螺旋CT实际层厚的影响因素与CT图像质量的关系

目的 通过实验分析影响螺旋CT实际层厚的因素，并分析实际层厚与CT图像质量的关系。方法 应用GE Hispeed DX/1 CT机及Elscinet的QC水模在不同扫描层厚及不同螺距情况下进行扫描，测量螺旋CT实际层厚并分析。结果 螺旋CT实际层厚随扫描层厚及螺距减小而减小：Z轴分辨率及扫描时间、病人接受的放射剂量随螺距增大而增大；螺旋扫描图像噪声与螺距呈非线性关系，螺距为1、5时噪声较螺距为1.0时要小。结论 螺旋CT实际层厚与扫描层厚、螺距有密切关系，选择合适的扫描层厚及螺距对提高CT图像质量、减少扫描时间、减少病人接受的放射剂量均大有益处。     

医用X射线诊断设备辐射剂量规范化管理共识

自伦琴发现X射线以来,人们一直在探索X射线在医学中的应用。过去十余年里,CT的临床应用增长迅猛,在疾病的早期诊断、分期、治疗方案制定、疗效评估等方面发挥了越来越重要的作用,与此同时,X射线也逐渐成为医源性电离辐射的主要来源,其产生的辐射安全问题也受到了广泛关注。目前,广大医疗机构已意识到并尝试联合使用低辐射剂量扫描方案,以在保证图像质量和诊断准确性的前提下,最大程度地降低受检者辐射剂量,但对辐射剂量的管理仍缺乏统一、规范的指导。本共识在设备及机房辐射防护设计、放射医务人员安全操作、低剂量扫描方法应用等基础上,重点引入辐射剂量诊断参考水平（DRL）这一管理工具,及时指导和优化对受检者（特别是儿童等特殊人群）的辐射防护和剂量管理。实际扫描过程中,辐射剂量持续超过DRL时,应及时进行调查并找出原因,在必要和可行的情况下采取纠正措施,进一步提升放射检查的安全性。     

64层螺旋CT在胸扫描中减少辐射剂量的方法研究

将进行胸部CT检查的78例患者随机分为试验组和对照组。试验组CT检查的参数设定为管电压120 kV,电流50 mA,对照组CT检查的参数设定为管电压120kV,电流200mA,其余参数不变,对2组被检者所受的辐射剂量进行测定,最后对结果进行统计学分析。结果试验组与对照组比较,图像质量无显著性差异,均符合扫描要求,2组患者的CT剂量加权指数(CTDI)平均值存在差异性,试验组患者所受的辐射剂量低于对照组(P<0.05)。通过改变CT扫描中的电流参数,对病灶显示无明显差别,并可以减少患者所受的辐射剂量。     

MSCT的辐射剂量及对比剂剂量对甲状腺癌诊断结果的影响

目的:探讨多层螺旋CT(MSCT)的辐射剂量及对比剂剂量对甲状腺癌诊断结果的影响。方法:以2019年2月至2021年2月我院收治的160例甲状腺疾病患者为对象。按照甲状腺癌：甲状腺良性结节1:1随机分为A组(n=40)、B组(n=40)、C组(n=40)、D组(n=40)。对比四组诊断甲状腺癌的价值。结果:C组、D组剂量长度乘积(DLP)、CT容积剂量指数(CTDIvol)、有效辐射剂量(ED)水平高于A组、B组(P<0.05);C组与D组CDTIvol、DLP、ED水平比较无差异(P>0.05)。C组、D组CT值、背景信号、背景噪声高于A组、B组(P<0.05);C组与D组CT值、背景信号、背景噪声水平比较无差异(P>0.05)。四组信噪比(SNR)、对比信噪比(CNR)水平比较无差异(P>0.05)。A组诊断甲状腺癌的灵敏度、特异度、准确度分别为95.00%、95.00%、92.50%;B组诊断甲状腺癌的灵敏度、特异度、准确度分别为90.00%、85.00%、87.50%;C组诊断甲状腺癌的灵敏度、特异度、准确度分别为85.00%、90.00%、87....     

