Repeatability and reproducibility of MTF, NPS and DQE in Full Field Mammography for baseline setting

Abstract

The European guidelines for Full Field Digital Mammography1 recommend using performance indicators such as Modulation transfer function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE). This study assessed the setup variables for each, examining the repeatability and reproducibility to inform on Quality Control setup and tolerance establishment. A Siemens Novation system was used, with W/Rh tube potential 28 kV, tube current 50 mAs, achieving an output of 50–100 μGy at the detector1. A 150 × 150 mm Cu plate of 1 mm thickness was positioned on the bucky1,2, with 2 × 1 mm Al plates at the tube head1,3. MTF, NPS and DQE were assessed for repeatability, with and without moving the Cu plate, varying the angle between 0 and 15 degrees and varying output (78–704 μGy). MTF showed little variance with angle ( ⩽ 10°) varying between 1 and 4% for the 0–7 lp/mm. NPS showed to be repeatable with confidence Interval (CI) of 2.50 × 10−5%. MTF data variance with angle showed a confidence level