Radiation Dose In Group Research Articles

Computed Tomography in Cystic Fibrosis: Combining Low-Dose Techniques and Iterative Reconstruction.

The aim of the study was to evaluate the impact of iterative reconstruction (IR) and low-kilovolt technique on dose reduction and image quality of chest computed tomography scans obtained in patients with cystic fibrosis (CF). A total of 124 CF patients were examined; group A (n = 63) was examined with a dose reduction protocol using IR and group B (n = 61) with a standard protocol using filtered back projection. Further subgroups with tube voltage modulations were established. Quantitative and qualitative image quality was assessed. The radiation dose in groups with comparable image quality was approximately 40% lower using IR compared with filtered back projection. The IR protocol combined with 80-kV tube voltage showed adequate image quality with a mean effective dose of only 0.47 mSv. Iterative reconstruction helps extensively reduce radiation dose by improving image quality. It permits the use of low-kilovolt protocols without significantly degrading image reading ability in the monitoring of the predominantly young patients with CF.

Application of low-dose dual-source computed tomography angiography in children with complex congenital heart disease.

The objective of the present study was to evaluate image quality and radiation dosage using a low-dose prospectively electrocardiogram (ECG)-gated computed tomography (CT) protocol for dual-source angiography in children with complex congenital heart disease. A total of 206 patients with complex congenital heart disease were equally assigned into two groups at random. The children in group A underwent low-dose retrospective ECG-gated CT scanning with an ECG-pulsing technique, and group B underwent prospective ECG-gated scanning with an ECG-pulsing technique. Radiation dose volume computed tomography dose index (CTDI vol), dose length product (DLP) and effective dose (ED) were recorded after scanning. Raw data were transferred to workstations for post-processing, diagnosis, grading, comparison with intra-operation findings or cardiac catheterisation, and the coincidence, false negative rate and misdiagnosis rates of groups A and B, respectively, were subsequently recorded. The results of the present study indicated that the height, age and weight of the children in the two groups exhibited no significant differences. The image quality of group A was graded as 3.94±0.08, whereas the grade for the image quality in group B was 4.05±0.08; no significant difference was detected. The coincidence rates of groups A and B were 89.37 and 88.48%, respectively; the false negative rates of groups A and B were 9.66 and 10.60%, respectively; the misdiagnosis rates of groups A and B were 0.97 and 0.92%. No significant differences between the two groups were detected. The CTDI value of group A was 3.24±1.62 mGy, the DLP value was 47.53±33.28 mGy·cm2, the ED value was 0.93±0.42 mSv. By contrast, the CTDI value of group B was 2.27±0.94 mGy, the DLP value was (27.03±17.64) mGy·cm2, and the ED value was 0.53±0.23 mSv. Significant differences were detected between the two groups (CTDI t=5.287, P<0.05; DLP t=5.523, P<0.05; ED t=8.497, P<0.05), and the radiation dose of group B was markedly decreased, compared with group A. In conclusion, the present study demonstrated that prospectively ECG-gated scanning of dual-source CT is an effective method of examination for dose reduction in children with congenital heart disease without impairment of image quality, which suggests that this protocol may be suitable for future application and dissemination.

Integrative analysis for the role of long non-coding RNAs in radiation-induced mouse thymocytes responses.

Long non-coding RNAs (lncRNAs) are a critical class of regulatory molecules involved in a variety of biological functions; however, their role in immune cells response to radiation is unknown. Therefore, in this study we used integrative analysis to determine the expression profile of lncRNAs in mouse thymocytes and the potential functions of lncRNAs in response to radiation. Microarray data profiling indicated that 53 lncRNAs (36 up-regulated and 17 down-regulated) and 74 coding genes (39 up-regulated and 35 down-regulated) were highly differentially expressed in the high dose radiation (HDR) group compared with the control group. In the low dose radiation (LDR) group, only one lncRNA was down-regulated. Moreover, as compared with the control group, 109 lncRNA pathways in the HDR group and 14 lncRNA pathways in the LDR group were differentially expressed. Our data revealed the expression pattern of lncRNAs in mouse thymocytes and predicted their potential functions in response to LDR and HDR. In the HDR group, GO analysis showed that the role of lncRNAs in damage responses of thymocytes to HDR mainly involved chromatin organization and cell death. These findings might improve our understanding of the role of lncRNAs in LDR- and HDR-induced immune cells and provide a new experimental basis for further investigation.

