MedGround-R1: Advancing Medical Image Grounding via Spatial-Semantic Rewarded Group Relative Policy Optimization. - Huihui Xu; Yuanpeng Nie; Hualiang Wang; Ying Chen; Wei Li; Junzhi Ning; Lihao Liu; Hongqiu Wang; Lei Zhu; Jiyao Liu; Xiaomeng Li; Junjun He (CoRR, 2025)