Study of Scanning Dose Optimization on Chest and Abdomen Enhanced CT Imaging

Objective: To investigate the correlation between radiation dose and radiation risk when patients are scanned by 64-slice spiral CT. Materials and Methods: SPSS 17.0 is used statistically for analyzing the patient’s scanning parameters, radiation dose of monitoring and examining the patients who are scanning of their abdomen, chest and pelvic in our affiliated hospital. Results: SPSS statistical analysis shows that the factor related to radiation dose is scanning layer;the basic characteristics such as height and heart rate don’t affect the patient’s scan dose directly. Conclusion: Increasing the delay time after injection can reduce the scan numbers and monitoring layers of the machine, thus reduce the patient’s radiation dose and tube’s exposure time.

Correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer

Objective:To study the correlation between CT dynamic enhanced scanning parameters and serum tumor markers before and after radiofrequency ablation in patients with lung cancer.Methods:60 patients with advanced non-small cell lung cancer who were treated in this hospital between January 2015 and January 2017 were divided into control group(n=30)and observation group(n=30)by random number table method.Control group received conventional intravenous chemotherapy,and observation group received intravenous chemotherapy combined with radiofrequency ablation.The differences in CT dynamic enhanced scanning parameter levels and serum tumor marker contents were compared between the two groups of patients before and after treatment.Pearson test was used to evaluate the correlation between CT dynamic enhanced scanning parameters and serum tumor marker contents in patients with advanced non-small cell lung cancer.Results:Before treatment,the differences in CT dynamic enhanced scanning parameter levels,non-organ-specific tumor marker contents and vascular tumor marker contents were not statistically significant between the two groups of patients(P>0.05).After treatment,CT dynamic enhanced scanning parameters PH and perfusion value levels of observation group were lower than those of control group(P<0.05);serum non-organ specific tumor markers CA125,CA153,CEA and CYFRA21-1 contents of observation group were lower than those of control group;serum vascular tumor markers VEGF,Ang-2,HIF-1 and MMP-9 contents were lower than those of control group(P<0.05).Pearson test showed that CT dynamic enhanced scanning parameters PH and perfusion value levels in patients with non-small cell lung cancer were positively correlated with serum non-organ specific tumor marker and vascular tumor marker contents.Conclusion:Adjuvant radiofrequency ablation can significantly reduce the tumor malignancy of patients with advanced non-small cell lung cancer.

An enhanced spectral diversity coregistration method for dualpolarimetric Sentinel-1A/B TOPS data

Sentinel-1A/B data are crucial for retrieving numerical information about surface phenomena and processes.Coregistration of terrain observation by progressive scans(TOPS)data is a critical step in its application.TOPS data must be fundamentally co-registered with an accuracy of 0.001 pixels.However,various decorrelation factors due to natural vegetation and seasonal effects affect the coregistration accuracy of TOPS data.This paper proposed an enhanced spectral diversity coregistration method for dual-polarimetric(PolESD)Sentinel-1A/B TOPS data.The PolESD method suppresses speckle noise based on a unified non-local framework in dual-pol Synthetic Aperture Radar(SAR),and extracts the phase of the optimal polarization channel from the denoised polarimetric interferometric coherency matrix.Compared with the traditional ESD method developed for single-polarization data,the PolESD method can obtain more accurate coherence and phase and get more pixels for azimuth-offset estimation.In bare areas covered with low vegetation,the number of pixels selected by PolESD is more than the Boxcar method.It can also correct misregistration more effectively and eliminate phase jumps in the burst edge.Therefore,PolESD will help improve the application of TOPS data in low-coherence scenarios.

