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 exis...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.展开更多
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 com...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.展开更多
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 pathological...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.展开更多
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 b...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.展开更多
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 ...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.展开更多
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-sm...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.展开更多
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 ad...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.展开更多
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...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.展开更多
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 ...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.展开更多
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...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.展开更多
基金sponsored by the National Natural Science Foundation of China under Grants 61972207,U1836208,U1836110,61672290,and the Project was through the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institution.
文摘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.
基金supported by the Key Research and Development Program of Hubei Province(No.2021BAA214)the Open Fund of Sanya Science and Education Innovation Park of Wuhan University of Technology(Nos.2021KF0022,2021KF0013,and 2020KF0026)+2 种基金Independent Innovation Projects of the Hubei Longzhong Laboratory(Nos.2022ZZ-34 and 2022ZZ-35)the National Science Fund for Distinguished Young Scholars of Hubei Province(No.201CFA067)the National innovation and entrepreneurship training program for college students(Nos.202310497010 and S202310497026).
文摘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.
基金This study was supported by the grant from the Program of Social Development Fund of the Jiangsu Provincial Science and Technology Commission (BS97046).
文摘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.
文摘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.
文摘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.
基金Health and Family Planning Commission of Zigong(No.2017wZCS09)
文摘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.
文摘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.
文摘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.
文摘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.
基金supported by Jilin Changbaishan Volcano National Observation and Research Station(Project No.NORSCBS20-04)National Natural Science Foundation of China(42174023)the Fundamental Research Fund for the Central Universities of Central South University(No.506021722).
文摘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.