# The existence of cranial bone flap displacement during brain radiotherapy

## TL;DR

This study found that cranial bone flaps can shift slightly during brain tumor radiotherapy, which may affect treatment planning.

## Contribution

It is the first documented report of cranial bone flap displacement during brain radiotherapy.

## Key findings

- Bone flap displacement occurred frequently in all 25 patients, though never exceeding 2.5 mm.
- The displacement challenges the assumption that bone flaps remain fixed during treatment planning.
- The findings suggest a need to reassess treatment margins based on this displacement.

## Abstract

•Retrospective study of 25-post-operative brain tumour patients.•First documented literature recording the displacement of cranial bone flaps over the course of radiation treatment.•Displacement, though never exceeding 2.5 mm, was found to have a high frequency in all patients.•Bone flaps found not to remain a fixed entity as is assumed when cropping the CTV to the bone.•Provides insight for future research to focus on determining the impact of displacement on planning treatment margins.

Retrospective study of 25-post-operative brain tumour patients.

First documented literature recording the displacement of cranial bone flaps over the course of radiation treatment.

Displacement, though never exceeding 2.5 mm, was found to have a high frequency in all patients.

Bone flaps found not to remain a fixed entity as is assumed when cropping the CTV to the bone.

Provides insight for future research to focus on determining the impact of displacement on planning treatment margins.

This retrospective study examined bone flap displacement during radiotherapy in 25 post-operative brain tumour patients. Though never exceeding 2.5 mm, the sheer frequency of displacement highlights the need for future research on larger populations to validate its presence and assess the potential clinical impact on planning tumour volume margins.