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Objective:To study the healthcare level (HCL) in China and its influencing factors.Methods:By using the data reported in the China statistical yearbook published by the National Bureau of Statistics and in other public literature, HCL was calculated in terms of the number of population and physicians in the whole country and various provinces. Multiple regression was used to analyze the relationship between HCL and regional population, area, number of administrative divisions and gross domestic product (GDP). Pearson correlation analysis was applied to analyze the relationship between healthcare level and medical radiation frequency. Results:Since 2015, Chinese HCL value was lower than 1 000, but there were two provinces with HCL value greater than 1 000 in 2019. Population and GDP were the influencing factors for the HCL, with correlation coefficients of 0.416 and -0.583, respectively. There was a correlation between HCL and medical exposure frequency of Chinese population( r= -0.620, P=0.028). Conclusions:Chinese HCL value was 542 in 2020, but there has been great differences between various provinces. HCL as an indicator of medical exposure assessment needs further research in China.
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In recent years, the diagnostic radiology, especially CT scanning, has a rapidly increased frequency in our country, becoming the largest artificial radiation source to the average individual doses to the population. In clinical diagnosis and treatment activities, the examined patients and individuals may undergo multiple procedures and multiple frequencies of medical imaging in a short period of time and receive high cumulative radiation doses even exceeding 50 or 100 mSv in a single day, posing a potential risk to their health. Therefore, it is necessary to carry out statistical analysis and management of diagnostic radiation dose information to minimize the probability of excessive dose and associated radiation risk. In this paper, the international cognition of radiation risks in diagnostic radiology, diagnostic equipment and medical imaging frequency, radiation dose and its management status are described. Four countermeasures for radiation dose management are put forward to provide reference for further improving radiation protection in clinical practice.
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Objective:To investigate the feasibility of simultaneous arteriovenous enhancement of neck CT with two-stage injection of contrast agent and its effect on image quality and radiation dose.Methods:A total of 30 patients undergoing neck CT enhancement scan due to space-occupying lesions in Beijing Tongren Hospital, Capital Medical University from February to April 2022 were prospectively included as the experimental group. The neck CT enhancement scan was performed with two-stage injection of contrast agent and arteriovenous simultaneous enhancement. The dosage of contrast agent was calculated according to the patient′s body weight, and the method of two-stage injection was adopted. The dosage of contrast agent in the first stage was 0.7 ml/kg, with normal saline in the middle stage, and the second stage (began at 35 s) was 0.3 ml/kg. A total of 30 patients with gender and age matching with the experimental group from December 2021 to January 2022 were retrospectively collected as the control group. The control group was treated with the traditional arterial phase and venous phase scanning method with the dosage of 1.0 ml/kg contrast agent. The arterial phase was scanned at the 30 s and the venous phase was scanned at the 60 s. The CT values of bilateral carotid arteries and jugular veins in the experimental group were measured, the CT values of bilateral carotid arteries in the arterial phase were measured in the control group, and the CT values of bilateral carotid arteries and jugular veins in the venous phase were measured. Carotid artery enhancement score was performed for images of experimental group and control group in arterial and venous phase, and jugular vein and lesion enhancement score was performed for images of experimental group and control group in venous phase. The effective dose was calculated for both groups. The difference of carotid artery CT values between images was compared by one-way analysis of variance, and LSD method was used for pairwise comparison. The CT values of jugular vein were compared using independent sample t test. Kruskal-Wallis test was used to compare carotid artery enhancement scores, and Nemenyi method was used for pairwise comparison. Jugular vein and lesion enhancement scores and effective dose were compared by Mann-Whitney U test. Results:The CT value of carotid artery of experimental group [left (276±24) HU, right (273±25) HU] was lower than that of control group in arterial phase [left (329±33) HU, right (327±32) HU], and higher than that in the venous phase [left (147±15) HU, right (148±16) HU]. All the differences were statistically significant ( P<0.001). The CT value of jugular vein of experimental group [left (206±18) HU, right (203±19)] was higher than that of control group in the venous phase [left (154±15) HU, right (151±15)], the difference was statistically significant ( t=11.88, 11.76, both P<0.001). There was no significant difference in carotid artery enhancement score between experimental group and control group in arterial phase ( P=0.624), but the carotid artery enhancement score of the experimental group was higher than that of the control group in the venous phase, and the difference was statistically significant ( P<0.001). The scores of jugular vein and lesion enhancement in experimental group were higher than those of control group in venous phase, and the difference was statistically significant ( Z=5.01, P<0.001). The effective dose of the experimental group [2.41(2.04, 2.72) mSv] was decreased by 52.2% compared with the control group [5.04(4.18, 5.44) mSv], and the difference was statistically significant ( Z=-6.24, P<0.001). Conclusions:The neck CT enhanced scan with two-stage injection of contrast agent and arteriovenous simultaneous enhancement method can obtain comprehensive images of arterial and venous phases, and realize simultaneous enhancement of carotid artery, jugular vein and lesions, and reduce radiation dose.
