Construction of anthropomorphic hybrid, dual-lattice voxel models for optimizing image quality and dose in radiography.

In radiography There is generally a conflict between The best image quality and The lowest possible patient dose. A proven method of dosimetry is The simulation of radiation Transport in virtual human models (i.e. phantoms). However, while The resolution of These voxel models is adequate for most dosimetric purposes, They cannot provide The required organ fine structures necessary for The assessment of The imaging quality. The aim of This work is To develop hybrid/dual-lattice voxel models (called also phantoms) as well as simulation methods by which patient dose and image quality for Typical radiographic procedures can be determined. The results will provide a basis To investigate by means of simulations The relationships between patient dose and image quality for various imaging parameters and develop methods for Their optimization. A hybrid model, based on NURBS (Non Linear Uniform Rational B-Spline) and PM (Polygon Mesh) surfaces, was constructed from an existing voxel model of a female patient. The organs of The hybrid model can be Then scaled and deformed in a non-uniform way i.e. organ by organ; They can be, Thus, adapted To patient characteristics without losing Their anatomical realism. Furthermore, The left lobe of The lung was substituted by a high resolution lung voxel model, resulting in a dual-lattice geometry model. “ Dual lattice†means in This context The combination of voxel models with different resolution. Monte Carlo simulations of radiographic imaging were performed with The code EGS4nrc, modified such as To perform dual lattice Transport. Results are presented for a Thorax examination