Objective:To investigate the trend of radiological diagnostic examination frequency and the related influencing factors in a general hospital in recent four years.Methods:The hospital information system and the radiology information system were used to collect the information on the numbers of the outpatients, the emergency patients, and the inpatients and the radiology examination information from 2019 to 2022. The examination frequency and proportion of various imaging equipment were counted by using the perspective table of data, and the examination items and the proportion of the radiological diagnostic examinations were calculated. The positive rates of the radiological examinations were measured from 2019 to 2022. The gender and age distribution of the patients were analyzed. Spearman correlation analysis was used to analyze the relationships between the numbers of the patients undergoing radiological examinations and the numbers of the outpatients, emergency patients and the inpatients.Results:The annual frequency of radiological diagnostic examinations from 2019 to 2022 were 307 306, 245 418, 317 250 and 325 625, respectively, with a total of 1 195 599. Among them, the proportions of CT, X-rays, bedside X-rays, bone density, gastrointestinal imaging and mammography were 59.74%, 38.04%, 1.39%, 0.42%, 0.21% and 0.19%, respectively. In each year, the proportion of CT in all radiological diagnostic examinations was 49.58%, 63.40%, 60.40% and 65.20%, respectively. The frequency of emergency CT and emergency chest CT was correlated with the number of emergency patients( r =0.63, 0.61, P<0.05), and the frequency of non-emergency CT was correlated with the number of outpatients and inpatients ( r =0.61, 0.66, P<0.05). The positive rates of the CT examinations were higher than 80% except the lowest of 79.95% in 2021. Conclusions:Radiological examinations especially CT examinations have increased significantly, and played an important role in the diagnosis of diseases. However, attention should be paid to the Justification of the CT examinations. Timely statistical analysis of radiological examination information can provide data supports and references for scientific management of radiological examinations.

Objective:To explore and compare the impacts of different scanning protocols on image quality and radiation dose in chest computed tomography (CT) scans.Methods:A retrospective analysis was conducted for the data of 65 randomly selected patients who underwent chest CT scans using a tube voltage of 120 kV, the automatic modulation technique for tube current, and z-axis radiation dose modulation at the Emergency Department of our hospital from June to July 2023. The enrolled cases were divided into two groups: the high-resolution group ( n = 34) and the conventional group ( n = 31), with the settings for scanning protocols identical to those for phantom scans. For patients in both groups, thin-layer images of the cross-sections in the lung and mediastinal windows were reconstructed using thickness/intervals of 1 mm/1 mm and 2 mm/1 mm, respectively. Meanwhile, high-resolution and conventional CT scans were conducted using a Catphan500 phantom under a tube voltage of 120 kV and a tube current of 150 mAs. Of both scanning protocols, the high-resolution CT scan utilized the lung nodule-orientated scanning mode, pitch of 1.5, and a detector combination providing a collimation of 16 × 0.75 mm. In contrast, the conventional CT scan was performed using the body-orientated scanning mode, pitch of 0.813, and a detector combination providing a collimation of 16 × 1.5 mm. Then, the high-contrast resolutions of the phantom images obtained using the two scanning protocols were objectively evaluated. Both coronal chest images in the lung window and cross-sectional images in the mediastinal window were reconstructed with a thickness/interval of 5 mm/5 mm for both groups. Then, the obtained images were imported into the Radimetrics system to compare the body size-specific dose estimation (SSDE), doses to sensitive organs on the body surface, and scanning time of both groups. For the cross-sectional images in the mediastinal window, the contrast-noise-ratio (CNR), signal-to-noise ratio (SNR), and figure-of-merit (FOM) were measured and calculated at the fixed anatomical parts. For the cross-sectional images in the lung window, their quality was subjectively evaluated by two senior diagnostic radiologists. Results:The result of phantom scans indicated that high-resolution CT scans yielded images with an approximately 5% increase in the spatial resolution in the xy-plane and a nearly 20% increase in the spatial resolution along the z-axis compared to conventional CT scans. The result of clinical data demonstrated that the conventional group exhibited significantly higher doses to the thyroid and the female breast ( t = 2.8, 2.3, P < 0.05), along with notably elevated SNR, CNR, and FOM values of the right trapezius, compared to the high-resolution group ( t = 4.1, 5.8, z=4.4, P < 0.001). However, the high-resolution group manifested significantly higher SNR, CNR, and FOM values of the thoracic aorta compared to the conventional group ( t = 3.4, 4.4, z=3.4, P < 0.001). In addition, the cross-sectional and coronal images in the lung window of the clinical cases in the high-resolution group exhibited more stable quality, with subjective scores exceeding 4 and the average scores of both groups not statistically significantly different. Conclusions:For chest CT examination, high-resolution CT scans are more suitable for observations focusing on the details of the lungs and mediastinum, while conventional CT is more suitable for those centering on soft tissues on the body surface.

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.

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.

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.

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.

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.

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.

Objective:To investigate the effect of organ dose modulation (ODM) technique on reducing the breast radiation dose in chest CT scanning.Methods:In the phantom test, the PBU-2 adult chest module was used. The clinical chest scan protocol was used and three sets of scans performed on the chest module： (1) ODM off group, ODM was not used; (2) ODM part group, ODM was applied only in the breast region； (3) ODM all group, ODM was applied in the whole scan scope. Other scan parameters were same for the three groups, with smart mA applied. The volume CT dose index (CTDI vol) was recorded for all three groups. A long rod ionization chamber was placed in a fixed position in front of the right breast area to measure the breast skin dose (D). The contrast noise ratio (CNR) and the figure of merit (FOM) were measured respectively. In clinical research, 72 female patients who underwent chest CT scanning in Beijing Tongren Hospital Capital Medical University from August to November 2018 were retrospectively recruited. According to the application of ODM, the patients were divided into ODM off group (without ODM, 36 cases) and ODM part group (ODM applied in the breast region, 36 cases). The CTDI vol and the dose length product (DLP) were recorded. CNR, noise of images were measured and calculated, respectively. The image quality was evaluated by subjective evaluation scores. The one way ANOVA analysis was used in comparing the difference of CNR among the 3 groups in module test. As for clinical cases, the independent samples t test was used to compare the difference in CTDI vol, DLP, CNR and the noise between two groups; and the rank-sum test was used for comparison in image quality subjective evaluation. Results:In module test, the radiation dose was highest in ODM off group, and lowest in ODM all group. The CTDI vol were (6.90±0.02), (6.26±0.02) and (5.99±0.02) mGy, and the D values were (9.17±1.01), (8.01±0.92) and (7.58±0.87) mGy for ODM off group, ODM part group and ODM all group respectively. The CNR values of images with soft tissue algorithm reconstruction were highest in ODM off group and lowest in ODM all group, while no statistically significant difference was displayed ( P>0.05). The CNR values of the images with lung algorithm reconstruction showed the same trend, with statistically significant difference among the three groups ( F=154.732, P=0.006). The FOM of the lung and soft tissue algorithm images was maximized when the ODM was partially applied. As for clinical cases, compared with ODM off group, the dose of ODM part group showed significantly decreased, with CTDI vol decreased by 16.12% ( t=2.604, P=0.011), and the DLP decreased by 16.85% ( t=3.293, P=0.002). No significant difference was found in CNR, noise and subjective score by two doctors between two groups ( P>0.05). Conclusion:The application of ODM in chest CT imaging can reduce the radiation dose of breast with simultaneously maintaining the image quality.

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.