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Potential for lower absorbed dose in digital mammography: A JAFROC experiment using clinical hybrid images with simulated dose reduction

Magazine article
Authors P. Timberg
M. Ruschin
Magnus Båth
B. Hemdal
I. Andersson
S. Mattsson
D. Chakraborty
R. Saunders
E. Samei
A. Tingberg
Published in Progress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume 6146
Pages 614614
ISSN 1605-7422
Publication year 2006
Published at Institute of Clinical Sciences, Department of Radiation Physics
Pages 614614
Language en
Links dx.doi.org/10.1117/12.653419
Keywords Average glandular dose , Digital mammography , Dose reduction , FROC , Hybrid images , JAFROC
Subject categories Radiological physics, Radiology

Abstract

To determine how image quality linked to tumor detection is affected by reducing the absorbed dose to 50% and 30% of the clinical levels represented by an average glandular dose (AGO) level of 1.3 mGy for a standard breast according to European guidelines. Materials and methods: 90 normal, unprocessed images were acquired from the screening department using a full-field digital mammography (FFDM) unit Mammomat Novation (Siemens). Into 40 of these, one to three simulated tumors were inserted per image at various positions. These tumors represented irregular-shaped malignant masses. Dose reduction was simulated in all 90 images by adding simulated quantum noise to represent images acquired at 50% and 30% of the original dose, resulting in 270 images, which were subsequently processed for final display. Four radiologists participated in a free-response receiver operating characteristics (FROG) study in which they searched for and marked suspicious positions of the masses as well as rated their degree of suspicion of occurrence on a one to four scale. Using the jackknife FROG (JAFROC) method, a score between 0 and 1 (where 1 represents best performance), referred to as a figure-of-merit (FOM), was calculated for each dose level. Results: The FOM was 0.73, 0.70, and 0.68 for the 100%, 50% and 30% dose levels, respectively. Using Analysis of the Variance (ANOVA) to test for statistically significant differences between any two of the three FOMs revealed that they were not statistically distinguishable (p-value of 0.26). Conclusion: For the masses used in this experiment, there was no significant change in detection by increasing quantum noise, thus indicating a potential for dose reduction.

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