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@#Cone beam computed tomography (CBCT) has been widely used in various fields of dentistry. The diagnosis of root fractures, especially vertical root fractures (VRFs) with CBCT images, has been a research hotspot since then. Research on this area mainly includes the following five aspects: ① the diagnostic efficiency of CBCT images for root fractures; ② the influence of scanning parameters on the diagnostic accuracy of CBCT images in root fractures, such as scanning field of view, spatial resolution, tube current and tube voltage; ③ whether the application of image postprocessing techniques, especially metal artifact reduction (MAR), can improve the diagnostic accuracy of root fractures after root canal treatment and/or there is a post core in the root canal; ④ establishment and validation of clinical diagnosis model for vertical root fracture; and ⑤ application of artificial intelligence technology and contrast agent in root canals for the diagnosis of CBCT image in root fractures. Compared with periapical radiographs, CBCT images can improve the diagnostic accuracy of root fractures in nonendodontic treated teeth; however, for teeth that have undergone endodontic treatment, the diagnosis of VRF must be combined with clinical signs. Vertical bone resorption in the buccolingual (palatal) direction is a characteristic indicator of VRF. The width of the VRF is an important factor affecting the diagnostic accuracy, but the voxel size used in CBCT scanning is not a necessary factor affecting its diagnostic accuracy; the fracture direction does not affect the diagnostic accuracy of the VRF. Image postprocessing techniques, especially MAR, cannot improve the diagnostic accuracy of VRF and may also reduce the diagnostic efficiency, so they are not recommended for clinical application.
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Objective:To explore the feasibility of 60 kV tube voltage combined with reduced contrast medium in CT pulmonary angiography (CTPA).Methods:Totally 60 outpatients and inpatients with a body mass index (BMI) of less than 25 kg/m 2 who had suspected pulmonary embolism and were arranged for CTPA examination were enrolled in this study. They were divided into a control group and an test group according to the random number table method. A protocol with a conventional dose was adopted in the control group. This scheme consisted of 100 kV tube voltage and injection of 50 ml of contrast medium at the rate of 4.5 ml/s. A scheme with a low dose was employed in the experimental group. Specifically, this scheme involved 60 kV tube voltage scheme and injection of 30 ml of contrast medium mixed with 20 ml of normal saline at a rate of 4.5 ml/s. The objective image quality was assessed by measuring the Hounsfield units (HU) of five regions of interest (ROIs), i. e., pulmonary trunk, right and left pulmonary arteries, and right and left lower lobar arteries, and the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were calculated. Moreover, the radiation doses were recorded. The subjective image quality was assessed by radiologists using a 5-point scale based on the overall image quality and the enhancement homogeneity of pulmonary arteries. The noise, SNR, CNR, and radiation dose of the two groups were compared using the Mann-Whitney U test, and the differences in the subjective image quality between the two groups were compared using the χ2 test. Results:All images met the requirements for clinical diagnosis. The two groups did not show significant differences in the overall subjective quality of CTPA images and enhancement scores ( P > 0.05), and in the average attenuation values of the pulmonary trunk and the left and right lower lobar arteries ( P > 0.05), but exhibited statistical differences in the average attenuation values of the left and right pulmonary arteries ( t = 2.75, 3.91, P < 0.05). There was no significant difference in the average background noise between the two groups ( P > 0.05). The test group had higher CNR of the left pulmonary artery and higher SNR and CNR of the right pulmonary artery than the control group, with statistically significant differences ( t = 0.04, 2.41, 3.08, P < 0.05). There was no significant difference in the SNR and CNR of other pulmonary artery branches between the two groups ( P > 0.05). The test group had an average effective dose of 1.24 mSv for CTPA, which was about one-third of that of the control group, with statistically significant differences ( t = 21.65, P < 0.05). Conclusions:The scheme of 60 kV tube voltage and reduced contrast medium for CTPA is feasible for patients with BMI < 25 kg/m 2. Using this scheme, the radiation and iodine dose can be reduced without affecting image quality.