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Objective:To evaluate the influence of different detector widths and signal acquisition positions of wide-detector CT in different scanning modes on CT number and noise, and to provide a basis for reasonable selection of scanning modes and related parameters in clinical practice.Methods:The body dose phantom was scanned by GE Revolution CT. The scan was performed with detector widths of 40, 80 and 160 mm in sequential scanning mode and with detector width/pitch combinations of 40 mm/0.516, 40 mm/0.984, 80 mm/0.508 and 80 mm/0.992 in spiral scanning mode. The phantom was placed at the central and peripheral of the selected detector widths, and the adjacent positions between two axial scans. The images of the phantom were evaluated subjectively and the CT numbers and SDs were measured. The differences between the measured values at different imaging parameters were compared. The multi-group Friedman test was used to compare CT numbers and SD under different scanning parameters in sequential scanning mode, and the Wilcoxon test was used to compare CT numbers and SD in spiral scanning mode.Results:There was no statistically significant difference in the geometric shapes of the phantom images obtained at any combination of parameters. In sequential scanning mode, the differences at different detector widths were statistically significant (χ 2=14.00, P=0.001) with CT numbers at 40 mm and 160 mm greater than CT numbers at 80 mm ( P<0.05). The differences at different signal acquisition positions were statistically significant (χ 2=12.04, P=0.002) with CT numbers at peripheral and adjacent greater than CT numbers at central ( P<0.05). In spiral scanning mode CT numbers at detector width at 80 mm were greater than CT numbers at 40 mm ( Z=-2.10, P=0.036). For SD, the differences at different detector widths were statistically significant in sequential scanning modes (χ 2=8.17, P=0.017) with SD at 160 mm greater than SD at 80 mm ( P<0.05). The differences at different signal acquisition positions were statistically significant (χ 2=13.50, P=0.001) with SD at peripheral greater than SD at central ( P<0.05). In spiral scanning mode SDs at pitches 0.984 and 0.992 were greater than SDs at 0.516 and 0.508 ( Z=-2.66, P=0.008). There were no significant differences among other groups. Conclusion:The selection of scanning mode, detector width and signal acquisition position of wide-detector CT will affect the image CT numbers and SDs.
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Objective:To explore the image quality and its evaluation method using virtual grid under different tube voltages in the clinical chest X-ray exam.Methods:According to the conditions of chest X-ray photography commonly used in clinical practice, the corresponding thickness of plexiglass (20 cm, including CDRAD phantom) was determined as the experimental object. With a fixed tube loading of 4 mAs and the tube voltage from 60 to 125 kV, the experimental object was imaged in three ways: physical grid, none grid and virtual grid. The common physical parameters (CNR, σ, C, SNR), texture analysis (Angular second moment, texture Contrast, Correlation, Inverse difference moment, Entropy) and CDRAD phantom score (IQF inv) were evaluated. Two-way ANOVA test was used for each group of common physical parameters, and further pairwise comparisons were made. At the same time, applying virtual grids on the obtained images with chest anthropomorphic model and texture indexing the images with and without virtual grids, then rank sum test of paired sample can be conducted. Results:There were differences in image quality among the three groups of grid mode( P<0.05), and the physical grid delivered the best image quality. The tube voltage had an impact on all image quality evaluation indexes ( P<0.05). The tube voltage was positively correlated with CNR, SNR, angular second moment, inverse difference moment and IQF inv ( P<0.05), and negatively correlated with σ, C, texture contrast and entropy ( P<0.05). There was no significant correlation between the tube voltage and Correlation ( P>0.05). The chest anthropomorphic model images were used to evaluate the virtual grids, and the texture indexes (Angle second moment, Contrast, Correlation, Inverse difference moment, Entropy) were statistically significant (P<0.05). Conclusions:The virtual grid can improve the image quality of chest X-ray photography, and the image texture analysis method can be a useful supplement to the image quality evaluation parameters.
