, bone changes which could not be seen with the marked eye.
Subject(s)
Densitometry/methods , Molar/diagnostic imaging , Periodontal Diseases/diagnostic imaging , Tooth Root/diagnostic imaging , Densitometry/instrumentation , Humans , Image Processing, Computer-Assisted , RadiographyABSTRACT
The authors have developed an experimental method for simultaneous determination of dose and image parameters in mammography. A global and objective quality concept, the image quality index, is proposed and its reliability demonstrated by tests of reproducibility. Objective quality tests and subjective evaluation by radiologists showed good correlation.
Subject(s)
Mammography/methods , Evaluation Studies as Topic , Female , Humans , Mammography/standards , Radiation DosageABSTRACT
A quality control program for mammography units was carried out, based on objective tests of image quality and dose. Results are reported for 31 units, including correlation between various parameters. Satisfactory results were obtained in the case of 21 installations; for the other 10, comparison between measured quality parameters and those of the reference system suggested ways in which quality might be improved.
