# Handheld Optical System for Pectus Excavatum Assessment
## 4 Discussion and Conclusions  
In this work, a process of redesigning a body scanner previously developed for the acquisition and evaluation of the pectus excavatum was undertaken. The need to create a more manageable and user-friendly scanner arose from the lack state-of-the-art tools that can help doctors in a custom definition of the treatment. Pectus excavatum is treated, in cases that do not demand surgical intervention, with an external instrument called a vacuum bell. Instruments like the one devised in this work, which allows for the evaluation of the severity of the pathology, are useful in adapting the parameters of use during the course of treatment based on the progression and response of the individual patient. These tools are even more necessary when considering the remote use of the device. A system easily accessible directly by the patient would open the doors of telemedicine in monitoring pectus excavatum. The scanner presented in [21] was modified to obtain a better portability and therefore a simpler use within outpatient clinics, and demonstrated an easier interaction with the scan acquisition, both in terms of portability and in terms of the graphical interface of the program, facilitating the clinical investigation. The new 3D body scanner evaluation can obtain a chest wall defect evaluation in less than one second, after which the patient is free to move, and the acquired data are processed in the background in few seconds. In this way, it is possible to inform parents about the progression of their child's disease at the time of the outpatient visit, which helps in the consideration of any therapeutic changes at the same moment. After an initial test that showed the accuracy of the device in acquiring the chest anatomy, the developed system was tested in terms of usability in both clinical and domestic usage. From the usability test performed with clinicians, the new improved scanner resulted in a high degree of appreciation, and obtained the maximum parameters with regard to effectiveness. The use times reached by the medical team were very close to the times reached by experienced technical users, resulting in high efficiency performances. Regarding the SUS questionnaire, the software tested obtained an average result of 89, and in general, all the scores were above the optimal line, indicating a high level of user satisfaction. The usability tests conducted to evaluate the possibility of using this as a remote monitoring system confirmed excellent levels of effectiveness and efficiency in home usage. Although slightly lower results were obtained compared with the tests performed in the clinical environment, high satisfaction values were found using the SUS questionnaire. It should be noted that patients affected by PE were not the users to whom this second test has been dedicated, but rather third parties who were able to perform the scan. The device is therefore suitable for both outpatient use and remote use by the patient, if properly supported by a short training process. The clinical use of the device showed the possibility of tracing the course of the pathology and the effectiveness of the treatment. The measurements carried out were in accordance with the related literature, which showed that the pathology tended to have the first clear improvement in the first 12 months of use of the vacuum bell, while a general decrease or a lack of worsening of the pathological condition was achieved when assisted by this instrument. In a few patients, the measured PE indices demonstrated a slight worsening of the chest deformation. Some of these results could be explained by the fact that the use of a vacuum bell worsens the pectus excavatum pathology in subjects where the thoracic wall defect would have worsened in terms of severity during the pubertal age. \begin{table}
\begin{tabular}{c c c} \hline
**Effectiveness** & **Efficiency** & **SUS** \\ \hline
98.5\% & 88.2\% & 91 \\ \hline \end{tabular}
\end{table} 
Table 3: Overall results for patient’s usability test.