Correct assessment of cervical lymph node metastasis is very important in the management of head and neck cancer. Although CT scan is beneficial to screening the metastatic cervical lymph nodes, CT scan diagnosis is usually based on a subjective assessment of the findings by the examiner. Subjective assessment differ from examiner to examiner/and is affected by first impression of examiner. It is possible that such subjective assessment lead to different results in CT scan diagnosis, even if the same diagnostic criteria are used. We have developed a computer diagnostic supporting system using fuzzy theory, which allows objective assessment of cervical lymph nodes metastasis in head and neck cancer. We used six items as the degree of variation in CT findings of lymph nodes which were included ring enhancement, low density area, internal density, size, shape, and margin of lymph nodes. Each item was measured using a "fuzzy scale" for estimating the degree of variation of features analogically. Fuzzy theory was adopted for the diagnostic logic. The input and output membership functions were prepared for each item and the final assessment was made by the center of gravity of the max-sets of the output membership function. Our diagnostic supporting system appears to be beneficial for medical educational system as well as an adjunct diagnosis for metastatic cervical lymph nodes.
