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RISS 인기검색어
- 검색키워드
- 저자 : Katsuhiro Matsuura (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Effect of the Number of Projected Images on the Noise Characteristics in Tomosynthesis Imaging
Fukui, Ryohei,Matsuura, Ryutaro,Kida, Katsuhiro,Goto, Sachiko Korean Society of Medical Physics 2021 의학물리 Vol.32 No.2
Purpose: In this study, we investigated the relationship between the noise characteristics and the number of projected images in tomosynthesis using a digital phantom. Methods: The digital phantom consisted of a columnar phantom in the center of the image and a spherical phantom with a diameter of 80 pixels. A virtual scan was performed, and 128 projected images (Tomo_w/o) of the phantoms were obtained. The image noise according to the Poisson distribution was added to the projected images (Tomo_×1). Furthermore, another projected image with additional noise was prepared (Tomo_×1/2). For each dataset, we created datasets with 64 (half) and 32 (quarter) projections by removing the even-numbered images twice from the 128 (fully) projected images. Tomosynthesis images were reconstructed by filtered back projection (FBP). The modulation transfer function (MTF) was estimated using the sphere method, and the noise power spectrum (NPS) was estimated using the two-dimensional Fourier transform method. Results: The MTFs did not change between datasets, and the NPSs improved as the number of projected images increased. The noise characteristics of the Tomo_×1_half images were the same as those of the Tomo_×1/2_full. Conclusions: To achieve a reduction in the patient dose in tomosynthesis acquisition, we recommend reducing the number of projected images rather than reducing the dose per projection.
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Hybrid balloon dilation treatment for cor triatriatum dexter in a small breed puppy
Akiko Uemura,Tomohiko Yoshida,Katsuhiro Matsuura,Zeki Yilmaz,Ryou Tanaka 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.5
The authors encountered a 4-month-old, female Shiba dog weighing 4.0 kg, who had been exhibiting abdominal distension and increasing ascites for 2 months. She was brought for further examination and treatment with the chief complaints of ascites and dyspnoea during sleep. The dog was diagnosed with ascites caused by cor triatriatum dexter based on the physical and imaging findings. Under general anaesthesia, she was treated with hybrid balloon dilation under transoesophageal echocardiography guidance. Her postoperative recovery was quite rapid and uneventful. This method appears to be a useful, new, and less-invasive treatment option for cor triatriatum dexter.
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Ryohei Fukui,Ryutarou Matsuura,Katsuhiro Kida,Sachiko Goto 한국의학물리학회 2023 의학물리 Vol.34 No.3
Purpose: In radiomics analysis, to evaluate features, and predict genetic characteristics and survival time, the pixel values of lesions depicted in computed tomography (CT) and magnetic resonance imaging (MRI) images are used. CT and MRI offer three-dimensional images, thus producing three-dimensional features (Features_3d) as output. However, in reports, the superiority between Features_3d and two-dimensional features (Features_2d) is distinct. In this study, we aimed to investigate whether a difference exists in the prediction accuracy of radiomics analysis of lung cancer using Features_2d and Features_3d. Methods: A total of 38 cases of large cell carcinoma (LCC) and 40 cases of squamous cell carcinoma (SCC) were selected for this study. Two- and three-dimensional lesion segmentations were performed. A total of 774 features were obtained. Using least absolute shrinkage and selection operator regression, seven Features_2d and six Features_3d were obtained. Results: Linear discriminant analysis revealed that the sensitivities of Features_2d and Features_3d to LCC were 86.8% and 89.5%, respectively. The coefficients of determination through multiple regression analysis and the areas under the receiver operating characteristic curve (AUC) were 0.68 and 0.70 and 0.93 and 0.94, respectively. The P -value of the estimated AUC was 0.87. Conclusions: No difference was found in the prediction accuracy for LCC and SCC between Features_2d and Features_3d.
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Fukui Ryohei,Miho Numata,Saki Nishioka,Ryutarou Matsuura,Katsuhiro Kida,Sachiko Goto 한국의학물리학회 2022 의학물리 Vol.33 No.4
Purpose: To clarify the relationship between the diameter of the simulated bead and the Z-resolution of the tomosynthesis image. Methods: A simulated bead was placed on a 1,024×1,024×1,024-pixel base image. The diameters were set to 0.025, 0.05, 0.1, 0.2, 0.3, 0.7, 1.0, and 1.3 mm. A bead was placed at the center of the base image and projected at a simulated X-ray angle range of ±45° to obtain a projected image. A region of interest was placed at the center of the bead image and the slice sensitivity profile (SSP) was obtained by acquiring pixel values in the z-direction. The full width at half maximum of the SSP was defined as the Z-resolution and the frequency response was obtained by the 1-D Fourier transform of the SSP. Results: Z-resolution increased with increasing bead diameter. However, there was no change in Z-resolution between 0.025 and 0.1 mm. The frequency response was similar to that of the Z-resolution, with a significant difference between 0.1 and 0.2 mm diameter. Conclusions: Z-resolution is dependent on the diameter of the bead, which should be selected considering the pixel size of the tomosynthesis image.
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Unruptured right sinus of Valsalva aneurysm in a Maltese dog: a case report
Akiko Uemura,Ryou Tanaka,Telma Mary Nakata,Ryousuke Namiki,Takashi Tanaka,Katsuhiro Matsuura,Tomohiko Yoshida 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.3
A rare case of an unruptured sinus of Valsalva aneurysm (SVA) in a 2-month-old male Maltese terrier weighing 1.0 kg with a heart murmur is presented. A right SVA and a ventricular septal defect (VSD) were diagnosed by echocardiography and cardiac catheterization. The dogdied due to a worsening of his condition. The necropsy revealed the sinus of Valsalva to have a diameter of 7 mm and a VSD hole was on the opposite surface. This report is the first to describe an unruptured SVA in the right coronary cusp of a small dog.
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