The use of detective quantum efficiency (DQE) in evaluating the performance of gamma camera systems

Abstract

The imaging properties of an imaging system can be described by its detective quantum efficiency (DQE). Using the modulation transfer function calculated from measured line spread functions and the normalized noise power spectrum calculated from uniformity images, DQE was calculated with the number of photons emitted from a plane source as a measure for the incoming SNR2. Measurements were made with 99mTc, using three different pulse height windows at 2 cm and 12 cm depths in water with high resolution and all purpose collimators and with two different crystal thicknesses. The results indicated that at greater depths a 15% window is the best choice. The choice of collimator depends on the details in the organ being investigated. There is a break point at 0.5 cycles cm-1 and 1.2 cycles cm-1 at 12 cm and 2 cm depths, respectively. A difference was found in DQE between the two crystal thicknesses, with a slightly better result for the thick crystal for measurements at 12 cm depth. At 2 cm depth, the thinner crystal was slightly better for frequencies over 0.5 cm-1. The determination of DQE could be a method to optimize the parameters for different nuclear medicine investigations. The DQE could also be used in comparing different gamma camera systems with different collimators to obtain a figure of merit.

Comparison of gamma (Anger) camera systems in terms of detective quantum efficiency using Monte Carlo simulation

“…In the clinical situation, the reviewer is disturbed by background noise in the region of interest, originating from uptake of activity in other organs, blood, and soft tissue. However, in the previous work by Eriksson et al [32] a comparison between Monte Carlo-generated DQE curves and the experimental determinations of DQE performed by Starck et al [8] was made, and a good agreement was found irrespective of energy window, collimator, and spatial frequency. As previously described, the importance of the anatomical background compared with the importance of the quantum noise is lower in nuclear medicine than in radiography.…”

Optimization of a parallel hole collimator/CdZnTe gamma‐camera architecture for scintimammography

“…It is useful for comparing detection systems including gamma cameras. 30 The DQE calculation method for gamma imaging is detailed in Ref. 26.…”

Information Capacity of Positron Emission Tomography Scanners

“…In this way, the optimum detector spatial resolution can be determined when the information capacity of the detector system is maximized, or in turn, when the signal-to-noise ratio (SNR) in the image is maximized [12,32]. Essential information regarding the maximum available signal-to-noise ratio, as a function of frequency, can be obtained through the noise-equivalent quanta (NEQ), which is the ratio of the modulation transfer function (MTF), describing the signal response of a system at a given frequency, and the noise power spectrum (NPS), describing the amplitude variance at a given frequency [33,34]. This information can be further utilized to optimize the examination procedure in terms of examination time and administered 18F-fludeoxyglucose (FDG) activity.…”