Biomimetic Phantom for Tumor Target Precision Verification Before Radiotherapy

ABSTRACT Tumor target localization accuracy is one of the key performance indicators in radiotherapy robots. Respiratory motion phantoms provide a safe alternative to human subjects for verifying this accuracy by replicating breathing‐induced motion. Existing rigid phantoms offer precise motion control but lack anatomical realism and cannot reproduce correlated surface–tumor displacements, while pneumatic‐driven flexible phantoms exhibit tissue‐like compliance but suffer from unstable and poorly reproducible motion. To overcome these limitations, a chest‐and‐abdominal biomimetic phantom (thoracoabdominal phantom) is developed using silicone elastomers with compliance comparable to thoracoabdominal tissue. The phantom integrates multiple deformable tumor surrogates that move synchronously with respiratory motion, enabling surface–tumor correlated displacement. A syringe‐based actuation system driven by stepper motors allows precise regulation of fluid volume per cycle, achieving a maximum thoracoabdominal displacement of 5.409 mm while ensuring quantitative control of respiratory amplitude and frequency. Validation using multimodal sensing confirmed accurate reproduction of thoracic motion dynamics, while kilovoltage radiography (KV) and cone‐beam computed tomography (CBCT) demonstrated tumor visibility. This platform provides a reliable tool for investigating respiration‐induced motion and supports the development of image‐guided radiotherapy strategies.