Characterization of soy-lignin bonded Rhizophora spp. particleboard as substitute phantom material for radiation dosimetric studies - Investigation of CT number, mass attenuation coefficient and effective atomic number

Dosimetric evaluation of Rhizophora spp. particleboard bonded with animal protein adhesive at X-ray energies below 100 kVp

This research developed a bio-based adhesive (AP) derived from industrial slaughterhouse waste, comprising over 85% protein. The adhesive was characterized by a melting point of 193.14 °C, a neutral pH of 7, and a viscosity comparable to common wood adhesives such as urea-formaldehyde and phenol-formaldehyde. Utilizing this adhesive, a Rhizophora spp. particleboard phantom was produced, featuring wood particles of ≤149 μm, an adhesive concentration of 12%, and a target density of 1 g/cm³, adhering to a standard phantom dimension of 30 cm × 30 cm × 30 cm. The dosimetric properties of this particleboard phantom were subsequently compared with those of water and Perspex phantoms within an X-ray energy range of 60-100 kVp, employing high-sensitivity thermo-luminescent dosimeters (TL-100H). The findings indicated that the percentage depth dose (PDD) values of the AP-Rhizophora spp. particleboard were closely aligned with those of the Perspex and water phantoms, with the greatest discrepancy observed at 60 kVp. Additionally, the half-value layer (HVL) of the particleboard was similar to those of Perspex and water, particularly at diagnostic X-ray energies. These results demonstrate that the AP adhesive is effective for creating Rhizophora spp. particleboard phantoms, exhibiting dosimetric properties comparable to tissue-equivalent materials.

Dosimetric Analysis of Rhizophora-based Phantom Material in Radiation Therapy Applications Using Monte Carlo GATE Simulation

Purpose

This study aims to determine the percentage depth dose (PDD) of a phantom material made from soy-lignin bonded Rhizophora spp. particleboard coated with a gloss finish by using Monte Carlo Geant4 Application for Tomographic Emission (GATE) simulation.

Materials and Methods

The particleboard was fabricated using a hot pressing technique at target density of 1.0 g·cm-3 and the elemental fraction was recorded for the simulation. The PDD was simulated in the GATE simulation using the linear accelerator Elekta Synergy model for the water phantom and Rhizophora phantom, and the results were compared with the experimental PDD performed by several studies. Beam flatness and beam symmetry were also measured in this study.

Results

The simulated PDD for Rhizophora and water was in agreement with the experimental PDD of water with overall discrepancies of 0% to 8.7% at depth ranging from 1.0 to 15.0 cm. In the GATE simulation, all the points passed the clinical 3%/3 mm criterion in comparison with water, with the final percentage of 2.34% for Rhizophora phantom and 2.49% for the water phantom simulated in GATE. Both the symmetries are all within the range of an acceptable value of 2.0% according to the recommendation, with the beam symmetry of the water phantom and Rhizophora phantom at 0.58% and 0.28%, respectively.

Conclusions

The findings of this study provide the necessary foundation to confidently use the phantom for radiotherapy purposes, especially in treatment planning.