ESTRO 2024 - Abstract Book

S5534

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

ESTRO 2024

with patient positioning and CBCT. We found that this decision rule helps to further enhance the workflow on the linacs for cervical cancer patients and decreases the need for repositioning because of inadequate target coverage on de the CBCT. Implementation of this decision rule was positively received by our RTT's.

Keywords: cervical cancer, bladder filling, ultrasound

1321

Proffered Paper

A prospective study of paediatric radiation therapy without anaesthesia – Are the children moving?

Tatiana Ritchie 1 , Susan Awrey 1 , Manjula Maganti 2 , Rehab Chahin 1 , Michael Velec 1 , David C Hodgson 1 , Hitesh Dama 1 , Sameera Ahmed 1 , Jeff D Winter 1 , Normand Laperriere 1 , Derek S Tsang 1 1 Princess Margaret Cancer Centre, Radiation Medicine Program, Toronto, Canada. 2 Princess Margaret Cancer Centre, Department of Biostatistics, Toronto, Canada

Purpose/Objective:

General anaesthesia is often required to deliver radiation treatment (RT) safely and accurately to paediatric patients. The age at which this is needed, however, varies significantly across different institutions. At our institution, we routinely treat children as young as 2 or 3 years old awake as they watch a favourite show or movie. With audiovisual distraction, we have successfully been able to minimize our use of general anaesthesia, improving the patients’ RT experience. What remains unknown is whether our paediatric patients are moving during their awake RT. The objective of our study was to evaluate intrafraction motion during RT, as well as to identify any factors associated with motion.

Material/Methods:

We prospectively evaluated the intrafraction motion of children who received their RT awake. All patients or their substitute decision makers provided written, informed consent. The study was reviewed by the hospital ethics committee and registered on ClinicialTrials.gov (NCT03995849). Eligibility criteria included children age ≤18 who received RT without any form of gaseous, intravenous or oral anaesthetic, sedative, benzodiazepine or antihistamine. Paediatric patients are offered audiovisual distraction and can choose a DVD to watch during RT. Current standard of care for patients at our institution is to receive a pre-treatment cone beam CT (CBCT) scan to ensure the patient is in the correct position. Study patients also received a post-treatment CBCT scan once a week. This post-treatment CBCT was compared to the pre-treatment CBCT to determine if there had been any intrafraction motion. The primary endpoint was the magnitude of vector change between the two scans (measuring intrafraction movement), which was calculated based on shifts in craniocaudal (CC), mediolateral (ML) and anteroposterior (AP) directions using image-guided radiation therapy (IGRT) software. Our hypothesis was that 90% of CBCT acquisitions would have