ESTRO 2024 - Abstract Book

S1844

Clinical - Mixed sites, palliation

ESTRO 2024

where a simulation CT-free radiotherapy workflow using CBCT-guided online adaptive radiotherapy (oART) was implemented. Challenges were synthetic CT (sCT) uncertainties and time spend on manual target adaptation, also reported by others 2 . We now report on the total of 100 FAST-METS procedures.

Material/Methods:

Patients included in the FAST-METS workflow were considered eligible if they were referred for palliative radiotherapy (RT) (8 – 12 Gray, single fraction) for painful bone metastasis. These patients were required to have recent diagnostic imaging (preferably <4 weeks) of the metastasis. Informed consent forms were obtained for processing of patient data and completion of questionnaires. The complete workflow included: (1) consultation conducted by the radiation oncologist (RO) via telephone; (2) import of the diagnostic CT followed by treatment planning using standard treatment planning templates and a customized IMRT configuration with 6-9 beams. On the day of treatment, this was followed by (3) the consultation with the physician and (4) the CBCT-guided adaptation and treatment. Study endpoints were treatment times and clinical goals of the reference, scheduled (pre-treatment plan projected on the daily anatomy) and the adaptive treatment plan. We conducted a comparative analysis of treatment time between two patient groups: those treated during the initial FAST-METS trial 1 (group 1) and those treated in clinical practice after the trial (group 2). Additionally, we assessed patient satisfaction through an in-house questionnaire and evaluated pain response using the EQ-5D tool, with ongoing follow-up for the first 60 patients. Based on the initial clinical experience with FAST- METS trail, we categorized the patient population into two subgroups: ‘’easy’’ and ‘’challenging’’ FAST -METS cases. Easy anatomical sites were defined as ranging from the 6 th cervical vertebra till the 9 th thoracic vertebrae and from the 3 rd lumbar vertebrae till the lowest part of the pelvic bone. Challenging sites encompassed all other vertebrae, femur, and shoulder. This division aimed to select patients based on a prediction of time required for treatment. From December 2021 to September 2023, 100 treatments for 88 patients were completed in the same-day FAST METS workflow. Seven patients were excluded from the analysis because of missing informed consent forms, and an additional two patients were unable to complete treatment due to technical issues. Some patients in our study received dose escalation to 12Gy (n=6), had concurrent systemic therapy (n=14), received re-radiation (n=8), or were bed-bound (n=8). A total of 45 patients completed the questionnaires, and the overall patient satisfaction was good, with 43 patients indicated preference for the same treatment workflow in the future. Group 1 included 55 treatments, while group 2 consisted of 45 treatments. All treatments, except for one, were conducted using the adaptive treatment plan that was optimized on the actual anatomy at the time of radiotherapy, which contributed to improved coverage of the CTV (Figure 1). Challenges regarding sCT uncertainties and target adaptation were consistent with the findings from our initial evaluation 1 . Results: