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KMID : 0357520150380030205
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Journal of Radiological Science and Technology
2015 Volume.38 No. 3 p.205 ~ p.211
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Comparison of Exposure Dose by Using AEC Mode of Abdomen AP Study in Radiography
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Kim Ki-Won
Kwon Yong-Rak
Seo Seong-Won
Kwon Kyung-Tae
Oh Joo-Young
Son Soon-Yong
Son Jin-Hyun
Min Jung-Whan
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Abstract
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We evaluated the effectiveness of TL (Time Limit) method by comparing with NTL (Non-time limit) method when it is used for examinations for abdomen Anterior Posterior (AP) in this paper. The evaluation was conducted based on the comparison of dose, and of signal to noise ratio (SNR) and contrast to ratio (CNR) on both methods. The experiments were conducted with XGEO GC 80 (Samsung, Korea), Unfors ThinX RAD (Unfors, Sweden) and Rando Phantom (Alderson research laboratories, USA) and shielding material with the size of 5.5 × 9 × 0.1 cm3. It was set to activate only two upper ionization chambers in automatic exposure control(AEC) mode and the tube-voltage was set to 80kVp. When the exposure
time was limited, it is limited to 51 msec. The images both by NTL AEC method and TL AEC method were acquired when with and without attachment of shielding material on the upper ionization chambers. The images were evaluated by SNR and CNR which are the image evaluation methods using ‘Image J’. The NTL AEC method showed increases in dose as much as 130.7% at maximum and 80% at minimum than other methods. The TL AEC method showed decreases in mAs and exposure dose than the NTL AEC method as much as 43.8% and 44.4% respectively. There were no significant differences in SNR or CNR for the experiments (p≥0.05). Therefore, it is suggested that the TLAEC mode is more effective
when examining patients who have high BMI index or a patient with a metallic substance in the body after surgery.
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KEYWORD
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Auto Exposure Control (AEC), Signal to Noise Ratio (SNR), Contrast Noise Ratio (CNR)
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