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Objective:To determine and optimize the radiation quality of the calibration system for mammography dosimeters in IAEA/WHO Secondary Standard Dosimetry Laboratory and to study the requirements for accuracy of thickness of the aluminum sheets used in the measurement, with a view to ensure the accuracy of the radiation quality.Methods:For the measurements of tube voltage and RQR-M radiation quality, a standard kV meter was used to determine the actual tube voltage value of the system under continuous exposure for 30 s by setting tube voltage of 25, 28, 30 and 35 kV, respectively, and aluminum sheet method was used to determine the first half value layer (HVL 1). The kV values were adjusted to make the reading of the standard kV meter as close as possible to its nominal value, so as to obtain the set kV value, actual tube voltage and HVL 1 per 1 kV within the nominal 25-35 kV range. For effects of different thickness of aluminum sheets on the result of HVL 1 measurement, a comparison was made between HVL 1 measured by aluminum sheet with thickness of 0.318 mm and 0.369 mm and HVL 1 measured under 18 different groups of aluminum sheet using a selected 30 kV tube voltage. Results:After the set kV values were adjusted, the actual tube voltage deviations from the nominal values under 25, 28, 30 and 35 kV were reduced from 0.55, 0.34, 0.33, 0.30 to 0.04, 0.02, -0.04, -0.01, and the HVL 1 deviations were reduced from 0.011, 0.007, 0.010, 0.012 to 0.000, 0.003, 0.003, 0.010, respectively. When the thickness differences between the two types of aluminum sheet and the reference HVL 1 were both within 0.1 mm, the deviations of the measured HVL 1 were all less than 0.01 mm Al, and the result was relatively accurate. However, when the differences exceeded that of 0.1 mm, most of the deviations of the measured HVL 1 were between 0.01 and 0.02 mm Al, and the measured result was not accurate. Conclusions:Although the RQR-M radiation quality of the calibration system was deviated, it is still within the range specified under the IEC 61267-2005. The radiation quality was closer to the standard values after fine-tuning the system tube voltage. In order to measure the HVL 1 more accurately, the thickness differences between the used aluminum sheet and nominal HVL 1 should not be greater than 0.1 mm Al.
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Objective:To investigate the feasibility of tube potential of 80 kV combined with personalized contrast agent protocol in carotid artery CT angiography (CTA).Methods:A total of 136 consecutive patients undergoing neck CTA were prospectively enrolled in this study. The patients were randomly divided into Groups A, B, C and D. Tube potential of 100 kV and 15 s contrast agent injection protocol was used for Group A (53 cases) as conventional group, while tube voltage of 80 kV and 10 s contrast agent injection protocol was used for Groups B, C and D as experimental groups, with the contrast agent dosages of 20, 25 and 30 ml used according to the body weights of ≤50 kg(Group B, 20 cases), 50-70 kg (Group C, 38 cases), and 70-90 kg (Group D, 25 cases), respectively. The subjective and objective evaluation results of image quality and the effective doses were compared among the four groups.Results:The effective doses in Groups B, C and D were 1.54±0.91, 1.89±1.08 and 2.14±1.27 mSv, respectively, significantly lower than that in Group A [(5.66±0.56) mSv] ( F=169.34, P<0.05). The image quality of four groups met the requirements of clinical diagnosis. No significant differences were found in subjective evaluation and diagnostic efficacy of the four groups ( P>0.05). The CT number of carotid artery, signal-to-noise ratio and contrast-to-noise ratio of the neck region were significantly lower in Groups B, C and D compared with Group A ( F=14.9, 12.94, 14.43, P<0.05). The CT numbers of target carotid vessel were all higher than 250 HU. Conclusions:The scanning protocol of low tube potential (80 kV) combined with 10 s contrast agent injection protocol could not only reduce the doses of radiation and contrast agent, but also preserve the diagnosis effect. Thus, this scanning protocol was feasible and valuable in clinical application.
