Program Information
Spatial Accuracy QA of An MR System
K Hwang1*, F Illerstam2 , T Torfeh3 , J Maier4 , S Shave5 , M Hoang6 , (1) GE Healthcare, Houston, TX, (2) GE Healthcare Europe, Danderyd, (3) Al Amal Hospital, Doha, (4) GE Healthcare, Waukesha, WI, (5) GE Healthcare, Waukesha, WI, (6) GE Healthcare, Waukesha, WI
Presentations
SU-E-J-146 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose: To develop a phantom and measurement protocol for quantifying spatial accuracy of an MR imaging system over its entire imaging volume.
Methods: The measurement protocol is comprised of a phantom, a set of MR sequence parameters for imaging the phantom, and analysis software for calculating spatial errors in the acquired phantom images. The phantom covers the entire imaging volume of the scanner above the patient table, and consists of layers of foam embedded with a matrix of spherical markers. To account for possible spatial errors in the construction of the phantom, the phantom may be imaged with CT to create a gold standard data set. On MR scanners, the phantom is acquired with a 3D FGRE sequence that covers the full imaging volume. Error measurements are performed by detecting markers in the image sets and identifying them based on their known locations on the phantom. The spatial error of a marker is defined as the difference between its locations on the MR and CT image sets. The phantom, protocol, and analysis program may also be adapted to different applications by allowing for differences in phantom size and region of analysis within the scanner.
Results: Three copies of the phantom were constructed and the measurement protocol was successfully executed on several MR scanners at multiple sites. Submillimeter precision and repeatability of the marker detection was also confirmed with manual measurements and repeated acquisitions on a single scanner.
Conclusion: The proposed phantom and protocol can be an effective tool for verifying the spatial accuracy of an MR system, which in turn can improve the accuracy and confidence of MR guided therapies. Data from this protocol may also serve as a basis for a specification for spatial accuracy or be used in the development of advanced distortion correction algorithms.
Funding Support, Disclosures, and Conflict of Interest: Hwang, Illerstam, Maier, and Hoang are employees of GE Healthcare.
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