## 4 Discussion
The writers in the field of research address the problem of mitigating the adverse impacts of metal implants on dose distribution by utilizing an appropriately selected calculating technique. VMAT technology offers exceptionalprecision and flexibility in preventing irradiation of metal implants, hence assuring a more uniform distribution of doses. Most studies concentrate on the pelvic region, specifically the site of hip replacements. [PERSON] et al. [28] examined the planning approach of VMAT at LU for prostate patients with bilateral hip arthroplasties. They focused on ensuring the plan's quality and feasibility while minimizing the radiation exposure to the prosthesis. Significant disparities were observed in fulfilling these goals across the three retrospectively constructed VMAT plans for 20 patients. The PA designs comprised six half-arcs that circumvented the need to enter each prosthesis. Nevertheless, it was demonstrated that these plans were suboptimal compared to plans that employed two complete arcs with optimized maximum dose (MD) and two complete arcs with maximized DVH constraint (MDVH). The MD and MDVH plan achieved comparable dosimetric quality assurance and demonstrated considerable enhancements in rectal and bladder DVH measures compared to the PA plan. The findings of this study unequivocally demonstrate that MD and MDVH plans surpass PA plans in terms of dosimetric QA and feasibility. Simultaneously, these two strategies efficiently minimized the input doses to the prosthesis, reaching a mere 1% of the authorized dose. The study emphasized the significance of utilizing the VMAT technique in bilateral hip joint endoprosthesis, which allowed for the testing of dosimetric values using a human pelvic phantom. There is much focus on selecting the appropriate exposure approach in ongoing research. The VMAT approach has great potential in minimizing irradiation of the metal implant region and achieving improved dose distribution. A study by [PERSON] et al. [28] showcased the efficacy of this strategy and yielded significantly enhanced outcomes compared to conventional methods. The findings of the studies highlight the significance of selecting an appropriate radiation therapy planning approach and the necessity for ongoing research to enhance the treatment of patients with metal implants. The results of our study obtained for different energy modalities (electrons, VHEE and protons) show the consistent and significant effects of metallic materials on the dose distribution and the extent of energy deposition in RT scenarios. Metallic implants, such as Co-Cr-Mo alloys, titanium, and stainless steel, greatly influence the physical processes of particle-tissue interaction, manifested in dose reduction and a shift in the depth of maximum deposition (Bragg peak for protons). Simulations for 15 MeV electrons show that metallic implants, especially Co-Cr-Mo alloy, cause a dramatic dose attenuation behind the implant. At a depth of 1 cm, the dose for Co-Cr-Mo alloy was more than 6% lower than for water. This difference increased with increasing depth, with a significant dose decrease behind the implant, resulting in a shadowing zone with low energy deposition. Lower-density alloys, such as titanium and steel, showed less but still significant attenuation. This phenomenon is a direct result of the high density of the metals causing intense scattering and absorption of electrons, leading to a dose reduction in the target region behind the implant. Electrons have a significantly limited range compared to VHEE or protons, meaning their interaction with metallic materials can be limited to the surface irradiation areas. Clinical implications include potential under-dosing in target areas, particularly behind metal implants, critical for near-surface irradiation. Thus, for patients with metal implants, it is essential to consider modification of the radiation schedule or a change in modality.