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Quantitative Evaluation of CT-Based Pulmonary Ventilation Imaging Using a New Non-Rigid Phantom That Ventilates Air

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S Miyakawa

S Miyakawa1*, H Tachibana2, S Moriya3, M Sato1, (1) Graduate school of Health Science, Komazawa University, Setagaya, Tokyo, (2) National Cancer Center, Kashiwa, Chiba, (3) University of Tsukuba, Tsukuba, Ibaraki


TU-C2-GePD-J(A)-5 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Joint Imaging-Therapy ePoster Lounge - A

Purpose: We have quantitatively evaluated the CT-based pulmonary ventilation image (CT-V) using with a new non-rigid phantom with the Xe gas.

Methods: The phantom with the Xe gas was scanned at an exhale and inhale phases respectively. The exhale 3D-CT image was deformed to the inhale 3D-CT image with an in-house program using NiftyReg software. Two sets of deformed 3D-CT images were generated using the two DIR parameter settings (two-step and four-step deformations). Sixteen landmarks were assigned around the trachea and lung arteries in the inhale image and the deformed exhale image. Target registration error (TRE) between the two images was calculated for each landmark. An additional TRE evaluation was performed using two commercial DIR software, MIM Maestro and RayStation. The CT-V was generated using Jacobian determinant (JD) metrics. Subsequently, the change in the Hounsfield unit (HU) value between the two images were measured. The correlation coefficient between the JD and the HU change was calculated. In addition, three 4D-CT scans were performed to evaluate the reproducibility of the phantom motion and Xe gas distribution.

Results: The mean TRE values for each landmark were 4.5 ± 4.7 mm, 1.47 ± 0.71 mm, 1.0 ± 0.3 mm and 0.8 ± 0.7 mm for the two-step NiftyReg, four-step NiftyReg, MIM Maestro and RayStation, respectively. The relationship between the JD and the HU change for the four-step NiftyReg (R = -0.71) showed a greater correlation coefficient than the two-step NiftyReg (R = -0.40).

Conclusion: The evaluation using the phantom with the Xe gas will provide accurate and efficient validation study for the DIR as well as the CT-V.

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