担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Korean Society of Medical Physics  

添付ファイル： 論文_PMP_福井.pdf

DOI： 10.14316/pmp.2021.32.2.50

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Tomosynthesis images are reconstructed from several projections. However, the number of projections is proportional to the exposure dose, and a reduction in the number of projections would result in a reduction of radiation dose to the patient but also degradation of image quality. The purpose of this study was to propose a new computerized method to supply interpolation images instead of real projection images for maintaining the number of projection images and image quality of reconstructed tomosynthesis images. A set of images comprising one-half the number of projection images [37 projections (Half set)], selected from the original full set of projection images [73 projections (Full set)], was used at an interval of one by one. In this study, the authors used a new linear interpolation technique (Shift-Linear method), which takes into account shifted distances between two corresponding pixels on two projection images. The image quality of tomosynthesis images reconstructed from the full set and the quasi-full projection images, which were produced from the Half set using the Shift-Linear method, was compared. Image quality was assessed in terms of modulation transfer function, noise power spectrum, contrast-to-noise ratio, and the detective quantum efficiency. Using this proposed method, the image quality of reconstructed tomosynthesis images could be maintained with the reduction of approximately 50% exposure dose.

DOI： 10.1007/s12194-018-0488-8

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Objectives: Cathepsin K is expressed by osteoclasts and synovial fibroblasts and degrades key components of bone and cartilage. Inhibition of cathepsin K protease activity may be beneficial for the prevention of bone erosion and cartilage degradation in rheumatoid arthritis (RA). The collagen-induced arthritis (CIA) rat model is well established for studying the pathology and treatment of RA. We investigated the effect of ONO-KK1-300-01, a cathepsin K inhibitor (CKI), on arthritis and bone mineral density (BMD) in rats with CIA. Methods: Seven-month-old female Sprague Dawley rats were divided into 5 groups: rats without CIA (CNT); CIA rats that underwent ovariectomy (OVX) and were treated with CKI; CIA rats that underwent OVX and were treated with vehicle (Veh); CIA rats that underwent sham surgery and were treated with CKI; and CIA rats that underwent sham surgery and were treated with Veh. CKI was orally administered at a dose of 15 mg/kg, thus initiating collagen sensitization, until death at 4 weeks. We evaluated hind paw thickness and the arthritis score every week until death. Radiographs of the resected left foot were obtained with a soft X-ray apparatus. Destruction of bone and cartilage was classified and scored as previously described by Engelhardt et al. BMD was measured by bone densitometry at the halfway point between the distal metaphysis and the diaphysis of the resected right femur. We also performed histomorphometry of the proximal left tibia, histological evaluation of arthritis, and a bone strength test. Results: CKI administration significantly reduced hind paw thickness and the arthritis score, and prevented a decrease in BMD. The radiographic score was significantly lower in the CKI group than in the Veh group. In the histomorphometric analysis, bone-resorption parameters were significantly lower in the CKI groups than in the Veh groups. CKI significantly inhibited synovial proliferation in the CIA rats. In the bone strength test, the ultimate stress was significantly higher in the CKI groups than in the Veh groups. Conclusion: Our findings indicate that cathepsin K inhibitors may inhibit systemic and local bone loss, ameliorate arthritis, and attenuate the decrease of bone strength in an animal model of arthritis.

DOI： 10.1016/j.bonr.2018.05.006

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Our aim in this study was to evaluate the effect of geometry for measuring section thickness in tomosynthesis by using a metal bead device (bead method). Tomosynthesis images were obtained from two types of tomosynthesis equipment, Safire17 (ST, Shimadzu, Kyoto, Japan) and XR650 (GT, GE Healthcare, Milwaukee, WI). After tomosynthesis radiography with each device, the bead tomosynthesis images were obtained by image reconstruction. The digital profile was obtained from the digital value of the bead central coordinate in the perpendicular direction, and we acquired the slice sensitivity profile (SSP). The section thickness was defined with the full width at half maximum obtained from the SSP. We investigated the change in section thickness under different evaluation conditions: the angular range, the height of the bead position, the source-image receptor distance (SID), and image processing. The section thickness decreased when the angular range and height of the bead position increased. Also, the section thickness varied with a change in the SID. The section thickness differed according to the geometry for measuring the section thickness. Thus, the effect of the geometry used for measurement should be considered when the section thickness in tomosynthesis is measured by the bead method.

DOI： 10.1007/s12194-013-0243-0

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

BACKGROUND: The aim of this study was to evaluate the usefulness of noise reduction procedure (NRP), a function in the new image processing for chest radiography. METHODS: A CXDI-50G Portable Digital Radiography System (Canon) was used for X-ray detection. Image noise was analyzed with a noise power spectrum (NPS) and a burger phantom was used for evaluation of density resolution. The usefulness of NRP was evaluated by chest phantom images and clinical chest radiography. We employed the Bureau of Radiological Health Method for scoring chest images while carrying out our observations. RESULTS: NPS through the use of NRP was improved compared with conventional image processing (CIP). The results in image quality showed high-density resolution through the use of NRP, so that chest radiography examination can be performed with a low dose of radiation. Scores were significantly higher than for CIP. CONCLUSION: In this study, use of NRP led to a high evaluation in these so we are able to confirm the usefulness of NRP for clinical chest radiography.

