Evaluation of dosimetric and physical properties of a normoxic polymer gel mimicking bone-tissue

Polymer gel dosimeters, recognized for their radiological tissue equivalence, play a crucial role in clinical radiotherapy dosimetry by enabling high-resolution, three-dimensional dose mapping. They allow verification of complex treatment plans and serve as effective tools for quality assurance. Their ability to mimic human tissue and provide spatially resolved dose measurements has been extensively validated in both external beam therapy and brachytherapy. Conventional treatment planning relies on computed tomography (CT) to provide physical and electron density data of the target region. However, CT artifacts caused by metallic implants can compromise dose assessment, highlighting the need for alternative materials that accurately simulate bone tissue. This study presents a bone-equivalent, normoxic polymer gel dosimeter developed to mimic spongy bone tissue. Hydroxyapatite was incorporated into a MAGICA (methacrylic acid and ascorbic acid in gelatin with copper and agarose) formulation to achieve physical properties that closely match those of bone. Key parameters such as mass density (1.190 g cm -3 ), effective atomic number (10.07) and electron density were consistent with those of trabecular bone, as reported in ICRU Report 44. The linear attenuation coefficients of the gel were experimentally determined at 6 and 15 megavolts (MV) using a linear accelerator (LINAC) system, and the results were in good agreement with theoretical values obtained from XCOM, XMUDAT and Phy-X calculations. These findings confirm the gel’s suitability as a bone-equivalent dosimeter with promising applications in radiotherapy research and quality assurance.