High dielectric and low loss capacitor thin films of Sr 2 Nb 2 O 7 (SN), Sr 2 Ta 2 O 7 (ST), and their solid solution Sr 2 (Nb x , Ta 12x ) 2 O 7 (SNT) were investigated using the sol-gel technique. The SN film grows with the (0n0) orientation in the case of heating at over 700 ± C. Heat treatment at a lower temperature results in the polycrystal ST-type structure. The SNT at x , 50% also resulted in the ST type. The dielectric constant for the SN film was 45, within 10% variation at 60.5 MV͞cm. Dielectric loss (tan d) was 0.3-0.5%. The small variation in dielectric constant and the paraelectricity with low loss are suitable for capacitor applications.

A thin film of Pb(Mg1/3Nb2/3)O3 was prepared by the sol-gel method using metal alkoxides. The X-ray analysis indicated that the perovskite phase was formed by sintering at over 600°C. The orientation and the crystallization rate were greatly influenced by the type of substrate and sintering conditions.

Surface oxidation of an iridium film and the possibility of epitaxial growth of PZT spin-coated film on sputtered iridium were investigated. The free surface on the iridium film oxidized over 400°C with random orientation. Nevertheless, both the PZT(111)/Ir(111) and PZT(100)/Ir(100) interfaces were realized using the highly oriented iridium layer. These results suggest that PZT nucleation has priority over iridium surface oxidation.

A major difficulty in conformal lung cancer radiotherapy is respiratory organ motion, which may cause clinically significant targeting errors. Respiratorygated radiotherapy allows for more precise delivery of prescribed radiation dose to the tumor, while minimizing normal tissue complications. Gating based on external surrogates is limited by its lack of accuracy, while gating based on implanted fiducial markers is limited primarily by the risk of pneumothorax due to marker implantation. Techniques for fluoroscopic gating without implanted fiducial markers (markerless gating) have been developed. These techniques usually require a training fluoroscopic image dataset with marked tumor positions in the images, which limits their clinical implementation. To remove this requirement, this study presents a markerless fluoroscopic gating algorithm based on 4DCT templates. To generate gating signals, we explored the application of three similarity measures or scores between fluoroscopic images and the reference 4DCT template: un-normalized cross-correlation (CC), normalized cross-correlation (NCC) and normalized mutual information (NMI), as well as average intensity (AI) of the region of interest (ROI) in the fluoroscopic images. Performance was evaluated using fluoroscopic and 4DCT data from three lung cancer patients. On average, gating based on CC achieves the highest treatment accuracy given the same efficiency, with a high target coverage (average between 91.9% and 98.6%) for a wide range of nominal duty cycles (20-50%). AI works well for two patients out of three, but failed for the third patient due to interference from the heart. Gating based on NCC and NMI usually failed below 50% nominal duty cycle. Based on this preliminary study with three patients, we found that the proposed CC-based gating algorithm can generate accurate and robust gating signals when using 4DCT reference template. However, this observation is based on results obtained from a very limited dataset, and further investigation on a larger patient population has to be done before its clinical implementation.

Highly oriented Pb(Mg1/3Nb2/3)O3 films prepared by the sol-gel method were studied with high resolution electron microscopy. The lattice image reveals epitaxial growth at the interface between the perovskite crystal and MgO single crystal substrate. A short-range ordered structure is ascertained to exist in the perovskite grains in the film.