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Figure 1b.   Simple silicosis in a 59-year-old man who worked in hard-rock mining for 10 years. (a) Chest radiograph shows diffuse nodular opacities with relative sparing of the basal lung zones. (b) High-resolution CT scan shows numerous micronodules in both upper lungs with posterior zonal predominance. Nodules are more profuse in the right upper lung zone than in the left. Some nodules are centrilobular in location (arrows). Note also the multiple subpleural nodules and the "pseudoplaques," which represent the aggregate of subpleural nodules.