Pediatric radiotherapy is an anxiety-provoking situation that can, on one hand, impair the child's cooperation and require sedation, and on the other hand,burden the care pathway by generating significant anxiety in both the child and their parents. Companion robots represent an innovative avenue for patient support, but they have never been evaluated in the context of radiotherapy. This study examines the effect of MIROKI, the first social robot capable of communication through a Large Multimodal Model (LMM), on children's state anxiety during radiotherapy. An experimental single-case design (SCED) will compare phases with and without the robot (withdrawal/reversal), both in the waiting room and in the irradiation bunker. The primary outcome variable is anxiety, assessed in several ways: through questionnaires at the beginning and end of treatment; through an objective measure of cardiac activity (heart rate in bpm) during the radiotherapy session, with or without the MIROKI robot; and through an observational grid assessing the child's behavior. The intensive repeated measure (bpm) constitutes the preferred variable in this SCED design, while behavioral observation and anxiety questionnaires will support interpretation. The results could pave the way for reducing sedation and improving the overall care pathway in pediatric radiotherapy.

Inclusion Criteria:

1. Children aged 4 to 18 years, distributed across the following age groups: 4-7 years, 8-12 years, and 13-18 years.
2. Child with an indication for radiotherapy treatment at ICM.
3. Child who speaks French.
4. Child accompanied by a parent or legal guardian who agrees to participate in the study and provide consent.
5. Child covered by the French national health insurance system.

Exclusion Criteria:

6. Child with a diagnosed neurodevelopmental disorder as a comorbidity. 7. Child with postoperative cognitive sequelae that make interaction during care difficult (e.g., language impairment). 8. Total body irradiation. 9. Child under legal protection, unable to express assent, or presenting major difficulties in understanding the study information. Parent Inclusion Criteria

1. Parent of a child enrolled in the study.
2. Able to speak French.
3. Willing to participate in the study. Parent Exclusion Criteria

1. Parents or legal representatives under legal protection, or presenting an inability to consent or to understand the study information, making it impossible to provide free and informed consent for the minor's participation.

Participants will be recruited from the pediatric radiotherapy unit at Montpellier Cancer Institute (ICM).During the initial consultation to initiate radiotherapy treatment at ICM, the investigator physician will present the KOKORO-01 study. They will answer all questions regarding its procedures and will provide the parents or legal representative with the information sheet and consent form. Parents or the legal representative will have at least one week to consider participation, during which they may ask any questions they wish.

All data will be available after publication of the results in peer-reviewed revues, and in national and international meetings. It includes all de-identified participants' data, the study protocol, the statistical analysis plan and the clinical study report. The corresponding author will provide data and datasets generated and/or analyzed during the study upon reasonable request.

Access to study data upon written detailed request sent to ICM, from 6 months until 5 years after publication of summary data.

The data shared will be limit to that required for independent mandated verification of the published results, the applicant will need authorization from ICM for personal access, and data will only be transferred after signing of a data access agreement.