Same-day adaptive palliative radiotherapy without prior CT simulation: Early outcomes in the FAST-METS study

Image quality evaluation of a new high-performance ring-gantry cone-beam computed tomography imager

“…These features could improve accuracy and decrease the need of correcting structures in the daily patient anatomy and auto-contouring could be more reliable, and this could enhance the CBCT dose calculation process. Additionally, due to the stability of the CT numbers, synthetic CTs or registration of the planning CT to the daily CBCT image would not be needed (de Jong et al 2021, Byrne et al 2022, Nelissen et al 2023. A limiting factor of this work is that it does not include dynamic phantoms to evaluate the rapid CBCT acquisition of 5.9 s compared to clinical routine of 60 s (C-arm linacs).…”

Evaluation of a cone-beam computed tomography system calibrated for accurate radiotherapy dose calculation

“…However, in this study such additional post-processing steps were not needed, since the CT numbers of the CBCT images were invariant, most likely due to the reduction of scatter using an anti-scatter grid in combination with an estimation of the scatter component as part of image reconstruction. These CBCT images would therefore be suitable for on-line adaptive radiotherapy workflows removing the need for synthetic CTs or registration of the planning CT image to the daily CBCT image [7] , [8] , [25] , which improve the trust in the workflow. The time gain needs to be further evaluated given longer reconstruction time using the iterative reconstruction algorithm.…”

“…The time gain needs to be further evaluated given longer reconstruction time using the iterative reconstruction algorithm. Images acquired with a calibrated conversion curve would also allow for off-line adaptive workflows or CBCT only workflows for palliative cases [8] . However, before implementing CBCT-only approaches, the novel system must be evaluated on target and OAR segmentation performance in real patients, as is done for previous CBCT systems [46].…”

“…Moreover, since anatomical variations in patients can occur, adaptive strategies are needed to account for discrepancies between planned and delivered dose. Therefore, there has been a growing interest in utilizing CBCT imaging for plan adaptation instead of repeat computed tomography (CT) [5] , [6] , [7] , [8] . However, the lower image quality caused by photon scatter, limited field-of-view (FOV), and inconsistency in CT numbers for conventional CBCT compared to fan-beam CT can lead to lower dose calculation accuracy [2] , [9] , [10] , [11] , [12] , [13] , [14] , [15] .…”

In silico trial of simulation-free hippocampal-avoidance whole brain adaptive radiotherapy

“…However, this approach is limited by the anatomical changes between the diagnostic imaging session and treatment where positional or target changes can be expected. Therefore, the use of adaptation at first fraction to better match the observed “anatomy-of-the-day” as seen on on-board treatment images can be used to create an original plan [8] , [9] , [10] . To date, the treatment targets in simulation-free approaches are relatively lower in complexity such bony or large lung metastases and have minimal dose-volume objectives to limit planning complexity.…”