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Technical Note: Comparison of first‐ and second‐generation photon‐counting slit‐scanning tomosynthesis systems
Author(s) -
Berggren Karl,
Cederström Björn,
Lundqvist Mats,
Fredenberg Erik
Publication year - 2018
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 - 10.1002/mp.12735
Subject(s) - detective quantum efficiency , tomosynthesis , optics , optical transfer function , image quality , physics , iterative reconstruction , calibration , collimated light , mammography , computer science , computer vision , image (mathematics) , medicine , cancer , quantum mechanics , breast cancer , laser
Purpose Digital breast tomosynthesis (DBT) is an emerging tool for breast‐cancer screening and diagnostics. The purpose of this study is to present a second‐generation photon‐counting slit‐scanning DBT system and compare it to the first‐generation system in terms of geometry and image quality. The study presents the first image‐quality measurements on the second‐generation system. Method The geometry of the new system is based on a combined rotational and linear motion, in contrast to a purely rotational scan motion in the first generation. In addition, the calibration routines have been updated. Image quality was measured in the center of the image field in terms of in‐slice modulation transfer function (MTF), artifact spread function (ASF), and in‐slice detective quantum efficiency (DQE). Images were acquired using a W/Al 29 kVp spectrum at 13 mAs with 2 mm Al additional filtration and reconstructed using simple back‐projection. Result The in‐slice 50% MTF was improved in the chest‐mammilla direction, going from 3.2 to 3.5 lp/mm, and the zero‐frequency DQE increased from 0.71 to 0.77. The MTF and ASF were otherwise found to be on par for the two systems. The new system has reduced in‐slice variation of the tomographic angle. Conclusions The new geometry is less curved, which reduces in‐slice tomographic‐angle variation, and increases the maximum compression height, making the system accessible for a larger population. The improvements in MTF and DQE were attributed to the updated calibration procedures. We conclude that the second‐generation system maintains the key features of the photon‐counting system while maintaining or improving image quality and improving the maximum compression height.