Development and assessment of the stability, elemental composition, and radiological equivalence for a tissue-equivalent phantom

The current work aims to develop and evaluate a laboratory olive wood specimen as a tissue-equivalent phantom against internationally recognized reference standards for radiological applications. Two key parameters, moisture content (MC) and elemental composition (EC), were evaluated. Eighteen cylindrical samples were prepared, conditioned, and tested under controlled laboratory conditions. A high-precision moisture analyzer and ISO 287:2017 procedures were used to determine equilibrium moisture content (EMC), while elemental composition was quantified using X-ray fluorescence (XRF) and Carbon, Hydrogen, and Nitrogen (CHN) elemental analysis. Results showed highly stable moisture content values ranging from 4.60% to 4.85%, with low standard deviations (≤0.1%) across all samples, indicating excellent reproducibility. Elemental analysis revealed strong similarity to human soft tissue, with major mass fractions of carbon (14.47%), hydrogen (10.21%), and oxygen (74.75%), and minor contributions of calcium (0.25%) and potassium (0.26%). The derived effective atomic number (Z eff = 7.48) and elemental similarity index (ESI = 0.957) further confirmed the material's radiological equivalence to soft tissue. Experimental CT validation was performed at 120 kVp, yielding a mean Hounsfield Unit (HU) value of 30.085 ± 1.4 HU across all samples. Dosimetric verification using TLD-100 chips confirmed a mean absorbed dose of 97.9% relative to water (vs. 95.8% for PMMA), within the AAPM/IAEA ±5% diagnostic tolerance. Overall, these findings demonstrate that olive wood is a radiologically suitable, locally accessible, and low-cost alternative to commercial phantom materials for computed tomography (CT) applications.