Diagnostic value of MSCT plain scan and dual-phase enhanced scan in thymic adenocarcinoma

Objective: To evaluate the value of MSCT plain scan and enhanced CT in the diagnosis of thymic adenocarcinoma. Methods: From May 2013 to June 2018, 37 cases of MSCT plain scan and dual-phase enhanced scan of thymic adenocarcinoma were retrospectively analyzed. The location, shape, size, density (CT value), enhanced features, peripheral invasion and mediastinal lymph node metastasis of the lesions were observed. Results: All 37 cases of thymic adenocarcinoma were diagnosed by CT before operation, and all cases were diagnosed by pathology after operation as malignant tumors,including 28 cases of thoracic adenocarcinoma and 9 cases of invasive thymoma. All 28 cases of thymic adenocarcinoma were single lesion of anterior superior mediastinum. The maximum cross-section was located in the midline in 7 cases and on the mediastinal side in 21 cases with significant difference (P<0.05). All lesions were irregular lobulated. The minimum diameter of lesions was 2.1 cm and the maximum diameter was 8.6 cm. Soft tissue density was dominant in the solid part. All cases of thymic adenocarcinoma showed inhomogeneous, moderate and severe enhancement in the arterial and venous phase after enhancement. The degree of enhancement in the venous phase was higher than that in the arterial phase, and there was no enhancement in the irregular liquefied necrosis area. 26 cases had necrotic lesions, 21 cases had mediastinal lymph node metastasis, and 8 cases had invasion of adjacent pleura. 19 cases had mediastinal vessels and 0 cases had distant pleural metastases. Conclusion: MSCT plain scan combined with dual-phase enhanced CT is helpful to display the details and metastasis of thymic adenocarcinoma, improve the coincidence rate of CT diagnosis and pathological diagnosis, and reduce the misdiagnosis rate. To provide help for clinical diagnosis and treatment of thymic adenocarcinoma.

Observations on the Diagnostic Effects of CT Examination(Enhanced Scan)on Hemorrhage Corpus Luteum Cyst

Objective:To investigate the diagnostic effects of enhanced CT scan on hemorrhage corpus luteum cyst(HCLC).Methods:The clinical data of 24 patients with hemorrhage corpus luteum cyst diagnosed by surgery and pathology in our hospital were collected.All patients received enhanced CT scan to evaluate the diagnostic value of CT.Results:The average diameter of the cysts in this group of patients was 5.1cm by CT.Further detection of the ruptured cyst wall showed that there was a liquid lowdensity shadow.Some of the cysts were accompanied by signs of increased density,indicating the presence of blood clots;all patients received surgical treatment.Intraoperative ultrasound examination of the cysts had an average diameter of 5.2cm and a wall of 0.2~0.4mm.Among them,19 cases of cysts contained"coffee-colored"liquid with varying degrees of blood clots,and 5 cases had no blood clots in the cysts but there were a lot of blood clots beside the cysts.Conclusion:The application of enhanced CT scan in patients with hemorrhage corpus luteum cyst is of great value.It can provide accurate data reference for clinical treatment and is worthy of promoting its clinical application.

Diagnostic Value of Spiral CT Chest Enhanced Scan in Adult with Active Pulmonary Tuberculosis

Aim:To explore the diagnostic value of spiral CT chest enhanced scan for adults with active pulmonary tuberculosis.Methods:The clinical data of 60 adult patients with active pulmonary tuberculosis who were treated in our hospital from January 2018 to November 2019 were retrospectively analyzed.All patients underwent conventional chest radiography and spiral CT chest enhanced scan.The number of tuberculosis diagnosis,the detection rate of special site lesions,and the detection rate of active pulmonary tuberculosis signs by the two methods were compared.Results:In 60 patients,the pathological results confirmed the existence of 75 tuberculosis lesions.The detection rate of spiral CT was 98.67%,which was not statistically significant compared with the detection rate of 92.00%(P>0.05)in the conventional chest X-ray.The detection rate of spiral CT enhanced scans for tuberculosis lesions in special sites was 100.00%,which was significantly higher than that of conventional chest X-ray of 7.69%,and the accuracy rate of active pulmonary tuberculosis signs was 98.85%higher than that of conventional chest X-ray of 79.31%.P<0.05).The difference was statistically significant(P<0.05).Conclusion:Spiral CT chest enhanced scan can not only find special tuberculosis lesions that cannot be detected by conventional chest radiography,but also accurately determine active pulmonary tuberculosis in adults,which is of high diagnostic value.

