巻号一覧
5 巻 (1988)
- 3 号 p. 93-
- 2 号 p. 37-
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5 巻, 1 号
選択された号の論文の4件中1～4を表示しています
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藤田 広志, 上田 克彦, 藤川 津義, 大塚 昭義1988 年 5 巻 1 号 p. 1-10
発行日: 1988年
公開日: 2012/08/27
ジャーナル フリーThe presampling MTFs of a digital radiographic system employing two types of photostimulable phosphor plates (imaging plates, HR and ST), which include the detector unsharpness and the unsharpness of the sampling aperture. were measured even beyond the Nyquist frequency (5 cycles/mm). An image of a slightly anguiated slit was employed in order to obtain Fourier transforms of line spread functions at different alignments. The presampling MTF was calculated by averaging the two Fourier transforms which we obtained from two extreme alignments (center and shifted) of the slit relative to the sampling coordinate. From the analysis of the presampling MTFs obtained and the detector MTFs previously determined, it was found that the effective sampling aperture size was considerably larger than the aperture size on the plate surface (laser beam spot size) due mainly to the scatterings of the incident laser beam and emitted laser-stimulated luminescence in the phosphors. The "digital characteristic curve" relating the pixel value to the relative x-ray intensity incident on the detector was also obtained for the liniarization, and was found to have a remarkably wider dynamic range (order of approximately 103) than that of conventional screen/film system.抄録全体を表示PDF形式でダウンロード (1560K) -
滝沢 正臣, 曽根 脩輔1988 年 5 巻 1 号 p. 11-17
発行日: 1988年
公開日: 2012/08/27
ジャーナル フリーThe display of diagnostic images are accomplished in the radiology department using a network and three different type image workstations including a 1ow pixel resolution with three 512×512×8bit non-interlace display, and high resolution image work station with single(three after integrated)1024×1024×8 bit non-interlace display. Both low and high resolution workstations use a PC 9801VX desktop computer (80286) with a 20 MB hard disk and use a PC/AT (80286) desk-top computer with 30 MB hard disk. The workstations provide the user with basic image processing functions by using an ACRTC (advanced CRT controller) which was attached to the display control board and include zoom, scroll, image reversal, contrast enhancement, calibrated distance and pixel density measurements. All image processing functions are performed in real time using the interactive mouse device. The workstation has a self contained network (MS-network) interface use an 80186 processor and requires an Ethernet coaxial cable in order to access the baseband network. The images are provided from the server station with a desk-top computer and an 1.2 GB optical disk.抄録全体を表示PDF形式でダウンロード (1928K) -
清王 尊仁1988 年 5 巻 1 号 p. 18-22
発行日: 1988年
公開日: 2012/08/27
ジャーナル フリーThe characteristic curve and the multiple-exposure method (MEM) are most commonly used in order to transform the density distribution of the slit image into the line spread function (LSF) in measuring the LSF of radiographic screen-film systems. SAKURA PDM-5 or SAKURA PDS-15 is generally used as a microdensitometer to measure the characteristic curve in that method. However, the density dependence was found out in using SAKURA PDS-15. The new method presented here made it possible to measure the LSF completely independent of any kind of microdensitometer. This method is characterized by using "micro-blackness characteristic (MBC) curve", together with the preexposure method (PEM), both of which were developed by Uchida. This method was proved useful by our experiment to obtain the LSF almost independent of any microdensitometer. The LSF obtained by the PEM well corresponded with that obtained by the MEM.抄録全体を表示PDF形式でダウンロード (713K) -
樋口 清伯1988 年 5 巻 1 号 p. 23-30
発行日: 1988年
公開日: 2012/08/27
ジャーナル フリーIn this paper concerning with the parameter estimation of the blurred images, original images are assumed to be the random variables generated from the autoregressive processes, and the blurred images are considered as the degraded versions of the above processes by the blurred function (or one dimensional point spread function). Futhermore the images which we will proceed to analyze, are corrupted by white measurement noises. Due to the addition of these noises, we cannot uniquely identify the system governing the generation of the blurred images. To avoid this difficulty, we assumed the blurred function to be straight line. By employing the steepest descent method, we obtained the maximum likelihood estimates. Simple simulation results are presented for the demonstration of the proposed method.抄録全体を表示PDF形式でダウンロード (1106K)
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