Tuesday Seminar Deformable Image Registration

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# Tuesday Seminar Deformable Image Registration - PowerPoint PPT Presentation

07 th of January, 2014. Tuesday Seminar Deformable Image Registration. HyunSeok Lee leehseok @snu.ac.kr. Contents. What is Image Registration? Deformable Image Registration Basic concept Algorithm Products Open source Debates about dose deform TG132. What is image registration?.

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07th of January, 2014

### Tuesday SeminarDeformable Image Registration

HyunSeok Lee

[email protected]

Contents
• What is Image Registration?
• Deformable Image Registration
• Basic concept
• Algorithm
• Products
• Open source
• TG132
What is image registration?
• Image registration is the process of transforming different sets of data into one coordinate system.
• Registration is necessary in order to be able to compare or integrate the data obtained from different measurements.
IR – Rigid Transformation
• Rotation
• Translation
• Scale
IR – Affine Transformation
• Rotation
• Translation
• Scale
• Shear
• No more preservation of lengths and angles
• Parallel lines are preserved
IR – Perspective Transformation
• (xo, yo, zo)  world coordinates
• (xi, yi)  image coordinates
IR – Projective Transformation
• (xp, yp)  Plane Coordinates
• (xi, yi)  Image Coordinates
• amn coefficients from the equations of the scene and the image planes
IR – Non-Rigid Transformation
• Needed for inter-subject registration and distortion correction
• Non-linear
• Many different parameterizations
• Too much flexibility in the transformation can lead to undesirable results
Deformable Image Registration
• Fundamental task in medical image processing
• Typical uses
• Longitudinal studies
• where temporal structural or anatomical changes are investigated
• Matching of images from different patients
• Multi-modal registration
• matching images of the same patient acquired by different imaging technologies
DIR – Products
• MIM Software Inc.
• Intensity-based free-form deformable registration (VoxAlign)
• PET/CT, MR/CT and 4D data sets deformable fusion
• Atlas-based auto-contouring
• Dose Accumulation
• Deformable registration QA and reporting
Intensity-based Methods
• Intensity-based methods compare intensity patterns in images via correlation metrics
• Sum of Squared Differences
• Normalized Cross-Correlation
• Mutual Information
Feature-based Methods
• Feature-based methods find correspondence between image features such as points, lines, and contours.
• Distance between corresponding points
• Similarity metric between feature values
• e.g. curvature-based registration
Free-form Deformations
• The general idea is to deform an image by manipulating a regular grid of control points that are distributed across the image at an arbitrary mesh resolution.
• Control points can be moved and the position of individual pixels between the control points is computed from the positions of surrounding control points.
DIR – Products
• Algorithms are based on published algorithms but have been developed and optimized for particular RO use-cases and modality combinations.
• e.g. CT-CT Optic Flow algorithm for PET/CT fusion
• e.g. CT-MR multi-modal algorithm for MRI fusion
• Multimodal deformable fusion
• CT, PET, PET/CT, MRI and CBCT, including 4D data sets
• Automatic contouring
• using an atlas or previously contoured case
• Dose warping and summation
DIR – Products
• Velocity Medical Solutions
• Multi-resolution modified basis spline algorithm
• Multi-modality demons algorithm
• Multi-modality deformable image registration
• CT, MR, PET and SPECT
• Atlas-based auto-contouring
• Treatment response assessment
DIR – Open Source
• ITK
• Insight Segmentation and Registration Toolkit
• An extensive suite of software tools for image analysis
• Implemented in C++
• http://www.itk.org/itkindex.html
DIR – Open Source
• DIRART
• It contains well implemented DIR algorithms and the essential functions for ART applications.
• Implemented in MATLAB
• Need CERR
DIR – Open Source
• Plastimatch
• For high performance volumetric registration of medical images
• ITK-based algorithms for translation, rigid, affine, demons, and B-spline registration
• Some methods are GPU and multicore accelerated
• Implemented in C++
• Plugin to 3D Slicer
• software package for visualization and medical image computing
• http://plastimatch.org/
• For ART it is common to collect images of the patient throughout the course of therapy.
• Because of temporal variations, it is usually necessary to deform images so as to merge them into a cohesive dataset.
• This image registration makes the accurate merging of dose distributions difficult.
• Some have decided to do this by “deforming” the dose distributions, somewhat analogous to deforming the images, but it has been suggested that this is not appropriate.