Magnetic emission intensity enhancement for amorphous alloys by constructing a multi-phase structure withα-Fe nanocrystals

The perturbation in the magnetic field generated by the rotation or oscillation of magnetic domains in magnetic materials can emit low-frequency electromagnetic waves,which are expected to be used in low-frequency communications.However,the magnetic emission intensity,defined by the perturbation ability,of current commercially applied amorphous alloys,such as Metglas,cannot meet the application requirements for low-frequency antennas due to the domain motion energy loss.Herein,a multi-phase Metglas amorphous alloy was constructed by incorporatingα-Fe nanocrystals using rapid annealing to manipulate the domain movement.It was found that 3.89 times higher magnetic emission intensity is obtained compared to the pristine due to the synergism of the deformation and displacement mechanisms.Moreover,the low-frequency magnetic emission performance verification was carried out by preparing magnetoelectric composites as the antenna vibrator by assembling the alloy and macro piezoelectric fiber composites(MFC).Enhancements of magnetic emission intensity are found at 93.3%and 49.2%at the first and second harmonic frequencies compared with the unmodified alloy vibrator.Therefore,the approach leads to the development of high-performance communication with a novel standard for evaluation.

A case of occult insulinoma localized by pancreatic dynamic enhanced spiral CT

Insulinomas are the most common category of pancreatic endocrine tumors,with an annual incidence of 1-4 cases per million people.Most are intrapancreatic,benign and solitary.Therefore,they have an excellent prognosis after surgical resection.However,the localization diagnosis of insulinomas still poses a challenge to surgeons and radiologists.In this case,the tumor was occult and could not be found by either abdominal enhanced spiral computed tomography(CT)or ultrasonography.Therefore,we tried a new method of CT scanning and localized the tumor.

Spiral multi-phase CT in evaluating resectability of pancreatic carcinoma

Objectives: To evaluate the specific manifestations of pancreatic carcinoma on spiral multi-phase CT and its resectability before operation. Methods: Ninety-seven patients were confirmed oper- atively and pathologically. Enhanced CT scan was performed with intravenous injection bolus of ap- proximately 75-120 ml (1-1.5 ml/kg body weight) contrast medium at a rate of 2.5-3 ml/s. In 68 pa- tients receiving dual-phase scan, the delayed scan time of arterial and venous phases was 18-20 s and 60-70 s, respectively, and in 29 patients receiving three-phase scan, the delayed scan time of arterial, pancreatic and portal venous phases was 18 s, 40 s and 75 s, respectively, with a slice of 3-5 mm thick- ness, a pitch of 1-1.5, and a reconstruction interval of 2.5-4.8 mm. Results: Positive and negative predictive values of un- resectable tumors were 97.65% and 75.86%, respec- tively. The sensitivity and accuracy were 90.67% and 90. 72%, respectively. Positive predictive values of dual-phase and three-phase were 95.83% and 100%, respectively; negative predictive values were 75% and 77.78%, respectively. Conclusions: Spiral multi-phase CT is superior in re- vealing the involvement of peripancreatic vessels, the invasion of the neighboring organs, the size, shape and range of carcinoma, and the metastasis of liver and lymph node. The predictability of resection is obviously increased for patients with pancreatic car- cinoma.