A prospective evaluation of contrast and radiation dose and image quality in cardiac CT in children with complex congenital heart disease using low-concentration iodinated contrast agent and low tube voltage and current

To the assess image quality, contrast dose and radiation dose in cardiac CT in children with congenital heart disease (CHD) using low-concentration iodinated contrast agent and low tube voltage and current in comparison with standard dose protocol. 110 patients with CHD were randomized to 1 of the 2 scan protocols: Group A (n = 45) with 120 mA tube current and contrast agent of 270 mgI/ml in concentration (Visipaque™; GE Healthcare Ireland, Co., Cork, UK); and Group B (n = 65) with the conventional 160 mA and 370 mgI/ml concentration contrast (Iopamiro®; Shanghai Bracco Sine Pharmaceutical Corp Ltd, Shanghai, China). Both groups used 80 kVp tube voltage and were reconstructed with 70% adaptive statistical iterative reconstruction algorithm. The CT value and noise in aortic arch were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate image quality. Contrast and radiation dose were recorded. There was no difference in age and weight between the two groups (all p > 0.05). The iodine load and radiation dose in Group A were statistically lower (3976 ± 747 mgI vs 5763 ± 1018 mgI in iodine load and 0.60 ± 0.08 mSv vs 0.77 ± 0.10 mSv in effective dose; p < 0.001). However, image noise, CT value, CNR, SNR and subjective image quality for the two groups were similar (all p > 0.05), and with good agreement between the two observers. Comparing the surgery results, the diagnostic accuracy for extracardiac and intracardiac defects for Group A was 96% and 92%, respectively, while the corresponding numbers for Group B were 95% and 93%. Compared with the standard dose protocol, the use of low tube voltage (80 kVp), low tube current (120 mA) and low-concentration iodinated contrast agent (270 mgI/ml) enables a reduction of 30% in iodine load and 22% in radiation dose while maintaining compatible image quality and diagnostic accuracy. Advances in knowledge: The new cardiac CT scanning protocol can largely reduce the adverse effects of radiation and contrast media to children. Meanwhile, it also can be used effectively to examine complex CHD.

Submillisievert coronary CT angiography with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction in patients with high heart rate on the dual-source CT

To assess the application value of submillisievert coronary CT angiography (CCTA) in patients with a high heart rate (HR) acquired with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction on the secondary generation dual-source CT. A total of 120 consecutive high-HR patients suspected with coronary artery disease underwent CCTA and invasive coronary angiography (ICA) within two weeks. Patients were randomly assigned into three groups: group A (n = 40), where the patients underwent retrospectively ECG-triggered acquisition CCTA at 100 kVp; group B (n = 40), where the patients received adaptive prospective ECG-triggered sequence acquisition at 100 kVp; and group C (n = 40), where the patients performed adaptive prospective ECG-triggered sequence acquisition at 80 kVp with iterative reconstruction. The mean CT values, signal noise ratios (SNR) and contrast noise ratios (CNR) in the ascending aorta and coronary arteries of the three groups were measured and compared. The image quality and radiation dose among the three groups were compared. The consistency of displaying the coronary stenosis of each group was assessed compared with the results of ICA as the gold standard. There was no significant difference in gender, age and body mass index (BMI) (all P > 0.05). The mean attenuations, SNRs and CNRs in the ascending aorta and coronary artery were not significantly different between group A and group B (P > 0.05). The mean attenuations of group C were significantly higher than group A and group B (P < 0.01), but the image noise and CNR were significantly lower in group C (P < 0.01). The number of appreciable segments among the three groups was not significantly different on a per-segment and per-vessel basis (P > 0.05). The subjective image quality among the three groups was not significantly different (P > 0.05). With the ICA result as a reference standard, there was good consistency in the evaluation of the coronary stenosis degree between CCTA and ICA (r > 0.75), as well as in the assessment of the coronary stenosis rate using the Bland- Altman analysis. The mean radiation dose in group B was half of that in group A. Moreover, the mean radiation dose in group C was less than one sixth of that in group A and less than 1 mSv (0.7±0.2 mSv). For patients with high HR, adaptive prospective ECG-triggered sequence acquisition on the FLASH dual-source CT results in equal image quality and half of the radiation dose reduction compared with retrospectively ECG-triggered spiral acquisition at the same tube voltage (100 kVp) and same R-R interval of exposure. In addition, adaptive prospective ECG-triggered sequence acquisition combined with low tube voltage and iterative reconstruction can further reduce the radiation dose to the submillisievert level without compromising image quality and the accuracy of assessing the coronary stenosis degree, and can be popularized as a routine technique.

Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease.

The aim of this study was to explore the feasibility of using low dose radiation and low concentration contrast media in enhanced CT examinations in children with congenital heart disease. Ninety patients with congenital heart disease were randomly divided into three groups of 30 patients each who underwent contrast-enhanced cardiac scans on a Discovery CT750 HD scanner. Group A received 270mgI/mL iodixanol, and group B received 320mgI/mL iodixanol contrast media and was scanned with prospective ECG triggering mode. Group C received 320mgI/mL iodixanol and was scanned with conventional retrospective ECG gating mode. The same weight-based contrast injection protocol was used for all three groups. Images were reconstructed using a 30% adaptive statistical iterative reconstruction (ASIR) algorithm and a 50% ASIR in groups A and B and a 30% ASIR in group C. The subjective and objective image quality evaluations, diagnostic accuracies, radiation doses and amounts of contrast media in the three groups were measured and compared. All images in the three groups met the diagnostic requirements, with the same diagnostic accuracy and image quality scores greater than 3 in a 4-point scoring system. However, ventricular enhancement and the objective noise, signal-to-noise ratio, contrast-to-noise ratio and subjective image quality scores in group C were better than those in groups A and B (all P<.001). The effective radiation dose in groups A and B was 84% lower than that in group C (P<.001); group A received the lowest contrast dose (14% lower than that of groups B and C). Enhanced CT scan images with low dose radiation and low concentration contrast media can meet the diagnostic requirements for examining children with congenital heart disease while reducing the potential risk of radiation damage and contrast-induced nephropathy.

Utility of dual-energy spectral CT and low-iodine contrast medium in DIEP angiography.

To evaluate the utility of dual-energy spectral computed tomography (CT) and low-iodine intake in CT angiography (CTA) of deep inferior epigastric perforator (DIEP) flaps. In this prospective study, 40 patients with a BMI <28.0kg/m(2) underwent CTA examination for breast reconstruction and were randomly assigned into two groups (n=20 for each group) as follows: Group A was submitted to dual-energy spectral CT and iodixanol (270mgI/mL) and Group B was submitted to conventional high iodine contrast agent iohexol (350mgI/mL). The volume CT dose index (CTDIvol ) and dose length product were recorded and the effective dose (ED) was calculated. The best mono-spectrum images of Group A were selected according to the optimal contrast to noise ratio (CNR). Both mono-spectrum images of Group A and polychromatic images of Group B were used to reconstruct maximum intensity projection (MIP) and volume rendering (VR) images of the perforating artery, respectively. Two radiologists evaluated subjective image quality using a 4-point score. The diameter of the perforating artery, CT value and SD value for the common femoral artery were measured and the CNR was calculated. The total iodine intake and radiation doses of the two groups were calculated and compared. The best mono-spectrum energy with the optimal CNR of the perforating artery was 63keV. The CT value of common femoral artery in Group A (380.96±42.75HU) was 7.40% higher than in Group B (354.71±42.01 HU) but with no statistical significance (P>.05). The CNR of the common femoral artery in Group A (23.84±6.73) was 6.88% lower than in Group B (25.60±6.20), with no significant difference (P>.05). The diameters of the perforator vessels were 2.44±0.15 and 2.49±0.14mm, respectively, with no significant difference (P>.05). Subjective image qualities for the two groups were both good for diagnostics, and the scores for Group A and Group B were (3.88±0.28) and (3.93±0.18), respectively. The scores of the two radiologists were consistent (kappa=0.634). The effective radiation dose in Group A (9.09±0mSv) was 10.62% lower than in Group B (10.17±1.91mSv). The total iodine intake in Group A (27000mg) was 22.86% lower than in Group B (35000mg). The combination of dual-energy spectral CT and low-iodine intake in CTA of DIEP flap examination with the optimal CNR technology can meet the requirements of clinical diagnostics, with a 22.86% reduction in total iodine intake and an 11.01% reduction in radiation dose.

Optimizing radiation dose by using advanced modelled iterative reconstruction in high-pitch coronary CT angiography.