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Objective:To investigate the effect of different scanning modes, detector width and location in detector on high and low contrast resolution of wide-detector CT image.Methods:The Catphan600 phantom with high and low contrast resolution modules was scanned with GE Revolution CT at the same CTDI vol. The scans were performed with the detector widths of 40, 80 and 160 mm for sequential scanning mode and with the detector width/pitch combinations of 40 mm/0.516, 40 mm/0.984, 80 mm/0.508 and 80 mm/0.992 for spiral scanning mode. The resolution modules were placed at the adjacent region between two sequential scans, central and foot side edge in the longitudinal scanning range seperately. The subjective evaluation of the high and low contrast resolution was performed by two radiologists. Results:The high contrast resolution was 8 LP/cm at adjacent region between two sequential scans with the detector width of 80 mm or 160 mm in sequential scanning mode, and at the pitch of 0.5 in spiral scanning mode, while it was 7 LP/cm for the rest of detector combinations. The distinguishable diameter was 3 mm at 1% low contrast resolution at foot side edge with the detector widths of 80 mm or 160 mm in the sequential scanning mode, and it was 2 mm for all the other conditions. The distinguishable diameter was 2 mm at 1% low contrast resolution with the detector width of 40 mm and pitch 0.516 in the spiral scanning mode and it was worse with the wider detector and larger pitch.Conclusions:For the wide-detector CT, scanning mode, detector width, location in detector and pitches will affect the high and low contrast resolution to some degree. Appropriate selection should be done according to actual needs in clinical practice.
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Objective:To explore the influence of different size related parameters of common CT scanned body parts on body-specific dose estimate (SSDE) , in order to establish rapid conversion factors for SSDE.Methods:A total of 189 clinical cases were collected from 6 common CT scanned body parts, including head, nasal bone, sinus, neck, chest, abdomen and pelvis, at Beijing Tongren Hospital, Capital Medical University from March 8 to May 10, 2021. Batch-processing of image was carried out by using Matlabcode. The axial images′area, anteroposterior (AP) dimension, lateral (LAT) dimension and average CT values were calculated. The conversion factors for estimating body-specific dose values were obtained from the real effective diameter ( De) and water equivalent diameter ( Dw) of the clinical cases, and the differences in values were compared between SSDE ED and SSDE WED. Based on the information on AP, LAT, AP + LAT, estimated De, the real De and Dw obtained in clinical practices, the SSDE rapid correction factors for adult body parts were established. The convenient conversion relation between Dw and De was obtained. Based on the correction factors for Dw, the relative errors of the correction factors for various sizes related parameters were compared. Results:The SSDE fast conversion factors for the real De of the 6 body parts were 1.01, 1.01, 1.01, 0.97, 1.28, 1.32, and those for Dw were 0.87, 0.97, 0.98, 0.99, 1.42, 1.36, respectively. The relative errors of different conversion factors ranged from 0.68% to 18.05%. The conversion factors for abdomen and pelvis had the smallest difference, and those for AP and LAT of the chest had the smallest error. The differences between CTDI vol, SSDE ED and SSDE WED in sinus, chest and abdomen were statistically significant ( tsinus=2.44, 4.23, tchest=17.67, 17.00, tabdomen and pelvis =17.93, 18.75, P<0.05) . The differences between CTDI vol and SSDE WED in head, nasal bone, were statistically significant ( t=-22.27, 2.80, P<0.05) , but not with SSDE ED ( P>0.05) . The difference between CTDI vol and SSDE ED in neck was statistically significant ( t=-3.06, P<0.05) but without statistical insignificance in camparison with SSDE WED ( P>0.05) . Conclusions:SSDE WED can be used to accurately evaluate the body-specific dose estimatates, and different size related parameters can be selected for correction in different scanned body parts. The rapid conversion factor can be easily used in clinical practice to improve the accuracy of estimated radiation dose.
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Objective:To investigate the effects of organ dose modulation (ODM) on image quality and radiation dose to lens during sinus CT scanning.Methods:The GE Revolution EVO CT was used to scan the anthropomorphic head with ODM turned off as the control group and ODM turned on as the observation group. With different parameter combinations of tube voltage (140, 120, 100 kV), noise index (N17, N18), pitch (0.531, 0.969 at 20 cm collimation width, 0.516, 0.984 at 40 mm collination width), 24 series of images were acquired respectively. The tube current (mA) valuesat the anterior (A), left (L), posterior (P) and right (R) positions, volume CT dose index (CTDI vol) and dose length product (DLP) were recorded. Average CT values (AV), standard deviation (SD), signal-to-noise ratio (SNR), contrast to noise ratio (CNR) and image quality factor (FOM) of ROI were calculated. Double blind method was used to evaluate the edge sharpness, soft tissue level, noise and artifact on a subjective scale of 3 points. Results:For the combinations of different scanning parameters, the radiation dose of the observation group was lower than that of the control group. The tube current attheposition A for the observation group was lower than that of the control group, and the difference was statistically significant ( t=2.28, P<0.05). The differences oftube currentsatposotions of L, P and R, CTDI vol and DLP values in twogroupswere not statistically significant ( P>0.05). There were no significant differences in SD, SNR, CNR and FOM between the two groups of images ( P>0.05). There were no significant differences in the subjective scores of edge sharpness, soft tissue gradation, noise and artifacts between the two groups ( P>0.05). Conclusions:ODM technique can effectively reduce the radiation dose of eye lens without decompromising the image quality, which could meet the requirements of diagnosis, and accord with the principle of radiological protection optimization.
