Factual Accuracy is not Enough: Planning Consistent Description Order for Radiology Report Generation

Radiology report generation systems have the potential to reduce the workload of radiologists by automatically describing the findings in medical images. To broaden the application of the report generation system, the system should generate reports that are not only factually accurate but also chronologically consistent, describing images that are presented in time order, that is, the correct order. We employ a planning-based radiology report generation system that generates the overall structure of reports as "plans" prior to generating reports that are accurate and consistent in order. Additionally, we propose a novel reinforcement learning and inference method, Coordinated Planning (CoPlan), that includes a content planner and a text generator to train and infer in a coordinated manner to alleviate the cascading of errors that are often inherent in planning-based models. We conducted experiments with single-phase diagnostic reports in which the factual accuracy is critical and multi-phase diagnostic reports in which the description order is critical. Our proposed CoPlan improves the content order score by 5.1 pt in time series critical scenarios and the clinical factual accuracy F-score by 9.1 pt in time series irrelevant scenarios, compared those of the baseline models without CoPlan.