Yuki Kanazawa

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For X-ray diagnosis, the proper management of the entrance skin dose (ESD) is important. Recently, a small-type optically stimulated luminescence dosimeter (nanoDot OSL dosimeter) was made commercially available by Landauer, and it is hoped that it will be used for ESD measurements in clinical settings. Our objectives in the present study were to propose a(More)
Our aim in this study is to derive an identification limit on a dosimeter for not disturbing a medical image when patients wear a small-type optically stimulated luminescence (OSL) dosimeter on their bodies during X-ray diagnostic imaging. For evaluation of the detection limit based on an analysis of X-ray spectra, we propose a new quantitative(More)
For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal(More)
Our purpose in this study was to reduce the noise in order to improve the SNR of Dw images with high b-value by using two correction schemes. This study was performed with use of phantoms made from water and sucrose at different concentrations, which were 10, 30, and 50 weight percent (wt%). In noise reduction for Dw imaging of the phantoms, we compared two(More)
Reinforcement learning is a framing of enabling agents to learn from interaction with environments. It has focused generally on Markov decision process (MDP) domains, but a domain may be non-Markovian in the real world. In this paper, we develop a new description of macro-actions for non-Markov decision process (NMDP) domains in reinforcement learning. A(More)
We propose a new practical method for the construction of an accurate secondary X-ray field using medical diagnostic X-ray equipment. For accurate measurement of the air kerma of an X-ray field, it is important to reduce and evaluate the contamination rate of scattered X-rays. To determine the rate quantitatively, we performed the following studies. First,(More)
OBJECTIVE This study aims to improve the signal-to-noise ratio (SNR) of the phase image focusing T2 and to develop an improved phase (iPhase) image acquired high SNR. METHODS The iPhase images of phantom and brain were acquired with multi-echo spoiled gradient-echo. The phantom component was a gadopentetate dimeglumine (Gd-DTPA) solution made of different(More)
The chemical exchange saturation transfer (CEST) effect on an egg white (EW) suspension was investigated for optimization of magnetization transfer (MT) power (B1,rms) and pH dependency with the addition of lactic acid. Applying a higher MT pulse, B1,rms, Z-spectrum shows higher asymmetry and the magnetisation transfer ratio (MTR)asym signal increases to(More)
OBJECTIVES To evaluate the hemodynamics of bladder tumors, we developed a method to calculate change in R(1) value (ΔR(1)) from T(1)-dynamic contrast-enhanced fast spin-echo magnetic resonance imaging (T(1)DCE-FSE-MRI). MATERIALS AND METHODS On a 1.5-T MR system, T(1)DCE-FSE-MRI was performed. This study was applied to 12 patients with urinary bladder(More)