58 Patients, suspicious to have rotation deformity of the femur, were examined. To compare the value of diagnostic methods in measuring the degree of malrotation we estimated this degree using clinical examination and calculated the anteversion of the femoral neck, taking radiographs in the technique of Dunn and Rippstein, and a modified method of computed tomography. Only in twelve cases the direction of malrotation was corresponding in all three methods, although considerable variations in quantitative results were noted. Maintaining the exact position of the patient, necessary to get reproducible results using conventional X-ray technique, was impossible in most cases of patients with posttraumatic joint-stiffness and malalignment. Determination of femoral neck anteversion using this modified method of CT is a quick, reproducible technique to calculate the degree of malrotation, insensitive to the position of the patient. By means of this CT method it was possible to approach the highest accuracy in precise preoperative planing. Furthermore the radiation exposure could be reduced in a range of 20%-40%.

Storage phosphor radiographs are equal to the tested analog screen-film-system. The optimization of post-processing can be helpful in the prevention of routine multiple documentations.

58 patients, suspicious to have a rotation deformity of the femur, were treated between 1981 and 1988 at our hospital. To compare the value of diagnostic methods in measuring the degree of malrotation we estimated this degree using clinical tests and calculated the anteversion of the femoral neck, taking radiographs in the technique of Dunn and Rippstein and a modified method of computed tomography. Surprisingly only in twelve cases the direction of malrotation, not to consider the degree, with all three methods was corresponding. Clinical evaluation only in cases with extreme deformity produces clear results. Maintaining the exact position of the patient, necessary to get reproducible results using conventional X-ray technique, was impossible in most cases of elderly patients with postraumatic joint-stiffness and malalignment. Determination of femoral neck anterversion by means of CT is a quick, reproducible method to calculate the degree of rotation deformation, insensitive to the position of the patient's extremities as far as there is no motion during the time of scan.

The extent to which the diagnostic performance of low-dosed storage phosphors can be improved by suitable image postprocessing was investigated. Storage phosphor radiographs and conventional 200- and 400-speed screen-film combinations of an anthropomorphic chest phantom with simulated nodules and linear structures were compared. The detection of test bodies was determined in a ROC analysis based on 16200 individual observations. The two analog screen-film systems did not differ significantly. As far as the storage phosphor radiographs are concerned, a higher diagnostic performance was achieved with a large filter kernel (S 40) whereas small filter kernels and edge-enhanced imaging modes reduced the detection of detail. The image quality of low-dosed storage phosphors is thus similar to high-amplification screen-film combinations if large filter kernels are used in postprocessing of the image.

Whenever optimized postprocessing is involved, storage phosphor radiography is equal to a modern screen-film system and can be substituted for the latter without any loss of image quality; this is especially valid for the imaging of interstitial infiltrates of the lung.