To evaluate the potential of advanced modeled iterative reconstruction (ADMIRE) for optimizing radiation dose of high-pitch coronary CT angiography (CCTA). High-pitch 192-slice dual-source CCTA was performed in 25 patients (group 1) according to standard settings (ref. 100 kVp, ref. 270 mAs/rot). Images were reconstructed with filtered back projection (FBP) and ADMIRE (strength levels 1-5). In another 25 patients (group 2), high-pitch CCTA protocol parameters were adapted according to results from group 1 (ref. 160 mAs/rot), and images were reconstructed with ADMIRE level 4. In ten patients of group 1, vessel sharpness using full width at half maximum (FWHM) analysis was determined. Image quality was assessed by two independent, blinded readers. Interobserver agreements for attenuation and noise were excellent (r = 0.88/0.85, p < 0.01). In group 1, ADMIRE level 4 images were most often selected (84%, 21/25) as preferred data set; at this level noise reduction was 40% compared to FBP. Vessel borders showed increasing sharpness (FWHM) at increasing ADMIRE levels (p < 0.05). Image quality in group 2 was similar to that of group 1 at ADMIRE levels 2-3. Radiation dose in group 2 (0.3 ± 0.1 mSv) was significantly lower than in group 1 (0.5 ± 0.3 mSv; p < 0.05). In a selected population, ADMIRE can be used for optimizing high-pitch CCTA to an effective dose of 0.3 mSv. • Advanced modeled IR (ADMIRE) reduces image noise up to 50% as compared to FBP. • Coronary artery vessel borders show an increasing sharpness at higher ADMIRE levels. • High-pitch CCTA with ADMIRE is possible at a radiation dose of 0.3 mSv.

Dose study of electrocardiogram automatic tube current modulation technology in prospective coronary computed tomography angiography scans of overweight patients.

The aim of the present study was to investigate the X-ray absorption dose and clinical applications of electrocardiogram (ECG)-gated automatic tube current modulation (ATCM) technology in prospective sequential computed tomography coronary angiography (CTCA) scans of overweight patients. A total of 40 patients with a body mass index of >24 were divided at random into groups A and B. Group A consisted of 20 patients, who were examined using ECG-ATCM scanning. For the patients in group A with heart rates <70 bpm, the scanning range was 20-80% of the R-R interval and the patients received full-dose X-rays for 60-80% of the R-R interval. For the group A patients with heart rates >70 bpm, the scanning range was 20-80% of the R-R interval and the patients received full-dose scanning for 35-55% of the R-R interval. For the 20 patients in group B, the scanning range was 20-80% of the R-R interval and patients received a full dose of X-ray radiation for the entire scanning period. The image quality and radiation dose was compared between the two groups. The average radiation dose in groups A and B was 6.91±2.78 and 10.43±3.36, respectively. The radiation doses in group A were reduced by 33.77% when compared with group B (P<0.05). However, there was no marked difference observed in image quality. In summary, using ECG-ATCM technology in prospective sequential CTCA scanning may significantly reduce the radiation dose required for overweight patients.

Imaging quality evaluation of low tube voltage coronary CT angiography using low concentration contrast medium.

PurposeTo compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium.Method and MaterialsA total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80kVp, 300 mgI/ml; group B: n=34, 100kVp, 300 mgI/ml; group C: n=36, 120kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests.ResultsThe values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.51±0.70 mSv) and group B (2.59±1.24 mSv) were both lower than group C (4.92±2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10±0.41), group B (3.90±0.48) and group C (4.04±0.36) (each P > 0.05).ConclusionLow tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction.

Combined Use of Automatic Tube Voltage Selection and Current Modulation with Iterative Reconstruction for CT Evaluation of Small Hypervascular Hepatocellular Carcinomas: Effect on Lesion Conspicuity and Image Quality.

ObjectiveTo assess the lesion conspicuity and image quality in CT evaluation of small (≤ 3 cm) hepatocellular carcinomas (HCCs) using automatic tube voltage selection (ATVS) and automatic tube current modulation (ATCM) with or without iterative reconstruction.Materials and MethodsOne hundred and five patients with 123 HCC lesions were included. Fifty-seven patients were scanned using both ATVS and ATCM and images were reconstructed using either filtered back-projection (FBP) (group A1) or sinogram-affirmed iterative reconstruction (SAFIRE) (group A2). Forty-eight patients were imaged using only ATCM, with a fixed tube potential of 120 kVp and FBP reconstruction (group B). Quantitative parameters (image noise in Hounsfield unit and contrast-to-noise ratio of the aorta, the liver, and the hepatic tumors) and qualitative visual parameters (image noise, overall image quality, and lesion conspicuity as graded on a 5-point scale) were compared among the groups.ResultsGroup A2 scanned with the automatically chosen 80 kVp and 100 kVp tube voltages ranked the best in lesion conspicuity and subjective and objective image quality (p values ranging from < 0.001 to 0.004) among the three groups, except for overall image quality between group A2 and group B (p = 0.022). Group A1 showed higher image noise (p = 0.005) but similar lesion conspicuity and overall image quality as compared with group B. The radiation dose in group A was 19% lower than that in group B (p = 0.022).ConclusionCT scanning with combined use of ATVS and ATCM and image reconstruction with SAFIRE algorithm provides higher lesion conspicuity and better image quality for evaluating small hepatic HCCs with radiation dose reduction.