肺动脉CT血管成像在双源CT大螺距模式下的低辐射剂量与低对比剂量研究

目的：研究肺动脉CT血管成像（CTPA）中,双源CT大螺距模式下低辐射剂量和低对比剂量的成像可行性。方法168例临床拟诊肺栓塞患者中,挑选BMI＜23 kg/m2的患者105例行CTPA。患者分为3组,每组35例,Ⅰ组：管电压80 kV,对比剂采用碘普罗胺（370 mgI/mL）,图像重建算法为正弦确认迭代重建算法（SAFIRE）;Ⅱ组：管电压100 kV,对比剂采用碘克沙醇（320 mgI/mL）,图像重建算法为滤过反投影重建法（FBP）;Ⅲ组：管电压80 kV,对比剂采用碘克沙醇（320 mgI/mL）,图像重建算法为SAFIRE。105例患者中57例经CTPA诊断为肺栓塞,分别测量3组肺动脉1-3级分支、栓子及背部肌肉的CT值,并计算信噪比（SNR）及对比噪声比（CNR）。采用独立样本t检验来分别比较Ⅰ组和Ⅲ组、Ⅱ组和Ⅲ组的图像质量的SNR及CNR;同时比较Ⅰ组和Ⅲ组的碘摄入量、Ⅱ组和Ⅲ组的有效辐射剂量（ED）。利用Kappa检验分析2名医师分析各组CTPA图像质量的一致性。结果Ⅰ组肺动脉1-3级分支SNR及CNR值分别为8.4±2.7、7.2±2.5、6.8±3.3及7.1±1.2、6.4±1.4、5.8±4.5。Ⅱ组肺动脉1-3级分支SNR及CNR值分别为8.2±4.3、7.7±3.6、6.2±2.7及7.4±2.4、6.6±2.6、6.0±3.4。Ⅲ组肺动脉1-3级分支SNR及CNR值分别为8.7±1.8、7.5±3.4、6.6±2.3及7.7±3.8、6.7±1.1、5.6±3.9。Ⅰ组和Ⅲ组,Ⅱ组和Ⅲ组的SNR及CNR值差异无统计学意义（P＞0.05）。Ⅲ组较Ⅰ组碘摄入量下降14%,Ⅲ组较Ⅱ组辐射剂量减少45%,3组CTPA图像质量差异无统计学意义（P＞0.05）。57例CTPA诊断为肺栓塞患者定量分析显示,3组栓子SNR及CNR值分别为1.3±0.4、1.2±0.4、1.4±0.6及7.4±3.3、7.6±1.6、7.3±3.7,3组SNR及CNR值比较差异无统计学意义（P＞0.05）。2名医师的评价结果经Kappa检验,各组图像质量分析的一致性较好（P＜0.01）。结论在BMI＜23 kg/m2的患者中可以使用双源CT大螺距模式、80 kV、S     

小儿头部多层螺旋CT检查的放射剂量评价

选取2013年2月~2015年2月我院收治的82例患儿为研究对象,随机划分为研究组和常规组,研究组分为两组各21例,研究1组患儿6个月,其扫描剂量为120k Vp、90m As,研究2组患儿6个月,且6岁,其扫描剂量为120k Vp、150m As;常规组分为两组各20例,常规1组6个月,常规2组患儿6个月,且6岁,其扫描剂量分别为120k Vp、260m As。同时,由4名医师评价CT图像。比较两组患儿不同扫描剂量的总m As、CT权重剂量指数(CT weight dose index,CTDIw)、剂量长度乘积(Dose length product,DLP)及不同等级图像的质量。本组82例患儿,研究组患儿扫描X线辐射剂量长度积值明显优于对照组,差异有统计学意义(P0.05);研究组符合临床诊断要求小儿头部图像98%,与常规组相比,差异无统计学意义(P0.05)。小儿头部多层螺旋CT检查过程中,在满足临床诊断要求的基础上,可以根据患儿年龄选择适合的低剂量扫描。     

