Investigation of a 3D system distortion correction method for MR images

Abstract

Interest has been growing in recent years in the development of radiation treatment planning (RTP) techniques based solely on magnetic resonance (MR) images. However, it is recognized that MR images suffer from scanner‐related and object‐induced distortions that may lead to an incorrect placement of anatomical structures. This subsequently may result in reduced accuracy in delivering treatment dose fractions in RTP. To accomplish the accurate representation of anatomical targets required by RTP, distortions must be mapped and the images rectified before being used in the clinical process. In this work, we investigate a novel, phantom‐based method that determines and corrects for 3D system‐related distortions. The algorithm consists of two key components: an adaptive control point identification and registration tool and an iterative method that finds the best estimate of 3D distortion. It was found that the 3D distortions were successfully mapped to within the voxel resolution of the raw data for a 260×260×240.2emmm3 volume.PACS numbers: 87.61.‐c, 87.53.Tf, 87.53.Xd, 87.56.‐v, 87.56.Fc, 87.62.+n

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

“…Most distortion correction techniques include three integral components: identification and registration of a fixed coordinate system (derived from a reference dataset), quantification of the distortion, and a distortion correction algorithm (21). Thus, one must be able to accurately measure the distortion so that procedures aimed at mitigating it can be implemented.…”

“…lists maximum system-related distortions measured in 10 studies(1,12,21,56,90,98,(103)(104)(105)(106)(107), along with relevant imaging parameters. Four of the studies(1,21,56,98) …”

A new phantom to assess and correct geometrical distortions for Magnetic Resonance Imaging: Design and preliminary experiments

“…Any residual distortion measured in the corrected images can then be used as an overall measure of the accuracy. This method has also been used by previous investigators [7,18]. Fig.…”

“…Images acquired from phantom are post-processed in order to build up distortion maps according to control points detected on the phantom images. This approach offers the advantage of correcting most of the field heterogeneities and gradient non-linearities [6,7,9,[18][19][20][21][22][23].…”

“…A similar phantom, used in [18,25,26], is now commercialized by Modus QA (Modus Medical Devices Inc. London, Canada) for brain MRI sequences in stereotactic condition [27]. This phantom is built-up from an acrylic cube containing a 1 cm 3D grid of channels filled with copper sulfate solution.…”