Radiation Protection Dosimetry Advance Access originally published online on August 6, 2007
Radiation Protection Dosimetry 2008 128(1):106-111; doi:10.1093/rpd/ncm384
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Comparison between 3-D and z-axis automatic tube current modulation technique in multidetector-row CT
1 Department of Radiological Technology, Kanazawa University Hospital, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8641, Japan
2 Department of Quantum Medical Technology, Kanazawa University, Graduate School of Medical Sciences, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan
3 Department of Radiology, Kanazawa University, Graduate School of Medicine, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8640, Japan
* Corresponding author: matsuk{at}rad.m.kanazawa-u.ac.jp
Received February 23, 2007, amended June 23, 2007, accepted June 26, 2007
In this study, the 3-D automatic tube current modulation (3-D ATCM) technique was compared with the z-axis ATCM technique on multidetector-row CT. Absorbed dose measurements were performed by inserting an ion chamber into the phantoms, and objective image noise shown as the standard deviation of CT value in Hounsfield units was measured on the obtained images. The ratio of absorbed doses with 3-D ATCM technique to z-axis ATCM technique was 94.7% using an elliptical cylinder phantom with an inner cylinder phantom and 96.3% using an elliptical cylinder phantom without an inner cylinder phantom. Differences in objective noise between the 3-D ATCM technique and z-axis ATCM technique were within a tolerable range compared with the setting noise index. Therefore, the 3-D ATCM technique effectively optimises the radiation dose, while maintaining an appropriate image quality compared with z-axis ATCM technique.