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Dispersible quaternary Cu1.0Ga x In2−x S3.5 and Cu1.0In x Tl2−x S3.5 nanocrystals were successfully prepared by a toluene-thermal and a hot-injection approach and characterized using UV−vis spectroscopy, X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). UV−vis absorption spectra of Cu1.0Ga x In2−x S3.5 nanocrystals revealed that the band gaps of alloyed nanocrystals can be precisely adjusted in the range of 1.43 to 2.42 eV by increasing the indium content. From XRD analysis, the lattice parameters of Cu1.0Ga x In2−x S3.5 nanocrystals decreased linearly with an increase in the Ga/(Ga + In) ratio in accordance with Vegard’s law, which confirmed that alloyed nanocrystals have a homogeneous structure. Alloyed Cu1.0Ga x In2−x S3.5 and Cu1.0In x Tl2−x S3.5 nanocrystals have a narrow size distribution according to TEM analysis results. Moreover, it was found that oleylamine played an important role in the formation quaternary homogeneous Cu1.0Ga x In2−x S3.5 and Cu1.0In x Tl2−x S3.5 nanocrystals due to eliminating the reactivity difference of copper, gallium, and indium as well as thallium precursors.

Purpose To propose and validate a respiratory motion resolved, self-gated (SG) 4D-MRI technique to assess patient-specific breathing motion of abdominal organs for radiation treatment planning. Methods The proposed 4D-MRI technique was based on the balanced steady-state free-precession (bSSFP) technique and 3D k-space encoding. A novel ROtating Cartesian K-space (ROCK) reordering method was designed that incorporates repeatedly sampled k-space centerline as the SG motion surrogate and allows for retrospective k-space data binning into different respiratory positions based on the amplitude of the surrogate. The multiple respiratory-resolved 3D k-space data were subsequently reconstructed using a joint parallel imaging and compressed sensing method with spatial and temporal regularization. The proposed 4D-MRI technique was validated using a custom-made dynamic motion phantom and was tested in 6 healthy volunteers, in whom quantitative diaphragm and kidney motion measurements based on 4D-MRI images were compared with those based on 2D-CINE images. Results The 5-minute 4D-MRI scan offers high-quality volumetric images in 1.2×1.2×1.6mm3 and 8 respiratory positions, with good soft-tissue contrast. In phantom experiments with triangular motion waveform, the motion amplitude measurements based on 4D-MRI were 11.89% smaller than the ground truth, whereas a −12.5% difference was expected due to data binning effects. In healthy volunteers, the difference between the measurements based on 4D-MRI and the ones based on 2D-CINE were 6.2±4.5% for the diaphragm, 8.2±4.9% and 8.9±5.1% for the right and left kidney. Conclusion The proposed 4D-MRI technique could provide high resolution, high quality, respiratory motion resolved 4D images with good soft-tissue contrast and are free of the “stitching” artifacts usually seen on 4D-CT and 4D-MRI based on resorting 2D-CINE. It could be used to visualize and quantify abdominal organ motion for MRI-based radiation treatment planning.