1. A medical image retrieval system comprising: an image database which stores medical images; an interpretation unit which acquires a currently diagnosed image for use in performing interpretation of one of the medical images and provides the currently diagnosed image to a computer terminal; an image requesting unit which issues an image request associated with the currently diagnosed image, wherein the image request is based on an operation of the computer terminal; an image retrieval unit which retrieves a reference image from the image database in accordance with the image request and provides the reference image to the computer terminal in order to propose the reference image as references for diagnosis to an user of the computer terminal; and an evaluation input unit which prompts the user of the computer terminal to input an evaluation indicating whether the reference image has been helpful for diagnosis based on the currently diagnosed image.