Multi-detector row spiral CT angiography of the thoracic outlet: dose reduction with anatomically adapted online tube current modulation and preset dose savings.

PURPOSE To evaluate image quality obtained with anatomically adapted online tube current modulation and preset minimum dose savings at multi-detector row spiral computed tomographic (CT) angiography of the thoracic outlet. MATERIALS AND METHODS A total of 100 patients were evaluated for thoracic outlet arterial syndrome with spiral CT angiography (collimation, 4 x 1 mm; pitch, 1.75) both with and without dose reduction by means of anatomically adapted online tube current modulation and preset minimum dose savings. Preset minimum savings of 20% and of 32% were applied in two groups of 50 patients (groups 1 and 2). In each group, low-dose scanning was performed in 25 patients in the neutral position and in 25 patients after postural maneuver. Tube current-time product, noise, presence and quality of graininess and of linear streak artifacts on transverse CT scans, and diagnostic value of sagittal reformations and volume-rendered images were evaluated and recorded for each data set. chi2 test was used to compare frequencies; paired Wilcoxon rank test, to compare subjective and objective image quality scores. P <.05 indicated a significant difference. RESULTS In group 1, mean tube current-time product was 3225 mAs for reference scans and 2101 mAs for low-dose scans (mean reduction, 35%; range, 27%-47%). In group 2, mean was 3070 mAs for reference scans and 2068 mAs for low-dose scans (mean reduction, 33%; range, 17%-38%). In group 1, no differences in frequencies of graininess and linear streaking or in noise level were found between images acquired with or without dose reduction. In group 2, no difference was found in noise level between low-dose and reference scans. On low-dose scans, moderate linear streaking was observed with lower frequency and moderate graininess was observed with higher frequency, but artifacts did not compromise image quality or prevent confident assessment of arterial diameter in the three compartments of the thoracic outlet. CONCLUSION Online tube current modulation with a preset minimum dose saving of 20% allowed 35% reduction in mean tube current-time product, with no loss in image quality.

[1]  D. McCauley,et al.  Low-dose CT of the lungs: preliminary observations. , 1990, Radiology.

[2]  N. Müller,et al.  Low-dose high-resolution CT of lung parenchyma. , 1991, Radiology.

[3]  B. Nelems,et al.  Thoracic outlet syndrome. Thoracic surgery perspective. , 1991, Neurosurgery clinics of North America.

[4]  N L Müller,et al.  High-resolution CT of the chest: radiation dose. , 1993, AJR. American journal of roentgenology.

[5]  J E Aldrich,et al.  Chronic infiltrative lung disease: comparison of diagnostic accuracies of radiography and low- and conventional-dose thin-section CT. , 1994, Radiology.

[6]  Anatomisch adaptierte Variation des Röhrenstroms bei der CT : Untersuchungen zur Strahlendosisreduktion und Bildqualität , 1995 .

[7]  E Grabbe,et al.  [An anatomically adapted variation of the tube current in CT. Studies on radiation dosage reduction and image quality]. , 1995, RoFo : Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin.

[8]  [Dose reduction in computerized tomography with a new scan procedure]. , 1996, Aktuelle Radiologie.

[9]  H. Ohmatsu,et al.  Peripheral lung cancer: screening and detection with low-dose spiral CT versus radiography. , 1996, Radiology.

[10]  K J Lehmann,et al.  [Clinical use of software-controlled x-ray tube modulation with "Smart-Scan" in spiral CT]. , 1997, Aktuelle Radiologie.

[11]  M Ashtari,et al.  Low-dose spiral computed tomography of the thorax: comparison with the standard-dose technique. , 1998, Investigative radiology.

[12]  Holger Greess,et al.  Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers , 1999, European Radiology.

[13]  W A Kalender,et al.  Dose reduction in CT by anatomically adapted tube current modulation. II. Phantom measurements. , 1999, Medical physics.

[14]  O. Miettinen,et al.  Early Lung Cancer Action Project: overall design and findings from baseline screening , 1999, The Lancet.

[15]  T Isomura,et al.  Lung cancer screening: minimum tube current required for helical CT. , 2000, Radiology.

[16]  G. Enríquez,et al.  Low-dose high-resolution CT of the chest in children and young adults: dose, cooperation, artifact incidence, and image quality. , 2000, AJR. American journal of roentgenology.

[17]  H. Greess,et al.  Dose reduction in computed tomography by attenuation-based on-line modulation of tube current: evaluation of six anatomical regions , 2000, European Radiology.

[18]  Ulrich Baum,et al.  Dose reduction in CT examination of children by an attenuation-based on-line modulation of tube current (CARE Dose) , 2002, European Radiology.

[19]  M. V. van Leeuwen,et al.  A rational approach to dose reduction in CT: individualized scan protocols , 2001, European Radiology.

[20]  J. Remy,et al.  Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation , 2001, European Radiology.

[21]  E. Zager,et al.  Thoracic Outlet Syndrome , 2004, Neurosurgery.