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Objective:To investigate the role of microRNA (miR)-155 in hydrogen peroxide (H 2O 2)-induced oxidative stress injury in lens epithelial cells (LECs) and its mechanism regulating silent information regulator factor related enzymes 1 (SIRT1). Methods:The HLE-B3 at the logarithmic growth phase was taken and cultured for 24 hours under different concentrations of H 2O 2 (0, 50, 100, 200, 400, 800 μmol/L), and the cell viability was detected by MTT assay to determine the optimal concentration of H 2O 2 for establishing an oxidative stress injury model.HLE-B3 cells were divided into 6 groups, untreated blank control group, model control group cultured with 100 μmol/L H 2O 2, miR-155 mimics group transfected with miR-155 mimics, miR-155 mimics negative control group transfected with miR-155 mimics negative control, miR-155 inhibitor group transfected with miR-155 inhibitor, and miR-155 inhibitor negative control group transfected with miR-155 inhibitor negative control.Transfected cells were cultured with 100 μmol/L H 2O 2.Cells in various groups were cultured for 24 hours, and cell morphology was observed under an inverted microscope.The relative expression of miR-155 and SIRT1 mRNA in cells was assayed by fluorescent quantitative PCR.Cell apoptosis rates were detected by flow cytometry.Reactive oxygen species (ROS) content was identified by 2', 7'-dichlorofluorescein diacetate (DCFH-DA) fluorescent probe method.Superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration were measured by ELISA method.The targeting of SIRT1 by miR-155 was tested by dual luciferase reporter gene system.Expressions of SIRT1, B-cell lymphoma/leukemia-2 gene (bcl-2), bcl-2 associated X protein (bax), cleaved-cysteine aspartase 3 (cleaved-Caspase-3) proteins were determined by Western blot. Results:With the increase of H 2O 2 concentration, the cell viability gradually decreased, and the differences in cell viability among different concentrations were statistically significant (all at P<0.05), and 100 μmol/L was selected as the experimental concentration.Cells in blank control group grew well adherently.The number of cells in model control group decreased, and the morphology of some surviving cells changed, and their boundaries were blurred.There were fewer cells in miR-155 mimics group than model control group, and the cell morphology changed.There were more cells in miR-155 inhibitor group than model control group, and the cells grew well.Compared with model control group, the relative expression level of miR-155, the apoptosis rate, ROS content, MDA concentration, as well as the relative expression levels of bax and cleaved-Caspase-3 proteins were increased, and the relative expression level of SIRT1 mRNA, the SOD activity, the relative expression of SIRT1 and bcl-2 proteins, as well as bcl-2/bax were decreased in miR-155 mimics group, and the differences were statistically significant (all at P<0.05). Compared with model control group, the relative expression of miR-155, the apoptosis rate, ROS content, MDA concentration, as well as the relative expression levels of bax and cleaved-Caspase-3 proteins were decreased, and the relative expression level of SIRT1 mRNA, SOD activity, the relative expression levels of SIRT1 and bcl-2 protein, as well as bcl-2/bax were significantly increased in miR-155 inhibitor group, and the differences were statistically significant (all at P<0.05). The relative luciferase activity of wild-type SIRT1 in cells transfected with miR-155 mimics was 0.41±0.07, which was significantly weaker than 1.00±0.11 in cells transfected with miR-155 mimics negative control, and the relative luciferase activity of wild-type SIRT1 in cells transfected with miR-155 inhibitor was 1.98±0.17, which was significantly higher than 1.00±0.12 in cells transfected with miR-155 inhibitor negative control, showing statistically significant differences ( t=7.838, 8.157; both at P<0.05). No obvious effect on the relative luciferase activity of mutant SIRT1 was found in transfected cells. Conclusions:miR-155 is involved in H 2O 2-induced oxidative damage of LECs, and its overexpression can target the expression of SIRT1 and play a role in cell injury.
