|
KMID : 1131320150170020169
|
|
Journal of Korean Society of Computed Tomographic Technology
2015 Volume.17 No. 2 p.169 ~ p.177
|
|
|
Study of the optimal Low-dose chest CT protocol applied Stellar Detector
|
|
Park Hye-Su
Lee Ki-Baek
Koo Hyun-Jung
|
|
|
Abstract
|
|
|
Purpose : The state-of-the-art “Stellar detector” has been developed to improve detector performance for acquisition of high quality images with reduced radiation dose. The purpose of this study was to compare the performance between Stellar and the conventional detectors, and to find out the optimal low-dose chest CT protocol.
Materials and Methods : 128-MDCT with newly built-in stellar detector, SOMATOM Definition Edge (Siemens, Erlangen, Germany) and 128-MDCT with conventional detector, SOMATOM Definition AS+ (Siemens, Erlangen, Germany) were used in this study. Scan settings were as follows: tube voltage of 100, 120, and 140 kVp, and tube current from 1 Oto 50 mAs in 5-mAs increment. Other parameters were the same as the standard low-dose chest CT protocol. Noise, CNR were analyzed for quantitative evaluation. For qualitative evaluation, two methods were used; radiologist’s interpretation of low-dose chest CT images of Lung Chest Phantom (FLUKE BIOMECAL, RS-330, CLEVELAND), and quantom noise appeared on the high spatial contrast resolution module of AAPM phantom.
Result : In quantitative evaluation, CNR value of SOMATOM Definition Edge was higher than SOMATOM Definition AS+ under all scan settings. P-value was below 0.05 in Paired t-test. So It showed a stastically significant difference. First qualitative evaluation was assessed the image using the following 5-point score. The results of high quality image are as follows: 100kVp/45mAs, 120kVp/20mAs, 140kVp/20mA in SOMATOM Definition Edge and 100kVp/50mAs, 120kVp/25mAs, 140kVp/20mAs in SOMATOM Definition AS+. The results of second evaluation are as follows: we can find many quantum noise at 100kVp/20mAs, 120kVp/15mAs in SOMATOM Definition Edge and 100kVp/25mAs, 120kVp/20mAs, 140kVp/10mAs in SOMATOM Definition AS+.
Conclusion : The optimal protocol for low-dose chest CT was found to be 120 kV/20 mAs and 120 kV/25 mAs for SOMATOM Definition Edge and AS+ scanners, respectively. It can provide 12% increase of CNR and 51% decrease of radiation dose. Stellar detector can provide high quality images with relatively lower radiation dose compared to the conventional detectors.
|
|
|
KEYWORD
|
|
|
Stellar detector, Low dose chest CT, Quantom noise, Dose Optimazation, SOMATOM Definition Edge,
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|