# Handheld Optical System for Pectus Excavatum Assessment
###### Abstract  
Disruptive 3D technologies, such as reverse engineering (RE) and additive manufacturing (AM), when applied in the medical field enable the development of new methods for personalized and non-invasive treatments. When referring to the monitoring of pectus excavation, one of the most common thoracic malformations, 3D acquisition of the patient chest proved to be a straightforward method for assessing and measuring chest deformation. Unfortunately, such systems are usually available in a dedicated facility, can be operated only by specialized doctors with the support of engineers and can be used only with patients on site. It is therefore impossible to perform any routine check-up when the patient is unable to reach the outpatient clinic. The COVID19 pandemic situation has placed even greater restrictions on patient mobility, worsening this problem. To deal with this issue, a new low-cost portable optical scanner for monitoring pectus excavation is proposed in this work. The scanner, named Thor 2.0, allows a remote diagnostic approach, offering the possibility to perform routine check-ups telematically. Usability tests confirmed the user-friendly nature of the devised system. The instrument was used at the Meyer Children's Hospital (Florence, Italy) chest-malformations center to treat PE patients. The performed measurements proved to be in line with the current state of the art. pectus excavation; telemedicine; optical chest index; Intel RealSense; vacuum bell; handheld scanner; usability test +
Footnote †: journal: MedicalNevertheless, a study in a large cohort of pediatric patients treated with VB is still missing. Moreover, all the evaluation methods described in literature assess the progress of the malformation in a qualitative way by using, for instance, patient chest photos, satisfaction scoring scales, and manual/visual evaluation of the deepest point of the deformity [8; 9; 16]. These aspects constitute an important limitation in literature studies about the conservative therapy of chest wall deformities. In fact, the qualitative measurement of the conservative treatment for percus excavation by means of the Vacuum Bell implies several problems that entail the reliability of the measurement itself, as well as the monitoring and setting of the VB treatment (e.g., time of the treatment and pressure intensity). On the other hand, it is deemed necessary to draw attention to this device, which shows the possibility to effectively treating several cases of PE without resorting to invasive treatments; from this perspective, it was considered appropriate to develop tools for a quantitative and reliable evaluation of the progress of the pathology in order to assess VB effectiveness and to better adjust the treatment to each patient. In this regard, in recent years the attention of the scientific community has shifted to measurement methods based on optical scanning rather than the more common CT measurements that are more invasive to the patient. Indeed, several state-of-the-art studies propose quantitative measurements based on more- or less-expensive optical scanners [17; 18; 19] to assess chestwall deformities in order to facilitate treatment decision-making and post-treatment follow-up. It is our opinion, however, that the realization of a device that is easily manageable in a pediatric outpatient clinic has not yet been achieved. In current literature, in fact, professional scanners, which require an important and cumbersome setup that not all hospital structures can provide, are used. By way of example, the recent and comprehensive study in [20] proposed a scanning system requiring several seconds to acquire the chest anatomy, thus resulting in limited utility in a pediatric environment. Furthermore, such a system requires the input of manually inserted landmarks for extraction of severity indices and pathology monitoring.