Similar images would be useful to radiologists for their image interpretation of unknown difficult clinical cases in their daily work. In fact, previous studies indicated that radiologists' performance was significantly improved by use of similar images in the distinction between malignant and benign lesions for lung nodules in low dose CT, and microcalcifications and masses in mammograms. In order to implement the retrieval and display of similar images, it is necessary to understand a number of questions related to subjective and objective evaluation, and their measures on similar images. Based on this review article for the work done over the last ten years or so, the similarity of images can be quantified reliably and consistently, and thus can be subjected to rigorous scientific investigations and discussion which would lead to the establishment of science of similar images.

抄録全体を表示

In this paper, we propose a visualization method for electron microscope tomogram intended of biological sample. As for electron microscope tomogram, the application to diagnosis is expected. In order to observe the 3D structure from electron microscope tomogram, most important process is extraction of contours from those 2D images. However, it is difficult to extract the contours automatically because of their typical noise and artifacts. The proposed method automatically extracts the contours by using three-dimensional level set method. In general, the result of the extraction with level set method depends on the initial contours and its parameters. These parameters are usually set manually. Our method automatically generates the initial contours and decides the fittest parameters of level set method. We verify the effectiveness of our method with the experiment to compare the result of the proposed method with manual extraction.

抄録全体を表示

In brain tumor surgery, the recent development of a neuronavigation system has enabled surgeons to understand the positional relationship between tumors and normal tissue. Accuracy of a navigation system is important for accurate resection of a brain tumor. Many factors influence the navigation accuracy;one of the important factors is the configuration of the fiducial markers. Because the configuration method varies among institutions, it is necessary to investigate the relationship between the configuration of fiducial markers and navigation accuracy. In this study, we evaluated the distribution of navigation accuracy inside the skull phantom for 2 different fiducial configurations: the scattered pattern and the clustered pattern. The scattered pattern was much more accurate than the clustered pattern for the entire phantom. Although the clustered pattern showed high accuracy on the fiducial points, the accuracy on the measurement points inside the phantom decreased with an increase in the distance from the fiducial markers. These results indicated that the sccatterd configration is appropriate for deep-seated or large tumor.

抄録全体を表示

A high-energy-resolution X-ray Computed Tomography(CT)system is of a first-generation type and consists of an X-ray generator, a turntable, a translation stage, a two-stage controller, a silicon-PIN detector system with amplifiers, a multichannel analyzer(MCA), a counter card(CC), and a personal computer(PC). CT is accomplished by repeating the translation and the rotation of an object, and projection curves of the object are obtained by the linear scanning by moving the object. Both photon-energy level and energy width are determined by the MCA, and the pulses of the discriminated event signal from the MCA are counted by CC in conjunction with PC. The maximum count rate was approximately 5 kcps, and energy-discrimination CT was carried out with a photon-energy resolution of 0.15 keV. To perform iodine K-edge CT, X-ray photons with an energy range from 33.2 to 43.2 keV were used. Next, to carry out cerium K-edge CT, an energy range from 40.3 to 50.3 keV was selected. Using K-edge CT, iodine and cerium molecules were observed at high contrast. Therefore, molecular-level imaging for cancer diagnosis might be accomplished.

抄録全体を表示

[Purpose] We investigated the correlation between diaphragm motion evaluated using fluoroscopy and a respiratory monitoring device(Abches: APEX Medical, Inc, Tokyo), which comprised two arms for measuring changes in the levels of the chest and abdominal walls. [Method] Fluoroscopic abdominal sequences(512×512 matrix, 5.36 f/s)during normal and forced breathing were taken from five healthy men aged 22-23 years. Simultaneously, a video of the respiratory indicator(Abches)was recorded(720×480 matrix, 30f/s). Diaphragm positions in the fluoroscopic sequences were measured and the indicator values were read from the videos. [Result] During normal respiration there was a linear relationship between the indicator values and diaphragm positions measured using fluoroscopy. The coefficients of correlation ranged from 0.958 to 0.985. During forced respiration the correlation of these values was quadric(r=0.919 to 0.996). Hysteresis in the relationship between these motions was observed in two of the five cases. [Conclusion] In normal breathing, we found that the correlation between fluoroscopic and respiratory indicator measurements had linearity. In forced breathing, the correlation was quadric, and phase shifting between diaphragm motion and respiratory indicator measurements was observed in two of the five cases.

抄録全体を表示