PubMed

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担当区分：責任著者   記述言語：日本語   掲載種別：速報，短報，研究ノート等（学術雑誌）  

添付ファイル： 38_108_Ota.pdf

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記述言語：日本語   出版者・発行元：医用画像情報学会  

<p>In this study, we evaluated the effect of a newly developed super-resolution processing using Deep Convolutional Neural Network (DCNN) on the images processed with the conventional dynamic processing in digital radiography (DR). We used human phantom images to obtain case samples of which each image included a lateral view of thoracolumbar junction. All case samples were processed without and with dynamic processing, which were ranging from 1 to 4 steps of image enhancement processing. Deep Denoising Super Resolution (DDSR) were trained and assessed using the supervised image (the original image) and the low-resolution image degraded to 1/3 of matrix size by binning from the original image. The effects of the DDSR on the conventional dynamic processing were assessed using the modified Ura method of Scheffe's paired comparison. The average psychological measures for interpreting vertebral body of thoracolumbar junction tended to increase as the enhancement of dynamic processing increased, regardless of the application of DDSR. The correlation between the average psychological measures without and with DDSR was very high with a correlation coefficient of 0.98. We conclude that the effect of the DDSR on the conventional dynamic processing would be neglected on the observation of a diagnosis object in DR.</p>

DOI： 10.11318/mii.37.21

CiNii Article

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記述言語：日本語   出版者・発行元：公益社団法人 日本放射線技術学会  

<p>Computed tomography (CT) is used for the attenuation correction (AC) of [F-18] fluoro-deoxy-glucose positron emission tomography (PET) image. However, acquisition of a CT image for this purpose requires increasing the radiation dose of the patient. To generate a pseudo-image, a generative adversarial network (GAN) based on deep learning is adopted. The purpose of this study was to generate a pseudo-CT image, using a GAN, for the AC of the PET image, with the aim of reducing the dose of the patient. A set of approximately 15,000 no-AC PET and CT images was used as the training sample, and the CycleGAN was employed as the image generation model. The training samples were inputted in the CycleGAN, and the hyperparameters, i.e., the learning rate, batch size, and number of epochs were set to 0.0001, 1, and 300, respectively. A pseudo-PET image was obtained using a pseudo-CT image, which was used for the AC of the no-AC PET image. The coefficient of similarity between the real and generated pseudo-images was estimated using the peak signal-to-noise ratio (PSNR) , the structural similarity (SSIM), and the dice similarity coefficient (DSC). The average values of PSNR, SSIM, and DSC of the pseudo-CT were 31.0 dB, 0.87, and 0.89, and those of the pseudo-PET were 35.9 dB, 0.90, and 0.95, respectively. The AC for the whole-body PET image could be accomplished using the pseudo-CT image generated via the GAN. The proposed method would be established as the CT-less PET/CT examination.</p>

DOI： 10.6009/jjrt.2020_JSRT_76.11.1152

CiNii Article

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記述言語：日本語   出版者・発行元：医用画像情報学会  

<p>The measurement method for the noise property of the digital tomosynthesis image has not been standardized in any guidelines or papers. Currently, a noise in a digital tomosynthesis image has been commonly measured using a 2-D fast Fourier transform（2D-FFT）method. The purpose of this paper is to propose a new method for measuring the noise property of a digital tomosynthesis image, which applies the radial frequency（Radial）method with a limited angular range （LAR）for data acquisition. Although the Radial method was used to obtain the power spectrum from all angles（360°）around the origin, the LAR method acquired the power spectrum in the limited angle regions. When the noise properties acquired by the LAR method with the limited angles of 3°, 5° and 15° were compared to those obtained through the Radial method and the 2D-FFT method. The results of the LAR method had the large differences compared to those of the Radial method in the u-axis direction. Further, the noise property of the LAR method and the 2D-FFT method showed a higher correlation in both axis directions. In conclusion, we believe that the noise properties of the digital tomosynthesis image can be measured by using the LAR method with a limited angle of 5°.</p>

DOI： 10.11318/mii.35.6

CiNii Article

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開催年月日： 2021年7月3日 - 2021年7月4日

記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

添付ファイル： 令和3年度_夏季学術大会_研究事例1.pdf

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開催年月日： 2021年7月3日 - 2021年7月4日

記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

添付ファイル： 令和3年度_夏季学術大会_シンポジウム.pdf

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記述言語：英語   会議種別：口頭発表（一般）  

添付ファイル： RSNA2020_education exibit.pdf

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記述言語：日本語   会議種別：口頭発表（一般）  

添付ファイル： 演題13_JSNM中四国支部会_oral_fukui.pdf

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記述言語：日本語   会議種別：口頭発表（一般）  

添付ファイル： 山デジ_PETtoCT_福井.pdf

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