胸部単純撮影における肺癌模擬病巣の描出能

抄録

For those peripheral type pulmonary carcinomas of not more than 10mm in diameter which are now regarded as difficult to visualize by plain chest roentgenography, we examined possible X-P technique enabling given us better visibility and higher lesion-detectability against conventional X-P of vascular and trachea distributed adjacent to the cancerous lesion, using a phantom simulating the real structures of the lesion and its circumferential vascular and trachea. The experiments were made as follows; 1) Measurement of effective energy of X-rays on X-ray equipments and variable focus-film distance. 2) Relationship between photographic density and X-ray tube voltage in clinical chest film. 3) Effective energy of X-rays and photographic density in the chest photograph using the phantom. 4) Visibility of nodule in the chest photograph for the position of nodule, the focus-film distance and the effective energy of X-rays. 5) Visibility of the nodule in the plumonary and mediastinum of the chest radiograph for the effective energy of X-rays. 6) Visibility and detectability of nodule for screen/film systems. 7) Detectability of nodule for photographic contrast and content rate of scattered radiation. 8) Visibility and detectability of the nodule for the exposure dose from the X-ray unit of 5 facilities. The results proved that with a combination of high-sharpness or sharpness screen and regular type film provided grid ratio of 12 : 1 (40 lines/cm) and the forcus-film distance of 200cm, X-P should be performed at the effective energy of X-rays of not more than 39.5keV (tube voltage of 120kV, 3 phase 12 peak rectification equipment) and at maximum photographic density of pulmonary area of not more than 2.0. If we gets higher visibility, using of high grid ratio and possible prolongation of the focus-film distance are required. Chest X-P systems (photographing condition, screen/film system, grid, exposure dose, etc.) in 5 medical institutions which we recently examined were under varied conditions of use, but their images showed no great difference.