Evaluating the accuracy of geometrical distortion correction of magnetic resonance images for use in intracranial brain tumor radiotherapy |
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Authors: | Seyed Mehdi Bagherimofidi Claus Chunli Yang Roberto Rey-Dios Madhava R Kanakamedala Ali Fatemi |
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Institution: | 1. Department of Biomedical Engineering, Aliabad Katoul Branch, Islamic Azad University, Aliabad Katoul, Iran;2. Department of Radiation Oncology, University of Mississippi Medical Center, Jackson, MS 39216, United States;3. Department of Neurosurgery, University of Mississippi Medical Center, Jackson, MS 39216, United States;4. Department of Radiology, University of Mississippi Medical Center, Jackson, MS 39216, United States |
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Abstract: | AimDetermine the 1) effectiveness of correction for gradient-non-linearity and susceptibility effects on both QUASAR GRID3D and CIRS phantoms; and 2) the magnitude and location of regions of residual distortion before and after correction.BackgroundUsing magnetic resonance imaging (MRI) as a primary dataset for radiotherapy planning requires correction for geometrical distortion and non-uniform intensity.Materials and MethodsPhantom Study: MRI, computed tomography (CT) and cone beam CT images of QUASAR GRID3D and CIRS head phantoms were acquired. Patient Study: Ten patients were MRI-scanned for stereotactic radiosurgery treatment. Correction algorithm: Two magnitude and one phase difference image were acquired to create a field map. A MATLAB program was used to calculate geometrical distortion in the frequency encoding direction, and 3D interpolation was applied to resize it to match 3D T1-weighted magnetization-prepared rapid gradient-echo (MPRAGE) images. MPRAGE images were warped according to the interpolated field map in the frequency encoding direction. The corrected and uncorrected MRI images were fused, deformable registered, and a difference distortion map generated.ResultsMaximum deviation improvements: GRID3D, 0.27 mm y-direction, 0.07 mm z-direction, 0.23 mm x-direction. CIRS, 0.34 mm, 0.1 mm and 0.09 mm at 20-, 40- and 60-mm diameters from the isocenter. Patient data show corrections from 0.2 to 1.2 mm, based on location. The most-distorted areas are around air cavities, e.g. sinuses.ConclusionsThe phantom data show the validity of our fast distortion correction algorithm. Patient-specific data are acquired in <2 min and analyzed and available for planning in less than a minute. |
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Keywords: | Corresponding author at: Department of Radiation Oncology and Radiology University of Mississippi Medical Center 2500 North State Street Jackson Mississippi 39216 United States MRI guided radiotherapy MRI image geometric distortion correction Radiotherapy Magnetic resonance imaging Intracranial brain tumor radiotherapy |
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