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Objective:To describe the distribution of volumetric breast density(VBD) in different ages of Chinese women based on X-ray mammograms.Methods:Based on mammographic images of 1 140 patients from January 2010 to December 2016 in a hospital in Beijing, the VBD of women was assessed by Volpara 1.5.1 and graded according to breast imaging reporting and data system published by American College of Radiology. The patients were divided into two groups according to the median age, and the two independent samples t-test was used to compare them. The patients were also divided into four groups according to age ( <40 years, 40-49 years, 50-59 years, ≥ 60 years), and the breast thickness, breast volume, glandular volume, and VBD were compared using a One-way ANOVA analysis. Results:The median age was 50 years. The compressed breast thickness and breast volume in patients over 50 years were significantly higher than those in patients below 50 years ( t= -8.99, -7.92, P<0.001), while glandular volume and VBD were significantly lower than those below 50 years ( t= 8.11, 18.49, P<0.001). The compressed breast thickness, breast volume, glandular volume, and VBD were statistically significant different among four groups ( F=27.10, 22.34, 25.70, 122.03, P<0.001). Patients over 60 years had the lowest VBD ( t=-12.56, -15.27, -4.57, P<0.001). VBD was negatively correlated with ages ( r=0.47, P<0.001). Conclusions:The compressed breast thickness and breast volume increased with ages, while the glandular volume and VBD decreased with ages.
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Since the Academic Degrees Committee of the State Council and the Ministry of Education officially listed medical technology as a first-level discipline in 2011, China has witnessed a rapid development in the classification of medical technology disciplines, the number of practitioners and professional level, the higher education of medical technology. The paper analyzes and summarizes the current status of the development in medical technology disciplines, explores the key difficult points therein and provides the relevant suggestions. The aim is to promote the discipline construction of medical technology, contribute to the cultivation of medical technical professionals and boost the development of medical and health services in our country.
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Objective:To explore the effects of scout scanning parameters (projection angle and tube potential) on image quality and radiation dose in chest CT and to provide guidance for the selection of scanning parameters in clinical practice.Methods:Different parameter combinations were selected to acquire the scout view of the anthropomorphic adult chest phantom. Fifteen scout views were obtained under parameter combinations of the projection angle (0/90/180 degrees), tube potential (70/80/100/120/140 kV) and tube current (25 mA). And then, chest spiral scans were performed according to the scout views. The other parameters were Assist kV, smart mA (maximum range), 80 mm detector width, 0.992∶1 pitch, 0.5 s rotation time, 330 mm scanning length, 5 mm thickness, NI (noise index) 10. The radiation dose modulation index (ASiR-V) was 30%, and the iterative level was 50%. Volume CT dose index (CTDI vol) and tube current at 4 body levels (pulmonary apex, trachea bifurcation, mammary level and diaphragmatic dome) were recorded. The thermoluminescent dosimeters (TLDs) were used to measure the organ dose of the breast glandular. Regions of interest (ROIs)were selected at the trachea bifurcation and diaphragmatic dome to calculate the contrast noise ratio (CNR). Results:The tube potential of the spiral scanning was automatically selected as 80 kV when the projection angle was 0 degree. The changing of the tube potential for the scout had little influence on the tube current at the four body levels, and the variation range was 0-2% (5/230). The tube potential in the spiral scanning was automatically selected as 100 kV when the projection angles were 90 and 180 degrees. The changing of the tube potential for the scout had a great influence on the tube current at the slice of trachea bifurcation and the variation range was from 14%(29/210)to 44%(93/210). According to the angle projection, there were statistical differences in CTDI vol( P< 0.017), organ dose of the breast glandular, and CNR at the slices of trachea bifurcation and at diaphragmatic dome ( F=13.027, 24.727, 10.630, P< 0.05). According to the tube potential in the scout scanning, there were no significant differences in CTDI vol, organ dose of the breast glandular and CNR at both levels ( P> 0.05). Conclusions:In chest CT, the influence of the projection angle in scout scanning on the image quality and radiation dose was more significant than that of the tube potential.
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Objective:To investigate the feasibility of the application of low tube potential scanning in dacryocystography CT.Methods:The mixture of iohexol and saline with the ration of 1∶3 as the dacryocyst was set on the nose wing of the head-neck phantom. The phantom was scanned at 80, 100, 120, 140 kV with appropriate mAs to set the volume CT dose index(CTDI vol)at 10, 15, 20, 25, 30, 35 or 40 mGy. All the images were objectively evaluated to find out the optimal scanning parameters of 80 kV/240 mAs with the same contrast-to-noise ratio(CNR)of conventional scanning condition of 120 kV/180 mAs. A total of 62 patients who conducted dacryocystography CT in Beijing Tongren Hospital from November 2019 to July 2020 were prospectively selected. They were randomly divided equally into conventional scanning group with 120 kV/180 mAs and low tube potential group with 80 kV/240 mAs. The CT number, noise (SD) and contrast-to-noise ratio (CNR) of the two groups were measured as the objective evaluation indicators of image quality. The subjective evaluation was performed by two senior radiologists using a double-blind method and a 5-scale system evaluation. Results:For the phantom study, the CNR was positively correlated with CTDI vol under the same tube potential ( r=0.985, 0.965, 0.971, 0.972, P < 0.05). With the same CNR, the radiation dose decreased with lower tube potential. Under the conventional scanning parameters of 120 kV/180 mAs, the CNR was 27.8. At the same CNR, the optimal scanning parameters were 80 kV/240 mAs. For the clinical study, the CTDI vol of conventional scanning group and low tube potential group were 31.2 and 12.8 mGy respectively, 59% decreased in low tube potential group. There were statistically significant differences in CT number of dacryocyst area, CT number of orbital fat area and noise between the two groups ( t=-3.476, 2.601, -5.704, P < 0.05). There was no statistically significante difference in CNR between 2 groups( P>0.05). Two observers had a good consistency ( Kappa >0.75). There was no statistically significante difference in subjective rating between 2 groups( P>0.05). Conclusions:Low tube potential scanning could obtain satisfactory image quality in dacryocystography CT at much lower radiation dose.
