Method and apparatus for measurement of microtome performance

An apparatus for imaging and interpreting the image of the cut surface on a histology tissue sample block in order to monitor and evaluate the condition and performance of a microtome and microtome components, said apparatus comprising:

• image-producing means for producing an image of the cut surface on a histology tissue sample block;
• recording means for recording the image produced;
• a digital computer that performs computational operations to interpret the image produced by said image producing means to extract information concerning the condition and performance of the mictrotome and its components, wherein said computational operations include the following:
• a) detection of global intensity characteristics for evaluation of the status of the microtome illumination system and the presence of large, amorphous defects on the histology tissue sample block face;
• b) application of a correction mask that adjusts the image and produces a uniform background intensity against which lines, pits, and other more distinct features are distinguished;
• c) assessment of the illumination system to detect irregular broad defects and to quantify and assess block composition and knife status;
• d) correction of the illumination field to uniformity;
• e) determination of whether the image is in the proper focus to yield sufficient information, sharpness of focus quantification, and termination of analysis if the quality of focus is substandard;
• f) if the image is properly focused, then application of an edge detection routine to create a binary map that indicates where edges of any surface imperfections are located;
• g) processing of the binary map by using next neighbor search to detect continuous lines that are categorized by shape and length;
• curved, closed lines denoting defects in the block, such as pits and bubbles, are interpreted and categorized by a curve-fitting routine;
• straight lines are classified on the basis of their orientations into horizontal and vertical types;
• straight lines not fitting these two categories are analyzed to yield information on alignment variations in the image recording system and/or to indicate deviations from flatness of focus;
• h) quantification of the width and number of vertical lines for knife operation assessment;
• i) quantification of the width, number, and periodicity of horizontal lines to assess the operation of the microtome drive and the knife;
• j) quantification of any lines rotated off from the pixel axis to assess camera alignment.

A method for monitoring and evaluating the condition and performance of a microtome and microtome components, said method comprising the steps of:

• producing an optical image of the cut surface of a histology tissue sample block sectioned by the microtome by using a partially reflective mirror to reflect and direct onto the cut face on the histology tissue sample block an incident beam of light originating from either a mercury vapor or xenon bulb;
• intercepting the optical image formed by any specular reflection from the cut surface on said histology tissue sample block and directing said image through a system of microscope lenses onto a light-sensitive planar surface, such as a charge-coupled imaging chip;
• converting said optical image of the cut surface of the histology tissue sample block into a digital electronic image;
• recording said digital electronic image onto a suitable recording medium, such as magnetic tape or optical disk;
• interpreting said digital image using a digital computer to extract information concerning the condition and performance of the microtome and its components;
• using a suitably programmed digital computer to determine whether the image of the cut surface of the histology tissue sample block is in the proper focus to yield sufficient information, sharpness of focus quantification, and to terminate image analysis if the quality of focus is substandard;
• using said digital computer, if the image is properly focused, to apply an edge detection operation, such as a Laplacian, Sobel, Frei, or Chen technique, to create a binary map that indicates where edges of any surface imperfections are located;
• processing said binary map by using next neighbor search to detect continuous lines that are categorized by shape and length;
• using a curve-fitting routine to interpret and categorize curved, closed lines denoting defects in the block, such as pits and bubbles;
• classifying straight lines on the basis of their orientations into horizontal and vertical types;
• analyzing straight lines not fitting these two categories to yield information on alignment variations in the image recording system and/or to indicate deviations from flatness of focus.