多层CT低管电压对胸痛三联检查图像质量及辐射剂量的影响

研究多层CT低管电压对胸痛三联征排查图像质量及辐射剂量的影响,探讨这种扫描方法的可行性。选择2014年1月~2016年1月清远市中医院因急性胸痛就诊并拟行64层螺旋CT回顾性心电门控胸痛三联扫描的50例患者,随机分为观察组(100KV)与对照组(120KV),采用4分法评价主动脉、肺动脉及冠状动脉图像质量(包括CT值,图像噪声N、信噪比SNR、对比噪声比CNR),记录剂量长度乘积(DLP),计算有效剂量(ED),并对比分析两组扫描长度、图像质量与ED。观察组患者的图像质量、扫描长度、图像噪声N、信噪比SNR及对比噪声比CNR与对照组无差异(P0.05),而主动脉CT值、肺动脉CT值及冠状动脉CT值与对照组相比较,两组差异有统计学意义(P0.05)。观察组患者的辐射剂量为(6.87±1.48)mSv,对照组的为(12.13±3.24)mSv,两组差异有统计学意义(P0.05)。多层CT低管电压对胸痛三联征排查的图像能够满足诊断要求,且辐射量较低,具有重要的临床应用价值。     

迭代统计重建在CT结肠成像中降低辐射剂量有效性的体模研究

目的评价宝石高分辨CT应用不同水平迭代统计重建法(ASIR)在CT结肠成像中降低辐射剂量的有效性。方法选用一段离体猪结肠通过结扎法获得20个5~10 mm的模拟息肉,运用HRCT在不同扫描条件(120 kVp,10、20、30、40、50及100 mAs)下扫描,其中HRCT分别应用6种不同ASIR水平(0、10%、30%、50%、70%及100%)进行数据重建,获得CT仿真内镜、多平面重建和虚拟分割图像。由两名有经验的放射医师采用盲法对不同采集条件、不同ASIR水平的图像进行客观和主观评价,测量并比较平均噪声、平均信噪比(SNR)及平均对比噪声比(CNR),以及结肠息肉的检出率,利用SPSS 16.0统计软件对每组数据进行方差分析。结果结肠模拟息肉模型研究显示不同管电流时HRCT图像噪声均随应用ASIR水平升高而降低,SNR及CNR随应用ASIR水平升高而增高(P0.05);CT容积剂量指数降低约50%。结论离体模型研究表明在CT结肠成像中,应用ASIR可以显著降低图像噪声,提高信噪比及对比噪声比,从而有效降低辐射剂量。     

双源CT大螺距Flash模式与双能模式在头颅血管成像中的图像质量和辐射剂量研究

目的：比较在头颅CT动脉造影（CTA）成像中,双源CT的大螺距Flash模式与双能模式（DECT）在成像质量,辐射剂量方面有无区别。方法从2012年8月～2013年1月疑似颅内动脉瘤109例患者中,选出两组不同检查模式的病例,每组20例。两名医师对图像质量进行5级评分,同时比较两组的CT容积剂量指数（CTDIvol）、剂量长度乘积（DLP）。结果 Flash组和DECT组扫描模式的CTDIvol、DLP分别为：30.17±1.74mGy,697.14±38.23mGy？cm;13.52±0.58mGy,289.92±16.56mGy？cm。两组间颅内血管的图像质量无明显差异（Z=-0.403,P=0.715）。颅底血管的椎基底动脉无统计学差异（Z=-1.286,P=0.12）,而颈内动脉C2-C5段图像质量DECT组明显低于Flash组（Z=-6.273,P＜0.001）。结论两种模式的图像质量在颅内血管和颅底椎基底动脉上无明显差异;对于颅底颈内C2-C5段,Flash模式明显优于DECT模式。Flash模式的辐射剂量要大于DECT模式。     

儿童颅脑CT与成年人所受辐射剂量的对比研究

随机选择我院2010年1月～2011年12月行颅脑CT检查的儿童和成年人各50例作为研究对象,估算辐射剂量,比较儿童与成年人的颅顶平均层剂量、颅底平均层剂量、有效剂量、传递能量。结果儿童组行颅脑CT检查的颅顶平均层剂量、颅底平均层剂量、有效剂量均明显高于成年组(P<0.05),而传递能量明显低于成人组(P<0.05)。权衡CT图像对比度、空间分辨率、辐射剂量三者间的关系,优选出一种对接受CT检查的儿童较为合适的辐射防护方法,以降低辐射对儿童的危害,具有重要临床意义。     

