Image interpretation
For conventional colposcopy, the colposcopists recorded the results of the colposcopy based on the staining of acetic acid and iodine solution and gave the colposcopic impression (normal/benign; low grade; high grade; cancer) before biopsy taking. Colposcopy-directed biopsy was taken as the gold standard to assess visual inspection readings. As for fluorescence colposcope, in addition to the visible fluorescent signal, we added a regions of interest (ROI) tool to the image acquisition software to calculate the SBR of a certain site in real time. Each sampling site got an SBR value. The larger the value, the greater the possibility of cervical intraepithelial neoplasia.