At Princess Margaret Cancer Centre, a comprehensive approach to help children stay still during radiation treatment (RT) such as audio-visual distraction (television) is routinely used. These techniques help reduce the need for sedation or general anaesthesia to keep children still to avoid the chance of missing the tumour during RT. This approach has not been systematically evaluated to determine its effectiveness at reducing movement of children receiving RT. The purpose of the study is to measure the movement of children between the beginning and the end of RT to see how much they moved during treatment.

Cone beam CT (CBCT) is a low-dose imaging technique routinely used at Princess Margaret Cancer Centre to check the position of patients before RT. Using CBCT, the doctor is able to reduce the amount of tissues that receive RT because patients can be set-up with greater accuracy to only target the tumour and not harm the surrounding healthy tissue. In this study, children will receive one CBCT scan before starting RT as part of standard approach. Then after RT, another CBCT scan will be used to measure movement between the beginning and end of RT. The information gathered from this study will benefit other patients and cancer centres in the future, who can learn from these methods of using audio-visual distraction so that children have minimal or no motion for a more precise delivery of radiation during cancer treatment.

Inclusion Criteria:

• Patient (paediatric or adolescent) age 18 or under receiving RT without anaesthetic or procedural sedation (anaesthetic gas or intravenous sedative medication)

Exclusion Criteria:

• Patients receiving oral midazolam or ketamine are ineligible
• Patient is receiving total body irradiation without CBCT

Paediatric patients receiving an existing multi-faceted approach to reduce anaesthesia use in paediatric and adolescent radiotherapy (RT)