Diagnostic imaging is carried out in patients with esophageal carcinoma in order to decide on the therapeutical procedure, to control therapy, to document complications and to assess concomitant diseases. Chest X-rays...Diagnostic imaging is carried out in patients with esophageal carcinoma in order to decide on the therapeutical procedure, to control therapy, to document complications and to assess concomitant diseases. Chest X-rays and esophagograms give a 2-dimensional view of the X-ray absorption in 3-dimensional examination volumes, the diagnostic accuracy thus being limited by overshadowing. Because of the robust examination technique, the broad availability and the low costs chest X-rays are usually used for short-term controls under therapy and follow-up. Esophagography is carried out in order to asses the exact location and length of a known esophageal carcinoma prior to therapy and in order to assess peristaltic disturbances and ?stulas. CT and MRI provide tomographic images with a spatial resolution of up to 1 mm3 allowing the reconstruction of high-resolution images not only in the transversal but also in any other plain. The diagnostic accuracy of esophagography is comparatively high in T1–T3 stages (80%–90%). T1 and T2 tumors cannot be diagnosed by CT and MRI, because both methods do not visualize the mucosa (unlike esophagography and endoscopy) and the esophageal wall layers (unlike EUS). In?ltration depth tends to be overestimated in T1 and T2 carcinomas and to be underestimated in T3 and T4 cancers. CT and MRI cannot detect metastases in normally sized lymph nodes and cannot accurately di?erentiate between benign and malignant lymphadenopathy in enlarged nodes with a reported sensitivities and speci?ties of 60% and 74%, respectively. However, further prospective studies using up to date CT and MR technology are needed to assess the present diagnostic situation. CT and MRI do not only visualize the mediastinum, but also the lungs, the pleura and the skeleton as well as the neck and the abdomen thus providing a comprehensive overview of the TNM stage in 3 body regions.展开更多
Bubble core fields as well bubble shape modification due to the nondepleted electrons inside the bubble is investigated theoretically. It is found that the Mope of transverse fields are reduced significantly, however,...Bubble core fields as well bubble shape modification due to the nondepleted electrons inside the bubble is investigated theoretically. It is found that the Mope of transverse fields are reduced significantly, however, the slope of longitudinal electric field, which plays a key role on electrons acceleration in bubble, changes little. Moreover a modified longitudinal compressed bubble shape leads to a shorter dephasing distance which makes the electrons acceleration energy reduced to some extent. As a comparison we perform particle-in-cell simulations whose results are consistent with that of our theoretical consideration.展开更多
文摘Diagnostic imaging is carried out in patients with esophageal carcinoma in order to decide on the therapeutical procedure, to control therapy, to document complications and to assess concomitant diseases. Chest X-rays and esophagograms give a 2-dimensional view of the X-ray absorption in 3-dimensional examination volumes, the diagnostic accuracy thus being limited by overshadowing. Because of the robust examination technique, the broad availability and the low costs chest X-rays are usually used for short-term controls under therapy and follow-up. Esophagography is carried out in order to asses the exact location and length of a known esophageal carcinoma prior to therapy and in order to assess peristaltic disturbances and ?stulas. CT and MRI provide tomographic images with a spatial resolution of up to 1 mm3 allowing the reconstruction of high-resolution images not only in the transversal but also in any other plain. The diagnostic accuracy of esophagography is comparatively high in T1–T3 stages (80%–90%). T1 and T2 tumors cannot be diagnosed by CT and MRI, because both methods do not visualize the mucosa (unlike esophagography and endoscopy) and the esophageal wall layers (unlike EUS). In?ltration depth tends to be overestimated in T1 and T2 carcinomas and to be underestimated in T3 and T4 cancers. CT and MRI cannot detect metastases in normally sized lymph nodes and cannot accurately di?erentiate between benign and malignant lymphadenopathy in enlarged nodes with a reported sensitivities and speci?ties of 60% and 74%, respectively. However, further prospective studies using up to date CT and MR technology are needed to assess the present diagnostic situation. CT and MRI do not only visualize the mediastinum, but also the lungs, the pleura and the skeleton as well as the neck and the abdomen thus providing a comprehensive overview of the TNM stage in 3 body regions.
基金Supported by the National Natural Science Foundation of China(NNSFC)under Grant Nos.11175023,10834008the Fundamental Research Funds for the Central Universities(FRFCU)
文摘Bubble core fields as well bubble shape modification due to the nondepleted electrons inside the bubble is investigated theoretically. It is found that the Mope of transverse fields are reduced significantly, however, the slope of longitudinal electric field, which plays a key role on electrons acceleration in bubble, changes little. Moreover a modified longitudinal compressed bubble shape leads to a shorter dephasing distance which makes the electrons acceleration energy reduced to some extent. As a comparison we perform particle-in-cell simulations whose results are consistent with that of our theoretical consideration.
