Inverse filtering approach to measure directional in-plane modulation transfer function using a sphere phantom for a...

Area of Science:

• Medical Imaging
• Radiology
• Image Quality Assessment

Background:

• Digital tomosynthesis (DT) systems require accurate spatial resolution assessment.
• Traditional methods for measuring in-plane modulation transfer function (MTF) can be complex and prone to errors.
• Sphere phantoms have been considered unsuitable for MTF measurements in DT due to anisotropic characteristics.

Purpose of the Study:

• To propose and validate a method for measuring the directional in-plane MTF of digital tomosynthesis systems.
• To assess the spatial resolution of in-plane images reconstructed from DT data.
• To demonstrate the suitability of a sphere phantom for MTF measurements in DT.

Main Methods:

• Generated projection data of a sphere phantom within a limited 40° acquisition range.
• Reconstructed phantom data using the filtered backprojection (FBP) algorithm.
• Calculated in-plane MTF by dividing the Fourier transform of the reconstructed phantom by that of an ideal phantom, with error reduction techniques applied.

Main Results:

• The proposed method demonstrated reliable performance in estimating the directional in-plane MTF.
• Quantitative evaluation showed good agreement between estimated and ideal MTF values at different frequencies and directions.
• The sphere phantom proved suitable for measuring directional in-plane MTF in DT systems.

Conclusions:

• The developed method provides a reliable approach for assessing directional in-plane MTF in digital tomosynthesis.
• The study validates the use of sphere phantoms for this specific measurement, overcoming previous limitations.
• This technique contributes to improved image quality assessment in digital tomosynthesis imaging.