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SBRT-VMAT planning is created manually, resulting in inconsistent plan quality and a time-consuming process. To improve efficiency and quality of planning, we evaluated the feasibility of AI-based automatic SBRT-VMAT planning for lung cancer. We developed the AI-based dose distribution prediction model (installed in RatoGuide prototype, AiRato. Inc) which was trained using manually optimized plans for 120 cases of stage I lung cancer (peripheral cases (55 Gy / 4 Fr) and central cases (50 Gy / 8 Fr), 54 cases each, both with PTV D95% prescription). Test data consisted of 6 treatment plans each of central and peripheral lung cancer. These plans were manually optimized and used for treatment, previously. The automatic plan was created following procedures: (i) predicting dose distribution based on target and OAR contours and CT images using RatoGuide, (ii) converting the predicted dose distribution into contours and importing them into the treatment planning system, and (iii) generating mimicked dose distributions using predefined optimization parameters and constraints. We measured the time to create plans and compared the DVH metrics between automatic and manual plans. Two expert radiation oncologists evaluated automatic and manual plans based on both visual inspection and DVH metrics in following aspects: (a) clinically acceptable or not and (b) preference for automatic or manual plan in clinical practice. DVH metrics and creation time for the 2 plans are shown in Table 1. No significant differences were observed in all DVH metrics between automatic and manual plans for peripheral cases, whereas significant differences were observed in some metrics of lungs for central cases. Radiation oncologists reviewed all automatic plans as clinically acceptable. The percentages of cases which 2 radiation oncologists preferred automatic plans to manual plans were 66.7% and 33.3%, respectively, for peripheral cases, and 91.7% and 50.0%, respectively, for central cases. Our newly developed method of automatic SBRT-VMAT treatment planning of lung cancer was fast and comparable to manually optimized plans in dose distribution. It can be feasible for clinical use, but we will focus on improving the accuracy of the prediction model and its workflow. [ABSTRACT FROM AUTHOR]

To evaluate properties of an initial growth layer for CoCrPt-Si[O.sub.2] perpendicular recording media, an initial growth layer has been investigated by micromagnetic simulation with initial layer model. It was found that with the initial growth layer, the in-plane magnetization [M.sub.in] shows a small jump at 0-field, leading to an additional peak around 0-field in 4 [pi] d[M.sub.in]/dH curve. The (additional) peak height increases with the increase in inter- lower subgrain exchange areal energy densities [w.sub.i] and thickness of the initial layer and also decreases in the anisotropy energy for the initial layer. Considering the change of the average anisotropy energy as a function of the thickness of recording layer, [w.sub.i] for a CoCrPt-Si[O.sub.2] perpendicular recording medium with Ru/Ru-Si[O.sub.2] intermediate layer is in the range from 0.5 to 0.6 erg/[cm.sup.2] and roughly 30% smaller than those with a Ru intermediate layer. Index Terms--CoCrPt-Si[O.sub.2] perpendicular recording media, differentiation of the in-plane magnetization, initial layer model, micromagnetic simulation, Ru/Ru-Si[O.sub.2] intermediate layer.

A Ru-SiO2 intermediate layer is introduced between Ru and recording layers to reduce the intermediate layer thickness of CoCrPt-SiO2 perpendicular recording media. A structural analysis revealed that the Ru-SiO2 intermediate layer enhanced the oxide segregation in the initial growth region of the recording layer.

CoB/Pd multilaycr films with a PtB/Pd/MgO intermediate layer were deposited on a soft-magnetic underlayer or on seeded substrates. A TEM analysis revealed that the multilayer films have a well-separated columnar structure just above an MgO layer. This structure may be initiated by the difference in the wetting nature of nonmetallic MgO and metallic Pd, and may be enhanced by the PtB layer. These boundaries were found to act in reducing the exchange coupling, resulting in an improvement in recording performance. Index Terms--CoB/Pd multilayer film, perpendicular magnetic recording, PtB/Pd/MgO intermediate layer.

The thermal stability and recording characteristics of a hybrid medium consisting of a granular CoCr-based alloy layer and an exchange-coupled Tb(Fe)Co layer are examined. High thermal stability is observed due to the increase in squareness and the decline in the nucleation field with the addition of a thin Tb(Fe)Co layer to a CoCrPt(B) medium.

A Ru–SiO2 intermediate layer was introduced between the Ru and recording layers to reduce the intermediate layer thickness of CoCrPt–SiO2 perpendicular recording media. A structural analysis revealed that the Ru–SiO2 intermediate layer enhanced the oxide segregation in the initial growth region of the recording layer. A micromagnetic simulation and magnetic property measurements indicated that the Ru–SiO2 intermediate layer reduced the intergranular exchange coupling in the initial growth region of the recording layer without magnetic anisotropy degradation. We reduced the intermediate layer thickness down to 9.1 nm by using the Ru–SiO2 intermediate layer while maintaining the signal-to-noise ratio. [ABSTRACT FROM AUTHOR]