Fig 1. The framework of CheXLocNet.

The features were extracted from the origin radiographs by the backbone network. RoI was screened out by RPN. RPN produced two losses $L_{CLS}^R$ and $L_{REG}^R$ during the training time. The classification network and the mask network produced their losses and predictions, respectively. The softmax was used for outputting the probability for being a lesion area for each RoI. The per-pixel sigmoid was used for outputting a mask. RoI, rectangular region of interest; RPN, region proposal network.