Construction of patient-specific digital phantoms from thoracic CT images for biomechanical simulation and CAE studies

Introduction

Transforming a patient's CT (Computer Tomography) scan into 3D anatomical phantom prints has revolutionized surgical study planning. However, established processes produce complex files with errors that prevent their use for CAE (Computer-Aided Engineering). In this work, we use DICOM slices of a tomographic exam to construct an STL model, and then we describe the procedures used to convert it into a geometric model adequate for performing multi-physics simulations to obtain patient-specific results.

Methods

This study takes DICOM images (*.dcm) to construct the stack that is transformed into a 3D model (*.stl), a triangular mesh of the anatomic region. Due to the resolution of the images, this model is complex and has several errors (holes, doubled elements, and inverted surfaces). To have a workable model it is necessary to simplify and reconstruct the model without losing the specific characteristics of the patient. This step is crucial to generate a geometric model of the region to build the model for multi-physics simulation.

Results

The segmentation of the images can be done with several pieces of software (we used 3D Slide and 3DDoctor), and then the STL mesh is filtered, corrected, and simplified with Meshlab and other free software. We show the utility of the method for simulating large deformations of tissues due to plates with loads or changes in the position of the body.

Conclusions

This study can be considered a toy approach to the problem of multi-physics simulation with patient-specific models; our results show the application of the model to the mechanics of tissues, but CAE can be extended to thermal problems and to the absorption and transport of energy.