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ITERATIVE BONE CORRECTION COEFFICIENT SELECTION METHOD FOR MEDICAL IMAGING

IP.com Disclosure Number: IPCOM000126274D
Publication Date: 2005-Jul-12
Document File: 5 page(s) / 383K

Publishing Venue

The IP.com Prior Art Database

Abstract

In an embodiment, an IBO coefficient selection method is configured based on the Normalized Bone Index (NBI). The doctors scan the patients with thinner slice when in the posterior fossa area and with thicker slice when in the mid or top of the brain. The NBI is introduced to be independent of the slice thickness. The NBI is defined as the total bone amount (the sum of CT numbers in the images that are above the pre-selected threshold for the tube voltage used) normalized to the image display matrix and slice thickness. This NBI will be a function of the patient population, the anatomic location of the imaging plane in the head. In brief, the method includes calibrating the systems to determine the IBO coefficients associated with the NBI values, and performing the IBO corrections using NBI-dependent IBO coefficients.

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ITERATIVE BONE CORRECTION COEFFICIENT SELECTION METHOD FOR MEDICAL IMAGING

FIELD OF THE INVENTION

[0001]               This invention relates generally, to iterative bone correction coefficient selection method in medical imaging especially, in Computed Tomography Scanning.

BACKGROUND OF THE INVENTION

[0002]               Generally, iterative bone option (IBO) correction is used to correct the bone induced beam hardening artifacts in CT scanning.  The initial images are first segmented into bone and soft tissue.  The bone part of the images are forward projected and multiplied by an IBO coefficient and then back-projected and combined with the original images to reduce the beam hardening artifacts.  Conventionally, a single coefficient is assigned for every tube voltage (kV) used.  This coefficient is patient-independent.  Because there is only single selection of the coefficient, the correction is found to be not enough in the top of the brain while there is over-correction in the posterior fossa area for the same patient.  In other cases, the IBO correction is good for certain patient population while not adequate or over-correcting for others

DETAILED DESCRIPTION OF THE INVENTION

[0003]    Various embodiments of this invention provide an iterative bone correction coefficient selection method in medical imaging especially, in Computed Tomography Scanning.

[0004]    In an embodiment, an IBO coefficient selection method is configured based on the Normalized Bone Index (NBI).   The doctors scan the patients with thinner slice when in the posterior fossa area and with thicker slice when in the mid or top of the brain.  The NBI is introduced to be independent of the slice thickness.  The NBI is defined as the total bone amount (the sum of CT numbers in the images that are above the pre-selected threshold for the tube voltage used) normalized to the image display matrix and slice thickness.  This NBI will be a function of the patient population, the anatomic location of the imaging plane in the head. 

[0005]   In an example, an iterative bone correction coefficient selection method includes the following steps:

[0006]    (A). Calibrate the systems to determine the IBO coefficients associated with the NBI values. 

[0007]   This process only needs to be done once for the system.

(i)                  Characterize the NBI as a function of the kV/patient-type/imaging-plane.  The NBI will then be divided into several groups, for example 4 groups that are separated by NBI_high, NBI_medium and NBI_low, and for the 80kV/pediatric cases, the typical values for NBI_high, NBI_medium and NBI_low could be 40, 30 and 20 respectively.

(ii)                Divide the head images into four regions based on the normalized bone index: region I with NBI > NBI_high, region II with NBI_medium < NBI <= NBI_high, region III with NBI_low < NBI <= NBI_medium, and region IV with NBI <= NBI_low. 

(iii)               Determine the respective IBO coefficients for these regions that produce the best images.

[0008]    (B) Perform the IBO corrections...