Objective To explore the feasibility of children age dependent chest tube voltage settings for optimizing radiation dose and image quality in digital radiography (DR). Methods Children aged 0 to 14 who visited the First Affiliated Hospital of Xinjiang Medical University from January, 2008 to December, 2010, were divided into the following 5 age groups: 0~, 1~, 3~, 7~, and 11~14-year-old, and each group was then randomly assigned to the optimization and control groups to take DR by computer. DR in automatic exposure control with different tube voltage depending on children age; the control group: DR in automatic exposure control with conventional fixed tube voltage. The dose area product (DAP) was adopted for the measurement of radiation dose, while the visual grading analysis score (VGAS) was for image quality. Then SPSS 17.0 was applied for statistical analysis. Results A total of 2 450 children were initially included. Finally there were 2 415 children included in the anteroposterior chest image in this study, and the other 35 children were excluded for their anatomical characteristics could not be showed due to serious primary diseases. There were 1 202 patients in the optimization group and 1 213 patients in the controlled group. The mean DAP in the optimization group was lower than that in the control group with a significant difference (t= –4.967, P=0.008). The mean VGAS in the optimization group was higher than that in the control group with a significant difference (t= 23.738, P=0.000). Conclusion Children age dependent tube voltage settings can effectively reduce radiation dose and improve image quality at the same time.
Objective To optimize image quality and radiation dose of infant chest digital radiography and to explore feasibility of reducing tube voltage and adjusting according to infant chest area. Methods 0 to 3-year-old infants were randomly divided into two average groups of 0- and 1-3 year-old, and then each age group was randomly assigned to optimization and control groups in digital radiography. Measurement of radiation dose used dose area product (DAP). Mean DAP between groups was compared by using t test, and the image quality of optimization was compared by rank sum test. Results A total of 400 cases of 0 to 3-year-old infants were identified, and finally 391 cases of infants anteroposterior chest image were included, including 196 cases in the optimization group (0-years: n=91; 1-3 years: n=105) and 195 cases in the control group (0-years: n=103; 1-3 years: n=92). The results showed: there were significant differences in the mean DAP in 0-years, 1-3 years and total infants between the optimization group and the control group (all P valuelt;0.05). The DAP of the optimization group was lower, and reduction of DAP was approximately 21.6% compared to the control subject. The Wilcoxon signed-rank test showed the difference of subjective evaluation of image quality was significantly different (P=0.000). High-quality image of the optimization group increased approximately 43.9% more than control subject. Conclusion Reducing tube voltage and adjusting according to infants chest area can not only reduce the radiation dose but also improve image quality in digital radiography.
Objective To investigate the effects of X-ray dose on the expressions of microRNA-221 （miR-221） and phosphatase and a tensin homolog deleted from chromosome10 （PTEN） in human colorectal carcinoma （CRC） cells. Methods Human CRC-derived cell line， Caco2， was cultured conventionally. The cells were divided into five groups and exposed to different doses of X-ray （0， 2， 4， 6， and 8 Gy） respectively. The total RNA and protein of the Caco2 cells were extracted after irradiation， and the miR-221 and PTEN mRNA expressions were detected by real-time RT-PCR.Moreover， the protein alteration of PTEN in Caco2 cells was detected by Western-blot analysis. Results The radiation dose of X-ray significantly affected the expressions of miR-221 and PTEN protein in human Caco2 cells in a dose-depen-dent manner. Moreover， the miR-221 expression level was up-regulated gradually with the increase of irradiation dose， on the contrary， the PTEN protein expression level was down-regulated gradually （P＜0.01）. Conclusion The radiation dose can affect the miR-221 and PTEN protein expression pattern in CRC cells.
ObjectiveTo investigate the influence of 70 kV low-dose CT perfusion technique on brain CT perfusion parameter maps and image quality. MethodsRetrospective analysis of all patients who underwent CT perfusion of brain between October 2013 and February 2014 was carried out. The patients were randomly divided into two groups according to diTherent CT examination dose: group A (80 kV, 200 mAs) and group B (70 kV, 200 mAs). All patients were scanned on a dual-source-CT (Siemens Definition Flash). Fifteen normal subjects without brain diseases in each group were selected to be studied. Region of interest (ROI) with an area of 80 mm2 was placed in the nucleus, putamen, thalamus, periventricular white matter of the frontal lobe and temporo-occipital area, and the parameters in the ROI including cerebral blood flow, cerebral blood volume, mean transit time and time to peak were detected. The carrierto-noise ratio and signal-to-noise ratio of thalamus and periventricular white matter of the frontal lobe were contrasted. The image quality of perfusion was assessed by two senior radiologists using 5 point system for blind assessment (5=best, 1=worst). The measurement of radiation dose was studied through effective dose, volume CT dose index (CTDIVOL) and dose length product (DLP). Statistical analysis was performed by independent sample t test. ResultsThere was no significant difference between group A and group B in brain CT perfusion parameters (P>0.05). There was no significant diTherence in image quality between the two groups in the objective and subjective assessment (P>0.05). In comparison with group A, the measured effective dose, CTDIVOL and DLP for group B decreased by 35%. ConclusionThere was no significant influence on the brain CT perfusion parameters and image quality using 70 kV tube voltage, and radiation dose is decreased obviously.
