多层螺旋CT在胰腺癌中的诊断价值

目的:探讨多层螺旋CT在胰腺癌中的诊断价值。方法:回顾性分析2017年2月至2019年2月我院接诊的72例经过手术病理证实的胰腺癌患者。比较多排螺旋CT平扫、动脉期、胰腺期、门脉期的检出率、神经、血管浸润情况、及选择55例正常胰腺组织比较两者多层螺旋CT扫描密度值的差异。结果:多层螺旋CT扫描,平扫、动脉期、胰腺期、门脉期检出率分别为63.89%、77.78%、95.83%、90.28%,胰腺期、门脉期检出率均显著高于平扫、动脉期(P<0.05);多层螺旋CT增强扫描诊断胰腺癌神经浸润的准确性为80.56%(58/72),敏感性为91.07%(51/56),特异性为43.75%(7/16),阳性预测值85.00%(51/60),阴性预测值58.33%(7/12);多层螺旋CT增强扫描诊断胰腺癌血管浸润的准确性为95.83%(69/72),敏感性为80.00%(8/10),特异性为98.39%(61/62),阳性预测值88.89%(8/9),阴性预测值96.83%(61/63);胰腺癌组织多层螺旋CT扫描密度值均显著高于正常胰腺组织密度值,(P<0.05)。结论:多排螺旋CT在胰腺癌中诊断价值高,可帮助临床提供正确诊断,以选择合适的治疗方案。     

多层螺旋CT 血管造影在脑动脉瘤中应用

目的:观察多层螺旋CT血管造影对脑动脉瘤的诊断价值.方法:对16例脑动脉瘤患者的多层螺旋CT血管造影结果进行总结分析.结果:多层螺旋CT血管造影的诊断准确性与DSA无明显差异;多层螺旋CT血管造影显示动脉瘤的部位、大小、动脉瘤颈结构及其与周围血管的关系等与手术结果基本符合.结论:多层螺旋CT血管造影对脑动脉瘤的诊断准确率高,具备十分重要的临床应用价值.     

多排螺旋CT扫描对骨折的诊断

目的: 普通X线片及CT平扫对于骨折,尤其是隐匿性骨折检出率较低,较易造成漏诊和误诊,随着多排螺旋CT的普及,利用曲面重建(MPR)和容积再现(VR)技术后处理图像,成为诊断隐匿性骨折的理想的影像诊断手段.探讨多排螺旋CT在对骨折的诊断中的临床应用价值。方法: 对213例临床怀疑骨折的患者进行CR摄片再进行多排螺旋CT扫描,通过三维重建技术处理后,得到受检部位二维、三维的图像。结果: 相同的对照组经多排螺旋CT、X线检查检查后,新增33例骨折。结论: 多排螺旋CT扫描及三维重建技术较传统X线平片能对骨折病例做出更正确的诊断。     

256排Revolution多参数调节下低剂量心脏冠脉成像应用

目的:研究256排Revolution多参数调节下低剂量扫描心脏冠脉成像(Coronary computed tomographic angiography,CCTA)的应用。方法:回顾性分析2016年3月15日至5月15日间在我院256排CT行CCTA的患者,分为心率稳定试验组(n=54例)和心率不稳定试验组(n=41例),同时选取在我院64排VCT行CCTA的患者为对照组(n=116例),对三组CCTA图像质量行主观和客观评估,比较有效辐射剂量的差异。结果:256排CT检查成功率和图像质量的主观评价均优于对照组(P0.05);信噪比(SNR)、对比噪声比(CNR)与对照组差异无统计学意义(P0.05);但有效辐射剂量明显降低(P0.05)。结论:256排CT多参数调节下检查冠脉在保证图像质量下可有效降低辐射剂量。     

多排螺旋CT 肾动脉成像技术与临床应用

近年来随着CT扫描技术的发展及高速和多排螺旋CT（multi-slices CT）的出现,CT血管成像技术日益完美,尤其是目前可临床应用的16层、64层螺旋CT具有时间分辨力高,可采集各向同性的容积数据,加之其微创、技术操作简单、耗时短及患者容易接受等优势因此在揭示肾动脉疾病方面具有很大的临床意义,与之相关的临床应用已经取得了长足的进步。     