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@#Introduction: Radiation exposure during the CT examination has always been a concern due to its associated cancer risk. The guidelines suggest the optimization of radiation dose reduction. Therefore, this study aims to determine the feasibility of dose reduction strategies on radiation dose reduction using a phantom. Methods: Head and body phantoms of 16 cm and 32 cm, respectively, were used to calculate the radiation dose and measure the quantitative image quality. The phantoms were positioned and scanned with the standard protocol and low dose protocol. For dose reduction strategies, scan length was reduced in head phantom, and tube voltage and tube current were manipulated individually and by combining both and tested in both head and body phantoms. Also, the influence of rotation time was investigated in body phantom. Quantitative image quality was determined by drawing a region of interest on the obtained image. Results: Reducing scan length showed 41% reduction of radiation dose and reducing tube current, and tube voltage showed up to 75% reduction of radiation dose in head phantom and 70% reduction of radiation dose in body phantom compared to the standard protocol. The reduction of the rotation time, however, reduced the scan time and the radiation dose but the maximum mAs or tube current allowed was limited. Quantitative image quality was reduced when using a lower dose protocol. Conclusion: The dose reduction strategies showed a reduced dose, but the quantitative image quality score was reduced when scanned with low dose protocol. Further manipulation can be performed to maintain image quality.
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Objective To investigate the effects of different tube voltages on the dose of superficial radiation-sensitive organs and image quality when using organ dose modulation( ODM) in chest CT. Methods Based on clinical chest CT protocol with the sameother parameters, chest phantom was scanned using 140, 120, 100, and 80 kv ( 100 kV was the recommended by the CT system) without ODM ( ODM off ) or with ODM from the starting layer to the breast area ( ODM part ) . A long rod ionization chamber was placed iat a fixed position in front of the right breast area. The scans were repeated for 7 times with each group of scanning parameters and dose values were measured for each scanning, the CTDIvol and breast skin dose measurements( D) were recorded. Coronal images of 5 mm thickness for the lung and soft tissue algorithms were reformatted. The images were divided into 8 parts along the z axis direction, the contrast noise ratios( CNR) for every region were measured. For CTDIvol , D, CNR for different ODM and tube voltage scanning modes, two factor non-repeat test ANOVA was performed. LSD method was used for comparison among groups. Results The CTDIvol was lowest at 80 kV, and the breast skin dose measurement was lowest at 100 kV, CTDIvol decreased in turn from140 to 80 kV ( F=105. 5795, P<0. 05) . The breast skin dose measurement decreased in turn from140 to 100 kV, but increased instead at 80 kV. The difference was statistically significant(F=27. 736, P<0. 05). Compared with ODM off , the CTDIvol and D for ODM part both declined and the differences were statistically significant ( F=39. 732, 81. 961, P<0. 05). The CNRs of the lung and soft tissue images decreased at every tube voltage(F=12. 809, 11. 261, P<0. 05 ) . The CNRs decreased from140 to 100 kV, but there was no statistical difference( P>0. 05) , and the difference was significant at 80 kV( P<0. 05) . Compared with ODM off, the CNRs of lung and soft tissue algorithm images with ODM part decreased, withnot statistically significant differences ( P>0. 05 ) . Conclusions In clinical practice, with the tube voltage not less than the recommended(100 kV), the optimal reduction of breast radiation dose can be achieved by reducing kV and using ODM on the premise of resonable image quality.
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Objective To investigate the feasibility, image quality, and safety of low?tube?voltage, low iodine load iso?osmolar contrast comprehensive cardiac and aortoiliac CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning. Methods Ninety?eight consecutive TAVR candidates prospectively underwent combined contrast?enhanced CTA of the aortic root complex and vascular access route. Patients were assigned to group A (2nd generation dual?source CT, 100 kV, contrast 270 mgI/ml iodixanol) or group B (2nd generation dual?source CT, 120 kV, contrast 370 mgI/ml). Mean vascular attenuation, noise, signal?to?noise ratio (SNR), and contrast?to?noise ratio (CNR) of aorta including aortic root, aortic arch, descending aorta at level of diaphragm, abdominal aorta at level of renal artery and femoral artery were compared. Patient creatinine levels before the examination of CTA and during follow?up (24—48 h) were measured. Results The image quality score of aortic root and whole aorta was (4.2±0.7) and (4.3±0.4) respectively in experimental group, (4.3±0.6) and (4.3±0.3) in control group. No significant difference in subjective image quality score between two groups including aortic root image and whole aorta image (t=-0.130,-0.155,P=0.694, 0.822). The image noise of aortic root and femoral artery were higher in experimental group than that in control group (P<0.05). Radiation dose in experimental group was higher than that in control group [(6.1 ± 0.4) vs. (8.0 ± 0.4) mSv, t=-9.253, P=0.001]. There were no significant changes in creatinine levels among groups during the follow?up. Conclusion TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low iodine load iso?osmolar contrast using low?tube?voltage acquisition.