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Objective:To investigate the uncertainty of the dose measurements of superficial organs and the image noise in CT scanning.Methods:GE Revolution CT was used to perform 20 repeated scans on the isolated skull specimen in sequential and helical mode. The chest phantom was scanned for 45 times with the pitch 1.0 and the collimation 80 mm for two scanners (GE Revolution CT, Philips Brilliance iCT) and 40 mm for the Siemens Somatom Definition Flash CT. The volume CT dose index (CTDI vol) was maintained during the above scannings. A dosimeter was used to measure the dose at the position of the right eye lens of the specimen and the center of right breast of the chest phantom. The position of dosimeter sensor remained unchanged. The standard deviation of CT values (image noise) in the air region of cross-sectional images at the center of the sensor reconstructed with lung/soft tissue algorithms were measured. The mean values ( Av), standard deviations ( SD), coefficients of variation ( CV) and relative ranges ( RR) of the dosimetric values and the standard deviations of CT values of 3, 5, 10, 20, 30 and 45 scans were calculated. Pearson and Spearman correlation analysis were used to evaluate the correlation between the dosimetric values and the standard deviations of CT values. Results:The measured dosimetric values of the skull specimen were almost unchanged in the sequential scannings. The relative range of dose in helical mode was 10.67%. The relative ranges of the measured values of the three CT scanners for 45 scans reached 43.83%, 25.31%, and 14.32%. The standard deviations of CT values of the lung/soft tissue images varied greatly and the differences were not completely related to the dosimetric values.Conclusions:The dosimetric values of superficial organs were stable in the sequential scanning mode. The dose measurements of superficial organs and the image noise changed greatly in helical scanning mode.
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Objective:To investigate the value of the size-specific dose estimate (SSDE) on dose estimations of children's head CT scans.Methods:A retrospective study was conducted on plain head CT scans of 252 patients with the 64-row detector CT device of Discovery 750HD in the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from January to September in 2019. The volume CT dose index (CTDI vol)values were recorded. The head circumference (HC), area, and CT value were measured using a self-developed computer program, and the water equivalent diameter (WED), size-specific conversion factors ( f293 and f220), and absorbed dose (SSDE 293 and SSDE 220) were calculated according to the AAPM reports 293 and 220.The patients were divided into three groups by the quartering meth odaccording to their HC(<47.8 cm, 47.8-52.7 cm, >52.7 cm)and four groups based on their ages(0-2, 3-6, 7-10 and 11-14 years old). The difference between parameters ( f220 and f293, SSDE 220 and SSDE 293、SSDE 293 and CTDI vol) were compared for different groups, and the correlation of HC with f293 and SSDE 293 was analyzed. Results:There was an overestimation of f220 by 11.11% ( t=252.61, P<0.05) compared with f293. SSDE 220 was overestimated by 10.31% ( t=228.21, P<0.05) compared with SSDE 293, and SSDE 293 was underestimated by 9.60% ( t=-31.34, P<0.05)compared with CTDI vol. For the three HC groups, SSDE 220 was overestimated by 8.54%, 10.37%, and 11.57% ( t=73.73, 438.58, 275.52, P<0.05)compared with SSDE 293, and SSDE 293 was underestimated by 1.30%, 9.79%, and 14.61% ( t=-1.91, -60.95, -47.64, P<0.05)compared with CTDI vol. For the four age groups SSDE 220 was overestimated by 8.45%, 10.00%, 10.57%, and 11.36% ( t=63.58, 232.29, 247.84, 302.95, P< 0.05)compared with SSDE 293, and SSDE 293 was underestimated by 1.49%, 8.27%, 10.63%, and 13.78% ( t=-1.83, -28.27, -37.30, -49.80, P< 0.05)compared with CTDI vol. Furthermore, HC was highly correlated with f293 and SSDE 293 ( r2=0.88 and 0.76, respectively, P< 0.05). Conclusions:The radiation dose in children′s head CT scanning can be more accurately estimated according to the AAPM Report 293, while it can be overestimated by CTDI vol. Meanwhile, the CT radiation dose can be patently overestimated with the AAPM Report 220 compared with Report 293.HC is closely correlated with f293 and SSDE 293 and it can be used to estimatee more accurately for SSDE and the radiation dose received by children during head CT scanning.
