A review article examined reports on pediatric organ motion, in anticipation of the increasing application of advanced radiotherapy techniques in pediatric radiotherapy. Misappropriation of target margins could result in disease recurrence from geometric miss or unnecessary irradiation of normal tissue, organ motion and deformation increase the complexity of defining safety margins.

In particular, the optimal margin to account for internal organ motion in children remains largely undefined. Continuing efforts to characterize motion in children and young people is necessary to optimally define safety margins and to realize the full potential of intensity-modulated radiotherapy, magnetic resonance-guided radiotherapy and intensity-modulated proton beam therapy.