Evolving data are showing the need of considering smaller planning target volume (PTV) margin in paediatrics compared with adults treated for the same body site. This study proposed to evaluate the current patterns of practice regarding the PTV margin in paediatric patients compared with adult patients through an international survey.

A four-item questionnaire was created to address the PTV margins for paediatrics and adults as part of a comprehensive survey. International Paediatric Radiation Oncology Society (PROS) members were selected to partake and were contacted via email.

In total, 43 responded to the survey. The majority of the responders have written guidelines for PTV margin while the majority of those who have guidelines do not have separate guidelines for paediatrics. The implemented PTV margin for paediatric patients was in the majority 3–5 mm for the head region and 5–10 mm for the torso region and the difference from the PTV margin implemented in adults was not statistically significant.

The majority of responders employ a series of site-specific PTV margin protocols that are applied to both adults and paediatrics, and do not take into consideration patient age or size. These results highlight the need of a separate policy for PTV margin in adults and paediatrics in every institution.