Katsuhiro Ichikawa

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OBJECTIVE Inappropriate patient centering on the gantry changes the size of the localizer radiographs used for CT examinations, influencing the operation of CT automatic tube current modulation because tube current is controlled with information from localizer radiographs. The purpose of this study was to examine the influence of inappropriate patient(More)
Recently, several types of post-processing image filter which was designed to reduce noise allowing a corresponding dose reduction in CT images have been proposed and these were reported to be useful for noise reduction of CT images of adult patients. However, these have not been reported on adaptation for pediatric patients. Because they are not very(More)
We evaluated the potential utility of a newly developed liquid-crystal display (LCD), which used an independent sub-pixel drive (ISD) technique for increasing the spatial resolution of a standard LCD three times in one direction, by use of receiver operating characteristic (ROC) analysis and a two-alternative-forced-choice (2AFC) method to determine(More)
PURPOSE To analyse the temporal resolution (TR) of modern computed tomography (CT) scanners using the impulse method, and assess the actual maximum TR at respective helical acquisition modes. METHODS To assess the actual TR of helical acquisition modes of a 128-slice dual source CT (DSCT) scanner and a 320-row area detector CT (ADCT) scanner, we assessed(More)
Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). It is important to keep the patient dose as low as possible while maintaining tracking accuracy. A simulation approach would be helpful to optimize the imaging conditions. This study was performed to develop a computer(More)
The purpose of this study was to evaluate the image quality of an iterative reconstruction method, the iterative reconstruction in image space (IRIS), which was implemented in a 128-slices multi-detector computed tomography system (MDCT), Siemens Somatom Definition Flash (Definition). We evaluated image noise by standard deviation (SD) as many researchers(More)
For head computed tomography (CT), non-helical scanning has been recommended even in the widely used multi-slice CT (MSCT). Also, an acute stroke imaging standardization group has recommended the non-helical mode in Japan. However, no detailed comparison has been reported for current MSCT with more than 16 slices. In this study, we compared the non-helical(More)