Comparison of Unmonochromatized Synchrotron Radiation and Conventional X-rays in the Imaging of Mammographic Phantom and Human Breast Specimens: A Preliminary Result

A simple imaging setup based on the principle of coherence-based contrast X-ray imaging with unmonochromatized synchrotron radiation was used for studying mammographic phantom and human breast specimens. The use of unmonochromatized synchrotron radiation simplifies the instrumentation, decreases the cost and makes the procedure simpler and potentially more suitable for clinical applications. The imaging systems consisted of changeable silicon wafer attenuators, a tungsten slit system, a CdWO4 scintillator screen, a CCD (Charge Coupled Device) camera coupled to optical magnification lenses, and a personal computer. In preliminary studies, a spatial resolution test pattern and glass capillary filled with air bubbles were imaged to evaluate the resOolution characteristics and coherence-based contrast enhancement. Both the spatial resolution and image quality of the proposed system were compared with those of a conventional mammography system in order to establish the characteristic advantages of this approach. The images obtained with the proposed system showed a resolution of at least 25 µm on the test pattern with much better contrast, while the images of the capillary filled with air bubbles revealed coherence-based edge enhancement. This result shows that the coherence-based contrast imaging system, which emphasizes the refraction effect from the edge of materials of different refractive indexes, is applicable to imaging studies in fundamental medicine and biology, although further research works will be required before it can be used for clinical applications.ope

Assessment of Attenuation Correction Techniques with a 137Cs Point Source

Purpose: The objective of this study was to assess attenuation correction algorithms with the 137Cs point source for the brain positron emission tomography (PET) imaging process. Materials & Methods: Four different types of phantoms were used in this study for testing various types of the attenuation correction techniques. Transmission data of a 137Cs point source were acquired after infusing the emission source into phantoms and then the emission data were subsequently acquired in 3D acquisition mode. Scatter corrections were performed with a background tail-fitting algorithm. Emission data were then reconstructed using iterative reconstruction method with a measured (MAC), elliptical (ELAC), segmented (SAC) and remapping (RAC) attenuation correction, respectively. Reconstructed images were then both qualitatively and quantitatively assessed. In addition, reconstructed images of a normal subject were assessed by nuclear medicine physicians. Subtracted images were also compared. Results: ELAC, SAC, and RAC provided a uniform phantom image with less noise for a cylindrical phantom. In contrast, a decrease in intensity at the central portion of the attenuation map was noticed at the result of the MAC. Reconstructed images of Jaszack and Hoffan phantoms presented better quality with RAC and SAC. The attenuation of a skull on images of the normal subject was clearly noticed and the attenuation correction without considering the attenuation of the skull resulted in artificial defects on images of the brain. Conclusion: the complicated and improved attenuation correction methods were needed to obtain the better accuracy of the quantitative brain PET images.ope

Three-dimensional image analysis of the skull using variable CT scanning protocols-effect of slice thickness on measurement in the three-dimensional CT images

Purpose : To evaluate the quantitative accuracy of three-dimensional (3D) images by means of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. Materials and Mathods : An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0/supTM(Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. Results: 11 line items in Conventional 3 mm, 8 in Helical 3mm, 11 in Conventional 5mm, 10 in Helical 5mm, 5 in Conventional 7mm and 9 in Helical 7mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2mm in 19 line items of Conventional 3mm, 20 of Helical 3mm, 15 of Conventional 5mm, 18 of Helical 5mm, II of Conventional 7mm and 16 of Helical 7mm. Conclusion: Considering image quality and patient's exposure time, scanning protocol of Helical 5mm is recommended for 3D image analysis of the skull in CT.ope

The development of DICOM CD data validation toolkit

Since Korean government decided to reimburse for filmless full-PACS (Picture Archiving and Communications System) installation, a number of PACS installations had been rapidly increased. Currently, the number of large (> 500 beds) and small (< 500 beds) hospitals installing full-PACS are over 50 and 110, respectively. In case of patients who wewe referred to other hospitals, their image data which was the set of DICOM (Digital Imaging and Communications in Medicine) studies was transferred to referred hospitals. The DICOM studies were exported by available portable storage media such as a CD (Compact Disk). The DICOM images were imported from CD-ROM and stored to new PACS sever. In Yonsei University Medical Center, the number of referred patients is over 3,500 a day. Hospital’PACS operators are trying to import the DICOM files to the server about 50 times a day and the number of the tasks is gradually increasing. However, many problems were occurred when the DICOM images were imported. For instance, some images could not be imported from the DICOM CD data. Although they were successfully imported, some of them were not able to display. After anayzing various CD Data from many hospital and PACS vendors, DICOM validation toolkit was developed to improve the compatibility between the DICOM CD data and PACS. The joint project was aiming at developing “DICOM CD validation toolkit”. This study reported the procedure which was to make “DICOM CD Recommended Data Guideline Document”and the result that we validated the DICOM data sets using the DICOM CD validation toolkit.ope

Roles and Activities of IHE

IHE(Integrating the Healthcare Enterprise) began in 1998 as the collaborative effort of HIMSS and RSNA to improve interoperability of computer systems in sharing healthcare information. IHE is a multi-year initiative that creates the framework for passing vital health information seamlessly from application to application, system to system, and setting to setting across the entire healthcare enterprise and promotes coordinated use of established standards (DICOM and HL 7) to address specific clinical needs in support of optimal patient care. IHE defines highly detailed implementations of these standards in a publicly available document called the IHE technical framework. IHE provides a detailed process of interoperability testing called the IHE “connectathon” and “demonstrations” to facilitate adoption of this framework by industries of the imaging and information systems. Standards-based integration solutions like those defined in IHE are flexible, durable, easier to implement and less expensive to maintain than proprietary methods.ope

IHE MESA Test and Connect-a-thon

IHE defines the detailed implementations of standards such as DICOM, HL7, in a publicly available document called the IHE technical framework (IHE-TF). IHE also held an annual interoperability testing event to facilitate adoption of IHE-TF by the imaging and information systems industry. Testing process is divided into two step. First step of that is a computer-based simulation test using a set of software called MESA (Medical Enterprise Simulators and Analyzers) tool, and next step is real connection test called “connect-a-thon”. MESA tool was developed to help participants prepare for connect-a-thon at the annual meetings, and to allow the pre-test before connect-a-thon by computer simulation. Products which are passed MESA test can be participated in the centerpiece of testing process, connect-a-thon, an interoperability-testing event. It offers vendors a unique opportunity for connectivity testing, removing barriers to integration that would otherwise have to be dealt with on site, at the customer’s expense. After of all process, IHE technical committee offer the results of connect- a-thon on their website.ope

MICROMETER SPATIAL RESOLUTION IMAGING SYSTEM USING SYNCHROTRON X-RAY

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