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Comparing eDQE and eNEQ metrics – is there an alternative approach to assessing image quality in digital mammography?

Wysocka-Rabin Anna, Dobrzyńska Magdalena, Pasicz Katarzyna, Skrzyński Witold, Fabiszewska Ewa

Polish Journal of Medical Physics and Engineering

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2023

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Vol. 29, Iss. 3

165--177

EN

Introduction: Early detection of breast cancer requires high-quality mammographic images that have been made possible by the introduction of new technologies, such as full-field digital mammography (FFDM). In this new study, we perform extended measurements to calculate effective detective quantum efficiency (eDQE) and introduce effective noise equivalent quanta (eNEQ). Our aim was to show how these two metrics relate to the image quality of two digital mammography systems. Material and methods: Measurements were performed for a Siemens Mammomat Inspiration and a GE Senographe Pristina system. Each was equipped with an automatic exposure control (AEC) for use in a clinical setting. We used a polymethyl methacrylate (PMMA) phantom at thicknesses of 20, 30, 40 and 70 mm to cover the range of scatter conditions expected in mammography, with and without an anti-scatter grid. The Siemens system had an a-Se detector, and the GE system had an indirect-conversion detector. Measurements of Kerma were performed with Piranha Black 657 meter (RTI Electronics AB). The majority of our calculations were automated, using a modified version of our software. Results: For the two mammographic systems evaluated, we characterized physical quality parameters, such as effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), eDQE and eNEQ for a wide range of exposures, phantom thicknesses, with and without an anti-scatter grid. Results are presented as a function of spatial frequency. A contrast-detail analysis was performed with a CDMAM 3.4 phantom with dedicated software (CDMAM analysis 1.5.5, NCCPM) and a set of different PMMA phantoms. Conclusions: We successfully demonstrated that the eNEQ metric can be used as a new option to evaluate image quality for images taken with and without a grid and with phantoms of different thicknesses for the Siemens and GE systems. These results were consistent with the results obtained from CDMAM.

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Determination of DQE as a quantitative assessment of detectors in digital mammography: Measurements and calculation in practice

Wysocka-Rabin Anna, Dobrzyńska Magdalena, Pasicz Katarzyna, Skrzyński Witold, Fabiszewska Ewa

Polish Journal of Medical Physics and Engineering

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2021

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Vol. 27, Iss. 3

223--232

EN

Introduction: Advances in digital detector technology and methods of image presentation in digital mammography now offer the possibility of implementing mathematical assessment methods to quantitative image analysis. The aim of this work was to develop new software to simplify the application of the existing international standard for DQE in digital mammography and show in detail how it can be applied, using a Siemens Mammomat Inspiration as a model. Material and methods: Consistent with the IEC standard a 2 mm Al filter at the tube exit and images in DICOM format as raw data, without applying any additional post-processing were used. Measurements were performed for W/Rh anode/filter combination and different tube voltage values (26 ÷ 34 kV) without any anti-scatter grid. To verify new software doses ranging from 20-600 μGy were used in measurements. Exposure (air kerma) was measured using a calibrated radiation meter (Piranha Black 457, RTI Electronics AB, Sweden). MTF was determined, using an edge test device constructed specifically for this work. Results: It has been demonstrated that with the new software the DQE can be measured with the accuracy required by the international standard IEC 62220-1-2. DQE has been presented as a function of spatial frequency for W/Rh anode/filter combination and different tube voltage. Conclusions: New software was used successfully to analyze image quality parameters for the Siemens Mammomat Inspiration detector. This was done on the basis of an internationally accepted methodology. In the next step, mammographs with different detector types can be compared.

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The threshold contrast thickness evaluated with different CDMAM phantoms and software

Fabiszewska E., Grabska I., Pasicz K.

