Table 1.

The number of CT samples used for training for each class collected by four different hospitals A, B, C, and D. Besides, details of the CC-CCII dataset are also listed, which was used in the independent testing stage. The ratio of positive and negative samples in training set is approximately 1:1, and 2:1 in test dataset.

Dataset	Number of patients			Number of CT images			Subset
	Total	Positive	Negative	Total	Positive	Negative
Hospital A	424	0	424	24,670	0	24,670	Train
Hospital B	58	58	0	5,512	5,512	0	Train
Hospital C	17	17	0	2,611	2,611	0	Train
Hospital D	305	305	0	12,374	12,374	0	Train
CC-CCII [8]	2,034	1,320	714	130,511	84,629	45,882	Test