Evaluation of software programs, ImageJ and IQworks, for MTF, NPS and DQE analysis

Abstract

This study compared two QA analysis programs, ImageJ and IQworks, to establish their repeatability and reproducibility in testing the performance indicators, Modulation transfer function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) as recommended by the European (EU) guidelines for Full Field Digital Mammography. Following the EU guidelines1, a Siemens Novation FFDM system with W/Rh Tube/Filter combination was used to acquire the desired MTF and NPS images. A Cu edge plate of 1 mm thickness used1,2, in addition to 2 × 1 mm Al plates (purity > 99%) at the tube head. Each metric was tested for repeatability and reproducibility on the selected software programs, with this data then used to establish correlation and agreement between programs. Both programs show a confidence interval of >3% for MTF and NPS images, respectively. Bland–Altman statistics showed a strong correlation across all metrics, further supported with R-squared values of 0.95, 0.84 and 0.91 for MTF, NPS and DQE, respectively. However, the DQE % difference showed a >10% differences above 3.5 lp/mm between the two programs. Both programs were capable of producing repeatable and reliable results when considering MTF and NPS; however, the DQE showed differing results between the two indicating that they should not be used interchangeably. From a practicality perspective, the ImageJ program was preferable given its user-friendliness and better repeatability. Additional calculations had to be performed with IQworks to establish DQE.