Nukleonika

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2016

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Vol. 61, No. 1

53--59

EN

The image quality in digital mammography is described by specifying the thickness and diameter of disks with threshold visibility. The European Commission recommends the CDMAM phantom as a tool to evaluate threshold contrast visibility in digital mammography [1, 2]. Inaccuracy of the manufacturing process of CDMAM 3.4 phantoms (Artinis Medical System BV), as well as differences between software used to analyze the images, may lead to discrepancies in the evaluation of threshold contrast visibility. The authors of this work used three CDMAM 3.4 phantoms with serial numbers 1669, 1840, and 1841 and two mammography systems of the same manufacturer with an identical types of detectors. The images were analyzed with EUREF software (version 1.5.5 with CDCOM 1.6. exe fi le) and Artinis software (version 1.2 with CDCOM 1.6. exe fi le). The differences between the observed thicknesses of the threshold contrast structures, which were caused by differences between the CDMAM 3.4 phantoms, were not reproduced in the same way on two mammography units of the same type. The thickness reported by the Artinis software (version 1.2 with CDCOM 1.6. exe fi le) was generally greater than the one determined by the EUREF software (version 1.5.5 with CDCOM 1.6. exe fi le), but the ratio of the results depended on the phantom and diameter of the structure. It was not possible to establish correction factors, which would allow correction of the differences between the results obtained for different CDMAM 3.4 phantoms, or to correct the differences between software. Great care must be taken when results of the tests performed with different CDMAM 3.4 phantoms and with different software application are interpreted.

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Ocena jakości obrazu w mammografii cyfrowej z zastosowaniem fantomu CDMAM

Skrzyński W.

Inżynier i Fizyk Medyczny

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2015

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Vol. 4, nr 2

69--74

PL

Jednym z testów wykonywanych dla mammografów cyfrowych i ucyfrowionych stosowanych w Polsce w skryningu mammograficznym jest ocena jakości obrazu z zastosowaniem fantomu CDMAM. Niepewność wyników tego testu jest wysoka. Różnice pomiędzy poszczególnymi egzemplarzami fantomu oraz stosowanie różnych wersji programu analizującego obrazy mają znaczący wpływ na wyniki. Mimo to należy mieć świadomość, że występujący dla części systemów ucyfrowionych problem z osiągnięciemwyników akceptowalnych oznacza przede wszystkimniską jakość obrazu – niższą niż dla przeciętnego systemu analogowego używanego w skryningu wWielkiej Brytanii wiele lat temu.

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Porównanie wybranych systemów obrazowania cyfrowego w mammografii

Jakubowska T.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2012

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Vol. 18, nr 4

260--266

PL

Mammografia jest najbardziej czułym i specyficznym badaniem w diagnozowaniu raka sutka. Zastosowanie techniki cyfrowej CR (Computed Radiography) i DR (Digital Radiography) ma na celu poprawę jakości obrazów, a co za tym idzie poprawę wykrywalności zmian przy jednoczesnym skróceniu czasu badania i obniżeniu dawki promieniowania. Niniejsza praca przedstawia porównanie stosowanych obecnie w mammografii wybranych systemów cyfrowych pod względem jakości obrazowania, jak również stosowanych dawek.

EN

Mammography is a most sensitive and specific examination used in the breast cancer diagnosis. Digital radiographic systems CR (Computed Radiography) and DR (Digital Radiography) offer the high quality imaging with shorter exposure times, thus lowering the radiation dose. In this paper, the comparison of frequently used mammographic digital systems in terms of the imaging quality and doses applied, is presented.

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Segmentation and feature extraction for reliable classification of microcalcifications in digital mammograms

Wróblewska A., Boniński P., Przelaskowski A., Kazubek M.

Opto-Electronics Review

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2003

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Vol. 11, No. 3

227-235

EN

Microcalcifications are one of more important signs enabling detection of breast cancer at an early stage. The main goal of the research was designing and realization of a system for automatic detection and classification of microcalcifications, taking advantage of the proposed automatic feature selection algorithm. The first step of the detection algorithm is to segment the individual objects : potential microcalcifications. This is achieved by applying opening by reconstruction top-hat technique and image thresholding based on approximation of an image local histogram with a probability density function of Gauss distribution. Selected features of the segmented objects are used as inputs to neural networks. The first classifier verifies the initial detection and the others assess a diagnosis of the input objects. The algorithm results are locations of suggested microcalcifications and optionally automatic diagnosis. The presented form of the system was verified in clinical tests using diagnosed databases (DDSM from the University of South Florida and own digitised database of mammograms). The achieved results are promising and comparable with other known systems. Efficiency of microcalcifications detection was up to 90%.