Diagnosis of Pulmonary Artery Embolism: Comparison of Single-Source CT and 3rd Generation Dual-Source CT using a Dual-Energy Protocol Regarding Image Quality and Radiation Dose
Bernhard PetritschAleksander KosmalaTobias GassenmaierAndreas Max WengSimon VeldhoenAndreas Steven KunzThorsten Alexander Bley
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Purpose To compare radiation dose, subjective and objective image quality of 3 rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice single-source CT (SSCT) for pulmonary CTA. Materials and Methods 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120 kV (ref.); group 2: single-energy DSCT 100 kV (ref.); group 3: DECT 90/Sn150 kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale. Results Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p < 0.001 [CTDIvol]; p < 0.001 [DLP]) and the DSCT group (p = 0.003 [CTDIvol]; p = 0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79 ± 0.95 mSv and significantly smaller than in the SSCT group (4.60 ± 1.68 mSv, p < 0.001) and the DSCT group (4.24 ± 2.69 mSv, p = 0.003). The SNR and CNR were significantly higher in the DSCT group (p < 0.001). Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75 % (135/180) of cases with an inter-observer agreement of 80 %. Conclusion Dual-energy pulmonary CTA protocols of 3 rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps. Key Points: Citation FormatKeywords:
Dual energy
To evaluate the difference of the 3D image quality between the low-dose and the standard-dose chest CT.Eleven patients were randomly scanned with the standard-dose CT and 9 with the low-dose CT. Quality of the images from both groups was evaluated by different postprocessing techniques.The effective tube current, total tube current, and CT dose index volume were (114.55 +/- 26.20) mAs, (1578.27 +/- 353.09) mAs, and (7.76 +/- 1.77) mGy, respectively, in the standard-dose scanning group, and were 20 mAs, (566.11 +/- 46.23) mAs, and (1.46 +/- 0.07) mGy, respectively, in the low-dose scanning group. All these indicators had significant differences between these two groups (P < 0.001). The image noises were (17.67 +/- 3.24) HU in standard-dose group and (31.61 +/- 9.42) HU in low-dose group (P < 0.001). As shown by different postprocessing techniques, the median score of the standard-dose group and the low-dose group were 4.52 and 4.78, respectively, which was not significantly different (P = 0.92).The low-dose CT scanned with 20 mAs effective tube current can remarkably reduce the radiation dose, and provide satisfactory postprocessing images for diagnosis.
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Fluorodeoxyglucose (18FDG) PET/CT imaging has become an important component of the management paradigm in oncology. However, the significant imparted radiation exposure is a matter of growing concern especially in younger populations who have better odds of survival. The aim of this study was to estimate the effective dose received by patients having whole body 18FFDG PET/CT scanning as per recent dose reducing guidelines at a tertiary care hospital.This prospective study covered 63 patients with different cancers who were referred for PET/CT study for various indications. Patients were prepared as per departmental protocol and 18FDG was injected at 3 MBq/Kg and a low dose, nonenhanced CT protocol (LD NECT) was used. Diagnostic CT studies of specific regions were subsequently performed if required. Effective dose imparted by 18FDG (internal exposure) was calculated by using multiplying injected dose in MBq with coefficient 1.9?102 mSv/MBq according to ICRP publication 106. Effective dose imparted by CT was calculated by multiplying DLP (mGy.cm) with ICRP conversion coefficient "k" 0.015 [mSv / (mG. cm)].Mean age of patients was 49 ±18 years with a male to female ratio of 35:28 (56%:44%). Median dose of 18FDG given was 194 MBq (range: 139293). Median CTDIvol was 3.25 (2.46.2) and median DLP was 334.95 (246.70 576.70). Estimated median effective dose imparted by 18FDG was 3.69 mSv (range: 2.855.57). Similarly the estimated median effective dose by low dose (nondiagnostic) CT examination was 4.93 mSv (range: 2.14 10.49). Median total effective dose by whole body 18FDG PET plus low dose nondiagnostic CT study was 8.85 mSv (range: 5.5613.00).We conclude that the median effective dose from a whole body 18FDG PET/CT in our patients was significantly low. We suggest adhering to recently published dose reducing strategies, use of ToF scanner with CT dose reducing option to achieve the lower if not the lowest effective dose. This would certainly reduce the risk of second primary malignancy in younger patients with higher odds of cure from first primary cancer.
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The widespread use of CT in resent years has improved the effect of clinical diagnose.The most important problem in CT using is excessive radiation dose.AQSIQ released the Verification Regulation of JJG 1026-2007 and lower than dose upper limit was the first target in this regulation.From the view of diagnose;only the CT images of good quality can be useful to doctors.Unlimited reducing the scanning condition in order to reach the goal of lower dose will affect the image quality inevitably.Different scanning parameters will be analyzed here to find their influences on dose index and image quality,thus realize the best image quality at the lowest radiation dose level.Correlative institution should pay more attention to this problem in order to make effective apprise on the radiation control for patients as well as improve the quality of diagnose.
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Objectives: We sought to determine the feasibility of using 80 kV in clinical cardiac CTA, by comparing radiation doses and image quality versus standardized 100 kV protocols.
