Computer planimetry in allergology skin prick tests

Abstract

Abstract Background. Estimation of skin prick test results in IgE allergy usually depends on subjective measurement ofperformer. One of usually used method of estimation skin reaction is measuring the longest and midpoint orthogonaldiameters of an erythema and a wheal. Then an average diameter is computed. The method is not precise for irregularobjects. Contours of the irregular wheal are encircled with a pen and transferred to a record sheet.Aim of study. There were elaborated methods of estimation results from skin prick test and methods of picture'sarchiving in the study. There were proposed own image processing algorithms, which are used to estimate an area of the erythema and wheal. Material and methods. Algorithm and conclusion were proposed using data taken from four patients: two children inage 5 years (tests were applied on the back) and two adults in age 21 and 30 years (tests were applied on the upper arms). Results. Skin reaction results are taken as medical images through the digital camera. Images are brought into computerand process in program. Algorithm automatically estimates area of the erythema and the wheal. The area was estimatedfrom H component in HSV color space. Contours of objects were separated using median filtering. The measured fieldwas computed in square millimeters using a calibrating pattern.Conclusion. Elaborated digital image's acquisition system gives possibility of archiving very good qualities images.There were proposed own image processing algorithms, which are used to estimate an area of the erythema and wheal.Algorithm using HSV colour space and H component allows receiving satisfactory results.Key words: skin prick test, electronic documentation, image processing, HSV colour space.