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Effect of scatter and an antiscatter grid on the performance of a slot‐scanning digital mammography system
Author(s) -
Shen Sam Z.,
Bloomquist Aili K.,
Mawdsley Gord E.,
Yaffe Martin J.,
Elbakri Idris
Publication year - 2006
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 - 10.1118/1.2184445
Subject(s) - mammography , optics , materials science , detector , digital mammography , flat panel detector , radiation , dosimetry , nuclear medicine , physics , medicine , cancer , breast cancer
The use of a grid increases perceptibility of low contrast objects in mammography. Slot‐scan mammography provides a more dose efficient reduction of the scattered radiation reaching the detector than obtained with an antiscatter grid in screen‐film or flat‐panel digital mammography. In this paper, the potential of using a grid in a slot‐scan system to provide a further reduction of scattered radiation is investigated. The components of the digital signal: primary radiation, off‐focus radiation, scattered radiation, and optical fluorescence glare in a CsI ( Tl ) detector were quantified. Based on these measurements, the primary and scatter transmission factors ( T p , T s ) , scatter‐to‐primary ratio (SPR), signal‐difference‐to‐noise ratio (SDNR), and the SDNR improvement factor ( K SDNR ) were obtained. Our results showed that the SPR ranged from 0.05 to 0.19 for breast thicknesses between 2 and 8 cm , respectively. The values ofK SDNRranged from 0.85 to 0.94. Because the slot‐scanning system has an inherently low SPR, the increase in dose required when the grid is used outweighs the benefit of the small increase in SDNR. It is possible that greater benefit could be achieved by using a grid with a higherT p , such as obtained using air‐core technology.