Orientation-enhanced nonlinear optical properties and phase-conjugate reflective system of a novel Azobenzene doped polymer film

This paper reports that the nonlinear refractive index of a novel organic optical storage film doped azodiphenylamine polymer is measured by using the Z-scan technique. The nonlinear refractive index up to 3.7× 10^-6 cm^2/W induced by thermo-optical effect is obtained. It indicates that the sample has excellent optical non- linear properties. The physical mechanism of the great nonlinear optical effect is analysed and the optical conjugate characteristic is also discussed with degenerate four-wave-mixing. The phase conjugate wave diffracted from the formative refractive index grating in the sample is acquired and its equivalent reflectivity reaches about 22%. On this basis, the reflective wave phase-conjugated mirror system was designed, and the image aberration experienced in propagation in the storage experiment is corrected by using the system.

A Text Image Watermarking Algorithm Based on Image Enhancement

Digital watermarking technology is adequate for copyright protection and content authentication.There needs to be more research on the watermarking algorithm after printing and scanning.Aiming at the problem that existing anti-print scanning text image watermarking algorithms cannot take into account the invisibility and robustness of the watermark,an anti-print scanning watermarking algorithm suitable for text images is proposed.This algorithm first performs a series of image enhancement preprocessing operations on the printed scanned image to eliminate the interference of incorrect bit information on watermark embedding and then uses a combination of Discrete Wavelet Transform(DWT)-Singular Value Decomposition(SVD)to embed the watermark.Experiments show that the average Normalized Correlation(NC)of the watermark extracted by this algorithm against attacks such as Joint Photographic Experts Group(JPEG)compression,JPEG2000 compression,and print scanning is above 0.93.Especially,the average NC of the watermark extracted after print scanning attacks is greater than 0.964,and the average Bit Error Ratio(BER)is 5.15%.This indicates that this algorithm has strong resistance to various attacks and print scanning attacks and can better take into account the invisibility of the watermark.

Multi-phase helical CT in diagnosis of early hepatocellular carcinoma

OBJECTIVES: To analyze the characteristics of early hepatocellular carcinoma by using multi-phase helical CT and assess the value of this method. METHODS: Multi-phase helical CT findings were reviewed double-blindly by radiologists. RESULTS: Altogether 24 lesions were found in 21 patients. In plain CT, the lesions were seen as hypodense or isodense areas. After contrast enhancement, 87.5% of the lesions showed regular or irregular hyperdense enhancement, whereas 12.5% demonstrated tumor vessels in arterial phase, which became hypodensed or isodensed nodules in portal phase or the hypodensed in delayed phase. The prevalence of density changes showed a hypo-hyper-hypo and hypo-hypo pattern. CONCLUSIONS: Multi-phase helical CT could reflect the blood supply of early hepatocelluar carcinoma, and is also convenient for the differential diagnosis of hepatic cavernous angioma, metastatic tumor, hepatic nodulous hyperplasia, and hepatic inflammatory granuloma.

The Distribution and Morphology Alterations of Microfilaments and Microtubules in Mesophyll Cells and Root-Tip Cells of Wheat Seedlings under Enhanced Ultraviolet-B Radiation

The distribution and morphology alterations of microfilaments and microtubules in the mesophyll cells and root-tip cells of wheat seedlings, which had been radiated by enhanced ultraviolet-B (10.08 KJ·m-2·d-1), were examined through the confocal laser scanning microscope (Model FV1000, Olympus, Japan). Microtubule was labeled with an indirect immunofluorescence staining method, and microfilament was labeled with fluorescein isothiocyanate-phalloidin (FITC-Ph) as probes. The results indicated that microtubules in mesophyll cells, compared with the controls, would be depolymerized significantly, and dispersed randomly showing some spots or short rods in the cytoplasm, under the enhanced UV-B radiation condition. The microtubule bundles tended to be diffused, and the fluorescence intensity of that significantly decreased. The distribution pattern of microfilaments, which usually arranged parallelly in control cells, was broken up by enhanced UV-B radiation. We further investigated the distribution and morphology of microtubules in root-tip cells during every stage of cell division, and found that these aberrant phenomena of microtubules were often associated with abnormal cell division. Our findings suggested that the distribution, morphology and structure of cytoskeleton in mesophyll cells and root-tip cells of wheat seedlings would be affected by enhanced UV-B radiation, which might be related to abnormal cell division caused by enhanced UV-B radiation as an extracellular signal.

