Towards novel methods of dosimetry in pediatric and neonatal head computed tomography: Comparative study using two novel and cost effective fabricated in-house phantoms.

PURPOSE: Accurate radiation dose assessment in pediatric computed tomography (CT) is essential due to children's higher radiosensitivity and anatomical differences from adults. Standard homogeneous adult phantoms often underestimate pediatric doses, especially in head imaging. This study performs a comparative dosimetry using two novel in-house developed heterogeneous head phantoms.

METHODS

Tissue-equivalent materials (TEMs) for cranial bone, brain matter, cerebrospinal fluid (CSF), and tumor/mass were formulated using Monte Carlo (GATE) simulations, XMuDat calculations, and Hounsfield unit data from pediatric head CT scans. Organ doses were measured using optically stimulated luminescence dosimeters under clinical protocols at 100 and 120 kVp using machined inserts in the phantoms for the different TEMs.

RESULTS

Physical and radiological properties, density, electron density, effective atomic number and mass attenuation, showed close agreement between simulations and theoretical values (<9% for most tissues). CT numbers matched reference pediatric HU ranges, confirming anatomical realism. Cranial bone peripheral doses ranged from 18.48 ± 0.16 mGy (neonatal, 100 kVp) to 24.66 ± 0.04 mGy (pediatric, 120 kVp), CSF peripheral doses from 17.75 ± 0.11 mGy to 24.00 ± 0.68 mGy, brain matter from 16.09 ± 0.27 mGy to 19.95 ± 0.38 mGy. Dose increases were ∼ 18-27% between neonatal and pediatric 100 kVp protocols, and ∼ 4-8% when increasing pediatric tube potential from 100 to 120 kVp.

CONCLUSION

These phantoms provide a realistic platform for pediatric head CT dose quantification, supporting patient-size-specific optimization and establishment of local diagnostic reference levels (DRLs) based on size-specific dose estimates.