Program Information
Quantification of Metal Artifact Reduction of Dual-Energy CT: A Phantom Study
K Li*, W Leung , Tuen Mun Hospital, Hong Kong
Presentations
MO-RAM-GePD-I-3 (Monday, July 31, 2017) 9:30 AM - 10:00 AM Room: Imaging ePoster Lounge
Purpose: To quantify metal artifact reduction of dual-energy CT using a phantom with metal implants
Methods: An additional in-house developed water-equivalent slice, which is sandwiched by Rando anthropomorphic head phantom, incorporated with animal’s cervical spine and two pairs of metal and plastic screws were used in this study. The phantom was scanned on Siemens Somatom Definition Flash dual-source CT system using helical scan with 0.5 pitch and 500 effective mAs. The resulting CTDIvol and DLP are 30mGy and 1000mGycm, respectively. Two CT datasets were acquired at 80kVp and 140kVp (Sn). Several monoenergetic images were generated, ranging from 40keV to 190keV. Elliptical region-of-interest (ROI) was positioned with same area and coordinates in between the two metal implants to measure the mean CT number of the streak artifact for all monochromatic energies. The size and position of the ROI was chosen to encompass the streak artifact in 80keV monoenergetic image, since it has the most apparent artifact. The results were compared with the reference image obtained from the same phantom but replaced by plastic implants.
Results: Mean Hounsfield units (HU) in between the two metal implants for different monoenergetic energies from 80keV to 160keV were summarized in Table 1. The 140keV monoenergetic image demonstrated the least percentage deviation (10%) of the mean HU value of the streak artifact from the actual one, while the 80keV monoenergetic image showed the largest percentage deviation (245%).
Conclusion: A phantom simulating a patient with metal implants was created to quantify the metal artifact reduction capability of dual energy monoenergetic CT. The significantly reduced artifacts shown by the 140keV image set allows the best target volume delineation for RT treatment planning. More anatomical structures will be included in the additional section of the phantom to closely resemble the human anatomy in the future studies.
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