All issues
Volume 30 (2013)
- Issue 4 Pages 76-
- Issue 3 Pages 44-
- Issue 2 Pages 31-
- Issue 1 Pages 1-
Volume 30, Issue 4
Displaying 1-5 of 5 articles from this issue
- |<
- <
- 1
- >
- >|
Educational Lecture
-
Haruhiko MACHIDAArticle type: Educational Lecture
2013 Volume 30 Issue 4 Pages 76-82
Published: 2013
Released on J-STAGE: December 25, 2013
JOURNAL FREE ACCESSWith flat panel detector radiography or x-ray TV systems, digital tomosynthesis (DT) has been recently introduced as limited-angle CT, which can remove overlying structures, enhance local tissue separation, and provide depth information about structures of interest by providing tomographic images of high quality. DT is advantageous in various clinical applications, including chest, head and neck, orthopedic, fluoroscopic, and mammographic studies. Specifically, compared to conventional radiography or fluoroscopy, DT can improve the detection of pulmonary nodules, the diagnosis of paranasal sinusitis, and the delineation of subtle fractures, particularly in complex anatomic structures, and gastrointestinal and breast tumors by less tissue overlap. Compared to CT, DT can reduce radiation exposure by limited sweep angle and improve the assessment of fine bony changes by better in-plane resolution and the postoperative evaluation in patients with metallic prostheses and osteosynthesis materials by less metallic artifact. DT is also useful for functional, weight-bearing and stress tests by more arbitrary patient positioning. To accomplish adequate patient management, a comprehensive understanding of the clinical utilities and limitations of those DT applications is important for the improvement of diagnostic quality, workflow, and cost-effectiveness.View full abstractDownload PDF (5364K)
Original Article
-
Yoshisada OGIHARA, Toshiaki MIYATI, Toshio KASUGAArticle type: Original Article
2013 Volume 30 Issue 4 Pages 83-87
Published: 2013
Released on J-STAGE: December 25, 2013
JOURNAL FREE ACCESSIn order to elucidate signals of abnormally high intensity which appear in angiostenotic loci in MRA by the TOF method, experiments were conducted using a phantom simulating angiostenosis. The signals of abnormally high intensity became more prominent with increased rate of stenosis, flow rate and TE. Due to the effects of flow acceleration in the stenotic loci, characteristic shapes were presented by these signals of abnormally high intensity. In experiments with the phantom tilted at 45 degrees, after replacement of the coordinate axes signals of abnormally high intensity appeared on the symmetric side of the long axis of the phantom. The signals of abnormally high intensity generated in the angiostenotic phantom are slice-encoding misregistration artifacts.View full abstractDownload PDF (1228K) -
Takashi AMANOI, Yasuhiko OKURA, Hajime HARAUCHI, Shinichi ARAO, Akira ...Article type: Original Article
2013 Volume 30 Issue 4 Pages 88-94
Published: 2013
Released on J-STAGE: December 25, 2013
JOURNAL FREE ACCESSThere is the most suitable photon energy in digital mammography depending on breast thickness and density. The most suitable photon energy is measured by CNR and SDNR. The purpose of this study is to construct a system for calculating CNR in digital mammography by simulation and to analyze the mechanism in which the most suitable photon energy is produced. Using the system to calculate CNR, we obtained the following results. Due to the effects of EDR, simultaneously, the contrast became constant and there was a negative peak of noise. When the negative peak of noise appears, photon energy accorded with the maximum value of CNR. In addition, we examined the effects of scattered radiation or a fixed noise on CNR.View full abstractDownload PDF (1517K) -
Yoshiyuki KAMAKURA, Yuki INOUE, Mehdi N. SHIRAZIArticle type: Original Article
2013 Volume 30 Issue 4 Pages 95-100
Published: 2013
Released on J-STAGE: December 25, 2013
JOURNAL FREE ACCESSExtracting structures of interest and their parts from medical and Electron-Microscope (EM) tomography slice images for 3D visualization is a time-consuming process. The problem is to extract the boundaries of the structures of interest from each slice image as fast as possible and preferably with no or minimal user interface. This article presents a class of region-based deformable contour models called restructuring centipedes, R-centipedes. On the contrary to the topologically flexible edge-based snakes and the implicit level-set snakes, R-centipedes and their two parallel versions which are the main focus of this article, 1) do not rely on any image preprocessing such as the isotropic Gaussian smoothing and/or threshold setting needed for removing spurious and weak edges, and 2) don't get stuck with textural artifacts which are abundantly found in EM tomography images. The presented R-centipedes have several other desirable features, including geometrical flexibility, high speed, accuracy and insensitivity to their initial positioning with respect to the structures of interest.View full abstractDownload PDF (2434K) -
Kazuki TAKEGAMI, Hiroaki HAYASHI, Yuki KONISHI, Ikuma FUKUDAArticle type: Original Article
2013 Volume 30 Issue 4 Pages 101-107
Published: 2013
Released on J-STAGE: December 25, 2013
JOURNAL FREE ACCESSIn order to collimate the X-ray produced by the diagnostic X-ray equipment, a new experimental apparatus was developed. The apparatus could be directly installed to the X-ray equipment by using the filter guides equipped with the movable diaphragm, and could produce the narrower X-ray beam (a diameter of several mm) than that was produced by the movable diaphragm. The apparatus was easy-to-set-up, and easy-to-reproduce the original condition. To evaluate the capability of our apparatus, phosphor plate was set to the cassette holder hanged from the Bucky stand for chest examination, and irradiated by the X-ray through our apparatus. As a result, by using one collimator for the narrow beam production and three collimators for reduction of the scattered X-ray, the intensity of the scattered X-ray was reduced to be 1/104, compared with that of the incident X-ray. Furthermore, in order to verify the availability of our apparatus, we improved two types of the experimental apparatuses reported by the previous works by means of the collimator. Then we found that the improved equipments were much more smaller and lighter than the previous equipments.View full abstractDownload PDF (1969K)
- |<
- <
- 1
- >
- >|