Tissue-maximum ratios (TMR) in a thorax phantom were measured using two types of chambers for 10 MV X-ray fields at a source-chamber distance (SCD) of 100 cm. One was a Farmer-2581 chamber with a cavity volume of 0.6 cm^3 and wall thickness of 0.04 g/cm^2, and the other was a Capintec-PR-05P with a cavity volume of 0.07cm^3 and wall thickness of 0.22 g/cm^2. It has been found that in the back soft-tissue layer for fields of 5×5 to 15×15 cm^2, the ralative deviation of the TMR value by the 0.6-cm^3 chamber from the one by the 0.07-cm^3 chamber ranges from -0.9% not necessary to +0.5%. No significant difference existed between the two chambers in TMRs within the soft-tissue (Mix-Dp) layers. However, the following results has been obtained in the lung (cork with a density of 0.23g/cm^3) layer: (1) When a wall correction is performed for both chambers, the ralative deviation of the TMR value by the 0.6-cm^3 chamber from the one by the 0.07-cm^3 chamber is about -3% for a field of 5×5 cm^2. (2) The 0.6-cm^3 chamber makes small readings for fields of 6×6 cm^2 and less die to lack of uniformity in the dose distribution yieded in the 0.6-cm^3 chamber cavity. (3) A wall correction is needed for the 0.07-cm^3 chamber for fields of 7×7 cm^2 and less because the chamber wall is relatively thick.
Recently, computerized units are generally used causing wide-ranging changes in our work posture. We analyzed work posture for X-CT, X-TV and R.I. making inquiries about the chairs used by the radiation units in 48 hospitals throughout Nara Prefecture with the following results being obtained. The sitting posture was most widely used because of Visual Display Terminal. Types, hight and purchasing method of the chairs differed greatly from hospital to hospital. These result indicate that both the maker and user were not to interested in the chairs regarding operation, work posture and environment. We thick that chairs should be examined from the view point of human engineering by both the maker and user.
It is important to demonstrate clearly the hepatic arteries, parasitic arteries and small stains in conventional hepatic angiography and lipiodol accumulations after transcatheter arterial embolization with lipiodol. A diaphragmatic compensating filter (DCF) covering the diaphragmatic region was made originally. The shape of DCF for a high density part of the angiogram is similar to the shape of diaphragm, but the shape for a low density part could not be specified. The smallest tolerance of the DCF was 13.2 mm on the film. Therefore, a DCF was effective in more than 95.8% of angiograms. Only one type of DCF is possible to use in combination with side compensating filters. The clinical value of the radiographic images were remarkable improved, more than 29%, by the image analyze system, PIAS LA-500. Therefore, a DCF is indispensable in conventional hepatic angiography.
Fro the viewpoint that the effective focal spot size of a X-ray tube is a major factor affecting the image quality of X-ray pictures, we have inspected periodically the effective focal spot size using star chart. We concluded from our measuring results that no significant change exests in size by operating year. Despite our conclusion, ORITO reported in 1987 that a tendency of an increase existed in size by operating year. Our redetermination found that the change in size was within 10% at maximum and no relevance prevailed between the effective focal spot change and exposure counts not operating year because we admitted there are ±2%~±5% error in chart reading and also ±1%~±5% error in chart arranging, so we recognized these changes in value are within the measuring error. In consequence, the data above suggest that it has no significant meaning in effective focal spot size measurement.
In order to take radiographic photos, it is necessary to know a great dial of information. For example, mA, kV, exposuretime, screen, grid, phototimer, etc. In this study, we examined 4 widely-used types computer-programmed X-ray equipment. These computer-assisted processes are designed to look at the data and make programmed individual decisions. The propose is to reduce the differences in radiographic quality and the risk of retaking caused by the differences in experience among technicians. We concluded that none of them has ideal functions but each can be used as a source supply information, if a little remodeling is done, and we confirm that computer-programmed X-ray equipment is, and will continue to go be, necessary.