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Masahiro Hashida

Publications and source records attributed to Masahiro Hashida.

3 recordsLinked to original sources

[Comparison of LCD and CRT monitors for detection of pulmonary nodules and interstitial lung diseases on digital chest radiographs by using receiver operating characteristic analysis].

Soft copy reading of digital images has been practiced commonly in the PACS environment. In this study, we compared liquid-crystal display (LCD) and cathode-ray tube (CRT) monitors for detection of pulmonary nodules and interstitial lung diseases on digital chest radiographs by using receiver operating characteristic (ROC) analysis. Digital chest images with a 1000x1000 matrix size and a 8 bit grayscale were displayed on LCD/CRT monitor with 2M pixels in each observer test. Eight and ten radiologists participated in the observer tests for detection of nodules and interstitial diseases, respectively. In each observer test, radiologists marked their confidence levels for diagnosis of pulmonary nodules or interstitial diseases. The detection performance of radiologists was evaluated by ROC analyses. The average Az values (area under the ROC curve) in detecting pulmonary nodules with LCD and CRT monitors were 0.792 and 0.814, respectively. In addition, the average Az values in detecting interstitial diseases with LCD and CRT monitors were 0.951 and 0.953, respectively. There was no statistically significant difference between LCD and CRT for both detection of pulmonary nodules (P=0.522) and interstitial lung diseases (P=0.869). Therefore, we believe that the LCD monitor instead of the CRT monitor can be used for the diagnosis of pulmonary nodules and interstitial lung diseases in digital chest images.

Data Display↗

[Selection of parameters for multi-objective frequency processing in CR mammography: visual evaluation of mammographic phantom images].

The multi-objective frequency processing installed in the FCR5000R (Fuji Film Medical) is superior to the conventional processing used in the FCR9000 (Fuji Film Medical) in evaluating frequency processing. A suitable combination of parameters for multi-frequency-processing in computed radiography (CR) mammography was evaluated. The paired-comparison method using phantom images was performed for the visual evaluation. Results showed that the evaluation score of mass and fiber lesions depended on the multi-frequency balance type (MRB) parameter, and the low-frequency-cycle emphasizing parameter had the highest score. In contrast, the score of microcalcifications depended on the degree of multi-frequency enhancement (MRE). The most suitable parameters for the multi-frequency processing of every size and type of breast lesion were not obtained. However, MRB=A, MRT=p, and MRE=1.0 can be recommend for CR mammography.

Humans↗

Digital cine angiography permits radiation dose reduction without reduction in image quality.

PURPOSE: To investigate how much the radiation dose in digital cine angiography (DCA) systems can be reduced while maintaining an image quality equivalent to that of conventional cine angiography (CCA). MATERIALS AND METHODS: Simulated vessel phantoms were subjected to DCA and CCA. In DCA, the input dose value to the image intensifier built in the system was 0.10, 0.12, 0.14, 0.17, 0.2, and 0.24 microGy. The detectability for simulated vessel phantoms was visually evaluated by five observers. The radiation dose was measured using radiofluorescent glass-rod dosimeters. Doses of digital cine imaging were measured as relative values with the dose of CCA considered as 1.0. RESULTS: The relative DCA/CCA values in DCA, measured by radiofluorescent glass-rod dosimeters, ranged from 0.414 to 0.901 for simulated vessel phantoms CONCLUSION: DCA allows a reduction by 59% of the radiation dose compared with CCA without reduction of image quality.

Analysis of Variance↗