CBCT images are used to assess the feasibility of dose calculation in head and neck cancer planning

This study aimed to assess the accuracy of dose calculation using iterative CBCT images in radiotherapy planning for head and neck cancers. A total of 36 patients with head and neck cancer treated with the Halcyon accelerator were included in the study. Intensity-modulated radiotherapy (IMRT) plans were developed using the Eclipse 16 planning system. CBCT images obtained during the initial treatment setup were registered with the planning CT images (pCT). Subsequently, the contours of target volumes and organs at risk from the IMRT plans based on pCT were transferred onto the CBCT images. Dose calculations were recomputed using the CT value-relative electron density curve specific to the CBCT images, generating new treatment plans (CBCT plans). Dosimetric parameters for target volumes and organs at risk were compared between the CBCT plans and the original CT plans using SPSS 26.0 for statistical analysis. The CT plans demonstrated significantly higher target volume prescription dose coverage, heterogeneity index (HI), and mean dose (Dmean) compared to the CBCT plans (P < 0.05). Statistically significant differences were observed in all parameters, except for the mean dose to the brainstem (P > 0.05). While the enhanced CBCT imaging in Halcyon treatment offers more accurate image guidance for radiotherapy, the limitations of CBCT in terms of dose calculation represent an ongoing challenge that requires resolution.