口腔种植定位术前评估中颌骨低剂量多层螺旋CT检查的应用

目的：探讨颌骨低剂量多层螺旋CT（muti-slice computed tomography, MSCT）成像技术在口腔种植定位术前评估中的临床价值。方法：将80例口腔种植术前的患者随机分为4组,每组20例,使用SIEMENS Definition AS40 CT机,在其他扫描参数相同的情况下分别采用60 mA、50 mA、40 mA的管电流进行颌骨MSCT扫描,并与常规管电流90 mA组（20例）进行对比,记录4组不同毫安的容积CT剂量指数（volume computed tomography dose index, CTDIv）和放射线剂量长度乘积（dose length product,DLP）,分析比较4组间的CTDIv、DLP及图像质量。结果：40 mA、50 mA、60 mA、90 mA 4组间比较,CTDIv、DLP存在差异（P<0.05）,而将4组进行两两组间比较,则除了60 mA组与90 mA组间的CTDIv、DLP差异无统计学意义（P>0.05）外,其余任意2组间的CTDIv、DLP差异均存在统计学意义（P<0.05）。4组间的图像质量差异无统计学意义（P>0.05）。结论：采用40 mA低剂量MSCT扫描既能保证图像质量,又能满足临床术前诊断的需求,并可大幅度（35.0%）降低患者所受辐射剂量。     

Techniques and parameters for estimating radiation exposure and dose in cardiac computed tomography

With increasing clinical use of cardiac CT imaging it is important that all health care providers referring for or administering such examinations are familiar with the concepts and values of radiation dosimetry in CT as well as with the basic principles of radiation protection. There are important technical differences pertinent to radiation dose between the CT scanner types that are currently being used for imaging of the heart and coronary arteries. As a result of these differences, the radiation dose typically is higher when a cardiac examination is performed with multidetector-row CT (MDCT) than when it is performed with electron beam CT. Several techniques have been described to reduce radiation dose of MDCT imaging by varying the X-ray tube current during a CT examination. The volume computed tomographic dose index (CTDI_vol), the dose length product (DLP), and the effective dose (E) are the most useful parameters to describe and compare radiation doses received from cardiac CT examinations. When comparing radiation doses between scanning protocols and scanner types, the degree of image noise must be considered. Diagnostic, rather than aesthetic, quality of images should be the most important factor guiding the development of scanning protocols for cardiac CT imaging. Cardiac CT examinations should be ordered only by qualified health care providers, and the ordering clinicians should be aware of their responsibility of weighing risks of the radiation exposure against the expected benefits.     

不同代320排螺旋CT机全肝灌注成像辐射剂量及灌注参数的比较

目的:回顾性分析第1代320排螺旋CT机和第2代320排螺旋CT机全肝CT灌注成像(CTPI)辐射剂量的差异及对灌注参数的影响。方法:随机抽取行全肝CTPI的78例患者的影像学资料,其中采用第1代320排螺旋CT机者42例(第1代组),第2代320排螺旋CT机者36例(第2代组)。比较两组间正常肝脏实质的灌注参数,包括肝动脉血流量(hepatic arterial flow,HAF)、门静脉血流量(portal venous flow,PVF)及灌注指数(perfusion index,PI)。比较两组辐射剂量,包括容积CT剂量指数(volume CT dose index,CTDIvol)、剂量长度乘积(dose length product,DLP)和有效辐射剂量(effective radiation dose,ED)。结果:两组灌注参数HAF、PVF及PI值差异无统计学意义。第2代组辐射剂量参数(CTDIvol、DLP、ED)值较第1代组明显减小(P0.01),减小幅度均约46%。结论:第2代320排螺旋CT机能降低全肝CTPI的辐射剂量,同时对灌注参数值无显著影响。     

