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Dose reduction in CT by anatomically adapted tube current modulation. I. Simulation studies
Author(s) -
Gies Michael,
Kalender Willi A.,
Wolf Heiko,
Suess Christoph,
Madsen Mark T.
Publication year - 1999
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598779
Subject(s) - attenuation , modulation (music) , amplitude modulation , amplitude , noise (video) , imaging phantom , noise reduction , image noise , reduction (mathematics) , optical transfer function , root mean square , phase modulation , frequency modulation , optics , physics , materials science , acoustics , mathematics , phase noise , computer science , telecommunications , geometry , bandwidth (computing) , quantum mechanics , artificial intelligence , image (mathematics)
Tube current modulation governed by x‐ray attenuation during CT (computed tomography) acquisition can lead to noise reduction which in turn can be used to achieve patient dose reduction without loss in image quality. The potential of this technique was investigated in simulation studies calculating both noise amplitude levels and noise distribution in CT images. The dependence of noise on the modulation function, amplitude of modulation, shape and size of the object, and possible phase shift between attenuation and modulation function were examined. Both sinusoidal and attenuation‐based control functions were used to modulate tube current. Noise reduction was calculated for both ideal systems and for real systems with limited modulation amplitude. Dose reductions up to 50% can be achieved depending on the phantom geometry and tube current modulation function. Attenuation‐based tube current modulation yields substantially higher reduction than fixed‐shape modulation functions. Optimal results are obtained when the current is modulated as a function of the square root of attenuation. A modulation amplitude of at least 90% should be available to exploit the potential of these techniques.