## 2 Materials and Methods
\begin{table}
\begin{tabular}{l c c c} \hline \hline \multicolumn{1}{c}{**Biomaterial**} & \multicolumn{1}{c}{**Chemical Composition (\%)**} & \multicolumn{1}{c}{**Atomic Density (10\({}^{22}\) atom/cm\({}^{3}\))**} & \multicolumn{1}{c}{**Density**} \\ \hline
**Skin** & H 10; O 59.4; C 25; N 4.6; S 0.3; Cl 0.3; P 10.3; Na 0.2; K 0.1 & 9.88 & 1.02 \\
**PMMA** & H 53.3; C 33.3; O 13.3 & 8.57 & 0.95 \\ \hline
**Parotid gland** & H 62.5; C 16.4; N 1 27.7; O 19.6; S 0.037; Cl 0.016; Na 0.025; P 0.019 & 10.32 & 1.02 \\
**PMMA** & H 53.3; C 33.3; O 13.3 & 8.57 & 0.95 \\ \hline
**SMAS** & H 58.3; C 37.4; N 1.45; O 1.89; F 0.532; Ca 0.266 & 10.65 & 1.03 \\
**PMMA** & H 53.3; C 33.3; O 13.3 & 8.57 & 0.95 \\ \hline
**Masseter muscle** & H 52.6; C 8.9; N 1.6; O 26.6; S 5.85; Cl 1.76; K 0.64; P 0.404 & 10.11 & 1.05 \\
**Parylene N** & H 50; C 50 & 10.26 & 1.11 \\ \hline
**Buccal Fat** & H 63.4; C 28.4; N 0.304; O 7.77; Cl 0.018; Na 0.011 & 10.35 & 0.92 \\
**Polyethylene** & H 66.6; C 33.4 & 12.23 & 0.95 \\ \hline
**Mucosa** & H 10.1; C 77.5; N 3.50; O 5.23; F 1.74; Ca 1.83 & 5.24 & 1.028 \\
**PMMA** & H 53.3; C 33.3; O 13.3 & 8.57 & 0.95 \\ \hline
**Saliva** & H 66.6; O 33.3 & 10.02 & 1.00 \\
**Water** & H 66.6; O 33.3 & 10.02 & 1.00 \\ \hline
**Gum** & H 52.6; C 32.9; N 0.862; O 7.89; Cl 1.72; Mg 3.63 & 8.88 & 1.01 \\
**PMMA** & H 53.3; C 33.3; O 13.3 & 8.57 & 0.95 \\ \hline
**Cortical bone** & H 39.2; C 15; N 3.48; O 31.6; S 0.108; P 3.86; Ca 6.53; Mg 9.57 & 9.94 & 1.92 \\
**Teflon** & C 33.3; F 66.6 & 7.95 & 2.20 \\ \hline
**Cancellous bone** & H 57.7; C 23; N 1.36; O 15.7; S 4.27; P 0.752; Ca 1.26; Fe 1.23 & 10.42 & 1.18 \\
**Teflon** & C 33.3; F 66.6 & 7.95 & 2.20 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Proportions of atomic elements, atomic density, and material density of the biological layers within the mandible. known as Bremsstrahlung radiation. Additionally, characteristic X-rays are emitted when the electrons dislodge the inner-shell electrons of the target atoms, and outer-shell electrons drop into the lower energy levels, releasing photons in the process. The resulting X-ray spectrum is a combination of Bremsstrahlung and characteristic X-rays [25]. However, simulating the production of X-ray photons within PHITS poses significant challenges due to the complexities of accurately generating the entire X-ray spectra as described. Therefore, instead of simulating the entire X-ray production process, the source definition in this study was based on pre-determined photon energies, simulating the photon energies post-production. This approach allowed the study to focus directly on the interaction of these X-ray photons with the tissue layers at specific energy levels [26]. Two simulation scenarios assessed the absorbed dose within the mandibular structure. The first scenario involved modeling the actual tissues as shown in Figure 2. The second scenario used the defined tissue-equivalent materials as illustrated in Figure 3. For each scenario, X-ray photon energies ranging from 50 to 100 keV in 5 keV increments (50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 keV) were directed at the model. The absorbed dose for each anatomical layer was calculated under these conditions. Figure 3: Tissue mimicking model for mandibular. Figure 2: Mandibula layer model. This dual-simulation approach incorporating both real and equivalent materials provided a comprehensive analysis of how different energy levels interact with both types of materials. The results of these simulations are critical for refining dosimetric calculations in radiotherapy and enhancing the understanding of tissue responses to various radiation doses.