# Class-balanced Open-set Semi-supervised Object Detection for Medical Images Source: [Class-balanced Open-set Semi-supervised Object Detection for Medical Images]() Collection index: [llms.txt]() Data updated: 2025-10-26T03:13:35.838Z Authors: Zhanyun Lu, Renshu Gu, Huimin Cheng, Siyu Pang, Mingyu Xu, Peifang Xu, Yaqi Wang, Yuichiro Kinoshita, Juan Ye, Gangyong Jia, Qing Wu Published: 2024-08-22T12:54:15.000Z ## Abstract Medical image datasets in the real world are often unlabeled and imbalanced, and Semi-Supervised Object Detection (SSOD) can utilize unlabeled data to improve an object detector. However, existing approaches predominantly assumed that the unlabeled data and test data do not contain out-of-distribution (OOD) classes. The few open-set semi-supervised object detection methods have two weaknesses: first, the class imbalance is not considered; second, the OOD instances are distinguished and simply discarded during pseudo-labeling. In this paper, we consider the open-set semi-supervised object detection problem which leverages unlabeled data that contain OOD classes to improve object detection for medical images. Our study incorporates two key innovations: Category Control Embed (CCE) and out-of-distribution Detection Fusion Classifier (OODFC). CCE is designed to tackle dataset imbalance by constructing a Foreground information Library, while OODFC tackles open-set challenges by integrating the \`\`unknown'' information into basic pseudo-labels. Our method outperforms the state-of-the-art SSOD performance, achieving a 4.25 mAP improvement on the public Parasite dataset. ## Recorded benchmark results A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage. ## Original sources and implementation [Original paper]() [PDF]()