Combining Coronary with Carotid and Cerebrovascular Angiography Using Prospective ECG Gating and Iterative Reconstruction with 256-slice CT.

To investigate the image quality and radiation dose of combined coronary and carotid/cerebrovascular angiography with ECG gating and iterative reconstruction using 256-slice CT compared with the findings with the two examinations performed separately. One hundred sixty-five consecutive patients underwent a single-injection single-pass combination of coronary and carotid/cerebrovascular CT angiography (group A), coronary CT angiography alone (group B), or carotid/cerebrovascular CT angiography alone (group C). We assessed the image quality of the combined and separate examinations and calculated the respective effective radiation doses. We evaluated the differences in the proportions of image quality grade between the combination and single-examination groups. Diagnostic performance of the combined scanning for detecting significant vascular stenosis has been compared with reference digital subtraction angiography (DSA) in the patient subgroup of group A. There was no significant difference in age, body mass index (BMI), or gender distribution among the 3 groups (all P>0.05). But there was significant difference in scan length, DLP, and effective dose among the 3 groups (all P<0.05). There were no significant differences in the effective radiation dose of coronary scanning between groups A and B (P>0.05), while the effective radiation dose of carotid/cerebrovascular scanning in group A was significantly lower than that in group C (P<0.05), and the total effective radiation dose in group A were relatively low (2.21±1.38mSv). The differences of the proportion of carotid/cerebrovascular image quality grades between groups A and C were not significant (P>0.05). In a subgroup of group A of 30 patients with DSA, combined computed tomographic angiography successfully detected 56 coronary stenosis on per-segment basis, and 62 stenosis on carotid and cerebral artery. The sensitivity, specificity, positive and negative predictive value (NPV) of coronary stenosis were 91.80%, 95.60%, 87.50% and 97.21%, respectively. The sensitivity, specificity, positive and NPV of carotid/cerebrovascular stenosis were 93.55%, 94.68%, 92.06% and 95.70%, respectively. Combination of coronary and carotid/cerebrovascular angiography with 256-slice CT scanner with prospective ECG gating and iterative reconstruction produces diagnostic-quality images of the coronary, carotid, and cerebrovascular systems in a single examination, using less contrast medium and a lower radiation dose than when the two examinations are performed separately. This novel technique has high accuracy in detecting significant stenosis in one image setting.

Preliminary study of low-dose CT coronary angiography by using low concentration isotonic contrast agent

Objective To compare the iodine intake,image quality and radiation dose of dual-source CT coronary artery angiography between the low concentration isotonic contrast agent with iterative reconstruction technique of sinogram affirmed iterative rEconstruction (SAFIRE) and common concentration contrast agent with filtered back projection (FBP).Methods One hundred patients [58 men,42 women; age:(62± 11)y] were enrolled in this study.Fifty consecutive patients (Group A) were scanned with FBP and common concentration contrast agent and another 50 consecutive patients (Group B) were scanned with low concentration isotonic contrast agent and iterative reconstruction technique.The image quality were assessed by two experienced radiologists with a double blinded fashion in a five score scale.The attenuation of coronary artery,scan time,imaging noise,signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR),radiation dose and iodine intake between these two groups were compared using two sample t test.The observer agreement for image quality was calculated using Kappa statistics.Results All examinations were completed successfully.There was no statistical difference (P＞0.05) between two groups in clinical characteristics and scan parameters.There was no statistical difference for the mean subjective image quality of group A (4.4±0.7) and group B (4.3±0.8) (t=0.924,P＞0.05).The Kappa value between two radiologists was 0.887 (P＜0.01)on image quality.The mean attenuation of coronary artery segments was higher than 300 HU,especially in group A (386.1±51.5) HU,which was slightly higher than the group B (384.1±77.1) HU,but there was no statistical difference (t=0.157,P＞0.05).The SNR and CNR in two groups did not have significant differences (P＞0.05).The total iodine and iodine injection rates were 21.0 g,17.5 g/s in Group A and 16.2 g,13.5 g/s in Group B,respectively.The iodine intake was decreased by 22.9％ in Group B.The effective radiation dose in Group B (1.09±0.19) mSv was significantly (t=20.260,P＜0.01) lower than that in Group A (2.85±0.59) mSv,with the radiation dose reduced by 61.8％.Conclusion Low concentration isotonic contrast agent and iterative reconstruction technique can significantly reduce the radiation dose and iodine intake in CT coronary artery angiography and achieve the same image quality using common concentration contrast agent with FBP. Key words: Contrast media; Tomography, X-ray computed; Radiation dosage; Comparative study

