Publications by authors named "Hidetoshi Yatake"

Purpose: Radiation protection glasses reduce eye lens exposure in Interventional Radiology (IR). However, the protection ratio differs for the lead equivalent content and shape of the lenses. This study aimed to examine factors effective in reducing the lens dose by measuring the protection ratio of scattered radiation due to changes in the surgeon's face orientation, various lead equivalents, and shapes.

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In recent years, radiochromic films have begun to be used for dosimetry in mammography; however, the most sensitive GAFCHROMIC XR-QA2 (XR-QA2) film is no longer available owing to its discontinuation. In this study, we evaluated the sensitivity characteristics of GAFCHROMIC LD-V1 (LD-V1) as an alternative to XR-QA2 in the field of mammography, at a low dose and low energy. Our results show that the average ratio of the concentration change of LD-V1 divided by the concentration change of XR-QA2 at each absorbed dose was 53.

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The effects of lead equivalent and lens area of radiation-protective eyewear on lens exposure control were examined. The simulated patient underwent 10-min X-ray fluoroscopy, and the lens dose of the simulated surgeon wearing radiation protection glasses was measured using lens dosemeters attached to the corner of the eye and eyeball. In total, 10 types of radiation protection glasses were selected for measurement.

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Mammography is one of the most effective diagnostic methods for the early detection of breast cancer; however, it poses the risk of radiation exposure. To date, mammography dosimetry has been performed according to the mean glandular dose; however, the actual exposure in the breast has not been assessed. Here, we have measured dose distributions and depth doses using both radiochromic films and mammographic phantoms, and a three-dimensional intra-mammary dose assessment was conducted.

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This study developed a phantom with a shape similar to that of the breast and use GAFCHROMIC films that can be placed inside the phantom to measure the detailed breast dose distribution in mammography. GAFCHROMIC EBT3 was placed on the block cube breast phantom and irradiated with a mammography device to measure the absorbed dose distribution inside the phantom in the horizontal and depth directions. The dose distribution in the horizontal plane was the highest in the centre on the chest wall side, and it decreased in a fan shape.

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Background: The objective of the study was to compare direct measurement with a conventional method for evaluation of clip placement in stereotactic vacuum-assisted breast biopsy (ST-VAB) and to evaluate the accuracy of clip placement using the direct method.

Methods: Accuracy of clip placement was assessed by measuring the distance from a residual calcification of a targeted calcification clustered to a clip on a mammogram after ST-VAB. Distances in the craniocaudal (CC) and mediolateral oblique (MLO) views were measured in 28 subjects with mammograms recorded twice or more after ST-VAB.

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Bone mineral density (BMD) is affected by lean body mass and body weight to various degrees in the course of aging. The attempt of this study is to determine the optimal time to begin prevention of osteoporosis. In this study, female hospital employees aged 20-59 years were divided into 2 age groups, 20-39 years and 40-59 years based on age at peak BMD, and the relations of total BMD, subtotal BMD and lumbar spine BMD to lean body mass and body weight were examined in both groups.

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Recently developed radiochromic films can easily be used to measure absorbed doses because they do not need development processing and indicate a density change that depends on the absorbed dose. However, in GAFCHROMIC EBT2 dosimetry (GAF-EBT2) as a radiochromic film, the precision of the measurement was compromised, because of non-uniformity problems caused by image acquisition using a flat-bed scanner with a transmission mode. The purpose of this study was to improve the precision of the measurement using a flat-bed scanner with a reflection mode at the low absorbed dose dynamic range of GAF-EBT2.

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Purpose: The aim of this study was to determine whether additional radiographs, as judged necessary by the radiographer, improves cancer detection during gastric cancer screening.

Materials And Methods: We analyzed 144 gastric cancer cases among 137 744 individuals who underwent X-ray screening for gastric cancer. Radiographs were obtained by 17 radiographers at a screening center in Japan from April 2004 to March 2008.

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Our aim in this study was to evaluate hyoid bone movement trajectories and the age-related changes during swallowing in healthy subjects by ultrasonography. Data were obtained from 30 healthy volunteers (15 men, 15 women) in three age groups (20-39, 40-59, 60-79 years). The subjects were examined while sitting in an upright position, with the back against a wall to control movement.

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Purpose: The aim of this study was to evaluate the film-reading ability of radiographers in detecting gastric cancer during screening X-ray examinations.

Materials And Methods: A test set of 100 patients (50 negative and 50 positive; mean age 62 years, range 33-78 years) given a stomach X-ray examination were selected from those who underwent gastric cancer screening in Osaka, Japan, between 2000 and 2003. Eleven radiographers and four radiologists scored the test set on a five-point scale.

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The aim of this study was to evaluate the usefulness of an imaging technique that takes into account the effect of posture change on the stomach in transabdominal ultrasonography (US). A total of 240 adult patients (healthy subjects) underwent gastric US. In all subjects, the lesser curvature of the stomach (LCS) and left liver were measured in two different positions [left lateral decubitus (LLD) and supine].

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Purpose: To use transabdominal sonography to determine the frequency of visualization of the adult normal appendix in patients with suspected acute infectious enteritis (AIE) compared with patients with acute appendicitis (AA) and a control group.

Methods: A total of 296 patients divided into 3 different groups underwent sonographic examination, including 120 randomly selected asymptomatic patients, 91 consecutive patients with AIE, and 85 consecutive patients with AA. In the 3 groups, visualization rate, outer appendiceal diameter, presence or absence of inflamed periappendiceal fat, and location of the appendix were recorded.

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