• Two methods were developed to create realistic CT phantoms of individual patients from radiopaque printed paper sheets. • Analysis of five tube current and four reconstruction settings on two radiopaque 3D printed patient phantoms yielded non-inferior SNR and CNR and up to 83.7% lower dose with iterative reconstruction in comparison with filtered back projection. • Radiopaque 3D printed phantoms can simulate patients and allow systematic analysis of CT dose and image quality parameters.

We report long-lived, highly spatially localized plasmon states on the surface of nanoporous gold nanoparticles—nanosponges—with high excitation efficiency. It is well known that disorder on the nanometer scale, particularly in two-dimensional systems, can lead to plasmon localization and large field enhancements, which can, in turn, be used to enhance nonlinear optical effects and to study and exploit quantum optical processes. Here, we introduce promising, three-dimensional model systems for light capture and plasmon localization as gold nanosponges that are formed by the dewetting of gold/silver bilayers and dealloying. We study light-induced electron emission from single nanosponges, a nonlinear process with exponents of n≈5...7, using ultrashort laser pulse excitation to achieve femtosecond time resolution. The long-lived electron emission process proves, in combination with optical extinction measurements and finite-difference time-domain calculations, the existence of localized modes with lifetimes of more than 20 fs. These electrons couple efficiently to the dipole antenna mode of each individual nanosponge, which in turn couples to the far-field. Thus, individual gold nanosponges are cheap and robust disordered nanoantennas with strong local resonances, and an ensemble of nanosponges constitutes a meta material with a strong polarization independent, nonlinear response over a wide frequency range.

• Radiopaque 3D printing combined with polyethylene foam achieves patient phantoms for CT-guided procedures. • Radiopaque 3D printed, anthropomorphic phantoms allow realistic simulation of CT-guided procedures. • Realistic visual guidance is a key aspect in simulation of CT-guided procedures. • Three-dimensional printed phantoms provide a platform for training and optimisation of CT-guided procedures.

Subcomponent self-assembly generates dynamic combinatorial libraries of Zn4L6 cages whose composition is strongly affected by catenation and encapsulation.

Electronic and vibrational properties of the two stable molecular configurations of Sn-phthalocyanine adsorbed on an ultrathin Sn-phthalocyanine buffer film on Ag (111) have been investigated with scanning tunneling microscopy and density functional calculations. Complex submolecular patterns are experimentally observed in unoccupied states images. The calculations show that they result from a superposition of Sn p orbitals. Furthermore, the characteristic features in spectra of the differential conductance are reproduced by the calculations together with a remarkable difference between the two configurations. First-principles calculations show that rather than a single vibrational mode and its higher harmonics the excitations of different molecular vibrational quanta induce replica of orbital spectroscopic signatures. The replicated orbital features appear for the configuration with a low molecule-surface coupling.Spectra of molecules with a larger coupling to the surface are described by considering elastic tunneling to orbital resonances alone.

We introduce zinc oxide (ZnO) functionalized porous gold nanoparticles that exhibit strong second harmonic (SH) emission due to an efficient coupling of localized surface plasmons to ZnO excitons. The nanosponges are perforated with a random network of 10 nm sized ligaments, localizing plasmons in a high density of hot spots. We use a broadband, few-cycle ultrafast laser to probe coherent nonlinear emission from individual bare gold and ZnO-functionalized sponges. While the third harmonic spectrum of the hybrid particles redshifts with respect to that of bare gold sponges, a distinct blueshift is seen in their SH spectra. SH emission around 390 nm, slightly below the ZnO band gap, is enhanced by 10×. We attribute this to doubly resonant plasmon−exciton interactions: the laser drives nanosponge plasmon hot spot resonances, and this locally enhanced field induces two-photon excitation of localized ZnO excitons. This opens a path toward the design of efficient coherent nonlinear optical sources by combining randomly disordered nanoantennas with semiconductor gain materials.

Purpose To develop a customized method to produce uniform phantoms for task‐based assessment of CT image quality. Methods Contrasts between polymethyl methacrylate (PMMA) and fructose solutions of different concentrations (240, 250, 260, 280, 290, 300, 310, 320, 330, and 340 mg/mL) were calculated. A phantom was produced by laser cutting PMMA slabs to the shape of a patient’s neck. An opening of 10 mm diameter was cut into the left parapharyngeal space. An angioplasty balloon was inserted and filled with the fructose solutions to simulate low‐contrast lesions. The phantom was scanned with six tube currents. Images were reconstructed with filtered back projection (FBP) and adaptive iterative dose reduction 3D (AIDR 3D). Calculated and measured contrasts were compared. The phantom was evaluated in a detectability experiment using images with 4 and 20 HU lesion contrast. Results Low‐contrast lesions of 4, 9, 11, 13, 18, 20, 24, 30, 35, and 37 HU contrast were simulated. Calculated and measured contrasts correlated excellently (r = 0.998; 95% confidence interval: 0.991 to 1). The mean ± SD difference was 0.41 ± 2.32 HU (P < 0.0001). Detection accuracy and reader confidence were 62.9 ± 18.2% and 1.58 ± 0.68 for 4 HU lesion contrast and 99.6 ± 1.3% and 4.27 ± 0.92 for 20 HU lesion contrast (P < 0.0001), confirming that the method produced lesions at the threshold of detectability. Conclusion A cost‐effective and flexible approach was developed to create uniform phantoms with low‐contrast signals. The method should facilitate access to customized phantoms for task‐based image quality assessment.

Porous nanosponges, percolated with a three-dimensional network of 10 nm sized ligaments, recently emerged as promising substrates for plasmon-enhanced spectroscopy and (photo)catalysis. Experimental and theoretical work suggests surface plasmon localization in some hot-spot modes as the physical origin of their unusual optical properties, but so far the existence of such hot-spots has not been proven. Here we use scattering-type scanning near-field nanospectroscopy on individual gold nanosponges to reveal spatially and spectrally confined modes at 10 nm scale by recording local near-field scattering spectra. High quality factors of individual hot-spots of more than 40 are demonstrated, predicting high Purcell factors up to 10. The observed field localization and enhancement make such nanosponges an appealing platform for a variety of applications ranging from nonlinear optics to strong-coupling physics.