Tissue mimicking hydrogel foam materials with mechanical and radiological properties equivalent to human lung

The motion of organs and tissues causes X-ray localization error during radiation therapy. Physical phantoms utilizing materials with tissue-equivalent mechanical and radiological properties are therefore desired to simulate organ motion for radiotherapy optimization. However, the development of such materials is still a challenge. Alginate hydrogel has similar properties to extra cellular matrix, which make it promising for use as a tissue-equivalent material. In this study, alginate hydrogel foams with desired mechanical and radiological properties were synthesized by in-situ release of Ca²⁺. The air volume ratio was carefully controlled to obtain hydrogel foams tailored to specific mechanical and radiological properties. Both the macroscopic and microscopic morphologies of the materials were characterized, and the compressive behaviors of the hydrogel foams were investigated. Radiological properties were estimated theoretically and validated through CT scanning experiments. This study has elucidated the development of future tissue-equivalent materials, which could be applied for optimization of radiation dosage and quality control during radiotherapy.