Published online before print October 21, 2004, 10.1148/radiol.2333031150
Techniques and Applications of Automatic Tube Current Modulation for CT1
Mannudeep K. Kalra, MD, DNB,
Michael M. Maher, MD, FFR (RCSI), FRCR,
Thomas L. Toth, DSc,
Bernhard Schmidt, PhD,
Bryan L. Westerman, PhD,
Hugh T. Morgan, PhD and
Sanjay Saini, MD
1 From the Division of Abdominal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Wht-270, 32 Fruit St, Boston, MA 02134 (M.K.K., M.M.M.); GE Medical Systems, Waukesha, Wis (T.L.T.); Siemens Medical Solutions, Forchheim, Germany (B.S.); Toshiba America Medical Systems, Tustin, Calif (B.L.W.); Philips Medical Systems, Cleveland, Ohio (H.T.M.); and Department of Radiology, Emory University School of Medicine, Emory University Hospital, Atlanta, Ga (S.S.). Received July 25, 2003; revision requested September 30; final revision received and accepted December 9. Address correspondence to S.S. (e-mail: mannudeep_k_kalra@yahoo.com).
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Figure 1a. Angular modulation with CARE Dose (Siemens Medical Solutions) ATCM technique. (a) Online modulation of tube current is performed at different projections in the x-y plane within each 360° x-ray tube rotation. Thin arrows indicate reduction of tube current relative to higher tube current (thick arrows). (b) Users specify an effective tube current value in milliamperes (circled) to perform scanning with this technique.
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Figure 1b. Angular modulation with CARE Dose (Siemens Medical Solutions) ATCM technique. (a) Online modulation of tube current is performed at different projections in the x-y plane within each 360° x-ray tube rotation. Thin arrows indicate reduction of tube current relative to higher tube current (thick arrows). (b) Users specify an effective tube current value in milliamperes (circled) to perform scanning with this technique.
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Figure 2a. Z-axis modulation with AutomA (GE Medical Systems) ACTM technique. (a) Automatic modulation of tube current from one section location to others in the scanning direction is performed. (b) User selects noise index or enters value for desired noise index and sets minimum and maximum current values. (c) Tube current values (in milliamperes) can be previewed prior to scanning.
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Figure 2b. Z-axis modulation with AutomA (GE Medical Systems) ACTM technique. (a) Automatic modulation of tube current from one section location to others in the scanning direction is performed. (b) User selects noise index or enters value for desired noise index and sets minimum and maximum current values. (c) Tube current values (in milliamperes) can be previewed prior to scanning.
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Figure 2c. Z-axis modulation with AutomA (GE Medical Systems) ACTM technique. (a) Automatic modulation of tube current from one section location to others in the scanning direction is performed. (b) User selects noise index or enters value for desired noise index and sets minimum and maximum current values. (c) Tube current values (in milliamperes) can be previewed prior to scanning.
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Figure 3a. Z-axis modulation with Real E.C. technique (Toshiba Medical). (a) Attenuation is measured on a digital radiograph (left) and is converted to water-equivalent thickness (right), allowing user to specify image quality by choosing different noise levels. (b) After user selects tube current or, more appropriately, desired noise level for the examination (left), the software displays the automatic modulation of tube current that will be used to achieve selected image quality.
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Figure 3b. Z-axis modulation with Real E.C. technique (Toshiba Medical). (a) Attenuation is measured on a digital radiograph (left) and is converted to water-equivalent thickness (right), allowing user to specify image quality by choosing different noise levels. (b) After user selects tube current or, more appropriately, desired noise level for the examination (left), the software displays the automatic modulation of tube current that will be used to achieve selected image quality.
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Figure 4a. Transverse CT scans obtained with AutomA technique (noise index, 15 HU; 75-380 mA; 140 kVp; gantry rotation time, 0.5 second) in a 32-year-old woman with treated lymphoma. (a) Chest image obtained at 136 mA shows satisfactory image quality with soft-tissue algorithm. (b) Pelvic image obtained at 295 mA shows that noise in soft tissue is similar to that in a.
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Figure 4b. Transverse CT scans obtained with AutomA technique (noise index, 15 HU; 75-380 mA; 140 kVp; gantry rotation time, 0.5 second) in a 32-year-old woman with treated lymphoma. (a) Chest image obtained at 136 mA shows satisfactory image quality with soft-tissue algorithm. (b) Pelvic image obtained at 295 mA shows that noise in soft tissue is similar to that in a.
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Figure 5a. Transverse CT images obtained with CARE Dose technique (140 kVp, 0.5-second rotation time, 1:1 pitch) in a 65-year-old woman evaluated for metastases from colon cancer. (a) Chest image obtained at 177 mAs (effective) and (b) abdominal image obtained at 188 mAs (effective) show satisfactory image quality.
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Figure 5b. Transverse CT images obtained with CARE Dose technique (140 kVp, 0.5-second rotation time, 1:1 pitch) in a 65-year-old woman evaluated for metastases from colon cancer. (a) Chest image obtained at 177 mAs (effective) and (b) abdominal image obtained at 188 mAs (effective) show satisfactory image quality.
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Copyright © 2004 by the Radiological Society of North America.
