Investigation on radiation doses and related influencing factors for CT adult examinations in Huai′an city / 中华放射医学与防护杂志

Objective:To investigate the level of radiation doses to adults caused by CT examination in Huai′an, and explore the local CT diagnostic reference levels (DRLs).Methods:Totally 45 CT scaners were selected to investigate the information on hospitals, equipment, scanning parameters, and radiation doses. Empirical formula were used to estimate the effective dose to adults. Nonparametric rank sum tests were used to analyze differences in radiation dose level between CT service age and hospital grade.Results:A total of 3 483 patients were collected, including 890 for head examinations, 890 for chest, 846 for abdomen, and 857 for lumbar spine. The 75% percentile values of CTDI vol to adult patients from CT scanning for head, chest, abdomen, lumbar spine examinations were 63.0, 12.4, 20.0 and 24.0 mGy, respectively. The 75% percentile values of DLP were 858.6, 416.0, 620.7 and 559.2 mGy·cm, respectively. The 75% percentile values of DLP for males was higher than those for females. There were significant statistical differences in radiation doses dependent on equipment service (head: U =10 326.00, P<0.05; chest: U=36 094.50, P<0.05; abdomen: U= 7 859.00, P<0.05; lumbar spine: U=42 408.00, P<0.05), and hospital grade (head: H=14.280, P<0.05; chest: H=17.85, P<0.05; abdomen: H=97.18, P<0.05; lumbar spine: H=138.94, P<0.05). Conclusions:The CT radiation dose levels in Huai′an city is basically consistent with standard-reommended values, which is in line with the current status of CT equipment dose levels in the country. It is necessary to strengthen the quality control and maintenance of CT equipment.

Size-specific dose estimation for chest CT examination in pediatric and adult patients / 中华放射医学与防护杂志

Objective To compare the differences in radiation doses from CT scanning between children of different age groups and adult patients by using both traditional radiation dose assessment parameters and size-specific dose estimates (SSDE).Methods A total of 406 patients undergoing lung CT examination were studied.They were sampled retrospectively and continuously from the Union Hospital and divided into six groups by age distritution (0-2,3-6,7-10,11-14,15-18,＞18 years old).The CTDIvol and DLP values were randomly sampled using MATLAB platform-based dicom data software.The SSDE and water equivalent diameter were also calculated according to the AAPM 220 Report.The differences in radiation doses from lung CT scaning between children and adult patients were analysed.Results The CTDIvol values for all age groups were significantly lower than the SSDE values.The differences were statistically significant (t =-36.36,-32.83,-30.36,-28.74,-23.89,P＜0.05).The SSDE values were 137％,94％,79％,57％ and 42％ higher than the CTDIvol values,respectively.The CTDIvol values for the adult group were also lower than the SSDE values,and the difference was statistically significant (t=-21.92,P＜0.05),and the SSDE value was about 41％ higher than the CTDIvol value.With the increased age,CTDIvol value,DLP value,Dw value and SSDE value for children of all age groups gradually increased and were significantly smaller than those for the adult group.The difference was statistically significant (F=63.39,203.28,89.27,103.44,P＜0.05).The conversion coefficient f for all age groups decreased significantly with age,which was significantly higher than that for the adult group,and the difference was statistically significant (F =109.83,P ＜ 0.05).Conclusions In lung CT scanning,the CTDIvol value significantly underestimated the radiation doses to children as compared to adults.CTDIvol values are more easily underestimated for younger patients.The SSDE method allows for more accurate reflection of the radiation doses to different patients,taking into account differences in the examined patient size.

Application of low tube voltage with low concentration contrast agent volume of coronary CTA examination in the diagnosis of coronary artery stenosis / 中国医学装备

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.

Application of 320-detector row dynamic volume CT angiography in follow up of coronary artery aneurysms caused by Kawasaki disease / 临床儿科杂志

