Method for automatic construction of 2D statistical shape model for the lung regions

1. A method for automatic construction of 2D statistical shape models for the lung regions in chest radiographs, comprising:

extracting the anatomical structure contours from a chest radiograph image;

rigidly aligning shape instances to a template shape using a coarse shape alignment algorithm;

optimizing the alignment of shape instances to said template shape by a detailed shape alignment process; and

generating a statistical shape model using said aligned shape instances;

wherein said coarse shape alignment process includes:

creating a template shape;

computing the minimal distance and associated transformation parameters between said template shape and a shape instance; and

transforming the shape instance based on the transformation parameters.

2. The method of claim 1 , wherein said computing the minimal distance includes;

computing the polygon approximations from said template shape and a shape instance;

computing the minimal distance between said polygon approximations; and

determining the associated scale, rotation, and translation parameters using the minimal distance.

3. The method of claim 2 , wherein said computing the minimal distance includes:

computing the turning functions of said polygon approximations; and

searching the minimal distance between said turning functions.

4. A method for automatic construction of 2D statistical shape models for the lung regions in chest radiographs, comprising:

extracting the anatomical structure contours from a chest radiograph image;

rigidly aligning shape instances to a template shape using a coarse shape alignment algorithm;

optimizing the alignment of shape instances to said template shape by a detailed shape alignment process; and

generating a statistical shape model using said aligned shape instances;

wherein said detailed shape alignment process includes:

locating landmarks related to the shape features along the shape contours;

calculating the transformation parameters using the distance between the template shape landmarks and the instance shape landmarks; and

transforming the shape instance based on the transformation parameters.

5. The method of claim 4 , wherein locating landmarks includes:

choosing a certain polygon vertices with salient shape features as landmarks; and

locating a fixed number of equidistant points between said landmarks as the rest of the landmarks.

6. The method of claim 4 wherein calculating the transformation parameters is carried out using the Procrustes distance.