Development of a Deformable Lung Phantom for the Evaluation of Deformable Registration

The purpose of this study was to develop a deformable lung phantom prototype for the evaluation of a deformable image registration algorithm. The phantom consisted of an acryl cylinder filled with water and a latex balloon located in the inner space of the cylinder. This latex balloon simulated the thoracic cavity, and it was filled with sponges and targets, which were embedded in the sponges. A silicon membrane was attached to the inferior end of the phantom. The silicon membrane was designed to simulate a real lung diaphragm and to reduce motor workload. This specific design was able to reduce the motor size of the phantom. Verification of deformable registration was based on peak exhale and peak inhale breathing phases. The isocenters of the targets on the Coreplan radiation planning system (Seoul C&J, KR) were compared for quantitative registration evaluation. The registration differences ranged from 0.85 mm to 1.47 mm, and accuracy was determined according to target deformation. This phantom was able to simulate the features and deformation of real human lung and has the potential for wide application in 4D treatment planning.