Evaluation of the effect of monochromatic images of Ti6Al4V implant material obtained with Dual Energy CT on radiotherapy plans using the Treatment Planning System and EGSnrc Monte Carlo simulation

This study aimed to evaluate the effect of Dual Energy Computed Tomography (DECT) imaging on radiotherapy planning for Ti6Al4V (grade 23), a high-density implant material, using the Treatment Planning System (TPS) and Monte Carlo (MC) simulation. For this purpose, Ti6Al4V implants with diameters of 6.4 mm and 28 mm were produced with a 3D printer and placed in a Cheese phantom. Single Energy Computed Tomography (SECT) and DECT images were obtained for each implant. SECT and DECT plans were created using TPS on SECT and DECT images and DECT plans were simulated using the EGSnrc-based BEAM nrc MC code system. SECT images of the Cheese phantom consisting entirely of water were transferred to TPS and artefact-free reference plans were created by virtually creating implants in planning. The obtained planning and simulation results were compared with the reference plan and dose errors in planning were determined. As a result of the study, it was observed that DECT imaging significantly increased the dose accuracy for the 6.4 mm diameter TI6Al4V implant compared to conventional planning. For the 28 mm diameter implant material, it was observed that DECT imaging decreased the success of artefact suppression, but significantly increased the dose accuracy in treatment planning. It was observed that DECT scanners could be used for simulation purposes in radiotherapy clinics for patients with Ti6Al4V implant material. The study needs to be extended to other high-density implant materials encountered in patients receiving radiotherapy.