The purpose of this study was to clarify the influence of the tube voltage on the graininess of nonscreen x-ray film. The tube voltage was set at 10 kV intervals from 40kv to 90kV. Total filtration used was 27mm as the aluminium equivalent. Ag-particle size was determined microscopically by easuring the length on the x-axis of the particle image incorporated in the memory one-dimensionally. In order to compare with the film graininess only, the particle size when x-ray film was exposed to visible ray from a fluorescent lamp was also determined. ULTRA speed film manufactured by Kodak Co. was used in this experiment.
Results obtained were as follows: Among 104 particle sizes thus determined, there were about 9 particles of 10μm in size from visible ray. On the other hand, approximately 30 particles were confirmed with 90kV,27mm Al filtration. When these particles were observed microscopically, it was revealed that the greater part of Ag-particles were identical irrespective of the tube voltage. However, a large mass of Ag-particle was found to be formed when the tube voltage was high.
In the case of nonscreen x-ray film, the film was directly sensitized with x-ray. It was also estimated that the mass formation of Ag-particles may be attributable to the scattered ray (photoelectron)from first interacted Ag-particle.
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