Paediatric Anatomical Models in Radiotherapy Applications

Abstract

Radiotherapy is commonly used to treat paediatric cancers, but is associated with long-term side effects in children. Anatomical models have key applications in radiotherapy, notably to help understand the relationship between radiation dosage and the development of side effects. This review analyses whether age-specific computational phantoms, developed from healthy and paediatric cancer patient data, are adequate to model a paediatric population. The phantoms used in the study were International Commission on Radiological Protection (ICRP) and 4D extended cardiac torso (XCAT), which were also compared to literature data. Organ volume data for 19 organs was collected for both phantoms and literature. ICRP was treated as the reference for comparison, and percentage differences (P.Ds) for the other phantom was calculated relative to ICRP. Overall comparisons were made for each age category (1, 5, 10, 15) and for each organ. Statistical analysis was performed using Microsoft Excel (version 16.59). Literature had a smaller P.D to ICRP (-17.4%), whereas XCAT had a larger P.D (26.6%). The rectum had the largest average P.D (477.7%) and the brain had the smallest (-1.7%). The P.D was 67.8% for age 1 but this decreased down to 30.9% by age 15. Linear regression analysis showed correlation between organ volume and age to be the strongest for ICRP (R² = 0.943) and weakest for XCAT (R² = 0.676).

The phantoms are similar enough to ICRP for potential use in modelling paediatric populations. ICRP and XCAT could be used to model a healthy population, but may not necessarily be ideal for a population undergoing/after radiotherapy.