Browse Prior Art Database

Location of Registration Objects by Moment and Eigen Analysis

IP.com Disclosure Number: IPCOM000115739D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 73K

Publishing Venue

IBM

Related People

Hanson, W: AUTHOR

Abstract

The algorithm presented here describes an accurate and efficient method to locate reference objects in 3D medical data (CT, MRI, PET, etc.). Reference objects are placed in the viewing volume during data acquisition in order to allow for precise geometric registration of the data (*). Although the technique is applicable to a variety of image modalities and reference objects, this bulletin will describe the specifics for the case of a metal pin located in CT image data. Typically, a metallic pin will have circular symmetry about one axis, and consist of roughly cylindrical objects (the head and the shaft). However, variations on this simple model are quite common. In particular, the pin shaft will generally be threaded and the pin head will have an opening to assist in the setting of the object into bone.

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Location of Registration Objects by Moment and Eigen Analysis

      The algorithm presented here describes an accurate and
efficient method to locate reference objects in 3D medical data (CT,
MRI, PET, etc.).  Reference objects are placed in the viewing volume
during data acquisition in order to allow for precise geometric
registration of the data (*).  Although the technique is applicable
to a variety of image modalities and reference objects, this bulletin
will describe the specifics for the case of a metal pin located in CT
image data.  Typically, a metallic pin will have circular symmetry
about one axis, and consist of roughly cylindrical objects (the head
and the shaft).  However, variations on this simple model are quite
common.  In particular, the pin shaft will generally be threaded and
the pin head will have an opening to assist in the setting of the
object into bone.  Since the orientation of the patient can be
arbitrary, there is, in general, no apriori information regarding the
orientation of the pin.  It is significant to point out that since
the orientation of the object in unknown, morphological enhancement
operations must constrained to isotropic structuring elements to
avoid introducing bias.

      The key element of the novel procedure is to determine the
object orientation by use of the eigen-structure of the moment
matrix.  Now once the orientation is known, the extraction of
geometric information and the application of non-isotropic
morphological operations is possible.

The first and second moments pixel locations that contains metal
material are given by:
  m sub 1 =
  < sum from i P sup i > over < sum from i 1 >
  m sub 2 =
  < sum from i ( P sup i - m sub 1 ) ( P sup i - m sub 1 ) sup T...