AJR:197, August 2011 367
diosensitive organs—lung, bone marrow,
and breast—are within the scan range [6].
Guidelines established in 2008 suggest
higher breast radiosensitivity than previously
thought [7]. The International Commission on
Radiological Protection has recommended a
140% increase in tissue-weighting factors for
the breast, from 0.05 to 0.12 [6]. An increased
incidence of breast cancer has already been
identified in populations exposed to radiation
[8–10]. Therefore, techniques to minimize
breast tissue radiation by optimizing CT tech-
nique would be beneficial [11, 12].
Coronary CTA typically includes most of
the breast tissue within its scan range, expos-
ing the breasts to radiation even though the
Breast Surface Radiation Dose
During Coronary CT Angiography:
Reduction by Breast Displacement
and Lead Shielding
Shane J. Foley
1
Mark F. McEntee
1
Stephan Achenbach
2
Patrick C. Brennan
3
Louise S. Rainford
1
Jonathan D. Dodd
4
Foley SJ, McEntee MF, Achenbach S, Brennan PC,
Rainford LS, Dodd JD
1
School of Medicine and Medical Science, University
College Dublin, Dublin, Ireland.
2
Department of Cardiology, University of Erlangen,
Erlangen, Germany.
3
Faculty of Health Sciences, University of Sydney,
Lidcombe New South Wales, Australia.
4
Department of Radiology, St Vincent’s University
Hospital, Elm Park, Dublin 4, Ireland. Address
correspondence to J. D. Dodd.
CardiopulmonaryImaging•OriginalResearch
AJR 2011; 197:367–373
0361–803X/11/1972–367
© American Roentgen Ray Society
C
linical acceptance of coronary
CT angiography (CTA) contin-
ues to increase. Two studies with
results published in 2008 [1, 2]
showed consistently high sensitivity and neg-
ative predictive value in the detection of ob-
structive coronary artery disease. Despite
the rapidly evolving technology of coronary
CTA and the increasing applications, radia-
tion dose continues to be a concern [3]. De-
pending on CT scanner capability and the
protocol applied, total effective doses during
coronary CTA vary from 2.1 to 21.4 mSv [4,
5]. These doses are among the highest deliv-
ered in diagnostic radiology and are of par-
ticular concern because three of the most ra-
Keywords: breast neoplasms, CT, epidemiology, radiation
dose, women
DOI:10.2214/AJR.10.4569
Received March 7, 2010; accepted after revision
January 10, 2011.
OBJECTIVE. The purpose of this study was to prospectively evaluate the effect of cra-
nial breast displacement and lead shielding on in vivo breast surface radiation dose in women
undergoing coronary CT angiography.
SUBJECTSANDMETHODS. Fifty-four women (mean age, 59.2 ± 9.8 years) pro-
spectively underwent coronary 64-MDCT angiography for evaluation of chest pain. The pa-
tients were randomly assigned to a control group (n = 16), breast displacement group (n =
22), or breast displacement plus lead shielding group (n = 16). Thermoluminescent dosime-
ters (TLDs) were placed superficially on each breast quadrant and the areolar region of both
breasts. Breast surface radiation doses, the degree of breast displacement, and coronary im-
age quality were compared between groups. A phantom dose study was conducted to com-
pare breast doses with z-axis positioning on the chest wall.
RESULTS. A total of 1620 TLD dose measurements were recorded. Compared with con-
trol values, the mean breast surface dose was reduced 23% in the breast displacement group
(24.3 vs 18.6 mGy, p = 0.015) and 36% in the displacement plus lead shielding group (24.3 vs
15.6 mGy, p = 0.0001). Surface dose reductions were greatest in the upper outer (displacement
alone, 66%; displacement plus shielding, 63%), upper inner (65%, 58%), and areolar quad-
rants (44%, 53%). The smallest surface dose reductions were recorded for A-cup breasts: 7%
for the displacement group and 3% for the displacement plus lead group ( p = 0.741). Larger
reductions in surface dose were recorded for B-cup (25% and 56%, p = 0.273), C-cup (38%
and 60%, p = 0.001), and D-cup (31% and 25%, p = 0.095) sizes. Most of the patients (79%)
had either good (> 50% of breast above scan range) or excellent (> 75% of breast above the
scan range) breast displacement. No significant difference in coronary image quality was
detected between groups. The phantom dose study showed that surface TLD measurements
were underestimates of absorbed tissue dose by a mean of 9% and that a strong negative cor-
relation exists between the amount of cranial displacement and breast dose.
CONCLUSION. Use of breast displacement during coronary CTA substantially reduces
the radiation dose to the breast surface.
Foley et al.
Breast Dose During Coronary CTA
Cardiopulmonary Imaging
Original Research
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