It is essential for projection radiography and mammography machines to undergo quality control checks or testing to ensure the machines are operating acceptably and optimally. The tests could be subjective or objective. Objective tests can include modulation transfer function, noise power spectrum, and detective quantum efficiency. Can any explain in a simple way the modulation transfer function, noise power spectrum, and detective quantum efficiency? If you have references, kindly please provide. Thank you!
Dr. Robert M Nishikawa has some slides from an AAPM presentation that explain this. You may want to start with this and explore his references to answer the questions you are asking.
https://www.aapm.org/meetings/99am/pdf/2798-87374.pdf
The modulation transfer function (MTF) describes the image properties of a system (in radiology, for example CT or MRI).The representation of a point/object is described in the frequency domain. MTF of 1 for a specific frequency of the object means, that this structure is not changed by the imaging system, whereas MTF of 0 means a supression of the structure. In case of an ideal imaging system, MTF would be 1 for each frequency. In reality, MTF is 1 for a frequency of 0 and than MTF drops to zero - characteristic for the specific imaging method.
Modulation Transfer Function (MTF):
The modulation transfer function measures a system's ability to reproduce fine details in an image. In simple terms, it assesses the sharpness of radiographic images. A high MTF indicates that the system can accurately render fine details, which is crucial in radiography for diagnosing medical conditions.
Noise Power Spectrum:
The noise power spectrum evaluates the distribution of fluctuations in light intensity within a radiographic image. In other words, it examines how noise is distributed at different frequencies. A low level of noise is desirable as it contributes to clearer and more easily interpretable images.
Detective Quantum Efficiency (DQE):
Detective Quantum Efficiency measures a system's ability to convert X-rays into diagnostically useful images. A high DQE means that the system is effective in transforming received information into a high-quality image. This is particularly important for ensuring high diagnostic accuracy.
References:
1- D. Dance, et al., "The non-uniformity of the modulation transfer function (MTF) of mammographic imaging systems." Physics in Medicine & Biology 42.11 (1997): 2191.
2- G. Samei, et al., "Investigation of Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) of digital mammography detectors using Monte Carlo simulation." Medical physics 32.5 (2005): 1354-1364.
3- A. S. Kuremsky, "Detective Quantum Efficiency." In: Encyclopedic Dictionary of Applied Physics. Springer, Berlin, Heidelberg, 2004.
4-Manuel de contrôle de la qualité pour la mammographie et la biopsie guidée par stéréotaxie
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