Development of chest anthropomorphic phantoms to be used in Monte Carlo simulations of radiographic images

SCK•CEN Mentor

Rodriguez Pérez Sunay, srperez@sckcen.be, +32 (0)14 33 27 57

Expert group

Research in Dosimetric Applications

SCK•CEN Co-mentor

Struelens Lara, lstruele@sckcen.be, +32 (0)14 33 28 85

Introduction

Optimization in diagnostic radiology is intended to ensure an image quality adequate to perform the clinical task while keeping the patient exposure as low as possible. Achieving a good image quality requires the generation of images with the correct acquisition parameters (i.e. tube voltage, mAs, filtration and anti-scatter method), which have a direct influence on the dose delivered to the patient. The acquisition parameters currently used in digital systems are those recommended by the European Commission Guidelines, despite they have been published in 1996 explicitly for screen-film systems. Nowadays, most of the radiology departments use digital X-ray detectors for projection imaging, which have the potential for improved image quality for a given level of patient dose compared with screen-film detectors. Therefore, the revision of old protocols to optimize chest radiographies becomes necessary. Among all the methodologies available for optimization the computer simulation approach has been chosen since it constitutes a practical and inexpensive way to test large system configurations.

Objective

At SCK•CEN a simulation framework for task specific optimization of chest radiography is under development. A methodology for the simulation of the imaging chain has been established and validated in terms of image quality and dose. Using simulations with Monte Carlo code and ray tracing algorithms, radiographic images can be created. The next step is to create realistic test objects, specifically chest anthropomorphic phantoms to be used in the simulations. To make the optimization task specific, different clinical tasks should be included in the phantom (i.e. lung nodules, catheters, ribs fractures, etc.) since different imaging tasks demand different levels of image quality. The lungs in the phantom should have a high level of detail in order to represent a realistic background for the clinical tasks. This will be done by segmentation of high resolution CT images or by generation of bronchial trees using an algorithm in a 3D modeling software. Images of the phantom will be created using different spectrum energies and show to experienced radiologists that will score them.

The student will be directly involved in the creation of the different voxel phantoms. The phantoms will also include clinical tasks considered of great interest in thorax imaging. Additionally she/he will use the developed phantoms in Monte Carlo simulations to obtain radiographic images. The simulations will be performed with PENELOPE/penEasy transport code. The student will gain experience in the use of such Monte Carlo code as well as in the development of voxelized phantoms. During this process he/she will also learn to work with different tools like ImageJ and 3D Slicer: software packages for visualization and image analysis.

The minimum diploma level of the candidate needs to be

Professional bachelor , Academic bachelor

The candidate needs to have a background in

Bio-engineering , Physics , Other