Recently, X-ray images through chest radiography (CXR) can distinguish gas, fat, soft tissue, bone, and metal based on their densities. It is the most basic chest imaging technique. With advancement of technology, CXR is becoming safer by lowering the radiation dose. It has become the first examination performed on patients with thoracic abnormality syndrome for early diagnosis of various chest diseases worldwide, accounting for up to 26% of all diagnostic radiology examinations. Despite its various advantages, CXR can distinguish only a few densities. Various thoracic anatomical structures can overlap in a single 2D image and various pathologies can show the same density, making accurate interpretation at various densities difficult. Errors in CXR interpretation have been present since the mid-20th century, with 10-20% of tuberculosis cases being interpreted differently by various radiologists and 19% of lung cancer cases being misinterpreted. To address these issues in interpreting chest CXR and to increase its usability in emergency situations and various environments, the quality of CXR images needs to be improved. In order to improve the quality of these images, this study aimed to establish a portable multi-energy X-ray field technique using MCNP with dual energies of 40 and 70 keV.