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@#The purpose of this study was to evaluate the image quality and diagnostic accuracy of coronary computed tomography angiography (CCTA) using 640-slice scanner. Advancement of multidetector computed tomography (MDCT) technology with higher spatial, temporal resolution, and increasing detector array have improved the image quality and diagnostic accuracy of CCTA. A total of 25 patients (12 men and 13 women) underwent CCTA examination was chosen and data was acquired by 640-slice scanner. All 16 segments of coronary arteries were evaluated by two reviewers using a 4-likert scale for qualitative assessment. In quantitative assessment, the evaluation of 4 main coronary arteries were analysed in terms of signal intensity (SI), image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). All 25 patients with a mean age of 52.88 ± 14.75 years old and body mass index (BMI) of 24.24 ± 3.28 kg/m2 were analysed. In qualitative assessment, from the total of 400 segments, 379 segments (95%) had diagnostic value while 21 segments did not have diagnostic value, which means 5% artefact was detected. In quantitative assessment, there was no statistical differences in gender, race, and BMI (p>0.05). Overall evaluation showed that higher SI at the left main artery (LM) at 393.7 ± 47.19. Image noise was higher at right coronary artery (RCA) at 39.01 ± 13.97. SNR and CNR showed higher at left anterior descending (LAD) with 12.73 ± 5.17 and LM 9.14 ± 4.2, respectively. In conclusion, this study indicates that 640-slice MDCT has higher diagnostic value in CCTA examination with 95% vessel visibility with 5% artefact detection.
RESUMO
@#This study was carried out to compare the effective dose, size specific dose estimation (SSDE) and scan length between genders and between CT scanner with different slice number. A total of 245 set data of radiation dose and scan length for CT scanning procedure involving thorax, abdomen and pelvis regions were obtained retrospectively for comparisons. 111 patients (60 males and 51 females) were scanned using 160-slices CT scanner while 134 patients (71 males and 63 females) were scanned using 640-slices CT scanner. Generally, there were no significant differences in the radiation dose and scan length among genders. However, differences for SSDE in CT thorax and CT thorax-abdomen-pelvis (TAP) protocols exist whereby in CT thorax protocol, 640-slices CT scanner had a significantly higher value of SSDE (9.06±2.67 mGy) than that in 160-slices CT scanner (7.82±1.33 mGy). Similarly to the CT TAP protocol, whereby 640-slices CT scanner had a significantly lower value in SSDE (9.17±1.59 mGy) than that in 160-slices CT scanner (10.76±3.72 mGy). In conclusion, there was no significant difference in the radiation dose and scan length between genders but significant difference was only observed in SSDE due to the presence of body size variation among the study population especially in different CT scanners.
RESUMO
Intravenous urography (IVU) and unenhanced helical computed tomography (UHCT) urography are the two main procedures performed in the radiological investigation for urolithiasis (urinary stone). However, exposure to ionizing radiation is the main concern in both procedures. Therefore, a dose comparison study was conducted between IVU and UHCT urography procedures to determine the optimum exposure parameters in this study. An anthropomorphic whole body phantom was used following the exact procedure of UHCT urography and series of imaging for IVU with an administration of contrast media. Three different exposure parameters were used for IVU with 75 kVp, 80 kVp and 85 kVp while 100 kVp, 120 kVp and 140 kVp for UHCT urography respectively. As a result, the radiation doses for IVU were 1.40 mSv, 2.10 mSv and 2.79 mSv corresponding to 75 kVp, 80 kVp and 85 kVp. On the other hand, the radiation doses for UHCT urography were 0.76 mSv, 1.32 mSv and 1.82 mSv for 100 kVp, 120 kVp and 140 kVp, respectively. However the optimum image was obtained at 85 kVp for IVU and 120 kVp for UHCT urography. In conclusion, the doses obtained from IVU were consistently higher than UHCT urography but not signifi cantly different
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The purpose of this study was to perform a systematic review of the diagnostic accuracy, image quality and radiation dose of prospective electrocardiography (ECG)-triggered coronary computed tomography angiography (CCTA). We searched databases containing studies of CCTA that used prospective ECG-triggering between 2008 and 2011. The effective dose and image quality reported in each study were analysed and compared between the types of multislice CT scanners. We identified 23 studies through this search, with mean assessable coronary segments and effective dose at 96.8% (95% confidence level [CI] 83%, 100%) and 3.6 mSv (95% CI 2.9, 4.3 mSv), respectively. Both quantitative and qualitative assessments of image quality indicated that image quality was achieved in studies using prospective ECG-triggered CCTA, regardless of the type of CT scanners. The pooled estimates of diagnostic values were more than 90% for patient-, vessel- and segment-based assessments. Prospective ECG-triggered CCTA results in high diagnostic accuracy and image quality, with a significantly low radiation dose.