ObjectiveTo assess the image quality and radiation dose of gemstone CT coronary angiography (CCTA) with low tube voltage and low concentration contrast medium. MethodsSixty-nine patients who underwent CCTA from January to March 2014 were randomly divided into group A and B. CCTA was performed in thirty-four patients in group A with tube voltage of 100 kV and concentration of contrast medium of 300 mgI/mL. And thirty-five patients in group B underwent CCTA with 120 kV and 370 mgI/mL. According to upgrading American Heart Association standard all segments and all vessels were evaluated. We measured the CT value of ascending aortic root, left main coronary artery, and the initial segment of left anterior descending branch, left circumflex, right coronary artery, and also adjacent tissues. Besides, we recorded CT dose volume index (CTDIvol) and the dose length product (DLP) and calculated effective radiation dose. ResultsThe image quality scores were not significantly different between two groups (P>0.05). The density in the contrast enhanced vessel lumens in group A were signifcantly higher than that in group B (P<0.05). There was no significant difference in signal to noise ratio and carrier to noise ratio between the two groups (P>0.05). Noise in group A was higher than that in group B (P<0.05). The CTDIvol and effective radiation dose in group A were significantly lower than those in group B (P<0.05). ConclusionThe combination of 100 kV with low concentration contrast medium (300 mgI/mL) still maintains the image quality, as well as significantly lowers the radiation dose and the dose of iodine.
ObjectiveTo estimate the radiation dose (RD) to the general public and nuclear medicine technicians from patients undergoing 99mTc-methoxy isobutyl isonitrile (MIBI) myocardial perfusion imaging. MethodsFrom January to June 2015, 55 patients including 30 males and 25 females aged between 25 and 87 years[averaging (63.6±15.1)years] ready to undergo myocardial perfusion scintigraphy with 99mTc-MIBI were prospectively recruited in this study. Approximately at hour 1.5 after injection of 99mTc-MIBI, whole-body dose-equivalent rate was measured with a radiation-survey meter at 0.3 meter and 1.0 meter from the patients. On the basis of human 99mTc-MIBI metabolic rate proposed by the International Commission of Radiological Protection and human social contact model proposed by the National Council on Radiation Protection and Measurements, the RDs to the general public from patients who had completed 99mTc-MIBI myocardial perfusion imaging and left nuclear medicine department were calculated. On the assumption that a nuclear medicine technician typically spent 5 minutes at a distance of 0.3 meter for positioning the patient, the technician's RD was also estimated. ResultsThe RD to a family member sleeping with the patient at night was predicted to be 42.88-160.55 μSv, to a family member contacting the patient at daytime 7.50-29.38 μSv, to a colleague 9.89-38.78 μSv and to a nearby passenger 124.48-466.06 μSv. The RD to a technician per 99mTc-MIBI myocardial perfusion imaging procedure was predicted to be 1.72-6.44 μSv. ConclusionThe predicted RDs to the general public and technicians from exposure of patients undergoing 99mTc-MIBI myocardial perfusion imaging are significantly lower than the regulatory dose limits.
ObjectiveTo evaluate the value of 70 kV and sonogram-affirmed iterative reconstruction technique in CT examination for children with congenital heart disease. MethodsThirty children with congenital heart disease who underwent CT scan between January and September 2014 were included in this study. According to the different tube voltage, they were randomly divided into group A (80 kV) and group B (70 kV), with fifteen in each. All the children were scanned on a dual-source-CT (Siemens Definition Flash). Group A used filtered back projection reconstruction. Group B used sonogram-affirmed iterative reconstruction. We measured and calculated the pulmonary artery signal-to-noise ratio at the level of main pulmonary artery window, the signal-to-noise ratio of the ascending aorta, noise ratio contrast between the pulmonary artery and erector spinae and between the ascending aorta and erector spinae. The image quality for congenital heart disease was assessed by two senior radiologists. The measurement of radiation dose included effective dose (ED), volume CT dose index (CTDIvol) and dose length product (DLP). ResultsThere were no significant differences between group A and B in terms of pulmonary artery signal-to-noise ratio (14.54±3.77, 11.23±2.52), the signal-to-noise ratio of the ascending aorta (14.76±3.41, 12.31±3.47), the noise ratio contrast between pulmonary artery and erector spinae (12.04±3.96, 9.18±3.76) and between the ascending aorta and erector spinae (12.47±4.59, 9.77±4.41) (P > 0.05). There was significant difference between group A and group B in CTDIvol[(0.53±0.09), (0.38±0.03) mGy], DLP[(12.93±1.79), (6.67±0.72) mGy·cm], and ED[(0.34±0.05), (0.17±0.02) mSv] (P < 0.05). ConclusionThe application of 70 kV and sonogram-affirmed iterative reconstruction technique in CT examination for children with congenital heart disease can significantly reduce the radiation dose without any influence on image quality.
