Aims and objectives
In recent years,
owing to the developments in CT equipment technology,
it has become possible to reduce the noise introduced by filtered back-projection (FBP),
which had been the method for image reconstruction thus far.
The current image reconstruction method has shifted to utilize iterative approximation reconstruction.
However,
there have also been significant developments in workstation technology,
and an iterative approximation-imaging filter utilizing the total variation method (TV method) that processes images based on the DICOM image output from the CT device,
is now available.
The...
Methods and materials
Scanning and Image Reconstruction
A 320-multi detector CT (Aquilion One Vision Edition,
Toshiba Medical Systems) was used as the CT device and an Aquarius iNtuition Server (TeraRecon,
Inc.) was used as the workstation.
The imaging conditions that were applied comprised capturing images by adjusting the dose measurement in the tube current product time (mAs) values through three steps (20,
35,
and 60 mAs).
We utilized a helical scanning system with the following attributes: collimation: 80 × 0.5 mm; pitch: 0.813; slice thickness: 5.0 mm; number...
Results
Modulation transfer function
The results of the MTF with respect to FBP and FBP images processed using the TV method (three stages of intensity; level 1,
3,
and 5) are displayed in Fig.
4.
We observed no changes in the results of the MTF for FBP and FBP images processed using the TV method.
We obtained the same results regardless of whether there were changes in mAs.
Noise power spectrum
The results of our evaluation of the NPS with respect to FBP and FBP images...
Conclusion
In this study,
we determined that,
because there was no difference in the MTF,
spatial resolution is not influenced by FBP images processed using the TV method.
Based on the results of our evaluation of the NPS,
we determined that because high-frequency sections of images were reduced,
there was no change in the structure of the original image,
and therefore,
noise decreased.
Because there was no significant difference in low-contrast detectability and the raw data used by the CT device for processing is based on...
Personal information
Yamato Shimomiya,
RT
Department of Medical Technology,
Kyushu University Hospital,
Fukuoka,
Japan.
E-mail:
[email protected]
References
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CT image quality improvement using adaptive iterative dose reduction with wide-volume acquisition on 320-detector CT....
