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Iodine Extraction Method Using Direct-Electron Density and CT Value with Dual Energy-CT

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D Kawahara

D Kawahara1,2*, S Ozawa3,4 , A Saito3 , S Tanaka5 , K Yokomachi1 , T Higaki6 , T Suzuki2 , M Tsuneda2 , T Nakashima1 , Y Ochi1 , T Okumura1 , Y Ohno1 , Y Nagata3,4 , (1) Radiation Therapy Section, Division of Clinical Support, Hiroshima University Hospital , Hiroshima,(2) Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, (3) Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University , Hiroshima, ,(4) Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima , (5) Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo , Tokyo, (6) Departments of Diagnostic Radiology and Radiology, Hiroshima University , Hiroshima


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

Purpose: Dual-energy CT (DECT) obtains various data such as direct-electron density (dED) and CT value and effective atomic number, thus which is expected to extract the tissue segmentation. In our work, we create the iodine extraction method using dED and CT value from DECT.

Methods: A CT-ED phantom (CIRS model 062M) which contains tissue-equivalent inserts and an acryl phantom which contains inserts with the various concentrations (0-130 mg/mL), of iodinated contrast medium were scanned by the DECT (Toshiba, Aquilion ONE CT Scanner). CT scans were performed at tube voltages of 80 and 135 kV. Iodine was separated from other tissue materials by using the threshold of CT value and the difference of the gradient in the dED-CT correlation, which was analyzed in an in-house software with Python. The accuracy of the iodine extraction was evaluated by measuring the diameter in terms of the full width at half maximum (FWHM), and the area on the axial plane.

Results: The CT number of the contrast medium was obviously greater than 0 HU. CT number of only bone materials and contrast medium obtained by 80 kV is higher than that by 135 kV. The gradient of the bone materials was greater than that of the iodine by factor of 4.0. The accuracy of the limit concentration of the contrast medium was 2 mg/mL and the ratio of the measurement to the actual diameter in FWHM and the area was 0.98-1.00.

Conclusion: We created the iodine extraction method and it is expected to extract only the region of the contrast medium from patient CT image using it.

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