ObjectiveTo assess the values of 320-detector row dynamic volume CT angiography (CTA) and transthoracic echocardiography (TTE) in follow up of coronary artery aneurysm (CAA) caused by Kawasaki disease (KD).Methods320-de-tector row CTA and TTE were applied in long-term follow-up of 8 patients with CAA caused by KD.ResultsIn 8 patients, the mean age at onset was 41.63±22.70 months and the mean follow up time was 43.50±10.99 months. In acute phase, 3 cases of giant coronary artery aneurysms (GCAA) and 5 cases of mid-small CAA were diagnosed by TTE. A total of 16/32 arteries (50%) were involved. At the end of follow-up, 3 cases of GCAA and 2 cases of mid-small CAA were still diagnosed by TTE, and small CAAs were regressed in another 3 cases. A total of 6/32 arteries (18.75%) were involved. Simultaneously at the end of follow-up, a total of 7/32 arteries (21.9%) were involved by 320-detector row CTA. The distribution was consistent with that of TTE. Mean-while, there were one case of left circumlfex artery, one case of GCAA at distal of the right coronary artery, 2 cases of thrombus, 1 case of coronary stenosis and 2 cases of calciifcation.ConclusionsCAA caused by KD may be persistent for a long time. The thrombus, stenosis, and calciifcation of coronary can occurr at late phase in GCAA. TTE is sensitive and reliable to detect proxi-mal and middle segment of coronary lesions, but has limitations in detection of distal segment of coronary arteries. 320-detector row CTA has more comprehensively view of each coronary artery lesions and is especially sensitive and reliable to detect coro-nary thrombosis, calciifcation and narrowing in proximal and distal coronary arteries after acute phase.

The impact of heart rate on image quality and radiation dose of coronary angiography using 640-slice dynamic volume CT / 实用放射学杂志

Objective To analyze retrospectively the impact of different heart rates on image quality and radiation dose of coronary angiography using 640-slice dynamic volume CT.Methods A total of 461 patients with suspected coronary artery disease or referred to health check underwent coronary angiography with 640-slice dynamic volume CT.Two groups were created according to their heart rates:Group A had heart rate < 65 beats per minute (n=337)and Group B had heart rate between 65 to 122 beats per minute (n=124).Image quality was assessed by analyzing the 1 5 segments of the main coronary branches using 3-grade scale (grade I-good,grade Ⅱ-acceptable,grade Ⅲ-poor).Effective radiation dose was also evaluated.Results Patients in both A group and B group performed successful CT coronary angiography with a total of 6 91 5 coronary segments.Among them,coronary segments that could be evaluated reliably accounted for 94.5% (6 535/6 91 5)while 5.5% (380/6 91 5)were too small (≤1.5 mm)to be assessed. For the image quality,Group A and Group B had grade I in 90.5% (305/337)vs 74.2% (92 /124),grade Ⅱ in 9.5% (32/337)vs 21.0% (26 / 124)and grade Ⅲ in 0 % (0 / 337 )vs 4.8% (6 / 124),respectively.Image quality was significantly different be-tween Group A and Group B (P <0.001).In addition,32 patients (9.5%)in Group A had slight cardiac motion artifacts but with-out affecting image quality,whereas 26 patients (21.0%)in Group B had higher degree of cardiac motion artifacts thus graded as grade Ⅱ.Stair-step artifacts were not found in all patients.The effective radiation dose was higher in Group B than in Group A by 32.05%(7.91±0.34 mSv vs 5.99±0.17 mSv).Conclusion Coronary angiography using 640-slice dynamic volume CT can guarantee excellent image quality when heart rate < 65 beats per minute.Although the image quality would decrease in some extent it is still diagnostic when heart rate is between 65 to 122(include 65 and 122)beats per minute.

Predicting dysthyroid optic neuropathy using computed tomography volumetric analyses of orbital structures

OBJECTIVE: To evaluate the ability of orbital apex crowding volume measurements calculated with multidetector-computed tomography to detect dysthyroid optic neuropathy. METHODS: Ninety-three patients with Graves' orbitopathy were studied prospectively. All of the patients underwent a complete neuro-ophthalmic examination and computed tomography scanning. Volumetric measurements were calculated from axial and coronal contiguous sections using a dedicated workstation. Orbital fat and muscle volume were estimated on the basis of their attenuation values (in Hounsfield units) using measurements from the anterior orbital rim to the optic foramen. Two indexes of orbital muscle crowding were calculated: i) the volumetric crowding index, which is the ratio between soft tissue (mainly extraocular muscles) and orbital fat volume and is based on axial scans of the entire orbit; and ii) the volumetric orbital apex crowding index, which is the ratio between the extraocular muscles and orbital fat volume and is based on coronal scans of the orbital apex. Two groups of orbits (with and without dysthyroid optic neuropathy) were compared. RESULTS: One hundred and two orbits of 61 patients with Graves' orbitopathy met the inclusion criteria and were analyzed. Forty-one orbits were diagnosed with Graves' orbitopathy, and 61 orbits did not have optic neuropathy. The two groups of orbits differed significantly with regard to both of the volumetric indexes (p<0.001). Although both indexes had good discrimination ability, the volumetric orbital apex crowding index yielded the best results with 92% sensitivity, 86% specificity, 81%/94% positive/negative predictive value and 88% accuracy at a cutoff of 4.14. CONCLUSION: This study found that the orbital volumetric crowding index was a more effective predictor of dysthyroid optic neuropathy than previously described computed tomography indexes were.

