Quality control measurements for digital x-ray detectors.

Area of Science:

• Medical Physics
• Radiological Imaging
• Quality Control

Background:

• Digital radiography (DR) systems are increasingly replacing traditional screen/film (S/F) technology.
• Standardized quality control (QC) protocols are essential for ensuring the reliable performance of DR detectors.
• The Institute of Physics and Engineering in Medicine (IPEM) is releasing a new report on DR QC.

Purpose of the Study:

• To describe and evaluate a new digital radiography (DR) quality control protocol for DR detectors.
• To assess the reproducibility and wider applicability of the developed protocol.
• To compare the imaging performance of DR detectors with conventional screen/film systems.

Main Methods:

• A protocol requiring twelve images with minimal spatial frequency processing was applied to multiple caesium iodide (CsI) DR detectors.
• Key performance metrics calculated include detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS), and threshold contrast-detail (c-d) detectability.
• X-ray spectrum: 70 kVp with 1 mm Cu filtration; target detector air kerma: 2.5 µGy for NNPS and c-d.

Main Results:

• The protocol demonstrated good reproducibility with low coefficients of variation (cov) for MTF, air kerma, NNPS, and c-d detectability across identical detectors.
• Detective quantum efficiency (DQE) averaged 0.56 at 0.5 mm⁻¹ for CsI detectors from different manufacturers.
• DR detectors showed superior contrast-detail performance (average threshold contrast 0.46%) compared to S/F systems (0.70%).

Conclusions:

• The developed DR quality control protocol is quick, reproducible, and provides a comprehensive assessment of detector performance.
• The protocol facilitates in-depth evaluation for various digital x-ray detectors.
• The findings indicate superior imaging performance of modern DR detectors over traditional screen/film technology.