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Title: AEC for scanning digital mammography based on variation of scan velocity

Abstract

A theoretical evaluation of nonuniform x-ray field distributions in mammography was conducted. An automatic exposure control (AEC) is proposed for a scanning full field digital mammography system. It uses information from the leading part of the detector to vary the scan velocity dynamically, thus creating a nonuniform x-ray field in the scan direction. Nonuniform radiation fields were also created by numerically optimizing the scan velocity profile to each breast's transmission distribution, with constraints on velocity and acceleration. The goal of the proposed AEC is to produce constant pixel signal-to-noise ratio throughout the image. The target pixel SNR for each image could be set based on the breast thickness, breast composition, and the beam quality as to achieve the same contrast-to-noise ratio between images for structures of interest. The results are quantified in terms of reduction in entrance surface air kerma (ESAK) and scan time relative to a uniform x-ray field. The theoretical evaluation was performed on a set of 266 mammograms. The performance of the different methods to create nonuniform fields decreased with increased detector width, from 18% to 11% in terms of ESAK reduction and from 30% to 25% in terms of scan time reduction for the proposed AECmore » and detector widths from 10 to 60 mm. Some correlation was found between compressed breast thickness and the projected breast area onto the image field. This translated into an increase of the ESAK and decrease of the scan time reduction with breast thickness. Ideally a nonuniform field in two dimensions could reduce the entrance dose by 39% on average, whereas a field nonuniform in only the scanning dimension ideally yields a 20% reduction. A benefit with the proposed AEC is that the risk of underexposing the densest region of the breast can be virtually eliminated.« less

Authors:
; ; ;  [1]
  1. Department of Physics, Royal Institute of Technology, AlbaNova, 106 91, Stockholm (Sweden)
Publication Date:
OSTI Identifier:
20726900
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 32; Journal Issue: 11; Other Information: DOI: 10.1118/1.2089487; (c) 2005 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BIOMEDICAL RADIOGRAPHY; DOSIMETRY; EVALUATION; IMAGES; KERMA; MAMMARY GLANDS; PERFORMANCE; RADIATION DOSES; SIGNAL-TO-NOISE RATIO; THICKNESS; X RADIATION

Citation Formats

Aaslund, Magnus, Cederstroem, Bjoern, Lundqvist, Mats, Danielsson, Mats, and Sectra Mamea AB, Kistaga ring ngen 2, 164 40 Kista. AEC for scanning digital mammography based on variation of scan velocity. United States: N. p., 2005. Web. doi:10.1118/1.2089487.
Aaslund, Magnus, Cederstroem, Bjoern, Lundqvist, Mats, Danielsson, Mats, & Sectra Mamea AB, Kistaga ring ngen 2, 164 40 Kista. AEC for scanning digital mammography based on variation of scan velocity. United States. https://doi.org/10.1118/1.2089487
Aaslund, Magnus, Cederstroem, Bjoern, Lundqvist, Mats, Danielsson, Mats, and Sectra Mamea AB, Kistaga ring ngen 2, 164 40 Kista. 2005. "AEC for scanning digital mammography based on variation of scan velocity". United States. https://doi.org/10.1118/1.2089487.
@article{osti_20726900,
title = {AEC for scanning digital mammography based on variation of scan velocity},
author = {Aaslund, Magnus and Cederstroem, Bjoern and Lundqvist, Mats and Danielsson, Mats and Sectra Mamea AB, Kistaga ring ngen 2, 164 40 Kista},
abstractNote = {A theoretical evaluation of nonuniform x-ray field distributions in mammography was conducted. An automatic exposure control (AEC) is proposed for a scanning full field digital mammography system. It uses information from the leading part of the detector to vary the scan velocity dynamically, thus creating a nonuniform x-ray field in the scan direction. Nonuniform radiation fields were also created by numerically optimizing the scan velocity profile to each breast's transmission distribution, with constraints on velocity and acceleration. The goal of the proposed AEC is to produce constant pixel signal-to-noise ratio throughout the image. The target pixel SNR for each image could be set based on the breast thickness, breast composition, and the beam quality as to achieve the same contrast-to-noise ratio between images for structures of interest. The results are quantified in terms of reduction in entrance surface air kerma (ESAK) and scan time relative to a uniform x-ray field. The theoretical evaluation was performed on a set of 266 mammograms. The performance of the different methods to create nonuniform fields decreased with increased detector width, from 18% to 11% in terms of ESAK reduction and from 30% to 25% in terms of scan time reduction for the proposed AEC and detector widths from 10 to 60 mm. Some correlation was found between compressed breast thickness and the projected breast area onto the image field. This translated into an increase of the ESAK and decrease of the scan time reduction with breast thickness. Ideally a nonuniform field in two dimensions could reduce the entrance dose by 39% on average, whereas a field nonuniform in only the scanning dimension ideally yields a 20% reduction. A benefit with the proposed AEC is that the risk of underexposing the densest region of the breast can be virtually eliminated.},
doi = {10.1118/1.2089487},
url = {https://www.osti.gov/biblio/20726900}, journal = {Medical Physics},
issn = {0094-2405},
number = 11,
volume = 32,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}