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In digital radiography system, the diagnostic utility of image quality mainly depends on processing technique of image data. The aim of this work is to quantitatively evaluate image quality of our aSi:H/CsI(Tl) flat-panel based digital radiography system using a chest phantom. The study on the human visual property and the detector response to four standard radiation qualities (from RQA 3 to RQA 9) was performed. The high and low contrast resolution was assessed with two commercially available digital systems based on the same detector. The resulting signal-to-noise ratios (SNRs) of the nine low contrast objects in the lung, heart and subdia-phragm regionns, and relative spatial resolution in the lung field were comparable with those of other systems. Low contrast objects were automatically detected and SNRs was computed by our image analysis algorithm. The quantitative analysis procedure of image quality designed in this work removes observer’s subjectivity. In addition, It can be easily applied for the detectability measurement of low contrast object in other digital modalities. by our Image analysis algorithm

A hemodynamic force imaging method on the basis of viscosity estimation is presented in this paper. Viscosity is estimated by ultrasonic velocity vector measurement and Navier-Stokes equations, and then shear stress and pressure gradient distributions are obtained as hemodynamic forces, in this method. The proposed method was investigated by flow-phantom experiments using two fluids with different viscosity and computer simulations. These results revealed that the proposed method can obtain the quantitative hemodynamic distributions reflecting the viscosity difference, which are close to the ideal ones calculated by simulations.

In spite of developed techniques in ultrasonic medical imaging, it is important to systematize each component in order to get the proper performances. One of the most important tasks in ultrasound medical imaging system is to design a proper probe that can estimate defects of elements having influence on the probe performance. In this paper, we propose an improved acoustic measurement method for the evaluation and characterization of medical ultrasonic probes with the hydrophone. The experimental results show that the suggested method is efficient to get and analyze data from the three ultrasonic linear array probes. We also present the compared results of experimental characterization of suggested acoustic field measurement and conventional measurement on three array probes. Each probe has 128 elements and one test channel is composed of 8 elements. In experiment, we randomly selected a channel in the probe arrays to evaluate the characterization of suggested method. We also show that the suggested method can properly estimate the deterioration of medical ultrasonic probes and we demonstrate the suggested method is more proper to evaluate the performance and characterization of ultrasonic array probes then the conventional technique.

In this paper, we examine experimentally the performance of suggested algorithm for this application. Understanding of the channel evaluation method is crucial in design of the multiple sensor array system. We show that the analysis of ultrasonic field by channel is one of the attractive evaluation techniques in array probe.

This paper describes a new image reconstruction method for the half-Fourier MR imaging. The signal to noise ration (SNR) is decreased almost one over square root of 2 as same as the conventional half-Fourier MR imaging. It is possible to apply into almost of every MR imaging using Fourier transformation for the image reconstruction such as SE, GRE, Fast-SE, EPI, etc.. Moreover, it is also apply to the spiral imaging and radial scan. The proposed method combined with the keyhole technology, navigator echo and random scanning are useful in practical use.

Slice-width dose profile (SWDP) is a measurement undertaken during acceptance testing of diagnostic CT scanners for determination of patient dose. Effective whole body dose from various diagnostic scanner protocols is determined from a SWDP measurement using a 100 mm calibrated ionization chamber. Normoxic polymer gel dosimeters in conjunction with magnetic resonance imaging (MRI) were previously used to measure SWDP and then calculate the computer tomography dose index (CTDI) during acceptance testing of a Philips ACQSIM CT scanner and compared with the conventional ionization chamber measurement for a range of imaging protocols. The resulting CTDI for both polymer gel dosimeter and ionization chamber was within 2%. Uniformity of dose and dose profile measured at the same time with the same polymer gel dosimeter were within the specifications of the equipment manufacturer. In this study PAGAT polymer gel dosimeters were used to evaluate the SWDP of a diagnostic CT scanner. The irradiated PAGAT gel dosimeter was successfully evaluated with a Vista (Modus Medical Devices Inc.) optical scanner. The use of normoxic polymer gel dosimeters with optical CT evaluation has been shown to be a suitable methodology for determining CTDI on diagnostic CT scanners.