不同剂量多排螺旋CT扫描对儿童肺结核的诊断价值比较研究

目的:探讨不同剂量多排螺旋CT扫描对儿童肺结核(PTB)的诊断价值。方法:以我院于2016年5月～2018年11月收治的156例PTB患儿为研究对象,根据患儿年龄分为A组52例(0～5岁)、B组52例(6～9岁)、C组52例(10～14岁)。三组患儿均进行低剂量64排螺旋CT扫描,其中A组剂量为20 MA,B组剂量为30 MA,C组剂量为40 MA,2 d后,三组患儿均进行常规剂量64排螺旋CT扫描,其中A组剂量为100 MA,B组和C组剂量均为150 MA。分别对比A组、B组、C组患儿低剂量与常规剂量CT扫描的扫描效果、图像优良率及辐射剂量。结果:A组、B组、C组患儿低剂量与常规剂量CT扫描对病灶数量、结节、空洞、胸膜粘连、钙化灶的显像率比较差异无统计学意义(P0.05),但A组、B组、C组患儿低剂量CT扫描对毛刺、磨玻璃影的显像率明显低于常规剂量CT扫描(P0.05);A组、B组、C组患儿低剂量与常规剂量CT扫描的图像优良率比较差异无统计学意义(P0.05);与常规剂量CT扫描相比,A组、B组、C组患儿低剂量CT扫描的剂量长度乘积(DLP)、CT剂量指数(CTDIvoI)、CT加权剂量指数(CTDIw)、放射剂量明显更低(P0.05)。结论:使用常规剂量多排螺旋CT扫描对PTB儿童毛刺、磨玻璃影的显像效果较好,但是使用低剂量多排螺旋CT扫描同样能够确保图像的质量,达到诊断要求,并且能够降低对患儿的辐射剂量,在考虑人体健康的前提下,建议使用低剂量多排螺旋CT扫描。     

多排螺旋CT在颈部淋巴结结核的诊断与鉴别诊断

目的探讨多排螺旋CT诊断颈部淋巴结结核的临床应用价值。方法对2014年10月~2016年10月在我院经病理证实且接受临床治疗的颈部淋巴结结核患者58例的临床资料及CT图像进行分析。结果 58例患者均存在多个淋巴结同时受累情况,其颈部淋巴结大多为椭圆形、圆形,发病部位则以胸锁乳突肌及其周围组织为主,其中43例为单侧发病(74.14%),15例为双侧同时累及(32.61%)。多排螺旋CT检查可见颈部淋巴瘤表现为颈内静脉深淋巴结肿大,CT增强扫描后周边强化不明显。结论多排螺旋CT对颈部淋巴结结核病症进行诊断鉴别时,能清晰显示疾病情况以及相应的病理特征,对淋巴结的定性诊断有较高的价值。     

多排螺旋CT后处理技术对不规则骨骨折的诊断价值

目的:探讨多排螺旋CT及其后处理技术在诊断不规则骨骨折中的诊断价值。方法:用16排螺旋CT对25例怀疑颅骨、脊柱或关节附近骨折的外伤患儿进行扫描并进行后处理(MPR、VR)。结果:25例病例中颅骨骨折15例,脊柱骨折5例,四肢关节骨折5例(其中3例关节内骨折伴有骺软骨损伤)。结论:对于不规则骨骨折,多排螺旋CT及其后处理重建具有很大的优越性,应横断位、MPR及VR三者相结合判断,为临床提供丰富的、科学的、准确的信息依据。     

多排螺旋CT对隐匿性肋骨骨折的诊断价值及最佳复查时间研究

目的:探讨多排螺旋CT对隐匿性肋骨骨折的诊断价值及最佳复查时间。方法:选取2017年7月到2018年7月期间在我院接受治疗的胸部外伤患者95例,在首次检查时均接受了X线平片和多排螺旋CT检查,比较首次检查时X线平片和多排螺旋CT的检出率,比较首次检查时X线平片和多排螺旋CT对不同类型骨折的诊断情况,比较各个时间段复查病例的肋骨骨折数与首次检查时的差异。结果:95例患者中最终86例确诊存在肋骨骨折,首次检查时多排螺旋CT的检出率为95.35%(82/86),高于X线平片的82.56%(71/86)(P0.05)。86例患者最终确定共存在骨折289处,首次检查时X线平片共检出246处,多排螺旋CT共检出274处,多排螺旋CT对线性骨折、凹陷性骨折的检出率高于X线平片(P0.05)。伤后11-20d、伤后41-50d、伤后51-60d的复查肋骨骨折数与首次检查肋骨骨折数比较无统计学差异(P0.05),伤后21-30d、伤后31-40d的复查肋骨骨折数高于首次检查肋骨骨折数(P0.05)。结论:多排螺旋CT对隐匿性肋骨骨折有较高的诊断价值,首次诊断时的检出率明显高于X线平片,伤后21-40d这个时间段是进行复查的较佳时间段,可获得较好效果。     