基于体质量指数双能量冠状动脉CTA低剂量检查

目的 探讨基于体质量指数(BMI)低管电流自动原始数据域迭代重建(SAFIRE)技术双能量冠状动脉CTA低剂量检查的可行性。方法 将200例患者分为4组:A组(19 kg/m²≤BMI<24 kg/m²),A管电流为180 mAs,采用FBP重建;B组(BMI<19 kg/m²),A管电流60 mAs;C组(19 kg/m²≤BMI<24 kg/m²),A管电流90 mAs;D组(24 kg/m²≤BMI<30 kg/m²),A管电流120 mAs,B、C、D组采用SAFIRE-3级重建。比较4组平均CT值、图像噪声、SNR、CNR、图像质量主观评分及辐射剂量。结果 4组患者冠状动脉显示节段、图像质量主观评分、平均CT值、SD、SNR、CNR差异均无统计学意义(P均>0.05);有效剂量(ED)差异有统计学意义(P均<0.05),ED值B、C、D组分别较A组下降65.82%、55.64%、24.18%。结论 基于BMI低管电流扫描SAFIRE重建双能冠状动脉CTA检查,能够保证图像质量并大幅降低辐射剂量。     

Dual-energy computed tomography for detection of coronary artery disease

Recent technological advances in computed tomography (CT) technology have fulfilled the prerequisites for the cardiac application of dual-energy CT (DECT) imaging. By exploiting the unique characteristics of materials when exposed to two different x-ray energies, DECT holds great promise for the diagnosis and management of coronary artery disease. It allows for the assessment of myocardial perfusion to discern the hemodynamic significance of coronary disease and possesses high accuracy for the detection and characterization of coronary plaques, while facilitating reductions in radiation dose. As such, DECT enabled cardiac CT to advance beyond the mere detection of coronary stenosis expanding its role in the evaluation and management of coronary atherosclerosis.     

CT研究蝶窦后壁可开窗范围及相关因素

目的:采用多层螺旋CT技术研究蝶窦后壁的可开窗范围,并分析其相关的限制因素。方法:对110例头部增强薄层CT扫描的原始资料行多平面重建,测量双侧颈内动脉外侧襻间距和内侧襻间距、蝶窦后壁面积、蝶窦后壁骨质厚度等数据,观察并记录蝶窦的位置和气化、蝶窦分隔、颈内动脉有无突入窦腔情况及斜坡处静脉窦强化等表现。结果:结合蝶窦气化情况,将蝶窦后壁按厚度分为厚壁型(35．6%)、薄壁型(55．9%)及菲薄型(8．5%)。两侧颈内动脉的外侧襻间距(19．2±2．9)mm、内侧襻间距(15．8±2．3)mm限定了蝶窦后壁可开窗的边界。蝶窦后壁的可开窗面积平均为(251．0±53．1)mm~2。结论:蝶窦后壁整体上可形成类梯形窗口。开放窗口的主要限制因素有双侧颈内动脉间距、蝶窦后壁骨质厚度及斜坡处静脉窦。CT重建和测量可显示蝶窦腔内、外的关键结构,对经蝶手术的术前评价和计划具重要意义。     

Chest radiograph vs. computed tomography scan in the evaluation for pneumonia

To determine, in an Emergency Department (ED) population, the incidence of pneumonia diagnosed on thoracic computed tomography (CT) in the setting of negative or non-diagnostic chest radiographs (CXR). This is a retrospective chart review of all ED visits of adult patients ultimately diagnosed with "pneumonia" in whom both CXR and CT were obtained. We note cases in which the CXR was either negative or non-diagnostic for pneumonia and the CT noted a definitive infiltrate consistent with pneumonia. Of the 1,057 patients diagnosed with pneumonia, both CXR and CT were performed in 97 cases. Of this group, there were 26 patients (27%), in whom the CXR was either negative or non-diagnostic, but the CT noted an infiltrate/consolidation consistent with pneumonia. In our retrospective review of ED patients, we find that in 27% of cases in which both a CXR and a CT scan were performed in the work-up of varied chief complaints, pneumonia was demonstrated on CT in the face of a negative or non-diagnostic CXR. This analysis demonstrates the need for further studies regarding the appropriate radiographic evaluation of pneumonia, particularly in high-risk patients.     

