Estimating the performance of lithium beam measurements of current density and electron density in an H-mode pedestal.

The lithium beam is an effective diagnostic tool for investigation of stability and particle transport in the pedestal. It was used successfully to measure edge current density on DIII-D, achieving qualitative agreement with neoclassical models. Electron density profiles were also measured. Proposed upgrades will continue these measurements with higher reliability as well as explore edge current measurements using spectroscopy. The optics will be redesigned to optimize throughput and aperture broadening and to replace the photomultiplier tubes with avalanche photodiodes. The new system will yield detailed measurements of the pedestal, complementing existing diagnostics for investigating pedestal stability, edge localized mode cycle, and particle transport through the pedestal.

[Application of three-dimensional ultrasound for diagnosis of congenital preauricular fistula].

Objective: To explore the application of real-time three-dimensional ultrasound in locating the course, the brand and the blind end of internal opening of congenital preauricular fistula. Methods: Congenital preauricular fistula patients from Changhai Hospital were studied. All the cases were evaluated using two-dimensional and three-dimensional ultrasound before surgeries. The surgery findings were utilized as the gold standard. The imaging features of 3D ultrasound were described to determine the accuracy of the blind end location, the course of the main fistula tract and the branch tracts. The diagnosis was compared with the surgery findings. Results: In 89 cases, among which there were 21 branch fistulae. There were 68 bend fistulae without branch. The diagnostic accuracy of both two-dimensional ultrasound and three-dimensional ultrasound was 100%. The accuracy in locating the blind end of internal opening, the course of the branch tracts with 3D ultrasound was 92.1%(82/89), 85.7%(18/21) , compared to 80.9%(72/89), 57.1%(12/21) with 2D ultrasound. It was obvious that 3D ultrasound had more advantages. These differences were statistically significant (χ(2)=4.8, P<0.05; χ(2)=4.2, P<0.05). Conclusions: Compared with 2D ultrasound, 3D ultrasound can accurately locate the blind end of internal opening, the course, and the branch of preauricular fistula, clearly display the morphology and the spatial structure of preauricular fistulaand its surroundings. It has high clinical application value in preoperative imaging examination.

Evaluation of optimal match between gantry rotation time and cardiac cycle on multislice spiral CT coronary angiography imaging.

OBJECTIVE: To evaluate the relationship between gantry rotation time, heart rate and image quality during multislice spiral CT coronary angiography (MSCTCA). PATIENTS AND METHODS: Data of 83 patients who underwent MSCTCA were reviewed. Based on the ratio between cardiac cycle and gantry rotation time, the patients were divided into two groups. Patients whose heart rates fell in the resonance frequency (the cardiac cycle / gantry rotational time ratio of 1.5, 2 or 2.5) ± 2 bpm were classified as synchronous (25 cases), while the remaining 58 patients (included a subgroup of 34 cases in whom heart rates were the same as in synchronous group but who had a different gantry rotation time). comprised the asynchronous group. Image qualities were compared between both groups. RESULTS: In the synchronous group, most (199/287; 69.33%) images were poor. When gantry rotation time was changed in the subgroup of the asynchronous group, the majority (423/442 or 95.70%) of images improved. There was a significant difference (p < 0.001) in the image quality among these patients. In 58 patients from asynchronous group, 757 segments of coronary arteries were evaluated, and 716 segments were of best quality (716/757; 94.58%). CONCLUSIONS: When heart rate and gantry rotation time correlate and synchronous, the so-called frequency harmonics, coronary artery image quality is poor. However, by changing gantry rotation time to avoid the harmonic helps to improve the image quality on MSCTCA. Based on the patient's heart rate, appropriate gantry rotation time can be selected in order to avoid resonance and obtain high quality images.