Different Doses of the Enhanced UV-B Radiation Effects on Wheat Somatic Cell Division

Being sessile, plants are continuously exposed to DNA-damaging agents presenting in the environment such as ultraviolet (UV). Sunlight acts as an energy source for photosynthetic plants;hence, avoidance of UV radiations (namely, UV-A, 315 - 400 nm;UV-B, 280 - 315 nm;and UV-C, 1 group: 4.05 kJ&#8226m-2&#8226d-1, B2 group: 10.08 kJ&#8226m-2&#8226d-1, B3 group: 7.05 kJ&#8226m-2&#8226d-1, B4 group: 23.02 kJ&#8226m-2&#8226d-1) treatment wheat, then, explored on the growth of wheat root and wheat root tip cell of chromosome aberration effect. In wheat, root-tip cells were observed with confocal laser scanning microscopy (CLSM), the results showed that low doses of B1 group (4.05 kJ&#8226m-2&#8226d-1) promoted the growth of wheat root and cell mitosis frequency. But high dose of B2 group (10.08 kJ&#8226m-2&#8226d-1), B3 group (17.05 kJ&#8226m-2&#8226d-1), B4 group (23.02 kJ&#8226m-2&#8226d-1) inhibited the growth of wheat root tip, and made crooked growth of wheat root, and inhibited the wheat root tip cell mitotic frequency and processed that induce root tip cells of wheat produce all kinds of aberration of chromosome in the interphase containing “multiple nucleoli nuclei”, “incomplete nuclei”, “long round nuclei”, “bean sprouts nucleus”. In mitosis M period contains “dissociative chromosome”, “chromosome bridge”, “adhesion chromosome”, “multi-bundle divide”, “nuclear anomalies”. After, high doses of enhanced UV-B radiation treatment, most of the cell cycle anomaly concentrated in mitosis interphase. In mitosis M period, with UV-B radiation dose enhanced chromosome aberration rate was on the rise and the aberration types also increasing.

CT增强扫描灰度直方图纹理分析技术对肺癌患者术前恶性程度评估及对预后的预测价值

目的探究CT增强扫描灰度直方图纹理分析技术对肺癌患者术前恶性程度评估及对预后的预测价值。方法选择2018年5月至2022年9月在我院就诊的且经术后病理证实的肺癌患者580例作为研究对象。依据术后病理分期,将研究对象分为高分化组(183例)、中分化组(195例)、低分化组(202例)。根据预后情况,将其分为预后良好组(356例)和预后不良组(224例)。由2名医师提取患者CT增强扫描灰度直方图纹理参数。受试者工作特征(receiver operating characteristic,ROC)曲线分析特征参数对肺癌患者术前恶性程度的诊断效能及预后的预测价值。多因素Logistic回归分析预后不良的重要影响因素并构建人工神经网络模型。Pearson分析检验参数间的相关性。结果均值、10%分位、50%分位等参数在高、中、低分化三组中有显著差异。三个参数对评估肺癌患者恶性程度均具有一定的诊断效能,且三者联合诊断效能最佳。均值、10%分位、50%分位是预后不良的保护因素,三者联合预测肺癌患者的曲线AUC值大于各指标单独预测的AUC值。ROC曲线和累积增益图表明该模型预测能力良好。纹理特征参数中,69.44%的参数具有相关性。结论CT增强扫描灰度直方图纹理参数在一定程度上反应肺癌患者术前恶性程度信息,给术前预测以及预后提供了重要方法。

