Extracting diagnosis from Japanese radiological report

This study is aimed at extracting diagnosis with positive or negative assertion from radiological report written in Japanese Natural Language. We get frequency of verb patterns that indicate pos/neg assertion, and extract a rule in order of the occurrence. We made customized dictionary of 36,152 terms relating to disease names or radiological findings, and tried to extract pairs of (pos/neg, disease and verb pattern ) by using rules according to the most frequent pattern from 1,524/5,000 CT reports (each report consists of 15.1 words on the average). We tried only a few rules so far, and continue to find other rules.