[Introduction to PCM technology].
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Artifacts↗
Biomedical subjects
Chika Honda
Publications and source records attributed to Chika Honda.
The first trial of phase contrast imaging for digital full-field mammography using a practical molybdenum x-ray tube.
RATIONALE AND OBJECTIVES: The image quality of a newly developed full-field digital phase contrast mammography (PCM) system and of a conventional screen-film (SF) mammography system were compared via images of a phantom and receiver operating characteristic (ROC) analysis of clinical images. METHODS: Magnified (1.75X) PCM images were scanned (sampling rate, 43.75 microm) and then reduced to original-sized, 25-micron pixel images printed on photothermographic film. Along with corresponding SF images, the phantom images were evaluated subjectively, and the clinical images of 38 patients were subjected to ROC analysis of mass and microcalcification. RESULTS: In the image quality of a phantom, the PCM exceeded the SF. In both mass and microcalcification, the ROC analysis Az values of the PCM clinical images surpassed those of the SF images. CONCLUSION: The PCM provides better images than the SF. Clinical trials suggest superior detection of both mass and microcalcification by full-field digital PCM over conventional SF mammography.
Breast Diseases↗
Horizontal inequity in health care utilization in Japan.
International comparisons of horizontal inequity in health has recently become one of the most pertinent issues in health economics. However, no previous studies have been undertaken on Japan. This omission is rectified in this paper. Moreover, we consider the dynamics of horizontal inequity in health over six years from 1992 to 1998. These dynamics have never been considered in this field. In a rigorous international comparison, though we cannot find any horizontal inequity in health in 1998, we find pro-rich inequity before 1995. The reason for this may be the reform of the health insurance system in 1997.
Adolescent↗
[X-ray phase imaging using a X-ray tube with a small focal spot -improvement of image quality in mammography-].
Phase contrast X-ray imaging has been studied intensively using X-rays from synchrotron radiation and micro-focus X-ray tubes. However, these studies have revealed the difficulty of this technique's application to practical medical imaging. We have created a phase contrast imaging technique using a molybdenum X-ray tube with a small focal spot size for mammography. We identified the radiographic conditions in phase contrast magnification mammography with a screen-film system, where edge effect due to phase contrast overcomes geometrical unsharpness caused by the 0.1mm-focal spot of a molybdenum X-ray tube. The edge enhancement due to phase imaging was observed in an image of a plastic tube, and then geometrical configuration of the X-ray tube, the object and the screen-film system was determined for phase imaging of mammography. In order to investigate a potential for medical application of this method, we conducted evaluation of the images of ACR 156 mammography phantom. We obtained higher scores for phase imaging using high speed screen-film systems without any increase of X-ray dose than the score for contact imaging using a standard speed screen-film system.
Female↗