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Objective:To compare the differences in radiation dose and image quality between cone-beam CT (CBCT) and multi-slice spiral CT (MSCT) applied to atlantoaxial spine imaging.Methods:Head and neck phantom was scanned at 30 exposure parameter combinations using Pramerica CBCT scanner and 15 parameter combinations using Toshiba 320-row MSCT. The effective dose ( E) of CBCT was calculated based on the Monte Carlo dose estimation software PCXMC, the E value of MSCT was obtained by multiplying the dose length product (DLP) by the related factor. t-test for two independent samples or Wilcoxon rank sum test were used for comparison of radiation dose and subjective and objective image quality between two modalities. The subjective evaluation was a 5-point subjective scale using double-blind method for edge sharpness, contrast, soft tissue level, and artifacts of the images. The signal and noise in the region of interest (ROI) were measured and the contrast signal-to-noise ratio (CNR) was calculated. Results:For radiation dose, the volumetric dose index and E values of 2.9 mGy and 27.61 μSv for CBCT were lower than those of 8.8 mGy and 433.16 μSv for MSCT, and the differences were statistically significant( z=-3.05, -5.25, P<0.05). For objective evaluation of image quality, the noise and CNR were 27.74 HU and 3.69 in CBCT group, 7.84 HU and 27.1 in MSCT group. The difference between them were statistically significant( z=-5.39, -5.42, P<0.05). The overall image quality, contrast and artifact scores of the CBCT group were 3.5, 3.0 and 5 were higher than those of the MSCT group at 2.0, 2.0, and 4.0, respectively ( z=-2.32, -2.46, -3.31, P<0.05). Conclusions:Both atlantoaxial CBCT and MSCT scans provide image quality that meets diagnostic requirements. Compared to MSCT, CBCT atlantoaxial scans can effectively reduce radiation dose according to the principle of optimization of radiation protection.
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Objective To explore the effects of different processing parameters of mobile digital radiography (DR) on image quality of bedside chest radiography.Methods Post processing parameter on 150 cases bedside DR chest image like multi frequency laplasse transform (MLT),image processing (IP) were modified,and the optimization scheme of post-processing parameters were analyzed and summarized.The paired sample t test was used to compare the difference of the imaging quality score and optical density between the default parameter group and the post processing parameter optimization group through measure the optical density of lung related area.Results Brightness,contrast and the low density in dynamic range were the main factors affecting the quality of bedside chest radiography.After modifying and optimizing the post-processing parameters,the density value of the second intercostal area was 1.68±0.04,the density value of the hilum was 0.77±0.46,the density value of pulmonary peripheral (near chest wall 1 cm and overlap with a single rib) was 0.62± 0.06,the density value of cardiac shadow was 0.44 ± 0.04,the density value of subphrenic was 0.37 ± 0.04,the lung markings was clearly showed in the lateral field of lung and was visible in the spine and heart shadow area which meet the diagnostic requirement.The density value of those parts before modify were lower than the modify value which was more closer to the reference density value,and the difference had statistically significant.The image quality score of the postprocessing parameter optimization group was 3.53 ± 0.14,which was higher than 3.02 ± 0.23 of the default parameter group,and the difference had statistically significant.Conclusion The appropriate post-processing parameters is the key to guarantee the reasonable density of lung areas image quality and the optimization post-processing parameter can improve the image quality of bedside chest radiography by the mobile DR.
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Objective To explore the optimal dose ratio set in the hip digital tomosynthesis (DTS),and to reduce patient's examination dose as low as possible.Methods Ninety patients who received hip DTS examination were randomly divided into 3 groups,with the dose ratio as 6,7 and 8,respectively.One-way ANOVA test was used to compare.the image quality and radiation dose among 3 groups.Results The values of entrance surface dose (ESD),dose-area product (DAP) and image quality score of 3 groups were [(3.76 ± 1.89) mGy,(18.41 ± 11.71) dGy·cm2,3.03 ± 0.24],[(5.24±2.76)mGy,(26.99±13.34)dGy·cm2),3.60±0.11],and [(6.39±1.75)mGy,(36.96± 22.49) dGy· cm2,3.64 ± 0.09],respectively.The difference among three groups was statistically significant (F =10.94,9.45,139.26,P ＜ 0.05).The S-N-K test showed that both ESD values and DAP values in 6,7,and 8 time-dose ratio group was from small to large.The image quality score of 6 time-dose ratio group was lower than that of the other groups with no significant difference.Conclusions Dose ratio is one of the important parameters to result in the radiation dose of DTS.Dose ration 7 is optimal in hip DTS,which could match the image quality and radiation dose best and finally protect patients from unnecessary radiation damage.
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Purpose To compare the wireless flat-panel detector with gadolinium oxide coating in X-ray photography in the small joints of the limbs compared with conventional flat panel detector with cesium iodide coating. Materials and Methods Comparison was randomly performed between gadolinium oxide coated sulfur wireless flat-panel detector and cesium iodide coated conventional flat-panel detector for 80 patients who received routine X-ray photography, and scoring data were applied with statistical analysis. Results There was no significant difference between the scoring data from two film-reading people (P>0.05). The resolution of anatomical structure of small joint of limbs and tube current showed no significant difference for two types of imaging systems (P>0.05). Conclusion Wireless flat panel detector sulfur with gadolinium oxide coatings can obtain satisfactory image quality at a reasonable inspection doses in the X-ray photography of small joint of limbs. The imaging quality and inspection doses are similar to conventional flat panel detector device with cesium iodide coating, but the posture is more convenient.