Hallucination Detection-Guided Preference Optimization for Clinical Summarization. - Shamanth Kuthpadi Seethakantha; Dung Ngoc Thai; Vara Prasad Gudi; Simran Tiwari; Rami Matar; Avijit Mitra; Wenlong Zhao 001; Andrew McCallum; Wael Salloum (CoRR, 2026)