Automatic exposure control at single- and dual-heartbeat CTCA on a 320-MDCT volume scanner: Effect of heart rate,exposure phase window setting,and reconstruction algorithm |
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| Institution: | 1. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan;2. Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan;3. The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, USA;4. Department of Radiology, Kumamoto University Hospital, Kumamoto, Japan;1. Heart & Vascular Center, Medical University of South Carolina, Charleston, SC, USA;2. The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore, MD, USA;3. The Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA;4. Cardiac MR PET CT Program, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA;5. Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany;6. Department of Cardiology and Intensive Care Medicine, Heart Centre Munich-Bogenhausen, Munich, Germany;7. Department of Radiology, University of Munich, Grosshadern Campus, and Munich Heart Alliance, Munich, Germany;8. Department of Radiology, University of Tuebingen, Germany;1. Department of Cardiovascular Medicine, Beaumont Health System, 3601 W 13 Mile Road, Royal Oak, MI 48073, USA;2. Oakland University William Beaumont School of Medicine, Rochester, MI, USA;3. Beaumont Health Research Institute, Royal Oak, MI, USA;4. Section of Allergy and Immunology, Department of Medicine, Beaumont Health System, 3601 W 13 Mile Road, Royal Oak, MI 48073, USA;1. Section of Urologic Oncology, Rutgers Cancer Institute of New Jersey and Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ;2. Department of Radiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ;1. Discipline of Thoracic and Cardiovascular Surgery, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil;2. Department of Radiology, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil;3. Discipline of Thoracic and Cardiovascular Surgery, School of Medicine, University of São Paulo, São Paulo, SP, Brazil;1. Department of Medical Imaging, Chung Shan Medical University Hospital, No. 110, Sec. 1, Chien-Kuo N. Rd., Taichung 402, Taiwan;2. School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, No. 110, Sec. 1, Chien-Kuo N. Rd., Taichung 402, Taiwan;3. Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, 259, Wen-Hwa 1st Rd., Kwei-Shan, Taoyuan 333, Taiwan;4. Healthy Aging Research Center, Chang Gung University, Taoyuan 333, Taiwan |
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| Abstract: | PurposeTo investigate whether electrocardiogram (ECG)-gated single- and dual-heartbeat computed tomography coronary angiography (CTCA) with automatic exposure control (AEC) yields images with uniform image noise at reduced radiation doses.Materials and methodsUsing an anthropomorphic chest CT phantom we performed prospectively ECG-gated single- and dual-heartbeat CTCA on a second-generation 320-multidetector CT volume scanner. The exposure phase window was set at 75%, 70–80%, 40–80%, and 0–100% and the heart rate at 60 or 80 or corr80 bpm; images were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR, adaptive iterative dose reduction 3D). We applied AEC and set the image noise level to 20 or 25 HU. For each technique we determined the image noise and the radiation dose to the phantom center.ResultsWith half-scan reconstruction at 60 bpm, a 70–80% phase window- and a 20-HU standard deviation (SD) setting, the imagenoise level and -variation along the z axis manifested similar curves with FBP and IR. With half-scan reconstruction, the radiation dose to the phantom center with 70–80% phase window was 18.89 and 12.34 mGy for FBP and 4.61 and 3.10 mGy for IR at an SD setting SD of 20 and 25 HU, respectively. At 80 bpm with two-segment reconstruction the dose was approximately twice that of 60 bpm at both SD settings. However, increasing radiation dose at corr80 bpm was suppressed to 1.39 times compared to 60 bpm.ConclusionAEC at ECG-gated single- and dual-heartbeat CTCA controls the image noise at different radiation dose. |
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| Keywords: | Automatic exposure control (AEC) Single- and dual-heartbeat CTCA Image noise Radiation reduction 320-Detector volume scanner |
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