Synthesis, characterizations and ions implantation into Er doped Aluminum Nitride thin films

Er doped Aluminum Nitride (AlN) thin films were prepared using magnetron sputtering technique in a Nitrogen (N) atmosphere on a Silicon substrate. The samples were annealed at a temperature of 900 0C. The fabricated specimen was irradiated with proton dose of 1×1014 ions/cm2 with incident energy of 335 keV using ions accelerators. The relative concentration, thickness and structural properties of the thin films were determined by Rutherford Backscattering Spectroscopy (RBS) and X-Ray Diffraction (XRD) respectively. Before and after the irradiation the energy levels for their types of bonding existing in our specimens were traced with Fourier Transform Infrared Spectroscopy (FTIR).

Dual-Energy Computed Tomography Proton-Dose Calculation with Scripting and Modified Hounsfield Units

Purpose To describe an implementation of dual-energy computed tomography (DECT) for calculation of proton stopping-power ratios (SPRs) in a commercial treatment-planning system. The process for validation and the workflow for safe deployment of DECT is described, using single-energy computed tomography (SECT) as a safety check for DECT dose calculation. Materials and Methods The DECT images were acquired at 80 kVp and 140 kVp and were processed with computed tomography scanner software to derive the electron density and effective atomic number images. Reference SPRs of tissue-equivalent plugs from Gammex (Middleton, Wisconsin) and CIRS (Computerized Imaging Reference Systems, Norfolk, Virginia) electron density phantoms were used for validation and comparison of SECT versus DECT calculated through the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, California) application programming interface scripting tool. An in-house software was also used to create DECT SPR computed tomography images for comparison with the script output. In the workflow, using the Eclipse system application programming interface script, clinical plans were optimized with the SECT image set and then forward-calculated with the DECT SPR for the final dose distribution. In a second workflow, the plans were optimized using DECT SPR with reduced range-uncertainty margins. Results For the Gammex phantom, the root mean square error in SPR was 1.08% for DECT versus 2.29% for SECT for 10 tissue-surrogates, excluding the lung. For the CIRS Phantom, the corresponding results were 0.74% and 2.27%. When evaluating the head and neck plan, DECT optimization with 2% range-uncertainty margins achieved a small reduction in organ-at-risk doses compared with that of SECT plans with 3.5% range-uncertainty margins. For the liver case, DECT was used to identify and correct the lipiodol SPR in the SECT plan. Conclusion It is feasible to use DECT for proton-dose calculation in a commercial treatment planning system in a safe manner. The range margins can be reduced to 2% in some sites, including the head and neck.