CT增强检查中碘对比剂外渗病人皮肤损伤风险预测模型的构建

目的:探讨CT增强检查中碘对比剂外渗病人皮肤损伤发生风险的影响因素,构建并验证风险预测模型。方法:采用便利抽样法抽取2023年1月—7月在广西医科大学第一附属医院放射科接受CT增强检查的碘对比剂外渗病人286例作为研究对象,自制CT增强检查碘对比剂外渗病人皮肤损伤风险调查问卷对病人进行调查,采用单因素分析、Logistic回归分析筛选CT增强检查中碘对比剂外渗病人皮肤损伤发生风险的影响因素,构建风险预测模型,绘制列线图,运用受试者工作特征(ROC)曲线、校准曲线评价模型。结果:CT增强检查中碘对比剂外渗病人皮肤损伤发生率为18.5%。Logistic回归分析结果显示,过敏史、碘对比剂黏稠度、碘对比剂注射速度是CT增强检查中碘对比剂外渗病人皮肤损伤的影响因素(P<0.05),基于上述结果构建的预测模型建模组ROC曲线下面积为0.842[95%CI(0.770,0.915)],约登指数为0.667,最优截断值灵敏度为0.893,特异度为0.774;验证组ROC曲线下面积为0.924[95%CI(0.872,0.975)],约登指数为0.793,最优截断值灵敏度为0.891,特异度为0.902。Hosmer-Lemeshow检验结果显示,χ2=9.566,P=0.221 5,校准曲线与参考线相接近。结论:CT增强检查中碘对比剂外渗病人皮肤损伤风险预测模型预测效能良好,可为医务人员制订个性化的预防措施提供参考。

小肝癌的MRI特征及诊断价值分析

目的探讨小肝癌(SHCC)的增强磁共振成像(MRI)特征并分析其诊断价值。方法选取2018年7月~2023年5月在本院收治的疑似SHCC患者63例作为研究对象,所有患者均行增强MRI与MRI平扫检查,以手术病理结果或病理活检为“金标准”,采用Kappa一致性检验,比较两种检查方式对SHCC的诊断价值,采用单因素和多因素Logistic回归分析确定SHCC的因素。结果63例疑似SHCC患者中共46例(73.02%)SHCC阳性,17例阴性。MRI平扫的确诊率78.26%(36/46)低于增强MRI确诊率93.48%(43/46)(P<0.05)。MRI平扫时T1WI序列以低信号居多,T2WI序列以高信号和略高信号为主;增强MRI扫描时,动脉期明显强化,门静脉期和延迟期强化下降,信号降低。MRI平扫诊断SHCC的灵敏度、特异度、准确率、阳性预测值、阴性预测值和Kappa系数值分别为78.26%、82.35%、79.37%、92.31%、58.33%和0.536,增强MRI诊断SHCC的灵敏度、特异度、准确率、阳性预测值、阴性预测值和Kappa系数值分别为93.48%、94.11%、93.65%、97.73%、84.21%和0.845,其中增强MRI诊断的灵敏度和准确率均高于MRI平扫(P均<0.05)。Logistic回归分析,结果显示MRI平扫T1WI序列低信号、T2WI序列高信号或略高信号、MRI增强扫描动脉期明显强化、门静脉期信号降低均为诊断SHCC阳性的独立危险因素(P<0.05)。结论较于MRI平扫检查,增强MRI检查对SHCC的诊断价值更高,具良好的应用价值。