X线片和多层螺旋CT诊断及鉴别周围型肺癌的对比研究

目的:对比X线平片和多层螺旋CT诊断及鉴别周围型肺癌的效果。方法:选取了100例周围型肺癌患者,所有患者入院后先行X线片检查,后进行多层螺旋CT检查。通过观察并记录X线片与多层螺旋CT对周围型肺癌的影像学特征、临床TNM分期的诊断效果,评价X线平片和多层螺旋CT对周围型肺癌的诊断效果。结果:多层螺旋CT对周围型肺癌的肿块、分叶征、支气管气象征、空洞、胸膜凹陷、血管集束征,胸腔积液的检出率均高于X线片(P0.05)。根据外科病理TNM分期结果,多层螺旋CT对周围型肺癌的临床TNM分期诊断符合率为92.0%,X线对周围型肺癌的临床TNM分期诊断符合率为61.0%,多层螺旋CT对周围型肺癌的临床TNM分期诊断符合率明显高于X线(P0.05)。结论:多层螺旋CT对于周围型肺癌各类型影像学征象具有较好的检出率,对周围型肺癌临床TNM分期诊断准确性接近病理诊断结果。     

Image quality characteristics for virtual monoenergetic images using dual-layer spectral detector CT: Comparison with conventional tube-voltage images

PurposeTo investigate the image quality characteristics for virtual monoenergetic images compared with conventional tube-voltage image with dual-layer spectral CT (DLCT).MethodsHelical scans were performed using a first-generation DLCT scanner, two different sizes of acrylic cylindrical phantoms, and a Catphan phantom. Three different iodine concentrations were inserted into the phantom center. The single-tube voltage for obtaining virtual monoenergetic images was set to 120 or 140 kVp. Conventional 120- and 140-kVp images and virtual monoenergetic images (40–200-keV images) were reconstructed from slice thicknesses of 1.0 mm. The CT number and image noise were measured for each iodine concentration and water on the 120-kVp images and virtual monoenergetic images. The noise power spectrum (NPS) was also calculated.ResultsThe iodine CT numbers for the iodinated enhancing materials were similar regardless of phantom size and acquisition method. Compared with the iodine CT numbers of the conventional 120-kVp images, those for the monoenergetic 40-, 50-, and 60-keV images increased by approximately 3.0-, 1.9-, and 1.3-fold, respectively. The image noise values for each virtual monoenergetic image were similar (for example, 24.6 HU at 40 keV and 23.3 HU at 200 keV obtained at 120 kVp and 30-cm phantom size). The NPS curves of the 70-keV and 120-kVp images for a 1.0-mm slice thickness over the entire frequency range were similar.ConclusionVirtual monoenergetic images represent stable image noise over the entire energy spectrum and improved the contrast-to-noise ratio than conventional tube voltage using the dual-layer spectral detector CT.     

A detection method for streak artifacts and radiological noise in a non-uniform region in a CT image

By using the CT images obtained by subtracting two CT images acquired under the same conditions and slice locations, we have devised a method for detecting streak artifacts in non-uniform regions and only radiological noise components in CT images. A chest phantom was scanned using 16- and 64-multidetector row helical CT scanners with various mAs values at 120 kVp. The upper lung slice image was employed as a target image for evaluating the streak artifacts and radiological noise. One hundred parallel line segments with a length of 80 pixels were placed on the subtracted CT image, and the largest CT value in each CT value profile was employed as a feature variable of the streak artifacts; these feature variables were analyzed with the extreme value theory (Gumbel distribution). To detect only the radiological noise, all CT values contained in the 100 line profile were plotted on normal probability paper and the standard deviation was estimated from the inclination of its fitted line for the CT value plots. The two detection methods devised in this study were able to evaluate the streak artifacts and radiological noise in the CT images with high accuracy.     

基于图像重建的CT三维重建提升腹部增强扫描图像质量的价值

摘要 目的：探讨基于图像重建的电子计算机断层扫描仪器(Computed Tomography,CT)三维成像提升腹部增强扫描图像质量的价值。方法：2019年11月到2020年10月选择在本院进行腹部CT增强扫描的患者76例作为研究对象,采用电脑随机数字法将研究对象分为对照组和重建组各38例,对照组给予常规扫描成像,重建组给予基于自适应统计迭代重建(adaptive statistical iterative reconstruction,ASIR)的CT三维成像,记录两组成像质量与噪声情况。结果：两名医师对重建组的图像主观质量评分都高于对照组(P<0.05)。重建组的图像相对细腻柔和,能清晰显示图像细小血管断面,末梢血管显示良好,血管壁光滑柔和。重建组的动脉期、门静脉期、平衡期的肝脏CT值高于对照组(P<0.05),动脉期、门静脉期、平衡期的肝脏、胰腺对比噪声比(contrast to noise ratio,CNR)值低于对照组(P<0.05)。重建组的容积剂量指数(volume CT dose index,CTDIvol)和剂量长度乘积(Dose-Length product,DLP)、有效剂量(effective dose,ED)值都低于对照组(P<0.05)。结论：基于图像重建的CT三维成像能提升腹部增强扫描主客观图像质量,降低图像噪声,更利于腹部疾病的显示,从而提高正确诊断率。     

