Method of evaluating respiratory induced organ motion by vector volume histogram

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Computational Anatomy

Background:

• Current methods for measuring respiratory organ motion rely on limited data points, failing to account for non-rigid organ deformation.
• Accurate quantification of organ motion is crucial for effective radiotherapy planning.

Purpose of the Study:

• To propose and evaluate a novel quantitative method for assessing respiratory induced organ motion using Deformable Image Registration (DIR).
• To compare the proposed method with traditional centroid-based motion analysis.

Main Methods:

• Utilized 4-dimensional computed tomography (4D CT) datasets from five patients.
• Applied a hybrid deformable registration algorithm to calculate deformation vector fields (DVFs).
• Computed Vector Volume Histograms (VVH) and Lmax to analyze organ motion, comparing results with centroid displacement.

Main Results:

• VVH effectively quantified the absolute distance and volume of organ motion.
• Centroid-based motion measurements were smaller than Lmax derived from VVH.
• Traditional centroid methods proved inadequate for evaluating deformable organ motion.

Conclusions:

• Vector Volume Histogram (VVH) analysis is a promising technique for evaluating organ volumetric changes during respiratory motion.
• DIR-based VVH offers a more comprehensive assessment of organ motion compared to centroid tracking.