腰椎平片投照体位对腰骶角的影响

目的：探讨腰椎侧位片站立位、侧卧位两种不同投照体位对腰骶角的影响。方法：对正常成人腰椎侧位片同时用站立位、侧卧位两种体位投照，共100例，分别测量其腰骶角，并对测量结果进行对比分析。结果：腰椎侧位片站立位投照腰骶角21—58度，平均37．5度，74％在30—45度之间。侧卧位投照腰骶角14—55度，平均33．60度．75％在25—42度之间。结论：腰骶角测量，站立位比侧卧位平均大3.87度，（t=3．46，p〈0．001）两者之间存在显著差异，投照体位不同正常值不一样。该测量可为临床上诊断腰骶部不稳提供放射学依据。     

腕豆状骨的投照体位

由于腕豆状骨位于腕关节尺侧的前下方，人体滑倒用手触地时，容易首先触及易使豆状骨骨折或脱位。常规腕关正侧位摄影，豆状骨被三角骨或其它骨头重叠，不易观察其祥细情况。经多次投照证实，通过下述方法投照能更好地显示豆状骨及其与周围的结构关系，诊断时结合腕关节正位，对豆状骨的诊断帮助很大。为了使两腕豆状骨对照和摄影体位的标准，摄影时同时摄双腕豆状骨。     

优化扫描范围对CT冠状动脉成像辐射剂量和图像质量的影响

目的 初步探讨优化扫描范围(FOV)对冠状动脉CT成像(CTA)辐射剂量和图像质量的影响.方法 选取100例临床疑似冠心病的患者进行冠状动脉CTA检查,随机分成A、B两组,每组各50例.A组FOV为气管分叉处至心脏下缘1 cm;B组FOV根据平扫图像确定,即冠状动脉树上缘1 cm至心尖部心包即将消失的层面.记录患者增强扫描的剂量长度乘积(DLP),选择冠状动脉不同节段测量其对比剂增强水平.分析A、B两组的FOV、有效辐射剂量(ED)及图像质量有无统计学差异.结果 两组患者平均年龄、性别、体重指数(BMI)比较均无统计学意义;A组平均FOV、ED分别为(15.31±1.51)cm、(15.10±2.00) mSv,均高于B组的(13.51±1.68)cm、(12.02±1.40)mSv,且差异均有统计学意义(P＜0.05).两组共显示冠状动脉1303个节段,A组669个节段,B组634个节段,两组间比较差异无统计学意义(P＞0.05).右冠状动脉(RCA)近段、左冠状动脉前降支(LAD)近段及左回旋支(LCX)近段CT值水平差异无统计学意义.结论 根据平扫图像优化冠状动脉CTA FOV,既能有效降低辐射剂量,同时又能保证图像质量,为临床诊断冠心病提供参考信息.     

不同心率单个心动周期冠状动脉CT成像质量和辐射剂量研究

目的 研究受检者不同心率宽体探测器CT单个心动周期冠状动脉CT成像（CCTA）的图像质量和辐射剂量。方法 连续选取泰达国际心血管病医院临床疑似冠状动脉病变行CCTA检查的患者821例,检查前均不给予降心率药物,根据心率不同将受检者分为6组,A组（心率≤65次/min）132例;B组（心率66~75次/min）244例;C组（心率76~85次/min）145例;D组（心率86~95次/min）101例;E组（心率96~105次/min）101例;F组（心率106~135次/min）98例,比较6组CCTA图像主动脉根部CT值、前降支（LAD）和右冠状动脉（RCA）中段CT值、信噪比（SNR）、对比噪声比（CNR）、有效辐射剂量（E）客观指标差异,以及6组冠状动脉可诊断血管和评分等主观指标的差异。结果 6组图像质量客观指标均差异无统计学意义（P>0.05）;6组LAD、LCX和RCA的可诊断血管差异无统计学意义（P>0.05）,但6组LAD、LCX和RCA 4分（优秀）差异有统计学意义（χ²=27.614、58.475、39.571,P<0.05）;6组辐射剂量差异均有统计学意义（F=37.32,P<0.05）,B组辐射剂量最高,D组、E组和F组辐射剂量较低。结论 不同心率宽体探测器CT单个心动周期CCTA成像可以满足临床诊断,但是随着心率的升高图像质量下降,高心率组（心率>85次/min）辐射剂量最低。     

320排CT冠状动脉成像平均心率对图像质量和辐射剂量的影响

目的:探讨不同心率条件下320排容积CT冠状动脉血管成像的图像质量和辐射剂量.方法:将259例临床怀疑或确诊的冠状动脉疾病的患者(含35例心律失常患者)分为3组;A组79例,心率≤65次/分;B组120例,65＜心率＜80次/分;C组60例,心率≥80次/分.扫描完成后选用最佳的重建时相,对冠状动脉进行容积再现(VR)...     