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Objective Exploration of the application value of the third-generation dual source CT low tube voltage (70 kVp) scanning combined with advanced modeling iterative reconstruction (ADMIRE) technique in children with adenoid examination. Methods CT scans were performed in patients with clinically suspected adenoid hypertrophy. They were divided into two groups according to the time of treatment. Group A (40 cases) : low tube voltage (70 kVp) scan, reference tube current 163 mAs, reconstruction with ADMIER, Intensity 3; Group B (40 cases) : conventional 100 kVp, reference tube current 163 mAs, conventional (filtered back-projection, FBP) reconstruction;rest of the scanning parameters remained unchanged. The subjective scores and objective quality indicators of the images (CT value, image noise, signal noise ratio (SNR) , contrast noise ratio (CNR)) and radiation dose of the two groups were compared. Results The difference of radiation dose between group A and group B was statistically significant (P < 0.05). The radiation dose of group A was lower than that of group B by 77.58％.Compared with group B, the image noise of group A increased by 0.002％; the SNR decreased by 0.01％; CNR increased by 0.03％; there was no significant difference in objective quality evaluation index and subjective score between two groups in the image quality (P> 0.05). Conclusion The third-generation dual-source CT low-tube voltage (70 kVp) combined with ADMIRE reconstruction technique for children with adenoid scan can effectively reduce the radiation dose while ensuring image quality.
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Objective To investigate the effect of the change of tube voltage on radiation dose and image quality in head-neck and chest scanning under automatic tube current modulation ( ATCM ) . Methods CT scanning was performed on the head-neck and chest phantom with ATCM and automatic tube voltage(CARE kV). The tube voltage was manually selected at 70, 80, 100, 120 and 140 kV separately, and a routine CT scanning of the head-neck and chest with ATCM was performed. The scout was scanned for 3 times and a spiral scanning was performed once at each of tube voltage. The regions of interest( ROIs) were selected in the slices of orbital center and C5 upper edge level for the head-neck phantom, in the slices of apical and tracheal bifurcation level for the chest phantom. The contrast to noise ratios ( CNRs) were measured and recorded. The organ dose of eye lens and mammary are measured with thermoluminescent dosimeters ( TLDs ) for every scanning ( the average of 3 measurements ) . The cumulative dose value of the scout and spiral scanning was calculated. The volume CT dose index ( CTDIvol ) of each scan was recorded, and the cumulative value of CTDIvol was calculated. Finally, the optimized tube voltage was obtained by calculating the FOM ( figure of merit) . Results With ATCM and CARE kV, 120 kV and 108 mAs were chose automatically by system for head-neck phantom, 80 kV and 167 mAs for chest phantom. With ATCM, the radiation dose of eye lens and CTDIvol were minimal with manually selected 70 kV ( 0.779 and 4.070 mGy respectively ) , and maximaum with manually selected 140 kV (2.571 and 25.670 mGy). The radiation dose of the mammary gland and CTDIvol were minimal with manually selected 70 kV ( 0.698 and 0.900 mGy ) , and maximal with manually selected 140 kV (3.452 and 7.400 mGy). The CNR values of orbital center and C5 upper edge level were 51.30-118.36 and 80.78 - 173.12 respectively. The CNR values of the apical and tracheal bifurcation level were 50.15-129.58 and 49.63-115.40, respectively. The optimal FOM was appeared at orbital center slice with 80 kV, at C5 upper edge level slice with 120 kV and at both the apical and tracheal bifurcation level with 70 kV. Optimum tube voltage for head-neck phantom: manual 100 kV at orbital level, CARE kV mode(120 kV) at neck level. Optimal tube voltage for chest phantom: manual 100 kV. Conclusions The selection of tube voltage is responsible for the radiation dose and image quality of CT scanning. For conventional CT scan, manual 100 kV is suitable for orbital scanning, automatic 120 kV is suitable for neck scanning, manual 100 kV is suitable for chest scanning.
