Proton beam therapy in paediatric radiation oncology: Defining the limitations, uncertainties and optimisation of treatment plans

<h2>Abstract</h2> Proton Beam Therapy (PBT) is an increasingly utilised modality for treating tumours by utilising the physical properties of accelerated proton beams. This review explores the development of PBT, its dosimetric advantages over conventional x-ray-based radiotherapy, and the rationale behind its use in paediatric oncology whilst simultaneously considering the various challenges associated with its delivery. The challenges faced by PBT include its delivery methods, uncertainties in the precise depth of dose deposition known as "range", and considerations of linear energy transfer. The review aims to highlight how these are of particular importance for a paediatric cohort and present methods of mitigation to best utilise this modality. Despite clinical benefits, the limited availability of PBT centres poses challenges in communication, patient travel, and resource allocation. The authors discuss the importance of a multidisciplinary team, inter-hospital collaborations, and resource management strategies to address the logistical hurdles associated with PBT. The review evaluates the application of PBT across different paediatric tumour sites, focusing on central nervous system tumours, extra-cranial tumours, and specific challenges associated with head and neck, thoracic, abdomen, pelvis, and spine tumours. Dosimetric benefits and challenges specific to each site are thoroughly examined. Although PBT offers the potential to minimize organ-at-risk doses while maintaining tumour control, the authors underscore the importance of an experienced multidisciplinary team to address the medical, technical, and logistical challenges associated with PBT. As technical limitations are overcome, the scope for utilizing PBT in paediatric oncology is expected to expand, contributing to improved outcomes for patients globally.