High-pitch computed tomography pulmonary angiography with iterative reconstruction at 80 kVp and 20 mL contrast agent volume.

To evaluate the image quality, radiation dose and diagnostic accuracy of 80kVp, high-pitch CT pulmonary angiography (CTPA) with iterative reconstruction using 20 ml of contrast agent. One hundred patients with suspected pulmonary embolism (PE) were randomly divided into two groups (n = 50 each; group A, 100 kVp, 1.2 pitch, 60 ml of contrast medium and filtered back projection algorithm; group B, 80 kVp, 2.2 pitch, 20 ml of contrast medium and sinogram affirmed iterative reconstruction). Image quality, diagnostic accuracy and radiation dose were evaluated and compared. Mean CT numbers of pulmonary arteries in group B were higher than those in group A (all P < 0.001). Contrast-to-noise ratio and signal-to-noise ratio of group B were higher than those of group A (both P < 0.001). There was no significant difference in subjective image quality scores between two groups (P = 0.807). The interobserver agreement was excellent (k = 0.836). There was no significant difference in diagnostic accuracy between the two groups (P > 0.05). Compared with group A, radiation dose of group B was reduced by 50.3% (P < 0.001). High-pitch CTPA at 80 kVp can obtain sufficient image quality in normal-weight individuals with 20 ml of contrast agent and half the radiation dose of a conventional CTPA protocol. CTPA is feasible at 80 kVp using only 20 ml of contrast agent. High-pitch CTPA at 80 kVp has an effective dose under 1 mSv. This CTPA protocol can obtain sufficient image quality in normal-weight individuals.

Improvement of image quality and radiation dose of CT perfusion of the brain by means of low-tube voltage (70 KV).

To investigate the feasibility of 70 kV cerebral CT perfusion by comparing image quality and radiation exposure to 80 kV. Thirty patients with suspected cerebral ischemia who underwent dual-source CT perfusion were divided into group A (80 kV, 150 mAs) and group B (70 kV, 150 mAs). Quantitative comparisons were used for maximum enhancement, signal-to-noise index (SNI), and values of cerebral blood flow (CBF), cerebral blood flow (CBV), mean transit time (MTT) on CBF, CBV, and MTT images, and radiation dose from these two groups. Qualitative perfusion images were assessed by two readers. Maximum enhancement for group B was higher than group A (P < 0.05). There were no significant differences between the two groups for SNI on CBF and CBV maps (P = 0.06 - 0.576), but significant differences for MTT when SNI was measured on frontal white matter and temporo-occipital white matter (P < 0.05). There were no differences among values of CBF, CBV, and MTT for both groups (P = 0.251-0.917). Mean image quality score in group B was higher than group A for CBF (P < 0.05), but no differences for CBV (P = 0.542) and MTT (P = 0.962). Radiation dose for group B decreased compared with group A. 70 kV cerebral CT perfusion reduces radiation dose without compromising image quality. • Radiation dose is a key concern with the increased using cerebral CT perfusion. Cerebral CT perfusion of 70 kV reduces radiation dose without compromising image quality. • A 70-kV protocol could be used for cerebral CT perfusion.