双源CT冠状动脉成像:最佳时间窗及心率对影像质量与放射剂量的影响

目的探讨可疑冠心病病人心电周期中最佳时间窗与心率、影像质量及放射剂量的关系。材料与方法本研究经伦理审查委员会通过,并获得所有病人知情同意。301例     

低管电压对双源CT冠状动脉成像图像质量和辐射剂量的影响

目的：分析低管电压双源CT冠状动脉成像（CTA）的图像质量,探讨低管电压扫描对减少冠状动脉CTA检查辐射剂量的价值。方法：150例患者分成两组行双源CT冠状动脉CTA检查,A组使用100kV管电压扫描,B组使用120kV管电压扫描。比较两组的辐射剂量,同时分析并比较两组冠状动脉的整体图像质量。结果：A、B两组的辐射剂量分别为（6.80±1.70）mSv和（13.01±2.61）mSv,A组辐射剂量明显小于B组,差异有统计学意义（t=17.168,P=0.000）。A、B两组冠状动脉图像质量评分分别为（2.87±0.25）分和（2.92±0.17）分,两组间差异无统计学意义（Z=-1.067,P=0.286）。结论：采用100kV管电压扫描行冠状动脉CTA检查能明显减小正常和略胖体型患者所接受的辐射剂量,同时图像质量不受影响。     

Effect of bismuth breast shielding on radiation dose and image quality in coronary CT angiography

Background

Coronary computed tomographic angiography (CCTA) is associated with high radiation dose to the female breasts. Bismuth breast shielding offers the potential to significantly reduce dose to the breasts and nearby organs, but the magnitude of this reduction and its impact on image quality and radiation dose have not been evaluated.

Methods

Radiation doses from CCTA to critical organs were determined using metal-oxide-semiconductor field-effect transistors positioned in a customized anthropomorphic whole-body dosimetry verification phantom. Image noise and signal were measured in regions of interest (ROIs) including the coronary arteries.

Results

With bismuth shielding, breast radiation dose was reduced 46%-57% depending on breast size and scanning technique, with more moderate dose reduction to the heart, lungs, and esophagus. However, shielding significantly decreased image signal (by 14.6 HU) and contrast (by 28.4 HU), modestly but significantly increased image noise in ROIs in locations of coronary arteries, and decreased contrast-to-noise ratio by 20.9%.

Conclusions

While bismuth breast shielding can significantly decrease radiation dose to critical organs, it is associated with an increase in image noise, decrease in contrast-to-noise, and changes tissue attenuation characteristics in the location of the coronary arteries.     

Patient radiation exposure during coronary angiography and intervention

Purpose: To prospectively register fluoroscopic and cine times in a random fashion, and to measure patient radiation exposure from routine coronary angiography and coronary balloon angioplasty. We also evaluated an optional dose reduction system used during interventions.Material and Methods: The incident radiation to the patient was measured as kerma area product (KAP) in Gycm², obtained from an ionisation chamber mounted on the undercouch tube during 65 coronary angiography procedures and another 53 percutaneous transluminal coronary angioplasties (including 29 stent procedures), mostly directly following complete coronary angiography.Results and Conclusion: The values from coronary angiography were comparable to other reports with a mean fluoroscopic time of 4.4 min and a mean KAP value of 62.6 Gycm². The corresponding figures from coronary balloon angioplasty without stenting were lower than otherwise reported, with 8.2 min and 47.9 Gycm², respectively. The use of coronary stents did prolong the mean fluoroscopic time (10.5 min) but did not significantly enhance the patient mean radiation dose (51.4 Gycm²). The dose reduction technique resulted in a significant KAP value reduction of 57%. In conclusion, with regard to radiation exposure, coronary angiography and balloon angioplasty are considered safe procedures.     

