## 5 Conclusions  
Monte Carlo simulations demonstrated how metals influence distribution as they traverse the metal implant. Our findings indicate that radiation therapy beams should avoid metal implants whenever possible due to the production of low- and high-dose regions before and after the implant, respectively. Owing to the potential for hot spots and cold spots in dose distribution. When treating these patients, it is essential to consider the position of individual metal components throughout their bodies to prevent them from reaching the irradiation area. This entails adhering to the principles of IGRT while ensuring adequate avoidance zones around metallic implants. It is essential to prevent superfluous bremsstrahlung and backscatter effects in the irradiated region. In the context of VHEE, evaluating the consequences induced by metallic implants within the human body is essential. Our results offer a critical understanding of the significant influence of metallic implants on dose distributions, particularly for high-density materials like Co-Cr-Mo. High-density materials like Co-Cr-Mo exhibit significant dose attenuation. For example, at \begin{table}
\begin{tabular}{c c c c c} \hline
**Beam** & **Material** & \begin{tabular}{c} **Dose Attenuation at** \\ **15 cm Depth** \\ \end{tabular} & **Bragg Peak Shift** & **Clinical Recommendation** \\ \hline  & Titanium alloy & \(-28\%\) & - & \begin{tabular}{c} Mild impact: acceptable if \\ there is no alternative. Prefer \\ avoidance if multiple arcs are \\ available. \\ Use avoidance sectors; avoid \\ direct beam path through \\ implant. \\ Strong attenuation; always use \\ avoidance sectors; re-optimize \\ plan geometry. \\ \end{tabular} \\ \hline  & Titanium alloy & \(-3\%\) & - & \begin{tabular}{c} Minimal impact; beam path \\ acceptable in specific clinical \\ contexts. \\ Moderate attenuation; avoid \\ beam path if possible. \\ Avoid beam path; use \\ avoidance sectors in VMAT \\ optimization. \\ \end{tabular} \\ \hline  & Titanium alloy & Dose at 5 cm: \(-39\%\) & - & \
\begin{tabular}{c} Strong attenuation; avoid \\ central beam axis through \\ implant. \\ Similar to titanium; avoid \\ implant regions when possible. \\ Similar to titanium; do not \\ place fields through implant. \\ \end{tabular} \\ \hline  & Titanium alloy & - & \(-4\) cm &
\begin{tabular}{c} Recalculate range; add safety \\ margins; avoid direct targeting \\ behind implant. \\ Strong shift; adjust beam range; \\ avoid implant shadow region. \\ Severe shift; avoid implant in \\ beam path; significant \\ replanning required. \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 1: Dose attenuation and proton range shifts caused by metallic implants across radiation modalities, including clinical recommendations. 15 cm depth, dose attenuation for 6 MV photons was \(-\)15.16% with Co-Cr-Mo, \(-\)8.11% with titanium, and \(-\)13.23% with steel. For 150 MeV VHEE, the impact was even more pronounced, with dose attenuation of \(-\)19.26% for Co-Cr-Mo, \(-\)3.46% for titanium, and \(-\)11.8% for steel. This trend continues with 100 MeV VHEE, demonstrating significant sensitivity to high-density materials. Furthermore, for electron therapy at 15 MeV, dose attenuation at 3 cm depth was \(-\)55.52% for Co-Cr-Mo, \(-\)54.79% for titanium, and \(-\)52.87% for steel, highlighting substantial attenuation even at lower energies and shallower depths. The Bragg peak shift in proton therapy, with a displacement of \(-\)9.5 cm for Co-Cr-Mo, \(-\)4.4 cm for titanium, and \(-\)7 cm for steel at 170 MeV, illustrates the challenges of dose accuracy around metallic implants for proton therapy. The findings of this work demonstrate that all treatment beams, including novel VHEE beams, must carefully consider patient implants to produce optimal dose distributions. The pronounced impact of titanium, stainless steel, and Co-Cr-Mo alloy on dose attenuation indicates that meticulous material selection and beam angle modification are essential when treating patients with metallic implants.