a semiautomatic algorithm for estimating cobb angle

Background: scoliosis is the most common type of spinal deformity. a universal and standard method for evaluating scoliosis is cobb angle measurement, but several studies have shown that there is intra and inter observer variation in measuring cobb angle manually.objective: develop a computer assisted system to decrease operatordependent errors in cobb angle measurement.methods: the spinal cord in the given xray image of the spine is highlighted using contractstretching technique. the overall structural curvature of the spine is determined by a semiautomatic algorithm aided by the operator. once the morphologic curve of the spine is determined, in the last step the cobbangle is estimated by calculating the angle between two normal lines to the spinal curve at the inflection points of the curve.results: evaluation results of the developed algorithms using 14 radiographs of patients (4 40 years old) with cobb angle ranges from 34 82 degrees, revealed that the developed algorithm accurately estimated cobb angle. statistical analysis showed that average angle values estimated using the developed method and that provided by experts are statistically equal. the correlation coefficient between the angle values estimated using the developed algorithm and those provided by the expert is 0.81. conclusion: compared with previous algorithms, the developed system is easy to use, less operatordependent, accurate, and reliable. the obtained results are promising and show that the developed computerbased system could be used to quantify scoliosis by measuring cobb angle.