Calculation of CT MTF and NPS

Calculation of CT MTF and NPS calculates axial modulation transfer function (MTF) and three-dimensional noise-power spectrum (NPS) from computed tomography (CT) images of an American College of Radiology (ACR) accreditation phantom to quantify CT system spatial resolution and noise characteristics.

Key Features:

• Standardized measurement: Utilizes the ACR accreditation phantom and specifically the third module to provide consistent reference geometry for measurements.
• MTF calculation: Determines radial/axial MTF using an edge method applied to the boundary of the third module of the ACR phantom.
• NPS analysis: Measures the three-dimensional NPS from the same module and quantifies noise magnitude and three-dimensional spatial correlation.

Scientific Applications:

• System performance evaluation: Provides quantitative MTF and NPS metrics for assessing and comparing CT system spatial resolution and noise characteristics across protocols and systems.
• Protocol optimization: Enables tuning of imaging parameters to improve image quality while managing radiation dose.
• Comparative studies: Supports benchmarking and comparative analysis of CT scanners and reconstruction methods using standardized metrics.
• Quality assurance: Facilitates routine measurement of resolution and noise parameters for clinical imaging quality assurance programs.

Methodology:

Radial MTF is measured via an edge method applied to the third module boundary of the ACR phantom, and 3D NPS is quantified using established techniques that consider noise magnitude and three-dimensional spatial correlation.