Prospective gating with 320-MDCT angiography: effect of volume scan length on radiation dose.
OBJECTIVE
The purpose of this study was to evaluate the relation between radiation dose reduction and volume scan length for prospectively ECG-gated 320-MDCT angiography in the diagnosis of coronary artery disease.


METHODS
MDCT with prospective ECG gating was performed at one of the three volume scan lengths depending on heart length. Of 175 patients, 95 (55%; body mass index, 29 ± 5.9; mean heart rate, 59 ± 7 beats/min) underwent scanning at 160 mm; 46 (26%; body mass index, 30 ± 4.1; mean heart rate, 56 ± 5.74 beats/min) at 140 mm; and 34 (19%; body mass index, 30 ± 3.71; mean heart rate, 58 ± 3.96 beats/min) at 120 mm.


RESULTS
The median radiation doses were 6.5 mSv (95% CI, 6.03-7.2 mSv) for the 95 patients who underwent scanning at a volume scan length of 160 mm, 4.33 mSv (95% CI, 4.06-6.62 mSv) for the 46 patients who underwent scanning at 140 mm, and 3.47 mSv (95% CI, 3.15-3.62 mSv) for the 34 patients who underwent scanning at 120 mm. The reduction in scan length from 160 to 140 mm represented a reduction in scan length of 12.5% and the reduction to 120 mm a reduction of 25%. The median radiation dose was reduced 33% when volume scan length was changed to 140 mm and 47% when the length was changed to 120 mm.


CONCLUSIONS
Dose optimization remains an important concern in cardiac CT, and for 320-MDCT angiography, substantial dose reduction can be achieved by reducing volume scan length so that it is in concert with the patient's heart length.
Department of Radiology, Harvard Medical School, Beth Israel Deaconess Medical Center, 1 Deaconess Rd., WCC 308A, Boston, MA 02215, USA.
Atif
A
Khan
Khurram
K
Nasir
Faisal
F
Khosa
Amina
A
Saghir
Sheryar
S
Sarwar
Melvin E
ME
Clouse
D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
J Am Coll Cardiol. 2006 May 2;47(9):1840-5
16682310
Ann Intern Med. 2006 Sep 19;145(6):407-15
16983128
N Engl J Med. 2007 Nov 29;357(22):2277-84
18046031
J Am Coll Cardiol. 2008 Nov 18;52(21):1724-32
19007693
Radiology. 2008 Mar;246(3):742-53
18195386
Radiology. 2008 Feb;246(2):384-93
18180337
Circulation. 2003 Feb 18;107(6):917-22
12591765
Circulation. 2009 Sep 8;120(10):867-75
19704093
Health Phys. 2008 Nov;95(5):508-17
18849683
Emerg Radiol. 2010 Jan;17(1):31-5
19468764
Radiology. 2008 Aug;248(2):431-7
18552312
AJR Am J Roentgenol. 2009 Oct;193(4):955-63
19770316
Eur J Radiol. 2010 Jul;75(1):e51-6
19671491
Acad Radiol. 2009 Jan;16(1):15-21
19064207
Br J Radiol. 2007 Aug;80(956):657-67
17762056
Circulation. 2006 Mar 14;113(10):1305-10
16520411
JAMA. 2009 Feb 4;301(5):500-7
19190314
J Electrocardiol. 2007 Nov-Dec;40(6 Suppl):S118-22
17993308
Abdom Imaging. 2003 Jan-Feb;28(1):110-4
12483398
JAMA. 2009 Jun 10;301(22):2340-8
19509381
AJR Am J Roentgenol. 2008 Feb;190(2):335-43
18212218
J Am Coll Cardiol. 2006 Nov 7;48(9):1896-910
17084268
N Engl J Med. 2008 Nov 27;359(22):2324-36
19038879
Br J Radiol. 1998 Jan;71(841):1-3
9534691
Eur Radiol. 2003 Dec;13(12):2560-6
14569412
Int J Cardiol. 2009 Mar 6;132(3):435-6
18068237
AJR Am J Roentgenol. 2009 Mar;192(3):635-8
19234258
Int J Cardiovasc Imaging. 2010 Jan;26(1):99-107
19898955
Eur Radiol. 2009 May;19(5):1132-8
19137305
AJR Am J Roentgenol. 2004 Apr;182(4):849-59
15039151
Proc Am Thorac Soc. 2007 Aug 1;4(4):316-20
17652493
Circulation. 2009 Feb 24;119(7):1056-65
19188512
Radiology. 2009 Dec;253(3):672-80
19864512
Radiology. 2009 Feb;250(2):604-5
19188331
J Radiol Prot. 2000 Dec;20(4):353-9
11140709
Int J Cardiovasc Imaging. 2009 Apr;25 Suppl 1:23-9
19255875
JAMA. 2007 Jul 18;298(3):317-23
17635892
Radiology. 2008 Sep;248(3):995-1003
18710988