Effect of focused protocol on reducing radiation dose for children who require computed tomography for suspected appendicitis

BackgroundDespite efforts to incorporate ultrasound into the evaluation of children for appendicitis, computed tomography (CT) is often used to aid in its diagnosis. CT scans, however, expose children to a considerable amount of radiation. In 2017, our institution began using a height-based Focused CT protocol for children with suspected appendicitis in need of CT.ObjectiveTo compare the radiation dose received by children with suspected appendicitis who underwent a Standard CT of the abdomen and pelvis (CTAP) with that of a Focused CT.MethodsWe conducted a retrospective study of children <18 years who underwent a CT scan for suspected appendicitis (2014–2020). We included all patients whose indication for CT was “appendicitis” or “right lower quadrant pain” and excluded those whose CT scan record lacked a radiation dose report. The effective radiation dose delivered was calculated using the dose-length product from the dose report. We compared the effective dose of those who received a Standard CTAP to those who received a Focused CT. To account for differences in radiation dose over time and by CT scanner, analyses were adjusted for CT dose index volume (CTDI_vol) and size-specific dose estimate (SSDE) using quantile regression.ResultsA total of 474 patients who underwent CT were included. Prior to CT, 362(76%) had received an ultrasound. In total, 309(65%) patients underwent a Standard CTAP and 165(35%) underwent a Focused CT. The appendix was identified in 259(84%) Standard CTAPs compared to 151(92%) Focused CTs (p = 0.02). Compared to the Standard CTAP, children who received a Focused CT were exposed to a significantly lower effective dose (relative difference: CTDI-adjusted −13%[95% CI:-21,-5]; SSDE-adjusted −14%[95% CI:-24,-3]).ConclusionsOur height-based Focused CT protocol reduces radiation for children undergoing CT evaluation for suspected appendicitis without sacrificing diagnostic accuracy. Further study is needed to validate these findings at other institutions.     

数字乳腺X线摄影中辐射剂量相关因素的研究进展

乳腺X线摄影是目前早期发现乳腺癌最有效的检查方法,电离辐射与乳腺癌的产生有很大关系,有效降低辐射剂量是目前研究的热点。本文主要阐述数字乳腺X线摄影在不同阳极靶面/滤过组合、不同曝光模式、不同腺体分型、不同厚度及压力时,患者所受的辐射剂量不同,在保证影像质量的基础上应有效降低辐射剂量。     

Multi-institutional evaluation of the indications and radiation dose of functional cardiovascular computed tomography (CCT) imaging in congenital heart disease

Ventricular volumes and ejection fraction are often used in clinical decision making in patients with congenital heart disease (CHD). The referral diagnosis, radiation exposure and image quality of functional cardiac computed tomography (CT) in a relatively large cohort of patients of CHD has not been reported. This is a retrospective evaluation of functional CT studies performed in CHD patients from three institutions (1/2007–3/2013). Patient and scanner characteristics, radiation dose estimates and image quality were compared. Two hundred ninety-eight functional CT studies were evaluated. The most common referral diagnosis were tetralogy of Fallot (33 %), transposition complexes (24 %) single ventricle heart disease (15 %), and left sided obstruction (15 %). The reason for cardiac CT was presence of pacemaker (60 %), need for detailed coronary artery imaging (18 %), metallic artifact in CMR (12 %), evaluation of prosthetic valve function (4 %), and claustrophobia or BMI too large for the available MR scanner (6 %). 266 (89.3 %) scans allowed quantification of ventricular function, 25 (8.4 %) scans allowed qualitative assessment of function, and 7 (2.3 %) of the scans were non-diagnostic for functional analysis. Median DLP was 399 mGy cm (186, 614), and median effective dose was 5.5 mSv (2.6, 8.5). Radiation dose and image quality varied across institutions. Cardiac CT function imaging can be performed in patients with congenital heart disease when CMR is contraindicated or has poor image quality. Radiation dose and image quality varies across institutions.