320排CT单心跳冠状动脉成像的图像质量及辐射剂量分析

目的:探讨320排CT低心率患者单心跳冠状动脉血管成像的图像质量及辐射剂量.方法:将241例临床可疑或确诊冠状动脉疾病的患者分为三组:A组122例,心率＜65bpm;B组62例,65≤心率＜80bpm;C组57例,心率≥80bpm.扫描完成后选用最佳的时相,对冠状动脉进行容积重组(VR)、多平面重组(MPR)、曲面重组(CPR).按照4分法将图像质量分类并统计分析,用卡方检验比较冠状动脉血管段的优良率、可评价比例的差异;记录各组的辐射剂量,用秩和检验比较辐射剂量的差异.结果:A、B、C三组冠状动脉血管段优良率差异有统计学意义(x2=87.46,P＜0.05),可评价比例差异无统计学意义(x2 =3.99,P＞0.05).所有病例共有5段冠状动脉不可评价.A、B、C三组的平均辐射剂量分别为(3.79±2.32) mSv、(11.60±5.05)mSv、(16.52±6.36) mSv,其差异具有统计学意义(x2=149.11,P＜0.05).A组与B组、A组与C组、B组与C组辐射剂量两两比较差异均有统计学意义(Z值分别为-11.39、-8.47、-4.32,P值均＜0.017).结论:320排CT冠状动脉成像对于心率＜65bpm的患者可提供高质量的图像,且显著降低辐射剂量.     

Effect of low tube kV on radiation dose and image quality in retrospective ECG-gated coronary CT angiography

IntroductionCoronary computed tomography angiography (CCTA) has emerged as a useful diagnostic imaging modality in the assessment of coronary artery disease. However, the potential risks due to exposure to ionizing radiation associated with CCTA have raised concerns.ObjectivesCCTA can be done with low dose technique to reduce radiation exposure, without compromise of image quality or diagnostic capabilities.Material and methodsForty patients referred for CCTA were examined with low kV (100 kV for patients ?85–61 kg and 80 kV for patients ?60 kg). The dose length product (DLP) were compared with other group (40 patients) with comparable body weight, scan length and acquisition parameters. The second group was selected from PACS database, for which CCTA was done with standard 120 kV.ResultsThere was considerable reduction of radiation dose about 40% with 100 kV and 60% with 80 kV compared to standard 120 kV CCTA protocols with preserved image quality.ConclusionThe use of lower tube voltage leads to significant reduction in radiation exposure in CCTA. Image quality in non-obese patients is not negatively influenced.     

The effect of adaptive iterative dose reduction on image quality in 320-detector row CT coronary angiography

Objective

To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA).

Methods

50 patients (14 females, mean age 68±9 years) who underwent CTCA (100 kV or 120 kV, 400–580 mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent).

Results

All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4±3.1 HU vs 36.9±4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75±0.38 vs 4.24±0.38; p<0.001).

Conclusion

The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA.CT coronary angiography (CTCA) is a robust non-invasive imaging modality with high spatial and temporal resolution that enables accurate diagnosis or exclusion of coronary artery disease [1-4]. However, CTCA usually exposes the patient to a substantial amount of radiation (9.4–21.4 mSv) [5-7]. Therefore, several scanning techniques, such as ECG-based tube current modulation, prospective ECG triggering and reduced tube voltage scanning, have been developed to reduce the patient''s radiation exposure [6-8]. Reductions of the tube current also lead to lower radiation exposure, as the tube current correlates to dose in a linear fashion. However, lower radiation leads to an increase in CT image noise because the current reconstruction method, filtered back projection (FBP), is unable to consistently generate diagnostic-quality images with reduced tube currents [9].Recently, the adaptive iterative dose reduction technique has been developed as a new reconstruction algorithm to improve image noise [10-12], and has already been shown to reduce the radiation dose in clinical practice [13-16]. Adaptive iterative dose reduction (AIDR) developed for CT by Toshiba Medical Systems Corporation is a modified iterative reconstruction technique in which the original high-noise image undergoes a number of reconstructions that reduce image noise until the resultant image displays the desired noise level. This technique is expected to reduce the radiation dose for a similar noise level to FBP.To our knowledge, no study has evaluated the quality of CT images using AIDR. The purpose of this study was to evaluate the effect of AIDR regarding image noise and image quality in comparison with FBP, using the same raw data set for both FBP and AIDR, in 320-detector row CTCA.