Program Information
Virtual Phantom: A First Step to a Comprehensive Automated Quality Control Program for Magnetic Resonance Image Guided Applications
T Torfeh*, R Hammoud , G Perkins , M McGarry , N Al-Hammadi , Hamad Medical Corporation, National Center for Cancer Care & Research (NCCCR), Doha, Qatar
Presentations
SU-E-I-59 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:
To design a virtual phantom for the calculation of quality metrics required for controlling MRI guided applications and to develop software tools to automatically perform the required controls.
Methods:
The virtual phantom is designed using 3D objects arranged in different dispositions in the space.
Six cylinders of 6mm diameter and 500mm length, tilted 30 degrees with respect to the Y axis, are used for slice thickness and location. These cylinders are placed in coronal planes distanced by 60mm. Their width and position allow measuring the slice location and thickness.
A 15*15*15 mm3 cube centered at the origin and rotated 3 degrees with respect to the Z axis is used for the calculation of the vertical and horizontal Modulation Transfer Function.
Spheres of 10 mm diameter distanced by 20 mm covering a field of view of 500mm are used for estimating the in-plane and through-plane geometric distortion.
Sets of cylinders with lengths ranging from 0.5mm to 2.0mm and diameters ranging from 4mm to 10mm are used for the low contrast. The Low Contrast test assesses the number of cylinders that can be detected.
In-house Java based software is developed and validated. The software automatically corrects positioning errors before constructing ROIs and acquiring measurements with respect to each control.
Results:
The virtual phantom was used to produce a large set of 2D DICOM images. Results showed that the software robustly calculated positions and distances with sub-voxel accuracy. For a 500mm FOV and a 0.9mm pixel size, mean errors were in the order of 0.15mm.
Conclusion:
This virtual phantom is an important step for building a new physical phantom and for validating new medical image processing algorithms. These tools represent a first step toward designing a comprehensive phantom and software for a complete Quality Control program for MRI guided application.
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