Methods: In this retrospective study, a tube potential of 80 kV was used in 40 consecutive patients (BMI 22.6 ± 2.8). 40 matched patients (BMI 23.1 ± 2.8) were scanned with a tube potential of 100 kV and served as the control group. Qualitative and quantitative image quality parameters were determined in the proximal and distal segments of the coronary arteries.
Results: Similar subjective image quality scores were seen between the two protocols. The mean CNR and SNR were at 100 kV vs 80 kV (CNR 19.9 ± 6.0 vs 15.7 ± 5.5; p<0.01 and SNR 17.7 ± 5.5 vs 14.4 ± 4.9). The median radiation dose for the 80 kV protocol was significantly lower compared to the 100 kV protocol (83.0 mGy x cm [58.0- 134.0] vs 193.0 mGy x cm [108.5-225.0]; p<0.01)
Conclusion: A tube potential of 80 kV is feasible and results in a radiation dose reduction of 57% compared to 100 kV protocols while preserving subjective image quality.
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IntroductionThe automated breast volume scanner (ABVS) is the fi rst of its kind and utilises a large, 17 cm × 15 cm high-frequency ultrasound probe which sweeps across the whole breast generating images that can be reformatted into multiple planes and a 3D volume.ABVS will change breast ultrasound practice by: introducing operator standardisation, reproducibility and repeatability of measurement and interpretation; changing who acquires the volume set and how breast ultrasounds are reported; and allowing accurate comparison of previous and current examinations for screening and assessing treatment change.Methods Patients presented to the symptomatic clinic for conventional 2D ultrasound assessment with a variety of conditions.An additional ABVS was performed.Results Cases were classifi ed into: benign -for example, cysts, fi broadenomas, diabetic mastopathy; and malignant. ConclusionWe present a review of our initial experience and highlight its advantages over conventional ultrasound, which include: improved mapping of lesions enabling more accurate future assessment and follow-up, and improved assessment of distortion over conventional 2D ultrasound.Further research is required to explore other potential benefi ts. O2Symptomatic breast services in Ireland: how do they compare with national and international standards?
Digital Mammography
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Objective: The aim of the study was to examine how to decrease of radiation dose caused by CT in PET/CT while ensuring quality of CT image.Methods: PET/CT(GE Discovery ST16),Catphan 500,different scan conditions,total 30 groups.The image quality was evaluated by high resolution、low contrast、uniformity、noise.CTDIw and CTDIvol were calculated.The relationship between CT image quantity and CT dose was analyzed.Results: CT dose was related to uniformity,but not to high resolution.The low contrast of CT image improved with the increasing of CT dose.And the decrease of noise with the increase of CT dose was showed with an expression.Conclusions: The radiation dose by CT in PET/CT could be decreased appropriately under the guarantee of the quality of the CT image.
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Objective There are lots of promotions in the performance of the dual-source CT. This study is to assess the image quality and radiation dose of dual energy CT intracranial angiography with the first and second generation dual-source CT. Methods Select 80 patients who have suspected of intracranial vessels diseases randomly. They are divided into two groups A and B,each has 40 patients. Then the A and B groups underwent dual-energy intracranial CT angiography respectively use the first and second generation dual-source CT. At the same time,a CT water phantom is scanned by the same scanning parameters as the group A and B. Then evaluate the acquired data of image quality and radiation dose by subjective method and objective method. Finally,the obtained measurement data were statistically analyzed using the SPSS 11. 5 software. In the objective evaluation of image quality,Independent-Samples T Test was applied for the patient radiation dose,the water phantom and patient image quality and the cerebrovascular CT values of the patient; In the subjective evaluation of image quality,Mann-Whitney Test were applied for the score of the image quality. Results The result of the A and B groups in the CTDIvol,the cerebrovascular CT values of the patients and the subjective image quality is P 0. 05,the difference was not statistically significant,which means that no significant difference between the two groups in these aspect. But the result of the A and B groups in the DLP,the ED,the image noise and the x-ray beam hardening artifacts on subjective evaluation is P 0. 05,the difference was statistically significant,which means that there is a difference between the two groups. Conclusion When do the dual energy CT intracranial angiography,if the scanning conditions( kV,reference mAs) under approximately the same conditions,compared with the first generation dual-source CT the second generation dual-source CT radiation dose to the patient suffered lower and the image noise is also lower,but the overall image quality is no significant difference.
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The advanced digital imaging systems are producing much less noise associated radiographs. Physical image quality are becoming recognizable in replacing visual human evaluating of image quality. When radiation does shows strong correlation with image quality, one can directly control image quality using dose. Thus, this study aim to explore relationship between physical image quality (taken from real patient with lung infection) and radiation quantity (or doses) and to investigate possible reduction in radiation doses. The study used public data source of plain radiographs, that contains around 160,000 x-ray images. Then filtered them according the study aim and practicality to be used in measuring signal to noise ratio (SNR) and contrast to noise ratio (CNR). Strong relation between radiation dose and SNR was found, while CNR showed weak relationship with radiation dose. Very low SNR value was found to be suitable to produce visible image quality. The study concluded the possibility of utilizing physical image quality with possibility in reducing dose to the patients.
Digital radiography
Contrast-to-noise ratio
Computed radiography
Image noise
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