Kazuki Takegami

Kazuki Takegami
Yamaguchi University Hospital, Yamaguchi, Japan · Department of Radioligical Technology

MS, RT

About

40
Publications
17,902
Reads
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201
Citations
Citations since 2017
12 Research Items
119 Citations
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201720182019202020212022202305101520
201720182019202020212022202305101520
Additional affiliations
April 2016 - present
Yamaguchi University
Position
  • Radiological Technologist
April 2014 - March 2016
The University of Tokushima
Position
  • Graduation Student

Publications

Publications (40)
Article
Fast chest CT scans with high-pitch factors are effective to reduce motion artifacts, but the over-ranging effect may increase harmful radiation exposure to organs which are located near the outside of the imaging area. This becomes a particular problem during chest CT imaging when managing the radiation dose to the radio-sensitive thyroid, which i...
Article
Low-energy X-rays are widely used during clinical examinations, therefore we need to reduce exposure dose to medical staff by using radiation shielding products. Current X-ray shielding materials are fabricated by embedding high-atomic-number metal particles into a base material. It is valuable to derive knowledge concerning metal particles and shi...
Article
Purpose: Accurate artery-vein separation on pulmonary computed tomographic (CT) angiography is desirable for preoperative 3-dimensional image simulation, while using a minimal amount of contrast medium. This study aimed to verify whether a split-bolus contrast enhancement protocol with test-bolus tracking would provide contrast differentiation bet...
Article
An image-display application for medical liquid-crystal display (LCD) monitors called the sharpness recovery (SR) function has been developed to compensate for image sharpness as a function of deficiencies in the modulation transfer function (MTF) of a monitor. We investigated the effects of the SR function for a five-megapixel (MP) mammography LCD...
Article
Full-text available
Ionizing radiation from Computed tomography (CT) examinations and the associated health risks are growing concerns. The purpose of this study was to directly measure individual organ doses during routine clinical CT scanning protocols and to evaluate how these measurements vary with scanning conditions. Optically stimulated luminescence (OSL) dosim...
Article
Full-text available
The eye lens is a sensitive organ of which an x‐ray exposure dose should be managed during interventional radiology (IVR). In the actual situations, the eye lens is exposed to scattered x‐rays; they have different from the standard x‐ray energies which are used for general dose calibration of the dosimeter. To perform precise dose measurement, the...
Article
When dose measurement is carried out using an optically stimulated luminescence (OSL) dosimeter which uses a disk-shaped dosimeter in the diagnostic X-ray examination, angular dependence of the dosimeter should be taken into consideration. Angular dependence is the characteristic in which the detector response varies depending on incident angle of...
Article
Full-text available
Entrance surface dose (ESD) measurements are important in X-ray computed tomography (CT) for examination, but in clinical settings it is difficult to measure ESDs because of a lack of suitable dosimeters. We focus on the capability of a small optically stimulated luminescence (OSL) dosimeter. The aim of this study is to propose a practical method f...
Article
Full-text available
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 ide...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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 p...
Article
Full-text available
【purpose】In order to measure the angular dependence on a personal dosimeter, a new experimental procedure using diagnostic X-ray equipment was proposed. Furthermore, our method was applied to measure the angular dependences of the small-type optically stimulated luminescence(OSL)dosimeter. To evaluate the experimental results, Monte-Carlo simulatio...
Conference Paper
Full-text available
[Aims and objectives] It is important to visualize scattered X-rays for the education. In a physics textbook, the Klein-Nishina formula is introduced, and everyone has studied the 2D graph of scattered X-ray distribution. However, it is difficult for the medical stuffs to understand the distribution. In this poster, we propose a new experimental ap...
Conference Paper
Full-text available
[Aims and objects] For proper management of medical irradiations, an entrance-skin dose (ESD) has to be measured. Recently, a small-type optically stimulated luminescence (OSL) dosimeter (nanoDot) was commercialized by Landauer, Inc. Because the dosimeter has no effect on the medical images, it is hoped that it can be applied for direct dose measur...
Conference Paper
Full-text available
[Aims and objectives] Evaluation of a patient dose is important for the patient to improve quality of life. A small-type OSL dosimeter (nanoDot) that can measure the entrance skin dose is applied to the dosimetry in radiotherapy, whereas only a small number of papers were reported in the dosimetry of diagnostic X-ray. As the entrance skin dose meas...
Article
Full-text available
An X-ray spectrum measured with CdTe detector has to be corrected with response function, because the spectrum is composed of full energy peaks (FEP) and escape peaks (EP). Recently, various simulation codes were developed, and using them the response functions can be calculated easily. The aim of this study is to propose a new method for measuring...
Article
Full-text available
The optically stimulated luminescence (OSL) dosimeter is a useful detector for measuring absorbed doses of X-rays. A small-type OSL dosimeter, "nanoDot", has recently been developed by Landauer, Inc., who also manufacture "microStar" reading equipment. However, additional annealing equipment is needed if the nanoDot OSL dosimeter is used repeatedly...
Article
Full-text available
Multi-slit equipment is a new experimental apparatus that can measure the input-output characteristics of a CR (computed radiography) system with limited influence of the fading effect. Kimoto et al. recently proposed a new type of multi-slit apparatus in which the multi-slit setup, the insertion region of the phosphor plate, and plate shielding ar...
Article
Full-text available
The lead disc method is conventionally applied to measure the scatter fraction directly in the energy range of diagnostic X-rays. There are numerous reports of use of this method, but it is difficult to make lead discs with sufficient fabrication accuracy. In this paper, we newly propose an indirect measurement method using collimators instead. In...
Article
Full-text available
A cloud chamber is a detector that can visualize the tracks of charged particles. Hayashi, et al. suggested a visualization experiment in which X-rays generated by diagnostic X-ray equipment were directed into a cloud chamber; however, there was a problem in that the wall of the cloud chamber scattered the incoming X-rays. In this study, we develop...
Article
Full-text available
An input-output characteristic curve is an essential piece of information for analyzing medical images taken using a phosphor plate. In the multi-slit method, an actuator moves shields that have numerous slits during X-ray irradiation. Numerous data can be measured by one-time irradiation, so the fading effect is negligibly small. This method was r...
Article
Full-text available
To visualize the scattered X-ray distribution in the diagnosis domain, we examined whether a Geiger Mueller (GM) counter could be applied to a pinhole camera as an X-ray detector. The GM counter detects radiation at certain detection points. To obtain two-dimensional images using the GM counter, the detector needs to be moved two-dimensionally. We...
Article
Full-text available
Diagnostic X-ray equipment was used to develop an experimental apparatus for calibrating a CdTe detector. Powder-type samples were irradiated with collimated X-rays. On excitation of the atoms, characteristic X-rays were emitted. We prepared Nb2O5, SnO2, La2O3, Gd2O3, and WO3 metal oxide samples. Experiments using the diagnostic X-ray equipment wer...
Article
Full-text available
We have built equipment that can visualize the angle distributions of scattered X-rays. The main body of the equipment is made of a lead-shielded box 340 mm long, 300 mm wide and 270 mm high. The collimated X-rays are introduced into the equipment from the front face, then scattered by the sample located in the center of the equipment. The X-rays s...

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