Ian Cunningham PhD, Presenter: Nothing to Disclose

Nick Jankovic MSc, Abstract Co-Author: Nothing to Disclose

The detective quantum efficiency (DQE) has generally been adopted by the scientific community as a primary measure of performance and "dose efficiency" of radiographic and mammographic detectors and is one of the only quantitative and objective metrics available. While the FDA requires submission of DQE information on new devices, it has not become part of routine acceptance testing and monitoring due to the difficulty of measurements. We have developed a portable instrument that measures the DQE automatically without the need for specialized laboratory facilities or expertise.

The instrument is placed in the x-ray beam in front of the detector. A number of images are acquired while it moves an air ionization chamber and other components in and out of the beam. Images are transferred from the imaging system in "raw" DICOM format and used in the analysis. All calibrations, measurements and analysis software algorithms are internally validated to ensure accurate DQE results.

The primary source of error is internal scatter. This has been minimized to achieve an incident exposure measurement within 1% of a calibrated electrometer and chamber in free air. A complete DQE measurement can be completed in 15 minutes without knowledge of proprietary system information. Agreement within a few percent has been achieved with both a conventional manual laboratory measurement and independently published results on a similar detector.

It has been shown that the DQE can be measured routinely both in a laboratory environment and in a clinical setting with this instrument. Accuracy is comparable with laboratory analyses.

The DQE is one of the only truely objetive metrics of system performance. A simplified method of measuring the DQE without the need for specialized laboratory facilities or expertise makes it possible to use DQE in routine testing of performance. In addition to helping make users of x-ray imaging equipment more "DQE savy", general awareness of the practical importance of the DQE will put additional pressure on manufacturers to ensure optimal DQE performance. This will ultimately benefit the patient by resulting in lower radiation exposures or higher image quality.

Cunningham, I, Jankovic, N, Automated Routine Measurements of the Detective Quantum Efficiency of Radiographic and Mammographic Detectors.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5016197.html