RESUMO
Depending on the severity of the condition and associated risk, surgical intervention may not always be the first choice. This is true for treating chest wall deformities such as pectus excavatum and pectus carinatum. For both conditions, novel non-surgical treatments have been developed to gradually alleviate the malformation making use of the elastic nature of the costal cartilages at an early age of the patient. To quantify the performance of such treatments, this paper introduces and discusses the development of a software-based instrument that utilizes 3D chest optical images (surface scans) as input and uses registration techniques to produce an objective gauge of a patient's physical improvement after undergoing treatments. Further discussed is an experiment designed to investigate the construct validity of the developed instrument.