All issues
Volume 6 (1989)
- Issue 3 Pages 125-
- Issue 2 Pages 85-
- Issue 1 Pages 1-
Volume 6, Issue 3
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Eiichi HIRAOKA1989 Volume 6 Issue 3 Pages 125-132
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSDownload PDF (2491K) -
Eiichi SATO, Arimitsu SHIKODA, Shingo KIMURA, Hiroshi ISOBE, Yoshiharu ...1989 Volume 6 Issue 3 Pages 133-138
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSA high-intensity igic flash x-ray generator with a hot cathode radiation tube for biomedical radiography is described. This generator consisted of the following components: a highvoltage power supply, a coaxial oil condenser of 0.15μF-120kV, a low-impedance transmission line, a turbo molecular pump, and a flash x-ray tube having a hot cathode. The x-ray tube was of the diode type which was connected to the turbo molecular pump. The pulse condenser was charged from 40 to 120kV by a high-voltage power supply, and the electric charges were discharged to the x-ray tube by an impulse switching system. The pulse widths of the x-ray output were about 50ns, and the x-ray intensities were less tha 2.44μC/kg at 1m per pulse. The effective focal spot size was determined by the diameter of the anode tip and ranged from 0.5 to 3.0mm in diameter.View full abstractDownload PDF (2020K) -
Hiroshi ISOBE, Eiichi SATO, Shingo KIMURA, Arimitsu SHIKODA, Yoshiharu ...1989 Volume 6 Issue 3 Pages 139-145
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSA simple flash x-ray tube with a new type of cathode and fundamental studies for generating a high-voltage pulse by using a Blumlein circuit are described. This radiation to had the following major parts: a rod-shaped anode tip made of tungsten, a plane cathode made of alum inum which gave two parts of a x-ray window and a metal filter, a vacuum vessel made of glass, and others. The output voltage of this Blumlein pulser ranged from 70 to 160kV, but the tube voltages were determined by the anode-cathode (A-C) space since a pulse-forming device was not employed. The x-ray pulse widths primarily increased according to increases in the A-C space, and their values ranged from 20 to 50ns. The x-ray intensity was less than 1.0μC/kg at 0.3m per pulse when the discharge capacity of about 430PF was employed. The effective focal spot size was determined by the diameter of anode tip and its value ranged from 0.5 to 3.0mm in diameter.View full abstractDownload PDF (2896K) -
Yuji AOKI, Norio MIURA1989 Volume 6 Issue 3 Pages 146-152
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSIn order to analyze relationships between screen mottle ad fundamental screen components, we introduce the average value of the wiener spectra which are calculated in the range from 0 to 0.5 cycles/mm. And we express its value WS(∼0.5).
By using the WS(∼0.5), we analyze relationship between screen mottle and the thicknesses of protective layer and phosphor layer of internsifying screens. Both of the increases of those thicknesses cause the reductions of sharpness. But the elects on the granularity are different. The increase of protective layer reduces the WS(∼0.5), but the increase of phosphor layer does not reduce the WS(∼0.5).View full abstractDownload PDF (1009K) -
Junji MORISHITA, Hiroshi FUJITA, Tsuyoshi FUJIKAWA, Sadamitsu NISHIHAR ...1989 Volume 6 Issue 3 Pages 153-162
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSWe measured the characteristic curve of a laser-beam sensitive film and display MTFs (Laser-printer MTFs) in an FCR-101 system. Laser-printer MTFs for two directions relative to the scan direction were measured by a “slit” method. The hypothetical “slit” image was produced by a personal computer and was output to the laser-beam sensitive film in a laser printer. Then the microdensitometer trace of the slit image was liniarized using the characteristic curve of the film, and the MTF was calculated from the Fourier transformation of the line spread function. The MTF measrured with the slit in the direction parallel to the laser scanning was greater than that obtained in the perpendicular direction. This is mainly related to the shape and size of the laser beam spot, i. e. display aperture. Moreover, we measured MTFs of the laser printer with new or old laser tubes, and also the “glare” of the laser printer. Results in our experimental conditions indicated that the effect of the laser tube on the MITF was negligible and the amount of the glare was also negligible.View full abstractDownload PDF (1658K) -
Du - Yih TSAI, Hiroshi FUJITA, Junji MORISHITA, Katsuhiko UEDA, Akiyos ...1989 Volume 6 Issue 3 Pages 163-169
Published: September 01, 1989
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSThe noise equivalent quanta (NE Q) and detective quantum efficiency (DQE) of an FCR-101 computed radiqi plc system (Fuji Photo Film Co., Ltd., Japan) with two different versions (types II and III) of ST (for standard applications) imaging plates were measured. The NEQ and DQE of the system excluding the display part were calculated as functions of incident exposure and spatial frequency. Both of them were obtained from the gradient of the digital characteri stic curve relating the pixel value to the retive x-ray intensity, the presampling modulation transfer function, and the digital Wiener spectrum of the FCR system. Compared to the type II, the type III showed an insignificant change in spatial-resolution properties but a significant improvement in noise, including luminescence noise and structure noise. The improvement of type III in noise properties gave a better NEQ and DQE. It is confirmed that types II and III of HR (for mammography and bone radiography) plates have the same trend as that of ST plates.View full abstractDownload PDF (1118K)
- |<
- <
- 1
- >
- >|