ObjectivesTo investigate the influence of scanning parameters (tube voltages and tube currents) on image quality and corresponding radiation doses with simulated lung nodules in chest CT.MethodsThe anthropomorphic chest phantoms with 12 simulated, randomly placed nodules of different diameters and densities in the chest were scanned by different scanning parameters. The detection rate, degree of nodular deformation, image quality (with both subjective and objective evaluation) and the corresponding radiation doses were recorded and evaluated, and the correlation between nodule detection rate, degree of nodular deformation, radiation dose and image quality using different scanning parameters was analyzed.ResultsThe image quality improved with the increase of tube voltage and tube current (P<0.05). When the tube current was constant, the CT values of the vertebral decreased gradually with the increase of tube voltages (P<0.05); however, significant difference was not detected in CT values of the lung field (P>0.05). When the tube current was 100 mAs, the lung nodules with CT values of +100 HU and −630 HU showed statistical difference when using different tube voltage (P<0.05); but there was no significant difference in nodules of −800 HU (P=0.57). When tube voltage was 100 kV and 120 kV each, it was possible to detect all lung nodules with a detection rate of 100%. The detection rate was 33% and 66% in 3 mm diameter when the tube current was 80 kV/15 mA and 80 kV/20 mA, respectively. The nodules deformation in nodules with a CT value of −630 HU and diameter less than 5 mm was the most prominent (P<0.05). After analyzing the relationship between image quality and radiation doses using different tube voltages, we established a system of correlation equations: 80 kV: Y=2.625X+0.038; 100 kV: Y=14.66X+0.158; 120 kV: Y=18.59X+0.093.ConclusionsThe image quality improves with the increase of tube current and tube voltage, as well as the corresponding radiation doses. By reducing the tube voltage and increasing the tube current appropriately, the radiation doses can be reduced. Follow-up CT examination of pulmonary ground glass nodules should apply the same tube voltage imaging parameters, so as to effectively reduce the measurement error of nodule density and evaluate the change of nodules more accurately.
Objective To explore the application value of Flash chest CT scan protocol in the follow-up of severe coronavirus disease 2019 (COVID-19). Methods Twenty-eight patients with severe COVID-19 who were admitted to this hospital from February 1, 2020 to March 15, 2020 were included. The follow-up CT examinations used conventional chest CT scan protocol and Flash scan protocol respectively, the image quality, signal-to-noise ratio (SNR) and effective dose of these two scan protocols were compared. Kappa test was used to evaluate the consistency of image quality scores of readers; Mann-Whitney test was used for image quality comparison; paired t test is performed for signal-to-noise ratio and effective dose comparison. Results The scores of the two readers had good consistency (Kappa=0.62, P<0.01 and Kappa=0.67, P<0.01). There was no statistically significant difference in image quality scores (Z=–0.275, P=0.783 and Z=–0.212, P=0.832). The signal-to-noise ratio of Flash protocol was statistically higher than that of conventional protocol (2.30±0.30 vs. 1.76±0.25, P<0.01). The effective dose of Flash protocol was 66.8% lower than that conventional protocol [(1.43±0.32) mSv vs. (4.31±1.36) mSv]. Conclusion Compared with conventional scan protocol, the Flash scan protocol does not require contact with COVID-19 patients, and effectively reduces the radiation dose and improves image quality of severe COVID-19 patients.
The Monte Carlo N-Particle (MCNP) is often used to calculate the radiation dose during computed tomography (CT) scans. However, the physical calculation process of the model is complicated, the input file structure of the program is complex, and the three-dimensional (3D) display of the geometric model is not supported, so that the researchers cannot establish an accurate CT radiation system model, which affects the accuracy of the dose calculation results. Aiming at these two problems, this study designed a software that visualized CT modeling and automatically generated input files. In terms of model calculation, the theoretical basis was based on the integration of CT modeling improvement schemes of major researchers. For 3D model visualization, LabVIEW was used as the new development platform, constructive solid geometry (CSG) was used as the algorithm principle, and the introduction of editing of MCNP input files was used to visualize CT geometry modeling. Compared with a CT model established by a recent study, the root mean square error between the results simulated by this visual CT modeling software and the actual measurement was smaller. In conclusion, the proposed CT visualization modeling software can not only help researchers to obtain an accurate CT radiation system model, but also provide a new research idea for the geometric modeling visualization method of MCNP.