[Spiral CT of the abdomen: weight-adjusted dose reduction].
OBJECTIVE
The influence of weight-adjusted current application in spiral CT of the abdomen on noise was investigated in a clinical study.


METHODS
In 77 routine abdominal CT investigations (120 kV, 8 mm, pitch 1.5) the patients were divided into three body-weight groups A (< 60 kg), B (60-80 kg), and C (> 80 kg). The tube current was randomized prospectively in low weight group A, either 125 mA or 150 mA, in middle and high weight groups B and C, 150, 175 or 200 mA, with a tube revolution time of one second. The noise was measured in liver, skeleton muscle, fat tissue, and bladder content for evaluation of image quality.


RESULTS
The bodyweight groups differ significantly in noise, e.g., in the liver (150 mA): group A: 15.8 HU, group B: 18.9 HU, group C: 21.5 HU. The increase of tube current (150, 175, 200 mA) within a body weight group resulted in a minor decrease of noise (18.9 HU, 17.6 HU, 17.5 HU, respectively, in group B). There is a good correlation of noise with body weight, body mass index and body cross section, but not with body size.


CONCLUSIONS
A body weight adjusted reduction of tube current is possible without an increase of noise.
Institut für Radiologische Diagnostik, Ludwig-Maximilians-Universität München, Klinikum Innenstadt. Eva.Coppenrath@radin.med.uni-muenchen.de
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Coppenrath
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Schmid
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Brandl
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Szeimies
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Hahn
D000273:Adipose Tissue / Q000000981:diagnostic imaging; D001824:Body Constitution; D015992:Body Mass Index; D001835:Body Weight; D003627:Data Interpretation, Statistical; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011860:Radiography, Abdominal / Q000379:methods* / Q000592:standards; D011897:Random Allocation; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards; D001743:Urinary Bladder / Q000000981:diagnostic imaging