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Objective:To investigate the effect of different additional filters on the image quality and radiation dose in abdominaldigital radiography (DR).Methods:Retrospective analysis was performed on 10 cases of abdominal DR from December 2020 to January 2021 in Fuxing Hospital, and the average mAs was calculated. Using automatic exposure control (AEC) technology, a polymethyl methacrylate (PMMA) slab of the corresponding thickness (18 cm) at the same output of above mAs was confirmed and used as the attenuator to simulate the abdomen. The phantom of CDRAD 2.0 and 17 slices of 10 mm thick PMMA plates (total thickness 18 cm) were placed on the bed. The additional filters were selected as no additional filter, 2 mmAl, 0.1 mmCu+ 1 mmAl, 0.1 mmCu+ 2 mmAl respectively. The AEC levels were selected at -2, -1, 0, 1, and 2 respectively. The images were collected and analyzed by using CDRAD 2.0 software to obtain the image quality factor (IQF inv). The incident air kinetic energy on the surface of the PPMA was measured for each exposure, and PCXMC software was used to estimate the organ dose and effective dose, and a comparative analysis was made. Results:The skin incident doses at no additional filter, 2 mmAl, 0.1 mmCu+ 1 mmAl, 0.1 mmCu+ 2 mm Al were (0.546 1±0.200 8), (0.376 2±0.133 8 ), (0.285 3±0.100 1) and (0.289 9±0.099 2) mGy, respectively. The estimated effective doses were (79.63±29.24)×10 -3, (71.05±25.56)×10 -3, (63.58±22.18)×10 -3 and (67.64±23.11)×10 -3 mSv, respectively. The gonadal doses were (0.058 1±0.020 8), (0.050 0±0.018 0), (0.044 8±0.015 6) and (0.047 7±0.016 3) mGy.The IQF inv values were 4.70±0.61, 4.80±0.84, 4.60±0.55, 4.60±0.60, respectively. There were linear correlations between the effective dose and the skin incident dose under different additional filtration, and the effective doses increased with the increase of the incident doses. The dose was lowest at the addition filtration of 0.1 mmCu+ 1 mmAl. There was no significant difference in the IQF inv between groups( P>0.05). Conclusions:The optimal additional filtration for abdominal DR was 0.1 mmCu+ 1 mmAl with the image quality meeting the requirements of clinical diagnosis, the radiation dose reduced reasonably, and the objective of the optimization of radiographic parameters achieved.
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Objective@#To investigate the relationship between current-exposure time products (mAs) and image quality in digital mammography.@*Methods@#The CDMAM phantom of 2 to 7 cm thickness were exposed by manual exposure modes using Mo-Rh anode-filer combinations. The exposure parameters were set as follows: (2 cm, 27 kVp, 10 to 90 mAs); (3 cm, 29 kVp, 20 to 120 mAs); (4 cm, 29 kVp, 20 to 200 mAs); (5 cm, 30 kVp, 40 to 220 mAs); (6 cm, 31 kVp, 40 to 260 mAs); (7 cm, 32 kVp, 80 to 280 mAs). The image quality figure (IQF), contrast to noise ratio (CNR), figure of merit (FOM) and the average glandular dose (AGD) were obtained from images. The optimum filtration and kVp for each breast thickness was found from the calculated FOMs. The optimum mAs for each breast thickness were found from the calculated FOMs and IQFs. And the Pearson correlation analysis was used to analyze the correlations among AGD, CNR and IQF.@*Results@#With the increase of mAs, the average glandular dose were linearly increased, and the FOM first increased and then decreased or changed slowly. The AGD, CNR and IQF were significantly correlated when the compression thickness was less than 7 cm (r all>0.87, P<0.05). The optimized exposure parameters were list as follows (2 cm,27 kVp,20 to 30 mAs);(3 cm,29 kVp,30 to 50 mAs); (4 cm,29 kVp,80 to 100 mAs); (5 cm, 30 kVp, 80 to 120 mAs); (6 cm, 31 kVp, 100 to 140 mAs); (7 cm, 32 kVp, 80 to 120 mAs).@*Conclusion@#The optimum range of mAs can be confirmed with different breast compression thickness and the setting of automatic exposure parameters should be chosen in clinical practice.
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The article briefly described the frequency of CT scans and the development trend of CT exposure doses in children, and introduced the main method and achievements in the cancer risk evaluation of pediatric CT scans in different time periods. This review will provide the references for optimizing the radiation dose of CT scans.
