The purpose of this study was to determine the average size and volume of lungs and to simulate the morphology of internal organs for the development of a Korean adult lung phantom. The body-size data of 2,195 males and 2,293 females aged between 20 and 60 y were included to calculate the average physical dimensions. Two hundred datasets of computed tomography corresponding to the average physique range were collected to measure the average linear dimensions (the length of x, y, and z-axis) of lungs. One set of lung CT images was finally obtained and converted to three-dimensional (3D) format. To confirm the validity of the new lung model, physical lung phantoms were constructed using International Commission on Radiation Units and Measurements (ICRU) density and similar density to what was obtained from the human CT image and then compared with the Lawrence Livermore National Laboratory (LLNL) phantom. The mean size of the chest width and thickness was 31.8 ± 2.8 and 21.4 ± 1.9 cm for males and 28.0 ± 1.6 cm and 19.4 ± 2.0 cm for females, respectively. The standard deviation of the lung dimension in this group was ± 3.0 cm in length, ± 0.8 cm in width, and ± 2.27 cm in depth. The two modified lung phantoms showed highly accurate geometry and linear attenuation coefficient vs. those of the LLNL phantom. The difference in CT number was ± 2% HU for the LLNL phantom and ± 4% HU for the human CT image based on a CT examination conducted using the chest CT protocol. Moreover, both lungs weighed 734 g to 1,246 g, within the range of the reference value of the ICRU report. These results demonstrate that a new lung model based on average linear dimension measurement in a group with average physique simulated the features and physical properties of real human lungs and facilitated further studies for phantom construction.

Objective Autologous bone grafting for cranioplasty is associated with a high infection rate and bone absorption. Synthetic implant materials for cranioplasty have been developed. In this study, we evaluated the efficacy of titanium mesh-type patient-specific implants (PSIs) for patients with skull defects using the dice similarity coefficient (DSC), clinical outcomes, and artifacts caused by implants. Methods This retrospective study included 40 patients who underwent cranioplasty with a titanium mesh PSI at our institution. Based on preoperative and postoperative computed tomography scans, we calculated DSC and artifacts. Results The calculated DSC of 40 patients was 0.75, and the noise was 13.89% higher in the region of interest (ROI) near the implanted side (average, 7.64 hounsfield unit [HU]±2.62) than in the normal bone (average, 6.72 HU±2.35). However, the image signal-to-noise ratio did not significantly differ between the ROI near the implanted side (4.77±1.78) and normal bone (4.97±1.88). The patients showed no significant perioperative complications that required a secondary operation. Conclusion Titanium mesh-type PSIs for cranioplasty have excellent DSC values with lower artifacts and complication rates.

The aim of this study was to assess the effect of exposure factors such as kVp and mA applied by BMI on the image quality and patients absorbed dose of Coronary angiography in CT. Each data sets were into 4groups with different exposure values : Group A at 100kVp, 240mAs, Group B at 120kVp, 240mAs, Group C at 100kVp, 270mAs and Group D at 120kVp, 270mAs, and the mean of the scores of 4 groups was calculated for image quality as 4grades that is, 1(poor), 2(fair), 3(good) and 4(very good). Patient absorbed dose was calculated as DLP on the monitor. In case of absorbed dose, deviation in 2groups at 100kVp was 5.6 mGy·cm, 11 mGy·cm was at 120kVp(DLP) with p<0.05. There was rather difference between groups with 100kVp or 120kVp respectively but the gaps were very little. No significant correlation was found between exposure factors and image quality in any images assessed(p>0.05), and the image quality was sufficient for diagnosis. As we applying coronary angiography, the selection of adequate exposure factors considering BMI identified might be effective for reduction of patient absorbed dose, improvement of image quality and diagnostic accuracy.

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The purposes of this work were to determine the optimal peak voltage for chest computed radiography (CR) using visual grading scores and to compare visual grading characteristics (VGC) and ordinal regression in visual grading analysis. An Afga CR system was used to acquire images of an anthropomorphic chest phantom. Both entrance surface dose and detector surface dose were measured using the Piranha 657 dosimeter. The images were acquired under various voltages from 80 to 120 kVp and exposures from 0.5 to 12.5 mAs. The image qualities were evaluated by 5 experienced radiologists/radiographers based on modified European imaging criteria using 1-5 visual grading scale. The VGC, ordinal regression as well as the conventional visual grading analysis (VGA) were employed for the image quality analysis. Both VGC and ordinal regression yielded the same results with both 100 kVp and 120 kVp producing the best image quality. The image quality of the 120 kVp was slightly higher than that of the 100 kVp but its dose was also higher than that of the 100kVp. On balancing image quality with dose, the 100 kVp should be the optimal kVp for the chest imaging using the Afga CR system. The ordinal regression is a powerful tool in the analysis of image quality using visual grading scores and the VGC can be handled by the ordinal regression.