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Objective To evaluate the clinical value of low kVp with iterative reconstruction in multislice spiral computed tomography of lumber vertebrae in young soldiers. Methods Sixty young soldiers who suffered from lumbar diseases were randomly divided into a control group(120 kVp)and a test group(100 kVp),who underwent CT examination with 120 kVp tube voltage in the control group and 100 kVp tube voltage in the test group.The control group went through filtered back projection (FBP)for image reconstruction.The test group applied FBP or sinogram-affirmed iterative reconstruction(SAFIRE)based on image reconstruction requirements,and then were divided into FBP test group and SAFIRE test group.The noise and SNR (signal to noise ratio)of the images were measured in each group.Meanwhile two experienced radiologists evaluated the quality of images.CTDIvol,DLP and ED were used to measure the scan dose in each group.Mean tube current was recorded by CARE Dose 4D.The data were analyzed with SPSS.Results There were no significant difference between the objective and subjective image evaluations in SAFIRE test group and the control group (P>0.05),while there were statistical differences between FBP test group and the control group or between the two test groups(P<0.05).The radiation doses in the test groups were both lower significantly than that in the control group,and the ED values in the test groups were decreased by 43% when compared with the control group. The test groups had the tube voltages not obviously different from that in the control group (P>0.05). Conclusion The radiation dose in the lumbar multislice spiral CT examination of young soldiers is decreased significantly when the tube voltage falls to 100 kVp,the same image quality as that by conventional 120 kVp tube voltage can be obtained by combining iterative reconstruction.
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Objective To investigate the effect of tube voltage on the organ dose of the superficial sensitive organs (lens,thyroid and mammary gland) and the image quality under the same volume CT dose index (CTDIvol).Methods Combining the appropriate scout image and scanning center,the head-neck and chest phantom were scanned by CT under CARE kV semi mode.Under the same CTDIvol,the tube voltage was set by 70,80,100,120,140 kV respectively,and the scout image was scanned three times under each tube voltage.Then each tube voltage was used for spiral scan.For head-neck phantom ROIs were selected in orbital center and C5 upper edge level,for chest phantom ROIs were selected in the apical and tracheal bifurcation level.The contrast noise ratio (CNR) was measured and recorded.The CTDIvol values of the headneck and chest phantom were set by 15.30 mGy,2.60 mGy respectively.The organ dose of lens,thyroid and mammary were measured by thermoluminescent dosimeters (TLD) in every scanning(take the average of 3 measurements),calculating the cumulative value of scout image and spiral scanning.Finally,the appropriate tube voltage was sought by calculating the FOM (figure of merit).Results When CTDIvol was 15.30 mGy,the lens radiation dose was the smallest at 70 kV(2.440 mGy),the lens radiation dose was the largest at 140 kV(2.823 mGy),the thyroid radiation dose was the smallest at 100 kV(4.052 mGy),and the largest at 80 kV (4.914 mGy).When CTDIvol was 2.60 mGy,the mammary radiation dose was the smallest at 70 kV(2.353 mGy),the largest at 120 kV(2.735 mGy).When the tube voltage was 120 kV,the CNR value was the highest at the orbital center and C5 upper edge level,and the range was 82.83 to 111.67 and 117.22 to 162.51 respectively.When the tube voltage was 140 kV,the CNR value was the highest at the apical and tracheal bifurcation level,and the range was 71.26 to 112.81 and 76.21 to 88.52 respectively.The optimal FOM factor was 100 kV at orbital center and 120 kV at C5 upper edge level (4 575.01,6 198.94 respectively).The optimal FOM factor was 140 kV at the apical and 70 kV at tracheal bifurcation level (4 937.01,3 208.01 respectively).Conclusion The change of the tube voltage has a certain effect on the dose of the superficial sensitive organs and the image quality under the premise of the same CTDIvol.