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Objective@#To explore the effect of pre- and post-adaptive statistical iterative reconstruction-Veo (ASiR-V) on image quality and radiation dose in paranasal sinus CT, and to find the best combinations.@*Methods@#One head specimen was scanned with the routine spiral CT scanning parameters [noise index (NI)=8] and different levels of pre-ASiR-V (0—100%, with an interval of 10%). The images were reconstructed with different post-ASiR-V (0—100%, with an interval of 10%) for the bone algorithm and standard algorithm. All of 242 thin-layer images of paranasal sinuses were obtained. The region of interest (ROI) was selected to measure the CT value to calculate the contrast to noise ratio (CNR) and figure of merit (FOM). The volume CT dose index (CTDIvol) and Smart mA were recorded. The linear regression was conducted to analyze the relationship between CTDIvol, SmartmA, CNR and FOM. And with the same pose-ASiR-V level, the CNR of images which reconstructed by bone and soft algorithms were compared with pair-wise t test. The image quality was subjectively evaluated by three independent experienced radiologists using a 4-point scale (4 was the best).@*Results@#As the pre-ASiR-V levels (0—100%) increased, Smart mA and CTDIvol were reduced with a linear negative correlation (r=-0.981, -0.976, both P<0.001). The Smart mA decreased by 72.05% and CTDIvol by 71.22%. Keeping the same pre-ASiR-V level,the CNR increased with the increase of post-ASiR-V level (for the bone algorithm images:R2=0.976, 0.992, 0.982, 0.982, 0.975, 0.975, 0.979, 0.996, 0.952, 0.978, 0.965;for the standard algorithm images: R2=0.944, 0.990, 0.988, 0.993, 0.996, 0.987, 0.984, 0.996, 0.996, 0.990, 0.965).Under the same level of post-ASiR-V, the CNR and FOM fluctuated with the pre-ASiR-V level (for the bone algorithm images:R2=0.335, 0.341, 0.344, 0.364, 0.385, 0.405, 0.418, 0.429, 0.455, 0.474, 0.516; for the standard algorithm images: R2=0.223, 0.278, 0.327, 0.285, 0.309, 0.329, 0.325, 0.346, 0.360, 0.390, 0.380). All subjective image quality could meet the diagnostic requirements (the score≥3).@*Conclusion@#At NI=8, for the bone algorithm, the best combination is 80% pre-ASiR-V and 100% post-ASiR-V; for the standard algorithm, the best iteration combination is 100% and 100%. The appropriate choice of pre- and post-ASiR-V levels in paranasal sinus CT scan can effectively reduce the radiation dose under the premise of maintaining the image quality that meets the diagnostic needs.
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Objective:To survey and supervise the risk of infection control and radiation safety in the radiological diagnostic workplace for COVID-19, and provide data support for the safety protection of radiographers and related staff.Methods:4 emergency hospitals for COVID-19 including 2 makeshift hospitals, module hospital and brick pattern hospital in Hubei province were performed for testing and evaluation of imaging performance and radiological protection for the 8 new installed CT scanners and places according to the national standards of WS 519-2019 and GBZ 130-2013. The infection control safety factors such as the layout of the equipment room were monitored and investigated. Two COVID-19 designated hospitals including general hospital and infectious disease specialized hospital were selected to carry out field investigation and sampling of environmental biological samples for 4 CT rooms. Then the samples were detected for the nucleic acid of novel coronavirus. The results of radiodiagnostic workplace overall arrangement, infection prevention and the nucleic acid testing were analyzed, and the biological safety reliability and risk point were evaluated.Results:The indicators of imaging performance and radiation protection for 8 CT scanners in emergency hospitals could meet the requirements of national standards.Each of 2 makeshift hospitals had 3 CT rooms with the area of 38.8 m 2 and 4 mm Pb equivalent thickness of protective shielding. The CT rooms in module hospital and brick pattern hospital were 20.0 m 2, and 35.8 m 2 in areas, with 4 mm Pb equivalent and 3 mm Pb equivalent thickness of protection shielding, respectively. The 8 radiological diagnostic workplaces of the emergency hospitals were designed and constructed based on " three zones with two passage ways" . The result of the nucleic acid test indicated that the positive samples were found at the multiple sites such as scanning bed, internal of gantry and ground touched by patients in CT scanning room. The areas such as console panel and ground were risked of pollution by the virus infected hands and feet of radiographers. In addition, the similar positive samples were found in the areas in scanning room with no touch of patients, such as observation window and air outlet. Conclusions:8 CT scanners and rooms in 4 emergency hospitals basically meet the requirements of imaging performance and radiation protection. The disinfection of COVID-19 radiodiagnostic workplace should be standardized.