宝石能谱CT GSI成像和常规成像在上腹部应用价值的对比研究

目的:探讨宝石能谱CT GSI扫描模式在上腹部检查中降低辐射剂量和优化图像质量的可行性及应用价值。方法:选择2016年9月至2016年12月期间我院40例拟行上腹部三期增强的患者,根据扫描模式将患者分为A组和B组,每组20例。A组患者采用宝石能谱CT常规扫描模式行螺旋扫描,管电压120 Kvp及自动毫安管电流,确定NI值为10。B组患者采用GSI模式行三期增强扫描收集门脉期图像。回顾性自适应统计迭代重建(ASIR)70kev单能量图像,应用ASIR Review工具收集0到100%ASIR的CT值、噪声值,计算图像信号噪声比(SNR)。记录各组剂量报告中CT剂量容积指数(CTDI vol)及剂量长度乘积(DLP),并计算有效剂量(ED),采用图像质量主观评分对图像进行评价。结果:B组CT值、噪声值及SNR均高于A组(P0.05),B组CTDIvol、DLP和ED均显著低于A组(P0.05);随着ASIR升高,SNR升高,但是图像质量主观评分先升高后降低。当ASIR为50%时,图像质量最高,不同ASIR的CT值、噪声值之间的差异无统计学意义(P0.05)。结论:宝石能谱CT GSI扫描模式的效果明显优于螺旋扫描,同时在降低图像噪声的前提下选择50%ASIR,可保障图像质量。     

Optimal photon energy comparison between digital breast tomosynthesis and mammography: A case study

A comparison, in terms of the optimal energy that maximizes the image quality between digital breast tomosynthesis (DBT) and digital mammography (DM) was performed in a MAMMOMAT Inspiration system (Siemens) based on amorphous selenium flat panel detector. In this paper we measured the image quality by the signal difference-to-noise ratio (SDNR), and the patient risk by the mean glandular dose (MGD). Using these quantities we compared the optimal voltage that maximizes the image quality both in breast tomosynthesis and standard mammography acquisition mode. The comparison for the two acquisition modes was performed for a W/Rh anode filter combinations by using a 4.5 cm tissue equivalent mammography phantom. Moreover, in order to check if the used equipment was quantum noise limited, the relation of the relative noise with respect to the detector dose was evaluated. Results showed that in the tomosynthesis acquisition mode the optimal voltage is 28 kV, whereas in standard mammography the optimal voltage is 30 kV. The automatic exposure control (AEC) of the system selects 28 kV as optimal voltage both for DBT and DM. Monte Carlo simulations showed a qualitative agreement with the AEC selection system, since an optimal monochromatic energy of 20 keV was found both for DBT and DM. Moreover, the check about the noise showed that the system is not completely quantum noise limited, and this issue could explain the experimental slight difference in terms of optimal voltage between DBT and DM. According to these results, the use of higher voltage settings is not justified for the improvement of the image quality during a DBT examination.     

Monte-Carlo simulation of a slot-scanning X-ray imaging system

We present a method for simulating slot-scanning X-ray imaging using the general-purpose Monte Carlo simulation package PENELOPE and penEasy Imaging. Different phantoms can be defined with the PENGEOM package, which defines bodies as combinations of volumes limited by quadric surfaces. The source-detector geometry, the position of the object, the collimator, the X-ray tube properties, the detector material and the pixel dimensions are defined. The output of the time-delay integration detector is simulated using sequential slot outputs derived from penEasy Imaging. The simulations are validated using tungsten and aluminium test objects, which are both simulated and imaged. The simulations are compared to the X-ray images using standard image quality metrics. The MTF, NPS and DQE curves show that the real and simulated X-ray images are comparable in terms of spatial resolution, noise and frequency information. The implementation can be modified to suit alterations in the system being simulated.     

