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Biomedical subjects

P Edholm

Publications and source records attributed to P Edholm.

8 recordsLinked to original sources
PubMed1978

Transverse tomography with incoherent optical reconstruction.

A thin layer of an object can be imaged by reconstruction from a so-called sinogram. It is produced by an x-ray fan beam rotating around the object while a recording film is moved in a direction perpendicular to the plane of the fan beam. Before reconstruction the sinogram image is convoluted according to a special function to remove artifacts consisting of spurious shadows between different object elements. The reconstruction is done from the convoluted sinogram by means of a back projector, which operates according to a prinicple that is the reverse of the recording of the original sinogram. Tomograms of phantoms, pork chops and the head of a dog show that the process is capable of high spatial resolution but is limited by low contrast.

Animals↗
PubMed1977

Knee instability and tibial osteotomy. A clinical study.

Twenty-one gonarthrosis patients were preoperatively assessed according to a newly developed orthoradiographic technique ("three-point measurement") and followed up for 2-3 years postoperatively using this technique. The medio-lateral instability of the knee joints was not influenced by the operation. The varus/valgus deviation was under-corrected, on average, but the deviation did not increase significantly with time after the operation. Judging from this pilot study the three-point measurement technique supplies relevant information and it is now being used in a prospective study on high tibial osteotomy in gonarthrosis.

Aged↗
PubMed1976

Attenuation equalizing filter in diagnostic radiography. Advantages calculated by a Monte Carlo technique.

The value of an attenuation equalizing filter (equalizer) has been examined by calculation using a Monte Carlo technique. The contrast enhancement caused by the equalizer is the net result of three factors: (1) The first factor arises from the contrast change caused by the difference in detector characteristics at the different energies absorbed in the detector with and without equalizer. (2) The second factor is due to the contrast change caused by the different ratios of primary to total radiation reaching the detector. (3) Finally, the third factor describes how the transparency of the object is changed by the different primary filtration with equalizer. An example is given of the reduction in radiation energy absorbed by the patient and the question of how far the attenuation equalization can be driven is discussed.

Computers↗
PubMed1976

Knee instability. An orthoradiographic study.

An orthoradiographic method for preoperative assessment of mediolateral instability and varus/valgus deviation in gonarthorsis is presented. A special definition of the varus/valgus deviation is given. The examination technique has been tested on 15 young, healthy subjects with no clinical signs or symptoms in their knee joints. To test the accuracy of the method, seven of the subjects were re-examined at a later date.

Humans↗