biostudies-literatureUnknown31Price ATVarian Medical Systems<h4>Background and purpose</h4>Improved hounsfield-unit accuracy of on-board imaging may lead to direct-to-unit treatment approaches We aimed to demonstrate the feasibility of using only a diagnostic (dx) computed tomography (CT)-defined target pre-plan in an <i>in silico</i> study of simulation-free abdominal stereotactic adaptive radiotherapy (ART).<h4>Materials and methods</h4>Eight patients with abdominal treatment sites (five pancreatic cancer, three oligometastases) were treated using an integrated adaptive O-Ring gantry system. Each patient's target was delineated on a dxCT. The target only pre-plan served primarily to seed the ART process. During the ART session, all structures were delineated. All simulated cases were treated to 50 Gy in 5 fractions to a planning target optimization structure (PTV_OPT) to allow for dose escalation within the planning target volume. Timing of steps during this workflow was recorded. Plan quality was compared between ART treatment plans and a plan created on a CT simulation scan using the traditional planning workflow.<h4>Results</h4>The workflow was feasible in all attempts, with organ-at-risk (OAR) constraints met in all fractions despite lack of initial OAR contours. Median absolute difference between the adapted plan and simulation CT plan for the PTV_Opt V95% was 2.0 %. Median absolute difference in the D0.5 cm³ between the adapted plan and simulation CT plan was -0.9 Gy for stomach, 1.2 Gy for duodenum, -5.3 Gy for small bowel, and 0.3 Gy for large bowel. Median end-to-end workflow time was 63 min.<h4>Conclusion</h4>The workflow was feasible for a dxCT-defined target-only pre-plan approach to stereotactic abdominal ART.Physics and imaging in radiation oncology100611https://www.ebi.ac.uk/biostudies/studies/S-EPMC11382001biostudies-literatureFeasibility of simulation free abdominal stereotactic adaptive radiotherapy using an expedited pre-plan workflow.PMC11382001Schiff JPBeckert RSilberstein APrice ATSamson PPZhao THugo GDLaugeman EHenke LEfalseFeasibility of simulation free abdominal stereotactic adaptive radiotherapy using an expedited pre-plan workflow.<h4>Background and purpose</h4>Improved hounsfield-unit accuracy of on-board imaging may lead to direct-to-unit treatment approaches We aimed to demonstrate the feasibility of using only a diagnostic (dx) computed tomography (CT)-defined target pre-plan in an <i>in silico</i> study of simulation-free abdominal stereotactic adaptive radiotherapy (ART).<h4>Materials and methods</h4>Eight patients with abdominal treatment sites (five pancreatic cancer, three oligometastases) were treated using an integrated adaptive O-Ring gantry system. Each patient's target was delineated on a dxCT. The target only pre-plan served primarily to seed the ART process. During the ART session, all structures were delineated. All simulated cases were treated to 50 Gy in 5 fractions to a planning target optimization structure (PTV_OPT) to allow for dose escalation within the planning target volume. Timing of steps during this workflow was recorded. Plan quality was compared between ART treatment plans and a plan created on a CT simulation scan using the traditional planning workflow.<h4>Results</h4>The workflow was feasible in all attempts, with organ-at-risk (OAR) constraints met in all fractions despite lack of initial OAR contours. Median absolute difference between the adapted plan and simulation CT plan for the PTV_Opt V95% was 2.0 %. Median absolute difference in the D0.5 cm³ between the adapted plan and simulation CT plan was -0.9 Gy for stomach, 1.2 Gy for duodenum, -5.3 Gy for small bowel, and 0.3 Gy for large bowel. Median end-to-end workflow time was 63 min.<h4>Conclusion</h4>The workflow was feasible for a dxCT-defined target-only pre-plan approach to stereotactic abdominal ART.2024-01-01T00:00:00Z2024 Jul2026-06-02T21:57:26.946Z2025-04-04T00:29:50.649ZS-EPMC113820013925373010.1016/j.phro.2024.100611