e-Περιοδικό Επιστήμης & Τεχνολογίας

e-Journal of Science & Technology, (e-JST)

Modeling detector performance in digital mammography using the linear cascaded systems approach 

V. Spyropoulou^a,b, N. Kalivas^a,b, A. Gaitanis^a,b, C. Michail^a,b, G. Panayiotakis^b, I. Kandarakis^a*

^a Department Medical Instruments Technology, Technological Educational Institution of Athens, Ag. Spyridonos,

 Aigaleo, 122 10 Athens, Greece

^bDepartment of of Medical Physics, Medical School, University of Patras, 265 00 Patras, Greece

* Corresponding author: kandarakis@teiath.gr

ABSTRACT

Digital x-ray mammography is a modern method for the early detection of breast cancer. The quality of a mammography image depends on various factors, the detector structure and performance being of primary importance. The aim of this work was to develop an analytical model simulating the imaging performance of a new commercially available digital mammography detector. This was achieved within the framework of the linear cascaded systems (LCS) theory. System analysis has allowed the estimation of important image quality metrics such as the Modulation Transfer Function (MTF), the Noise Power Spectrum (NPS), the Detective Quantum Efficiency (DQE) and the Signal to Noise Ratio (SNR). The detector was an indirect detection system consisting of a large area, 100μm thick, CsI:TI scintillator coupled to an active matrix array of amorphous silicon (a-Si:H) photodiodes combined with thin film transistors (TFT). Pixel size was 100μm, while the active pixel dimension was 70μm. MTF and DQE data were calculated for air kerma conditions of 25, 53, 67 μGy using a 28 kVp Mo-Mo x-ray spectrum. In addition, the scintillator thickness was changed in order to find the optimum material characteristics. The theoretical results were compared with published experimental data. The deviation between the theoretical and experimental MTF curves was less than 4%, while the DQE differences were found at an acceptable level.

Keywords: Digital mammography; Image quality;Linear cascaded systems theory; Indirect detectors;

Μοντελοποίηση της απόδοσης ανιχνευτή ψηφιακής μαστογραφίας μέσω της θεωρίας γραμμικών αλληλοδιαδοχικών συστημάτων

Β. Σπυροπούλου^1,2 , Ν. Καλύβας¹ , Α. Γαϊτάνης^1,2 , Χ. Μιχαήλ^1,2 , Γ. Παναγιωτάκης²

και  Ι. Κανδαράκης¹

¹Τμήμα Τεχνολογίας Ιατρικών Οργάνων, ΤΕΙ Αθήνας, Aγ. Σπυρίδωνος, Αιγάλεω,122 10 Αθήνα

²Εργαστήριο Ιατρικής Φυσικής, Σχολή Επιστημών Υγείας, Πανεπιστήμιο Πατρών, 26500 Πάτρα

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