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Objective To study the application of the intelligent optimum tube voltage ( Care kV) combined with automatic tube current ( Care Dose 4D) technique in dual source CT scanning for the abdomen .Methods 180 adult patients underwent whole abdominal CT examination from February 2016 to March 2016 of were selected as the retrospective research objects .On the basis of reference mAs of the image quality the patients were divided into three groups using completely randomized grouping method with 60 patients in each group, such as 250 mAs group, 200 mAs group, and 150 mAs group.The other scanning parameters and image reconstruction parameters were the same .The liver parenchyma CT values and image noise( SD) at the second hepatic portal level were measured .The signal-to-noise ratios ( SNR) in the three groups were compared as well as contrast to noise ratio ( CNR ) , noise ( SD ) , the average volume CT dose index (CTDIvol), dose length product (DLP) and effective dose(E).Results The kV and mAs values in the plain scan , arterial phase scan and portal phase scan in the three groups of patients had statistically significant differences(F=35.25, P0.05).In 250 mAs group and 150 mAs group, the SNR and the noise of plain scan and arterial phase images had no statistically significant difference ( F=1.98, P>0.05) , and SNR of portal phase images and CNR of three phases had statistically significant difference (F=27.64, P0.05), and the SNR and CNR of portal phase images had significant difference (F=19.63, P<0.05).Conclusions For the combined use of Care kV and Care dose 4D,it is feasible to select appropriate reference mAs in reducing radiation dose without sacrificing imaging quality .
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Objective To analyze the CT pulmonary angiography(CTPA) image quality and radiation dose of obesity patients with high and low tube voltage iterative reconstruction(IR) and the filtered back projection(FBP) reconstruct algorithm,and to explore the feasibility of low tube voltage IR algorithms in CTPA of obese patients.Methods Obese patients with suspected pulmonary embolism were randomly assigned into 80 kV or 120 kV group, and the images were treated with IR and FBP reconstructions.CT value of the basal segment of the right pulmonary artery, right upper lobe and main pulmonary artery were measured, and the average CT value of the pulmonary artery was further calculated, and the independent sample t test analysis was used.Results Comparing the CT value of the IR and FBP subgroup of two tube voltage groups, the differences were not significant (P>0.05), the differences of noise, signal noise ratio(SNR) and contrast noise ratio (CNR) were statistically significant (P<0.05), respectively.The CT value,noise,SNR and CNR of 80 kV group were significantly higher than those of the 120 kV group, and the differences were statistically significant (P<0.05), while the radiation dose were significantly lower than those of 120 kV group (P=0.000).Conclusion The CTPA image quality of 80 kV IR algorithm is significantly improved compared with the 120 kV FBP algorithm, and the radiation dose is significantly reduced, which could be used for CT pulmonary angiography in obese patients.
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Objective To explore the feasibility of low-tube-voltage and low-concentration contrast agent applied to coronary computed tomography angiography (CTA) in the overweight patients. Methods Totally 83 overweight patients with suspected coronary heart disease who underwent coronary artery angiography were randomly assigned into two groups. Group A used 100 kVp and ioversol-320 mg/ml, and Group B received 120 kVp and iopamidol-370 mg/ml. Both the groups went through prospectively ECG-gated scanning. The two groups were compared on the image quality, radiation dose, iodine intake and coronary artery segments scores. Results The effective radiation dose and iodine intake in Group A were significantly lower than those in Group B (P<0.05). Group A had the coronary artery CT value and image noise lower significantly than Group B (P<0.05). No significant differences in signal to noise ratio, contrast to noise ratio and coronary artery segments scores were observed between the two groups (P>0.05). Conclusion For coronary artery CTA in the overweight patients, low-tube-voltage and low-concentration contrast agent still preserves the image quality, as well as significantly reduces the radiation dose and iodine intake.
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Objective To assess the effects of different level iterative reconstructions (IR) on image quality of obese patients of 80 kV CT pulmonary angiography (CTPA).Methods Forty obese patients with clinically suspected pulmonary embolism were examined with CTPA,filtered back projection method (FBP) and three IR levels (iDose1,20％ IR/80％ FBP;iDose3,40％ IR/60％ FBP;iDose5,60％ IR/40％ FBP) to reconstruct images were used.The CT value of pulmonary artery trunk,upper lobe artery and lower lobe basal segment artery of right pulmonary were measured,and the image noise,SNR and CNR of four groups were calculated and compared.Results The image noise,SNR and CNR had significant difference in 4 groups (all P＜0.05),and the image noise had significant difference between each two groups (all P＜0.05),the SNR and CNR had statistical difference between FBP and iDose3,between FBP and iDose5 (P＜0.01).Conclusion Compared with FBP,80 kV combined with different level IR technologies can significantly decrease image noise and improve objective image quality in CTPA,the radiation dose that obese patients received can be reduced.