Application value of low radiation dose coronary angiography using 320-slice volume CT / 中华放射医学与防护杂志

Objective To evaluate the image quality and radiation dose of prospective electrocardiography-triggered coronary 320-slice volume CT angiography with different kV, and the feasibility of coronary scan with ＜ 1 mSv radiation dose.Methods Eighty consecutive patients were randomly divided into two groups equally.The tube voltage according to paradigm was 100 kV in group A and 120 kV in group B.All raw data in group A was reconstructed by the software AIDR in CT system to create a new group named as A1. Such parameters as the mean intraluminal attenuation (SI),noise (SD),signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR),effective radiation dose(E) and image quality score measured in group A were compared with those in group B.The values such as SI,SD,SNR,CNR,image quality scores were compared between group A and group A1.The significance of group B and group A1 was compared in SI,SD,SNR,CNR,image quality scores as well.Results E in group A was significantly lower than that in group B[ E =(0.67 ± 0.18) mSv in group A vs.E =(3.08 ± 1.04) mSv in group B].The value of E in group A was decreased by 78％ compared to group B(t =- 14.30,P＜0.05 ).There was no significant difference in mean image quality scores between two groups(4.57 ± 0.57in groupA vs.4.59 ± 0.59 in group B,t=-1.17,P＞0.05).The values of SI,SD,SNR,CNR in group A were (570.8 ±131.5)HU,25.1 ±6.9,24.5 ±9.1,19.8 ±6.1.And the values of SI,SD,SNR,CNR in group B were (460.6 ± 14.3) HU,15.1 ±3.6,31.7 ±7.7,29.3 ±6.8.The values of SI and SD in group A were significantly higher than those in group B(t =4.49,8.18,P ＜0.05). The values of SNR and CNR in group A were lower than those in group B (t =-4.24,-6.19,P＜0.05).The valuesofS1,SD,SNR,CNR,image quality scores in group Al were (557.9 ±24.5) HU,21.1 ±6.0,27.7±10.0,23.4±7.8,4.60 ± 0.56.There was no difference in the SI and the image quality scores between group A and group A1 ( t =1.09,- 1.90,P ＞ 0.05).Conclusions 320-slice volume CT with 100 kV tube voltage and prospective ECG-triggered technique can reduce the radiation dose to less than 1 mSv and obtain optimal images in diagnosis of coronary arterial diseases.

The evaluation of intracranial aneurysms:comparison with subtraction CT angiography and volume CT digital subtraction angiography / 重庆医科大学学报

Objective:To evaluate the diagnostic value of subtraction CT angiograph(SCTA)and volume CT Digital subtractionangiography(VCTDSA) in detecting intracranial aneurysms,and compare their performance.Methods:Previously publishedliteratures concerning the diagnostic performance of SCTA between 1990 and 2008 were retrospectively reviewed(seven in English andtwo in Chinese),and were analyzed and compared with the performance of VCTDSA in detecting and characterizing of intracranial aneurysms.Then the correlated information was extracted,and the diagnostic sensitivity and specificity of intracranial aneurysms by the two kinds of technique were analyzed.Results:Except the data of Imakita、Romijn which the sensitivity of detecting intracranial aneurysms were 92% and 99%,the sensitivity of others were 100%,and the specificity of detecting intracranial aneurysms were 90% to 100%.88.9% of images were excellent quality(8/9)in the display of cerebral vessels and diagnostic information of intracranial aneurysms.The image quality of VCTDSA was excellent compared with other subtraction CT angiography,and it could completely display the whole cerebral vessels,including 5 grade branches and the clear relationship among artery-veins,aneurysms and parent artery of aneurysms.Conclusion:Compared with Subtraction CT angiography,VCTDSA has an advantage in the diagnosis of intracranial aneurysms.