AN INSTRUMENT TO MEASURE THE DIMENSIONS OF SKIN WOUNDS

A new instrument based on the principle of color-coded structured light has been developed to measure the area, volume, and color of skin ulcers and pressure sores. A set of parallel stripes of alternating colors is projected onto the ulcerated skin and recorded by a CCD camera. The color, width, distance, and coding of the stripes have been adjusted to maximize the precision of the instrument. Algorithms have been developed to extract the stripes and determine their centers to better than 0.1 mm, even under circumstances where the skin reflectivity varies widely over short distances. A depth map for the ulcerated skin is calculated by triangulation. The volume of the ulcer is that sandwiched between the base of the lesion and the original healthy skin, which is simulated by a cubic spline interpolation between the surrounding areas of healthy skin. The instrument measures the ulcer's volume with a precision of about 5% provided the ratio of the ulcer's volume to area is greater than 0.4 cm. The technique has been used in hospital clinics for a wide variety of wounds.