Generation of Novel Synthetic Portable Chest X-Ray Images for Automatic COVID-19 Screening

Introduction

The COVID-19 is a pathology that can affect several parts of the body, while its main affectation is located on the respiratory tissues. The pathogen that causes this disease is known as SARS-CoV-2, a type of coronavirus, which is highly contagious, reason why it was rapidly spread worldwide forcing the World Health Organization to declare the COVID-19 as a global pandemic in 12^th March 2020 (Ciotti et al., 2020). Currently, more than 242 million confirmed cases alongside more than 4.9 million deaths were reported worldwide (Coronavirus Resource Center, Johns Hopkins, 2020). There are several techniques to diagnose the COVID-19 but the gold-standard is the RT-PCR test (Tahamtan & Ardebili, 2020). However, it could be interesting for clinicians to have more information than the simple diagnostic provided by this technique. The main affectation of the COVID-19 is located in the pulmonary area and, therefore, chest X-ray imaging can be very useful to visualize this region to diagnose the pathology, to study its severity and to understand its evolution (Jacobi et al., 2020), as it has been widely used in the last decades to diagnose other typical pulmonary diseases and detect pathological structures as is the case, for example, of the pneumonia (Fiszman et al., 2000), the tuberculosis (Van Cleeff et al., 2005), the fibrosis (Puderbach et al., 2007) or the lung nodules (Wei et al., 2002). In the context of the COVID-19, this image modality can be used as a complement to the diagnostic result of the RT-PCR. With all these ideas into account, we can conclude that chest X-ray emerges as a powerful approach to visualize the affection of this pulmonary disease. Despite its lower quality in comparison with other advanced methods, as the Computerized Tomography (CT) (Hayden & Wrenn, 2009), the chest X-ray captures are easier and cheaper to perform. On the other hand, as the SARS-CoV-2 is easily spread, it is very important to decontaminate the capture devices. In the same way, many patients are bedridden and, therefore, it is impossible for them to move to the radiology room. To solve these problematics, radiologists are recommended to use portable chest X-ray devices instead of the fixed machinery (Kooraki et al., 2020), as this kind of devices are easier to decontaminate and can be moved to where the patient is placed. However, in some cases, clinicians could decide to use more advanced techniques that provide a more detailed visualization of the pulmonary regions if it is necessary, in order to have a more precise localization of the pathological structures, despite the higher cost and difficulty of the captures. This is the case of the CT, that provide a 3-dimensional visualization of the captured region.