Development and validation of a novel three-dimensional patient-specific pediatric brain phantom for computed...

Pediatric head computed tomography (CT) is widely used for urgent neuroimaging, but children's higher radiosensitivity makes protocol optimization and quantitative validation essential. Many available phantoms lack patient-specific pediatric anatomy and realistic brain-mimicking attenuation, limiting their relevance for neuro-CT research and benchmarking.

To develop and validate a CT-derived, patient-specific pediatric brain phantom that preserves anatomically faithful geometry and reproduces brain-mimicking soft-tissue attenuation with physics-validated energy dependence.

A fully anonymized head CT of a 5-year-old child was segmented in 3-D Slicer, exported to standard tessellation language (STL), and partitioned into hemispheres. A polylactic acid (PLA) master was three-dimensional (D)-printed to fabricate a reinforced silicone mold. A homogeneous brain-mimicking soft-tissue surrogate was produced by modifying an epoxy system with acetone. The assembled phantom was scanned at 80, 100, 120, and 140 kilovolt peak (kVp). Region of interest (ROI)-based CT numbers were measured across both hemispheres. Computational attenuation verification was performed using Particle and Heavy Ion Transport code System (PHITS) Monte Carlo simulations with a mono-energetic transmission method over 15-150 kiloelectronvolt (keV) and compared with PhyX-Photon Shielding and Dosimetry (PhyX-PSD) and National Institute of Standards and Technology XCOM database (NIST/XCOM) reference.

The fabricated phantom preserved the main bilateral morphology and retained 96.85% of the original patient-derived brain volume, with volumes of 1,129.15 cm³ and 1,165.89 cm³, respectively. CT-number and CT-derived mass attenuation coefficient values are reported as mean±standard error of the mean (SEM). At the matched tube voltage of 120 kVp, the mean CT number was 44.94±1.38 Hounsfield units (HU) in the phantom and 40.66±4.13 HU in the source pediatric brain parenchyma, corresponding to an absolute difference of 4.28 HU. Across the complete phantom acquisition series, mean CT numbers increased from 18.55±1.14 HU at 80 kVp to 51.04±0.93 HU at 140 kVp. CT-derived mass attenuation coefficients decreased from 0.1664±0.0002 to 0.1445±0.0001 cm² g^-1 over 80-140 kVp. PHITS-derived attenuation coefficients closely matched the theoretical reference, with relative differences within ±5% across the predefined 15-150 keV diagnostic photon-energy range.

This work establishes the feasibility of producing a 3-D patient-specific pediatric brain component with preserved geometry and clinically relevant bulk CT attenuation, providing a methodological basis for subsequent integration of the skull and other structures into a modular complete-head phantom.