## 5 Conclusions  
In this study, the absorption of X-rays in mandibular tissues was comparatively analyzed using real tissues and tissue-equivalent materials at different energy levels. The findings revealed that, particularly at lower energy levels, the real tissues absorbed more X-rays than the tissue-equivalent materials. The differences between soft tissues like the skin and PMMA, and the parotid gland and the PMMA were more pronounced at lower energy levels, and this difference diminished as the energy increased. However, for dense muscle tissues like the masseter muscle and Parylene N and bone simulation materials like Teflon, the differences were significant at both low and high energy levels. These results indicate that current tissue-equivalent materials do not accurately simulate real tissues, especially in low-energy X-ray applications. The discrepancies observed between the real tissues and tissue-equivalent materials can affect the accuracy of radiation dose calculations in clinical settings. This is particularly critical in medical and dental imaging applications where low-energy X-rays are utilized, as it poses a potential risk to patient safety. This study contributes to the literature by providing a detailed examination of the differences between real tissues and tissue-equivalent materials. It demonstrates that commonly used materials like PMMA, Parylene N, and Teflon do not always accurately reflect the behavior of real tissues, especially at lower energy levels. The findings emphasize that these discrepancies can lead to inaccurate results in the calibration of medical imaging devices and in the calculation of radiation doses. The study underscores the need to develop more precise tissue-equivalent materials and to optimize existing materials to resemble real tissues more closely. The current tissue-equivalent materials used in this study fall short in fully representing real tissues, especially when interacting with low-energy X-rays. For instance, parameters such as mass density, atomic number, and X-ray attenuation coefficient are not accurately mirrored by existing tissue equivalents. This is particularly evident in the simulation of denser tissues, like muscle and bone, where significant differences in X-ray absorption are observed. Therefore, it is essential to optimize tissue-equivalent materials to more realistically emulate tissue behavior, particularly in low-energy applications. In future research, it is essential to compare the results of this study, which used the PHITS simulation program, with other Monte Carlo simulation programs such as GEANT4, FLUKA, SRIM, and MCNPX. By using different simulation methods, a better understanding of how radiation interactions with real tissues and tissue-equivalent materials are modeled can be achieved. Additionally, it is crucial to validate the simulation results with experimental data. Testing with different tissue-equivalent materials in experimental environments can improve the accuracy of simulations and lead to more reliable results. Using more accurate materials, particularly for simulating dense muscle tissues and bone structures, will enhance the reliability of dose calculations in radiotherapy and imaging systems. The development of new tissue-equivalent materials and more precise simulation systems will not only improve patient safety in medical imaging and radiotherapy but also allow for the application of more accurate diagnostic and treatment methods. Conceptualization, Y.G. and F.E. ; Methodology, F.E. ; Software, Y.G. ; Validation, M.S.G. and F.E. ; Formal Analysis, F.E. ; Investigation, F.E. and M.S.G. ; Resources, F.E., K.A., A.B. and T.A. ; Writing--Original Draft Preparation, F.E., Y.G. and M.S.G. ; Writing--Review and Editing, F.E., K.A. and T.A. ; Visualization, F.E. and A.B. ; Supervision, F.E. and M.S.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable.