BLUE RIBBON POSTER THERAPY: Biological in vivo Three-Dimensional Dose Distribution Verification for Lung Cancer: From Rigid-Body Model to Porcine Lung
Abstract
Purpose
Biological in vivo three-dimensional dose distribution verification, introduced as a new concept in radiotherapy, was proposed to enable evaluation of the impact of respiratory motion on dose-delivery accuracy and to allow the inherent limitations of conventional rigid verification methods to be overcome.
Methods
A three-dimensional biological ex vivo respiratory simulation system (3D-BioLungEx) was developed to reproduce the respiratory characteristics of lung cancer patients. Through biological image registration, each patient’s radiotherapy plan was mapped onto freshly harvested porcine lungs with anatomically matched structures. A thoracic cavity conforming to the patient’s CT geometry was fabricated using 3D printing to provide an anatomically accurate housing for the porcine lung. Driven by 3D-BioLungEx, the lungs were guided to reproduce both regular and irregular breathing patterns observed during radiotherapy. Real-time three-dimensional dose distribution within the lungs was calculated using a self-developed Iterative Optimization and Scatter Inversion-based Dose Distribution Retro-Analysis Algorithm for porcine lung.
Results
Biological in vivo three-dimensional dose distribution verification was performed for lung cancer patients. When the respiratory amplitude and period recorded during CT simulation were replicated in 3D-BioLungEx, the gamma passing rate was increased. With respiratory frequency held constant, the gamma passing rate decreased progressively as respiratory amplitude increased, whereas it remained stable when amplitude was fixed. Moreover, under three irregular breathing patterns simulated by 3D-BioLungEx—Cheyne-Stokes breathing, yawning, and coughing—the gamma passing rate declined and did not exceed 90%.
Conclusion
Lung cancer patients often fail to replicate the respiratory pattern observed during CT simulation in actual treatment sessions, resulting in lower-than-expected gamma passing rates. Respiratory amplitude is identified as the primary factor affecting dose delivery accuracy. The proposed biological in vivo three-dimensional dose distribution verification method enables real-time dose monitoring and provides critical theoretical and practical support for dose-guided radiotherapy.