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Biomedical subjects

M Kakegawa

Publications and source records attributed to M Kakegawa.

3 recordsLinked to original sources
PubMed1988

Computed radiographic evaluation of simulated pulmonary nodules. Preliminary results.

We evaluated the capabilities of a computed radiography system (CRS) and a standard radiography system (SRS) in the detection of simulated solitary pulmonary lung nodules of various sizes and contrast. A phantom simulated the pulmonary anatomy, and specially shaped plexiglass disks were externally mounted to simulate solitary pulmonary nodules of different diameters and thicknesses. ROC curves were generated based on the performance of each of the radiologists observing each film set. In this preliminary study, the overall performance for both the CRS and the SRS were comparable in detecting simulated pulmonary nodules.

Humans↗
PubMed1978

[A new method for elimination of artifacts produced by collimator septum effect in gamma-camera images (author's transl)].

Collimator artifacts may be present within the images produced by collimators whose septal width approaches the inherent resolution of the gamma-camera system. As the inherent resolution of the gamma-camera is improved, collimator artifacts become more prominent. The purpose of this study is to eliminate collimator artifacts from gamma-camera images. To eliminate the septum effect produced by high-energy parallel-hole collimators with thick septa, the following method was used: X and Y signals from the detector are made to ride on the triangular waves changing periodically, and resultant position signals obtained by this processing are applied to the corresponding deflection circuits in the CRT display. The oscillation amplitude of processed position signals can be regulated by the frequency and amplitude of the triangular waves. Regulation of the oscillation amplitude of position signals, which would produce maximum reduction of collimator artifacts, was to approach the spatial frequency responses of the overall processed line spread functions obtained experimentally to those of the Gaussian functions with FWHM equal to the geometric resolution calculated from the equation given by Gerber and Miller. In images of a pancreas phantom containing 131I, collimator artifacts were clearly seen in the unprocessed case, but were eliminated in the processed case.

Models, Theoretical↗