The aim of this study is to investigate the technical feasibility of brain radiotherapy without immobilization masks using surface imaging to ensure accurate patient positioning and continuous motion monitoring.

In brain radiotherapy, immobilization using a thermoplastic mask is a standard practice to ensure treatment accuracy. However, this method causes discomfort and anxiety for patients. The development of surface imaging (Surface Guided Radiation Therapy, SGRT) could offer a solution to this problem. SGRT is a non-invasive and non-ionizing imaging technique that uses cameras to capture the patient's position in real-time. In mask-free treatment, the radiation beam can be interrupted when motion exceeds a certain threshold and restarts only when the position is corrected.

Nowadays, very few studies have examined the concept of radiation therapy without immobilization masks using SGRT.

As part of this study, participants will take part in a simulated mask-free session. We will determine the stability of the patient's position in the absence of a mask. Participants will also complete questionnaires concerning their feelings during sessions with and without masks.

Inclusion Criteria:

• Age >= 18 years old
• Brain tumor treated with fractionated radiotherapy
• Able to read and complete a questionnaire in French

Exclusion Criteria:

• Inability to remain still