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Objective To discuss the feasibility of double-low technique applied in aortic MSCTA.Methods Totally 70 patients with BMI not more than 25 kg/m2 were divided into a routine group and an experimental group randomly and equally,and then went through aortic MSCTA.Iohexol (350 mgI/ml) was injected with the velocity of 4 ml/s.The routine group had the parameters as 120 kV,120 mAs and 1.5 ml/kg contrast agent,and the experimental group had the parameters as 90 kV,120 mAs and 1.0 ml/kg contrast agent,while the other scanning parameters were kept the same in the two groups.The radiation doses,contrast agent doses and iodine contents were recorded in the two groups,and the image quality was assessed with double-blind method objectively and subjectively.Results The experimental group had the CT dose index volumes (CTDIvol),dose length product (DLP) and effect dose (ED) significantly lower than those in the routine group (P＜0.05).The two groups had the consistency of subjective scores (Kappa＞0.6) and image quality scores (not lower than 2) meet the desired requirements,and there were no significant differences between the scores (P＞0.05).Objective evaluation showed that the signal values of aortic trunk and major branch vessels as well as image noise SD of the experimental group were obviously higher than those in the routine group (P＜0.05).There were no statistical differences between the signal noise ratios (SNR) and contrast to noises (CNR) in the two groups (P＞0.05),The iodine content in the contrast agent of the experimental group was significantly lower than that in the routine group (P＜0.05).Conclusion Double-low technique applied in aortic MSCTA of the patient with BMI not more than 25 kg/m2 reduces the radiation dose and iodine content in the contrast agent,has the image quality meet the desired requirements,and thus is of great value for clinical application.
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OBJECTIVE: To evaluate the feasibility and image quality (IQ) of prospectively high-pitch coronary CT angiography (CCTA) with low contrast medium injection rate at 70 kVp. MATERIALS AND METHODS: One hundred and four patients with suspected coronary artery disease (body mass index < 26 kg/m², sinus rhythm and heart rate < 70 beats/min) were prospectively enrolled and randomly divided into two groups. In group A and group B, 28 mL and 40 mL of 370 mgI/mL iodinated contrast media was administrated at a flow rate of 3.5 and 5 mL/s, respectively. CT values, noise, signal-to-noise ratio, contrast-to-noise ratio (CNR) of the proximal segments of coronary arteries and subjective IQ were evaluated. RESULTS: The CT values and noise in group A were significantly lower than those in group B (434–485 Hounsfield units [HU] vs. 772–851 HU, all p < 0.001; 17.8–22.3 vs. 23.3–26.4, all p < 0.005). The CNRs of the right coronary artery and left main artery showed no statistical difference between the two groups (42.1 ± 13.8 vs. 36.8 ± 16.0, p = 0.074; 38.7 ± 10.6 vs. 38.1 ± 17.0, p = 0.819). No statistical difference was observed between the two groups in IQ scores (3.04 ± 0.75 vs. 3.0 ± 0.79, p = 0.526) and diagnostic ratio (96.1% [50/52] vs. 94.2% [49/52], p = 0.647). CONCLUSION: Prospective high-pitch CCTA at 70 kVp with 28 mL of contrast media and injection rate of 3.5 mL/s could provide diagnostic IQ for normal-weight patients with heart rate of < 70 beats/min.