磁共振成像增强扫描及弥散加权成像预测小肝癌微血管侵犯的价值

目的探讨磁共振成像(MRI)增强扫描及弥散加权成像(DWI)预测小肝癌患者微血管侵犯(MVI)的临床价值。方法选取成都医学院第一附属医院2021年5月至2023年5月收治的90例小肝癌患者(术前1周内均接受MRI增强扫描)为研究对象,根据术后病理检查结果分为MVI阳性组(n=25)和MVI阴性组(n=65),比较两组一般资料、增强扫描特征及DWI参数,采用多因素Logistic回归分析确定MVI的影响因素。基于回归分析结果建立评分模型,绘制评分模型预测小肝癌患者MVI的受试者工作特征(ROC)曲线。结果90例小肝癌患者中MVI阳性率为27.78%(25/90)。MVI阳性组低分化、动脉期瘤周强化、肿瘤边缘不光滑、肝胆期瘤周低信号的占比高于MVI阴性组,而D值、ADC值低于MVI阴性组(P<0.05)。Logistic回归分析显示,动脉期瘤周强化、肿瘤边缘、瘤周低信号、D值、ADC值是小肝癌MVI的影响因素(P<0.05)。根据回归分析建立的评分模型预测小肝癌患者MVI的ROC曲线下面积为0.898,最佳截断值为5分,其敏感度与特异度分别为0.920、0.877。结论MRI增强扫描联合DWI可有效预测小肝癌患者的MVI风险。

双源CT双动脉期增强扫描对肝动脉-门静脉瘘的评估价值及风险因素分析

目的:探讨双源CT双动脉期增强扫描模式对肝动脉-门静脉瘘(HAPVF)的评估价值及风险因素分析。方法:选取HAPVF和非HAPVF患者各60例,分别为HAPVF组和非HAPVF组,行双源CT双动脉期增强扫描,比较2组临床指标及CT征象差异。以DSA为金标准,对比动脉早期、动脉晚期和双动脉期对HAPVF的诊断敏感度、特异度,以及对HAPVF分型的诊断准确率。应用logistic回归分析探讨HAPVF的危险因素,采用ROC曲线评估危险因素预测HAPVF的价值。结果:双动脉期诊断HAPVF的敏感度、特异度、阳性预测值、阴性预测值及分型准确率均明显高于单独2期(均P<0.05)。2组肝癌大小、包膜类型、门静脉癌栓比较,差异均有统计学意义(均P<0.05)。logistic回归分析显示,肝癌大小、包膜类型、门静脉癌栓均是HAPVF的独立危险因素。ROC曲线表明,单因素预测HAPVF效果最好的是包膜类型,其次是门静脉癌栓,再次是肝癌大小。综合多因素联合预测分析显示,肝癌大小+包膜类型+门静脉癌栓预测效果最好。结论:双源CT双动脉期增强扫描模式对HAPVF的诊断敏感度、特异度较高,且在HAPVF分型中具有较好的诊断效果。HAPVF的临床及影像学征象具有一定特点,其中肝癌大小、包膜类型、门静脉癌栓均是HAPVF的独立危险因素,三者联合预测效果最好,能为临床及时诊治提供可靠依据。

太赫兹时域光谱成像增强算法

低分辨率是扫描太赫兹时域光谱(THz-TDS)系统图像的一个重要缺点.本文提出了一种针对太赫兹时域光谱图像的超分辨率增强算法,该算法结合了多层感知机(MLP)和超分辨率卷积神经网络(SRCNN),创建了一个复合网络.本文算法针对太赫兹光谱图像的特点,通过引入新的目标函数,避免了传统机器学习算法需要采集或模拟生成大量训练集的弊端,实现了训练图像即目标图像的单幅光谱图像增强.为了实现这一目标,本文算法的基本原理是,让试件产生一个刚体位移,利用THz-TDS系统采集位移前后两幅三维(1个时间维,2个空间维)光谱图像作为输入数据.机器学习网络包括两部分:首先,利用一个MLP网络实现三维光谱图像到二维光强图像的转化;其次,采用传统针对二维图像的SRCNN网络获取一幅高分辨率图像,对位移前后图像处理后计算得到新的高分辨率图像的位移场,并将位移场方差作为目标函数,再通过机器学习算法,优化网络中的成像参数,实现太赫兹光谱图像的分辨率增强.典型验证性实验最终得到的峰值信噪比为42.65 dB,结构相似度为0.816,均比其他现有方法高,表明本文算法能获得良好的图像增强.