光耦功率放大技术在CT超低剂量扫描的研究

目的将全新的光电耦合高电压强电流放大处理技术用于CT机的前置放大处理中,隔离噪声和高电压大电流放大图像信号,实现超低剂量扫描,高清晰成像。方法将光电耦合放大器制作成射线剂量仪,并用CT机等超低剂量120KV、3-6mA…对其曝光,并与标准射线剂量仪校准,使其输出值不仅为射线剂量值,更能显示为高电压和大电流的优质图像信噪比。结果超小电流扫描经探测和光耦放大后最大值为87.5V和0.96A,而噪声电压为0.13μV、电流仅为0.02μA,给超低剂量扫描和传输处理时的功耗及高电压的宽动态范围显示留了很大空间。结论 CT超低剂量扫描时光耦放大器可在源头彻底隔离各种噪声并超高倍放大、高电压大电流输出图像信号,可保证高清晰高分辨率成像。     

Practical Confocal Microscopy and the Evaluation of System Performance

The laser scanning confocal microscope has enormous potential in many fields of biology. Currently there is a subjective nature in the assessment of a confocal microscope's performance by primarily evaluating the system with a specific test slide provided by the user's laboratory. To achieve better performance from the equipment, it is necessary to run a series of tests to ensure that the optical machine is functioning properly. We have devised these methods on the Leica TCS-SP and TCS-4D systems. Tests measuring field illumination, lens clarity, laser power output, dichroic functioning, spectral alignment, axial resolution, laser power stability, machine performance, and system noise were derived to test the Leica laser scanning confocal microscopy system. These tests should be applicable to other manufacturers' systems as well. The relationship between photomultiplier tube (PMT) voltage, laser power, and averaging using a 10-microm-diameter test bead has shown that the noise (coefficient of variation of bead intensity, CV) in an image increases as the PMT increases. Therefore increasing the PMT setting results in increased noise. For ideal image quality, it appears that it is better to decrease the PMT setting and increase laser power, as noise generated by high PMT settings will reduce the image quality far more than the bleaching caused by higher laser power. Averaging can be used to improve the image at high PMT values, provided the sample is not bleached by repeated passes of the laser.     

Signal transduction across alamethicin ion channels in the presence of noise.

We have studied voltage-dependent ion channels of alamethicin reconstituted into an artificial planar lipid bilayer membrane from the point of view of electric signal transduction. Signal transduction properties of these channels are highly sensitive to the external electric noise. Specifically, addition of bandwidth-restricted "white" noise of 10-20 mV (r.m.s.) to a small sine wave input signal increases the output signal by approximately 20-40 dB conserving, and even slightly increasing, the signal-to-noise ratio at the system output. We have developed a small-signal adiabatic theory of stochastic resonance for a threshold-free system of voltage-dependent ion channels. This theory describes our main experimental findings giving good qualitative understanding of the underlying mechanism. It predicts the right value of the output signal-to-noise ratio and provides a reliable estimate for the noise intensity corresponding to its maximum. Our results suggest that the alamethicin channel in a lipid bilayer is a good model system for studies of mechanisms of primary electrical signal processing in biology showing an important feature of signal transduction improvement by a fluctuating environment.     

Assessment of the variation in CT scanner performance (image quality and Hounsfield units) with scan parameters,for image optimisation in radiotherapy treatment planning

PurposeTo define a method and investigate how the adjustment of scan parameters affected the image quality and Hounsfield units (HUs) on a CT scanner used for radiotherapy treatment planning. A lack of similar investigations in the literature may be a contributing factor in the apparent reluctance to optimise radiotherapy CT protocols.MethodA Catphan phantom was used to assess how image quality on a Toshiba Aquilion LB scanner changed with scan parameters. Acquisition and reconstruction field-of-view (FOV), collimation, image slice thickness, effective mAs per rotation and reconstruction algorithm were varied. Changes were assessed for HUs of different materials, high contrast spatial resolution (HCSR), contrast-noise ratio (CNR), HU uniformity, scan direction low contrast and CT dose-index.ResultsCNR and HCSR varied most with reconstruction algorithm, reconstruction FOV and effective mAs. Collimation, but not image slice width, had a significant effect on CT dose-index with narrower collimation giving higher doses. Dose increased with effective mAs. Highest HU differences were seen when changing reconstruction algorithm: 56 HU for densities close to water and 117 HU for bone-like materials. Acquisition FOV affected the HUs but reconstruction FOV and effective mAs did not.ConclusionsAll the scan parameters investigated affected the image quality metrics. Reconstruction algorithm, reconstruction FOV, collimation and effective mAs were most important. Reconstruction algorithm and acquisition FOV had significant effect on HU. The methodology is applicable to radiotherapy CT scanners when investigating image quality optimisation, prior to assessing the impact of scan protocol changes on clinical CT images and treatment plans.