The feasibility study of low tube voltage combined with low contrast dose in multi-slice CT skull arteriography

Objective To evaluate the feasibility of a low-dose contrast medium protocol for 64-slice CT angiography (CTA) of head using a low-tube-voltage setting. Methods ①Phantom study: 64-slice spiral CT respectively sets 80,100,120,140 k V and 100,200,300,400,500 and 600 m A as scanning parameter lines.Analysis of the best Signal-to-noise ratios (SNR) and contrast to noise ratios (CNR).②Clinical study: to prospectively continuous select sixty-six patients with suspected intracranial aneurysm and arteriovenous malformation and so on from April to October of 2012 to perform hand CTA inspection.The random number table method for A,B two groups,33 patients in each group.Group A (conventional group) scanning parameters:120 k V,400 m A and amount of contrast agent: 1 ml/kg; Group B (test group) scanning parameters:80 k V,600 m A,amount of contrast agent 0.5 ml/kg.Using independent samples t test for each group radiation dose,SNR,CNR were statistically analyzed.By two experienced radiologists to 5 points on two groups of image quality subjective evaluation.Mann-Whitney U test was used for statistical analysis of subjective evaluation. Results Group A and B group CTDIvol respectively is 59.1,27.5 m Gy.Group B than in group A,CTDIvol decreased by 53.5%.A,B groups of the SNR,CNR were 71.5±10.7,92.0±7.4; 58.5±10.5,79.6±7.7,Group B than in group A SNR,CNR were enhanced by 22.3%,26.4%,differences were statistics significance (t=584.0,388.6,P<0.01).The subjective image evaluation of group B was bigher than group A (Z=31.2,23.4,P<0.05),differences were statistics significance.Two physicians on CTA images to assess the consistency of uniform height (Kappa=0.904,P<0.05). Conclusion In the head CTA examination,use of low tube voltage combined with low contrast dose not only can improve the image quality but also radiation dose were significantly lower. Key words: Tomography,X-ray computed; Radiation dosage; Comparative study

The different biological effects of single, fractionated and continuous low dose rate irradiation on CL187 colorectal cancer cells.

PurposeTo determine the biological effectiveness of single, fractionated and continuous low dose rate irradiation on the human colorectal cancer cell line CL187 in vitro and explore the cellular mechanisms.Materials and methodsThe CL187 cells were exposed to radiation of 6 MV X-ray at a high dose rate of 4Gy/min and 125I seed at a low dose rate of 2.77 cGy/h. Three groups were employed: single dose radiation group (SDR), fractionated dose radiation group (FDR) by 2Gy/f and continuous low dose rate radiation group (CLDR). Four radiation doses 2, 4, 6 and 8Gy were chosen and cells without irradiation as the control. The responses of CL187 cells to distinct modes of radiation were evaluated by the colony-forming assay, cell cycle progression as well as apoptosis analysis. In addition, we detected the expression patterns of DNA-PKcs, Ku70 and Ku80 by Western blotting.ResultsThe relative biological effect for 125I seeds compared with 6 MV X-ray was 1.42. 48 hrs after 4Gy irradiation, the difference between proportions of cells at G2/M phase of SDR and CLDR groups were statistically significant (p = 0.026), so as the FDR and CLDR groups (p = 0.005). 48 hrs after 4Gy irradiation, the early apoptotic rate of CLDR group was remarkably higher than SDR and FDR groups (CLDR vs. SDR, p = 0.001; CLDR vs. FDR, p = 0.02), whereas the late apoptotic rate of CLDR group increased significantly compared with SDR and FDR group (CLDR vs. SDR, p = 0.004; CLDR vs. FDR, p = 0.007). Moreover, DNA-PKcs and Ku70 expression levels in CLDR-treated cells decreased compared with SDR and FDR groups.ConclusionsCompared with the X-ray high dose rate irradiation, 125I seeds CLDR showed more effective induction of cell apoptosis and G2/M cell cycle arrest. Furthermore, 125I seeds CLDR could impair the DNA repair capability by down-regulating DNA-PKcs and Ku70 expression.

