Abstract
<title>Abstract</title> <p>Background Cone-beam computed tomography (CBCT) is increasingly being integrated into adaptive radiotherapy workflows; however, its use for accurate dose calculation has historically been limited by image quality and Hounsfield unit inconsistencies. The introduction of advanced CBCT systems such as HyperSight aims to improve CT number accuracy and consistency and enable more reliable dose calculation directly on CBCT datasets. Independent validation using clinically relevant audit frameworks is therefore essential to assess its suitability for treatment planning and adaptive applications. Purpose This study aimed to evaluate the feasibility of HyperSight cone-beam CT (CBCT) for radiotherapy treatment planning by assessing its ability to meet the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) Level III independent dosimetry audit requirements. A secondary aim was to compare HyperSight-based audit outcomes with seven non-HyperSight Halcyon Level III audit results acquired across the author’s clinical network between 2021 and 2023. Methods CBCT-based treatment plans were generated across three planning categories of increasing complexity and submitted for Level III external dosimetry audit. Dosimetric agreement between CBCT-based and fan-beam CT (FBCT)-based plans was evaluated, and HyperSight audit results were compared with historical non-HyperSight Halcyon audit performance where available. Results CBCT-based plans met Level III audit criteria for conformal and modulated plan groups, while the lung SBRT case failed in both audit sessions. HyperSight audit outcomes were comparable to historical non-HyperSight Halcyon results across the ICON network, with no clinically significant degradation in dose delivery accuracy observed. Conclusion HyperSight CBCT-based planning can achieve Level III audit compliance comparable to FBCT-based approaches; however, implementation in stereotactic body radiotherapy (SBRT) planning should be undertaken with extreme caution due to the higher sensitivity of complex dose distributions to imaging and calculation uncertainties.</p>