PSF and MTF from a bar pattern in digital mammography.

Area of Science:

• Medical Imaging
• Radiology
• Quality Assurance

Background:

• Determining Modulation Transfer Function (MTF) in digital mammography is challenging in hospitals due to resource limitations.
• Existing methods often require specialized equipment or complex procedures, hindering routine clinical application.

Purpose of the Study:

• To propose a quantitative, accessible method for calculating the Point Spread Function (PSF) and MTF of digital mammography systems.
• To enable accurate system performance evaluation using readily available bar pattern images.

Main Methods:

• The method involves measuring the Contrast Transfer Function (CTF) from a bar pattern image.
• A theoretical PSF model is iteratively adjusted to match the experimental CTF, derived via convolution with a square wave.
• The MTF is obtained by Fourier transforming the derived PSF.

Main Results:

• The proposed method demonstrated good agreement (within 5%) for CTF calculations across three digital mammography systems compared to the PSF model.
• Comparisons of MTF derived from the model PSF and a gold wire method validated the accuracy of the PSF model.

Conclusions:

• The developed method provides a simple, accessible means to obtain PSF and MTF for digital mammography systems in clinical settings.
• This technique bypasses the need for complex configurations or hard-to-access phantoms.
• The method can be extended to calculate other crucial imaging parameters like Normalized Noise Power Spectrum (NNPS) and Detective Quantum Efficiency (DQE).