ESTRO 2024 - Abstract Book

S5505

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

stereotactic radiotherapy (FSRT), and a conventional fractionation schedule with stereotactic margins) , patients were randomized between DS or M Encompass. All treatment plans were created with HyperArc™ utilizing stereotactic PTV margins. Surface guidance with AlignRT™ by VisionRT was used for patient positioning and monitoring of patient movements during the treatment. A cone-beam CT (CBCT) pre-treatment was taken to correct interfractional variations, followed by a verification CBCT to confirm 6DoF-couch parameters. A post-treatment CBCT was acquired to verify for intrafractional variations. For the long conventional fractionation schedules, no post-CBCT was obtained due to radiation safety. At the end of the treatment, patients were asked to complete a Likert-based survey on paper with two questions assessing their overall experience and the ease of remaining still during the treatment (scale of 0 10, where 0 indicates no discomfort). Unpaired t-tests were conducted to determine the level of significance concerning interfractional and intrafractional absolute variations, as well as patients' perceived comfort.

Results:

Patient and treatment characteristics are depicted in Table 1. For the interfractional translations, no significant differences between the two systems are observed. These variations remain within 3 mm. More noticeable rotational variations are observed, with a significant difference in roll rotation, where DS Encompass allows for smaller deviations. Intrafractional variations are collected from 48 patients. For translations, the mean deviations remain largely under 1 mm for both systems. Regarding rotations, similar deviations are revealed. The mean rotational intrafractional deviations are less than 0.5°. The patient comfort questionnaire was completed by 51 patients. Among the 9 patients who did not fill it out, this was attributed to reasons such as patient's demise, failure to provide the questionnaire, or the patient's choice not to complete it. The patients who did complete the survey reported similar experiences in both groups with a mean score of 2-3.