Low-dose Radiation Induces Antitumor Effects and Erythrocyte System Hormesis

Low dose radiation may stimulate the growth and development of animals, increase life span, enhance fertility, and downgrade the incidence of tumor occurrence.The aim of this study was to investigate the antitumor effect and hormesis in an erythrocyte system induced by low-dose radiation. Kunming strain male mice were subcutaneously implanted with S180 sarcoma cells in the right inguen as an experimental in situ animal model. Six hours before implantation, the mice were given 75mGy whole body X-ray radiation. Tumor growth was observed 5 days later, and the tumor volume was calculated every other day. Fifteen days later, all mice were killed to measure the tumor weight, and to observe necrotic areas and tumor-infiltration-lymphoreticular cells (TILs). At the same time, erythrocyte immune function and the level of 2,3-diphosphoglyceric acid (2,3- DPG) were determined. Immunohistochemical staining was used to detect the expression of EPO and VEGFR of tumor tissues. The mice pre-exposed to low dose radiation had a lower tumor formation rate than those without low dose radiation (P < 0.05). The tumor growth slowed down significantly in mice pre-exposed to low dose radiation; the average tumor weight in mice pre-exposed to low dose radiation was lighter too (P < 0.05). The tumor necrosis areas were larger and TILs were more in the radiation group than those of the group without radiation. The erythrocyte immune function, the level of 2,3-DPG in the low dose radiation group were higher than those of the group without radiation (P < 0.05). After irradiation the expression of EPO of tumor tissues in LDR group decreased with time. LDR-24h, LDR-48h and LDR-72h groups were all statistically significantly different from sham-irradiation group. The expression of VEGFR also decreased, and LDR-24h group was the lowest (P < 0.05). Low dose radiation could markedly increase the anti-tumor ability of the organism and improve the erythrocyte immune function and the ability of carrying O2. Low-dose total body irradiation, within a certain period of time, can decrease the expression of hypoxia factor EPO and VEGFR, which may improve the situation of tumor hypoxia and radiosensitivity of tumor itself.

Optimizing Radiation Dose Levels in Prospectively Electrocardiogram-Triggered Coronary Computed Tomography Angiography Using Iterative Reconstruction Techniques: A Phantom and Patient Study

AimTo investigate the potential of reducing the radiation dose in prospectively electrocardiogram-triggered coronary computed tomography angiography (CCTA) while maintaining diagnostic image quality using an iterative reconstruction technique (IRT).Methods and MaterialsProspectively-gated CCTA were first performed on a phantom using 256-slice multi-detector CT scanner at 120 kVp, with the tube output gradually reduced from 210 mAs (Group A) to 125, 105, 84, and 63 mAs (Group B–E). All scans were reconstructed using filtered back projection (FBP) algorithm and five IRT levels (L2-6), image quality (IQ) assessment was performed. Based on the IQ assessment, Group D(120 kVp, 84 mAs) reconstructed with L5 was found to provide IQ comparable to that of Group A with FBP. In the patient study, 21 patients underwent CCTA using 120 kV, 210 mAs with FBP reconstruction (Group 1) followed by 36 patients scanned with 120 kV, 84 mAs with IRT L5 (Group 2). Subjective and objective IQ and effective radiation dose were compared between two groups.ResultsIn the phantom scans, there were no significant differences in image noise, contrast-to-noise ratio (CNR) and modulation transfer function (MTF) curves between Group A and the 84 mAs, 63 mAs groups (Groups D and E). Group D (120 kV, 84 mAs and L5) provided an optimum balance, producing equivalent image quality to Group A, at the lowest possible radiation dose. In the patient study, there were no significant difference in image noise, signal-to-noise ratio (SNR) and CNR between Group 1 and Group 2 (p = 0.71, 0.31, 0.5, respectively). The effective radiation dose in Group 2 was 1.21±0.14 mSv compared to 3.20±0.58 mSv (Group 1), reflecting dose savings of 62.5% (p<0.05).Conclusioniterative reconstruction technique used in prospectively ECG-triggered 256-slice coronary CTA can provide radiation dose reductions of up to 62.5% with acceptable image quality.

Effect of Low dose Radiation on Differentiation of Bone Marrow Cells into Dendritic Cells

Low dose radiation has been shown to be beneficial to living organisms using several biological systems, including immune and hematopoietic systems. Chronic low dose radiation was shown to stimulate immune systems, resulting in controlling the proliferation of cancer cells, maintain immune balance and induce hematopoietic hormesis. Since dendritic cells are differentiated from bone marrow cells and are key players in maintaining the balance between immune activation and tolerance, it may be important to further characterize whether low dose radiation can influence the capacity of bone marrow cells to differentiate into dendritic cells. We have shown that bone marrow cells from low dose-irradiated (γ-radiation, 0.2Gy, 15.44mGy/h) mice can differentiate into dendritic cells that have several different characteristics, such as expression of surface molecules, cytokine secretion and antigen uptake capacity, when compared to dentritic cells differentiated from the control bone marrow cells. These differences observed in the low dose radiation group can be beneficial to living organisms either by activation of immune responses to foreign antigens or tumors, or maintenance of self-tolerance. To the best of our knowledge, this is the first report showing that total-body low dose radiation can modulate the capacity of bone marrow cells to differentiate into dendritic cells.