We propose a prospective longitudinal observation study at Ann and Robert H. Lurie Children’s Hospital of pediatric patients with a chest wall deformity diagnosis of either congenital or acquired pectus excavatum. Our aim is to assess the precision and accuracy of the Rodin M4D White Light Scanner in preoperative evaluation of patients with pectus excavatum by documenting the accuracy of the M4D scanner as compared to current standard of care (physician manual assessment and when appropriate a CT scan derived Haller index), for assessing progression of the deformity in these patients. Results of this study could influence how a child with pectus excavatum is followed over time without the need for x-ray exposure and, when applicable, in assessing post-operative correction over time.