抄録
We have developed a computer diagnostic system of prostate cancer using fuzzy theory, which allows objective assessment and gives consistent diagnosis even if performed by a less-experienced urologist. The Japanese Urological Association and the Japanes Society of Ultrasonics in Medicine have published "General Rules for Ultrasonic Diagnosis of Prostatic Cancer". We used 5 of their 7 criteria: shape of the plane, architecture of the shape, capsule echogenicity, similarity of the planes, and internal echogenicity. To these, we added two items, identification of a hypoechoic lesion and shift of the postero-basal margin. A fuzzy scale was used to estimate the degree of presence of feature analogically, and fuzzy theory was adopted for the diagnostic logic. Two Membership functions (the input and output) were prepared for each item and the final assesment was made by the center of gravity of the max-sets of the output menbership function. The data regarding each criterion was input onto a fuzzy scale on a computer display, using a mouse key. In our clinical trial with this computer system, there was only one false-negative case and two cases in the borderline zone among 34 untreated patients with prostate cancer. There were two false positive case and four cases in the borderline zone amond the 43 patients with benign prostatic hyperplasia. Therefore, sensitivity was 96.2 % and specificity was 88.5 % in our series. Our diagnostic system appears to be beneficical for medical education.