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Humans , Angiography , Arteries , Contrast Media , Coronary Artery Disease , Coronary Vessels , Heart Rate , Noise , Prospective Studies , Signal-To-Noise RatioABSTRACT
OBJECTIVE: To evaluate the feasibility and image quality (IQ) of prospectively high-pitch coronary CT angiography (CCTA) with low contrast medium injection rate at 70 kVp. MATERIALS AND METHODS: One hundred and four patients with suspected coronary artery disease (body mass index < 26 kg/m², sinus rhythm and heart rate < 70 beats/min) were prospectively enrolled and randomly divided into two groups. In group A and group B, 28 mL and 40 mL of 370 mgI/mL iodinated contrast media was administrated at a flow rate of 3.5 and 5 mL/s, respectively. CT values, noise, signal-to-noise ratio, contrast-to-noise ratio (CNR) of the proximal segments of coronary arteries and subjective IQ were evaluated. RESULTS: The CT values and noise in group A were significantly lower than those in group B (434–485 Hounsfield units [HU] vs. 772–851 HU, all p < 0.001; 17.8–22.3 vs. 23.3–26.4, all p < 0.005). The CNRs of the right coronary artery and left main artery showed no statistical difference between the two groups (42.1 ± 13.8 vs. 36.8 ± 16.0, p = 0.074; 38.7 ± 10.6 vs. 38.1 ± 17.0, p = 0.819). No statistical difference was observed between the two groups in IQ scores (3.04 ± 0.75 vs. 3.0 ± 0.79, p = 0.526) and diagnostic ratio (96.1% [50/52] vs. 94.2% [49/52], p = 0.647). CONCLUSION: Prospective high-pitch CCTA at 70 kVp with 28 mL of contrast media and injection rate of 3.5 mL/s could provide diagnostic IQ for normal-weight patients with heart rate of < 70 beats/min.
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Humans , Angiography , Arteries , Contrast Media , Coronary Artery Disease , Coronary Vessels , Heart Rate , Noise , Prospective Studies , Signal-To-Noise RatioABSTRACT
Objective:To investigate the effect and application feasibility of low tube voltage, low concentration of contrast agent volume to CTA in the diagnosis of coronary artery stenosis and its effect.Methods: Seventy two cases of suspected patients with coronary atherosclerosis selected as the object Using random number table method, all patients were divided into group A and group B 36 cases in each group, two groups of patients underwent 320 slice CTA examination, in group A the tube voltage is 120kV, the contrast agent was 350mgI/mL iodixanol group, B tube voltage is set to 100kV, the contrast agent was 270mgI/mL iodixanol. According to the examination results of group A, group B and catheter coronary angiography (CCA), evaluated group A, group B of acquiring the image quality and radiation dose of patients, and analyzed the sensitivity of A, B and CCA examination of the extent of coronary artery stenosis degree and deliberately.Results: The quartering method showed no significant difference between the group A and the group B of image quality. There was significant difference between the two groups of patients with the image noise and enhance the effect (t=-4.736, 11.927;P<0.05); Group B of coronary artery stenoses (more than 50%) and severe stenosis (more than 75%) sensitivity, specially degree and coincidence rate compared with the results of CCA showed no significant difference. Kappa consistency analysis showed that the two consistency is good(kappa=1.320,P<0.001).Conclusion: In the premise of ensuring the image quality with low tube voltage, low concentration of contrast agent volume coronary CTA examination had safety and reliability of inspection.
ABSTRACT
Abstract. The use of CT has continued to increase in the last few years, making it the largest contributor to the collective world dose. Children are not exempt from this, with a potentially increasing risk. The effect of tube voltage as a tool for dose reduction has been studied with the aim of investigating methods for optimisation in MSCT, including assessing its effect on image quality. It has been observed that when using the same kV values, the CTDIw is higher by a factor of 2 for the paediatric phantom compared to the adult phantom. A significant reduction in CTDIw was corroborated when lowering the kV, with fewer effects on noise in the paediatric image. On the other hand, a kV reduction allows better contrast when imaging bony structures and using contrast media.
El incremento en el uso de la TC es sostenido en los últimos años, llegando a ser la mayor contribución a la dosis colectiva mundial. Los niños no están exentos de ello, con un riesgo potencialmente creciente. Con el objetivo de estudiar métodos de optimización en TCMC se investigó el efecto del voltaje de tubo como herramienta de reducción de dosis gracias al uso de fantomas representativos, evaluando paralelamente su efecto sobre la calidad de imagen. Se observó que para el fantoma pediátrico el CTDIw es mayor en un factor de 2 con respecto a su símil adulto para iguales valores de kV. Se constató que una reducción en el kV permite una notoria disminución de CTDIw, con menores efectos sobre el ruido en la imagen pediátrica. Por otro lado, una reducción de kV permite mejorar el contraste de estructuras óseas y con medio de contraste yodado.