Neurinoma is one of brain and spine cord tumors (WHO, 1993)

Recently MRS is becoming a routine diagnostic tool for evaluation of many diseases. Reproducibility of the results in healthy individuals is the main and initial justification means for determining meaningful state of diseases and their follow up studies. We have carried out a study to investigate the reproducibility of HMRS in healthy adults.

In the research fields, such as cancer research, micro-structure morphology, or micro-anatomy, etc., the need to development of micro-CT scanner with micro-leveled spatial resolution has been raised keeping in face with the demand of many researchers. The reason is in that internal organs or structures of laboratory mouse are tiny so that most of clinical CT scanners of which has a spatial resolution of several hundred micrometer are inadequate to apply to small animal studies. Small animals such as mouse, rat and rabbits are one of the most widely used objects in medical and biological studies. Genetically engineered mice, particularly, have emerged as primary research tools for genetic studies, disease research and pharmaceutical development.

The usefulness of these animal models has been limited by the need to sacrifice the animals in order to accurately determine the state of a disease or the therapeutic effect of a treatment. Recently, a great deal of research has been devoted to the development of a variety of small animal imaging systems including x-ray micro-CT systems developed. High resolution imaging systems designed for such a small animal study allow researchers to study on investigation, reducing the number of animals required for a given study and giving it studies of same animal according to time parameter. It has been well recognized from many researchers that the studies provide a variety of research.

In this paper, the 2D and 3D reconstructed images using the developed micro CT system for small animals are presented. The characteristics of the CT system are also described.

Different radiation techniques have been developed and applied to determine the elemental composition of biological hard tissue-teeth. Fluorine was determined by prompt gamma activation analysis through the F(p,αγ)O reaction. Carbon was measured by activation analysis with He-3 ions, and the technique of Proton-Induced-X-ray Emission (PIXE) was applied to simultaneously determine Ca, P, and trace elements in well documented teeth. Dental hard tissues: enamel, dentine and cementum, were examined separately. The depth profiles of F in the enamel surface has also been studied non-destructively to a record depth of 12 µ.

Previously, we investigated a 4D maximum a posteriori rescaled-block iterative (MAP-RBI)-EM image reconstruction method with corrections of image degrading factors for gated myocardial SPECT. It provided a significantly improved trade-off between normalized mean squared error (NMSE) and normalized standard deviation (NSD) of the reconstructed images as compared to conventional reconstruction methods allowing more timing gates per cardiac cycle for better detection of wall motion abnormalities. In this study, we investigate the use of human observer study to evaluate the 4D MAP-RBI-EM method. We used a population of realistic 4D NURBS-based Cardiac-Torso (NCAT) phantoms modeling variations in cardiac motion. Half the population was normal; the other half had hypokinetic cardiac motion abnormalities. Noise-free and noisy projection data with 16 cardiac gates were generated using an analytical projector that included the effects of attenuation, collimator-detector response and scatter (ADS). The projection data were reconstructed using the 3D FBP and 3D OS-EM methods with corrections for ADS followed by a linear filter and the 4D MAP-RBI-EM method with ADS corrections. The reconstructed images were used in a human observer study. The observers were trained to the simulated gated SPECT images animated with a realistic real-time frame rate and were instructed to rate their confidence on the absence or presence of a motion defect on a continuous scale from 1 to 5. We applied receiver operating characteristic (ROC) analysis and used the area under the ROC curve as an index of comparison. The result showed significant differences in detection performance among the different NMSE-NSD combinations. Images obtained from the optimized 4D MAP-RBI-EM with corrections gave better human observer detection performance among the other image reconstruction methods. We conclude that the optimized 4D MAP-RBI-EM method with corrections of image degrading factors provides improvement in detecting wall motion abnormalities in gated myocardial SPECT.