PubMed · 14461482
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
F LAFAY. 1961. [Electron microscopy].. https://pubmed.ncbi.nlm.nih.gov/14461482/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
PURPOSE: In breast radiotherapy, delivery of manually-calculated electron boosts limits retrospective dose-response analyses as dose distribution is unavailable. This work evaluates the feasibility of reconstructing dose distributions from manually planned electron boosts in breast-conserving radiotherapy. METHODS: Only 72 out of 198 breast cancer patients had complete stored dose distributions from sequential electron boosts in the REQUITE study. Arbitrary data from 70/72 patients were used to develop and validate dose reconstruction method. Twenty patients were used to determine optimal parameters for Monte-Carlo-based (MC) electron dose reconstruction on RayStation (v.11B-R), considering CT-calibration curve, MC-history number, andcalculation grid resolution. Remaining 50 patients were used to quantify dose reconstruction accuracy. The similarity between reconstructed and stored dose was evaluated using 3D-gamma index and dosimetric parameters extracted from breast and tumour bed contours. Dose difference location was evaluated using dose-location histogram. RESULTS: Calculation grid resolution significantly impacted electron dose distribution (p < 0.01), where the finest grid (0.15 cm) showed highest similarity to stored doses. CT-calibration curve and MC-history number had a negligible influence on dose reconstruction. Dosimetric difference between reconstructed and stored doses was < 1 Gy for breast and tumour bed. Reconstructed dose was achieved > 90% gamma passing rate in the validation set. However, around 2.5 Gy dose differences were observed at the skin and tissue interface regions. CONCLUSIONS: Retrospective electron boost dose reconstruction is feasible with acceptable accuracy, and could increase data completeness in large cohort studies. Caution is advised when assessing dose near tissue interface and further validation is needed outside the REQUITE dataset.
Explore the source record for details and available documents.
In this work, we report the synthesis and characterization of a series of hexagonal nanostructured platinum/tin/tellurium inorganic/surfactant composites. The composites are formed through solution-phase self-assembly of SnTe4(4-) Zintl clusters, which are cross-linked with platinum salts in the presence of a cetyltriethylammonium cationic structure directing agent. The cross-linking utilizes various combinations of Pt(II) and Pt(IV) salts. Low-angle X-ray diffraction indicates that all composites form hexagonal honeycomb (p6mm) structures. A combination of elemental analysis and XANES is used to describe the composition and oxidation states within the composites. We find that the extent of tin telluride self-oligomerization and the platinum:tin telluride ratio both vary, indicating that the composite compensates for different platinum oxidation states by tuning the inorganic composition. Near-IR/visible reflectance spectroscopy and UPS can be used to measure both band gaps and absolute band energies. The results show that while moving from all Pt(II) to all Pt(IV) increases the band gap from 0.6 to 0.8 eV, it increases the absolute valence and conduction band energies by almost a full electronvolt. AC impedance spectroscopy further reveals that the conductivities of the materials can be tuned from 0.009 to 0.003 Omega(-1).cm(-1). Additionally, a capacitance arising from the periodic nanoscale organic domains was observed. The conductivity and band gap were used to estimate carrier mobilities in these composites. Chemical tuning of the electronic properties within related nanostructured composites is a useful tool for designing applications that exploit the properties of nanostructured semiconductors.