SU‐C‐202‐06: Design and Development of a Non‐Rigid Phantom Ventilating Air Quantitatively Evaluating CT‐Based Pulmonary Ventilation Imaging

Abstract

Purpose:A validation study using human or sheep for CT pulmonary ventilation (CT‐V) imaging are inefficient and partially unstable. In this study, we designed and developed non‐rigid phantom ventilating air to quantitatively evaluate the CT‐V image.Methods:The phantom consisted of an acryl cylinder filled with polyurethane foam designed to pulmonic alveoli and a polyurethane membrane was attached to the inferior end of the phantom to simulate a lung diaphragm. Also, trachea‐shaped polyurethane tubes were covered by the foam and the tubes passed through the outside in order to exchange a gas. Lung arteries were also modeled with polyurethane and were located adjacent to the trachea model. Two 3D‐CT scans were performed at exhale and inhale using an air contrast agent of xenon gas, respectively. The exhale 3D‐CT was deformed to the inhale 3D‐CT using the in‐house program with the NiftyReg. Sixteen landmarks were assigned around trachea and lung arteries in the inhale image and the deformed exhale image. Target Registration Error (TRE) for each landmark between the two images was calculated for commissioning of our program. CT‐V image was generated using Jacobian determinant metrics (JD). Subsequently, HU value change between the two images was measured. The correlation coefficient was calculated between the JD and the HU change.Results:The deformable and ventilation phantom shows a variety of displacement for each landmark (1 mm − 20 mm). The mean TRE was 4.5 ± 4.7 mm (Maximum: 12.3 mm). The relationship between the JD and the HU change shows high correlation. (R = −0.86). At the several landmarks where TRE values were over 3 mm, the correlation was poor.Conclusion:The phantom may be a useful QA tool to validate CT‐V imaging. We will improve our deformable image registration program for CT‐V imaging with the efficient way using the phantom.