In october 1975,the first home manufactured CT unit (Hitachi) was installed in our university hospital. Since that time several methods how to set a level of scan in CT examination were investigated and reported by us. At first we discussed on the slit scanography which was used to determine a most adequated level for the examination of CT scanner. After that, two dimensional image, reconstructed from the data of CT detector, was introduced into clinical use, and some CT unit, ie. Scoutview of GE CT/T 8800 and others, has adopted at present these methods, which we called a "Computed Radiography" (CR) system. To improve the quality of the CR image and to find a new radiological technique by CT for clinical applications, efforts were made in our hospital. The conclusions obtained are as follows ; Advantages 1. As far the digital data are accumlated and memorized in this system, CR image can be modified in many way and be displayed on the CRT. The contrast resolution of the system are as well superior than that of the conventional radiography. 2. As the lineality of the detector sensitivity is superior to the conventional screen film system, quantitative analysis of the image can be practiced. 3. The CR image enables to confirm the level of the scan without moving the patient to another table. In addition of gantry inclination as well as swing angle of the CT table can easily be measured. 4. The X Ray dose of CR system reduces to 1/5 in comparison with the routine X Ray radiography of the skull and the abdomen. Disadvantage 1. The conspicuous disadvantage of the CT image comparared with the conventional X-ray radiography is an insufficient ability in spatial resolution which, however, will be solved in near future.
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Jan 1, 1992
Junji Shiraishi + 5
Open Access
