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TU‐EE‐A4‐04: A New Antiscatter Grid for High‐Resolution Region‐Of‐Interest (ROI) X‐Ray Imaging
Author(s) -
Yadava G,
Rudin S,
Kuhls A,
Bednarek D
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2761407
Subject(s) - imaging phantom , flat panel detector , optics , grid , image resolution , detector , materials science , image quality , pixel , dot pitch , medical imaging , nuclear medicine , physics , computer science , artificial intelligence , medicine , mathematics , geometry , image (mathematics)
Purpose: A new custom‐designed antiscatter grid for high‐resolution angiographic detectors is presented that would improve the image quality without introducing substantial grid‐line artifacts. Method and Materials: The new antiscatter grid is a custom‐made, parallel‐focus, crisscross cellular grid that employs gold septa material (CREATV MicroTech, Potomac, MD). The prototype 4.25 cm × 4.25 cm field‐of‐view grid has 20 μm thick septa with interspace distance of 380 μm, height 1.95 mm, and grid‐ratio of 5. This study was performed with the Microangiographic detector (43 μm pixel, 1024×1024 pixel matrix, 4.5 cm × 4.5 cm field‐of‐view, 250‐μm‐thick structured CsI(Tl) scintillator coupled to a CCD camera via minifying taper) in simulated neurovascular angiographic conditions, where a uniform head‐equivalent phantom was used as scattering media. The air‐gap between the phantom and the detector‐with‐grid was kept at 2.5 cm as used in clinical conditions for minimal blurring, but increased scatter. The standard lead‐beam‐stop technique was employed to determine the scatter‐fraction with and without the grid. In order to evaluate the low‐contrast imaging performance of the grid, phantoms with three different bone patterns of varying thickness and three different simulated iodinated vessel inserts in acrylic were imaged with and without‐grid at 70 kVp. Results: The grid demonstrated approximately 59% scatter reduction at 70 kVp for the uniform head‐equivalent phantom without introducing substantial grid‐line artifacts following flat‐field correction. The average contrast‐improvement‐factor for the low‐contrast vessel‐phantom was found to be 1.75, whereas for the relatively higher contrast bone‐phantom it was 1.5. The primary transmission factor was measured to be 66%. Conclusion: The grid demonstrated significant scatter reduction when used in simulated neurovascular angiographic conditions even for the small FOV. Use of this grid with the Micro‐angiographic detector with reduced air‐gap can provide substantially improved image quality. (Partial support: NIH R01‐NS43924, R01‐EB002873, Toshiba Medical System Corp.)