Abstract

Purpose

Radiotherapy treatment planning (RTP) using MR has been used increasingly for the abdominal site. Multiple contrast weightings and motion‐resolved imaging are desired for accurate delineation of the target and various organs‐at‐risk and patient‐tailored planning. Current MR protocols achieve these through multiple scans with distinct contrast and variable respiratory motion management strategies and acquisition parameters, leading to a complex and inaccurate planning process. This study presents a standalone MR Multitasking (MT)-based technique to produce volumetric, motion‐resolved, multicontrast images for abdominal radiotherapy treatment planning.

Methods

The MT technique resolves motion and provides a wide range of contrast weightings by repeating a magnetization‐prepared (saturation recovery and T2 preparations) spoiled gradient‐echo readout series and adopting the MT image reconstruction framework. The performance of the technique was assessed through digital phantom simulations and in vivo studies of both healthy volunteers and patients with liver tumors.

Results

In the digital phantom study, the MT technique presented structural details and motion in excellent agreement with the digital ground truth. The in vivo studies showed that the motion range was highly correlated (R² = 0.82) between MT and 2D cine imaging. MT allowed for a flexible contrast‐weighting selection for better visualization. Initial clinical testing with interobserver analysis demonstrated acceptable target delineation quality (Dice coefficient = 0.85 ± 0.05, Hausdorff distance = 3.3 ± 0.72 mm).

Conclusion

The developed MT‐based, abdomen‐dedicated technique is capable of providing motion‐resolved, multicontrast volumetric images in a single scan, which may facilitate abdominal radiotherapy treatment planning.

• Book : 93(1)
• Pub. Date : 2025
• Page : pp.108-120
• Keyword :

Abstract

Brittle materials such as concrete, rock, and coal emit weak electromagnetic radiation (EMR) signals during their cracking process. This study analyzed the time-frequency variation law during the concrete cracking process from the perspectives of energy changes and vibration processes. The relationship between EMR signals and concrete samples of different scales and strength standards, as well as between EMR signals and acoustic emission (AE) signals were investigated. The results indicate that the size and strength of the concrete samples primarily alter the dissipated energy stored within them. A positive correlation exists between the amplitude of EMR signals and the internal dissipated energy during the concrete cracking process. During the linear elastic stage, only a small amount of cracks form in concrete, resulting in negligible EMR signals. However, during the cracking process, EMR signals of various frequency bands are generated. The amplitude of low-frequency EMR signals exhibits minimal variation, showing a slight increase in the later stages of cracking. Medium and high-frequency EMR signals reach peak amplitudes at the point of maximum stress reduction and then rapidly decrease. Additionally, the primary frequency of the EMR signals closely matches the frequency of both crack vibration signals and AE signals. Therefore, analyzing the changes in amplitude and frequency of EMR signals during the concrete cracking process holds promise as a novel, non-destructive method for monitoring concrete cracks.

• Book : 36(1)
• Pub. Date : 2025
• Page : pp.015106
• Keyword :

Plasmonic nanostructures have emerged as indispensable components in the construction of high-performance gas sensors, playing a pivotal role across diverse applications, including industrial safety, medical diagnostics, and environmental monitoring. This review paper critically examines seminal research that underscores the remarkable efficacy of plasmonic materials in achieving superior attributes such as heightened sensitivity, selectivity, and rapid response times in gas detection. Offering a synthesis of pivotal studies, this review aims to furnish a comprehensive discourse on the contemporary advancements within the burgeoning domain of plasmonic gas sensing. The featured investigations meticulously scrutinize various plasmonic structures and their applications in detecting gases like carbon monoxide, carbon dioxide, hydrogen and nitrogen dioxide. The discussed frameworks encompass cutting-edge approaches, spanning ideal absorbers, surface plasmon resonance sensors, and nanostructured materials, thereby elucidating the diverse strategies employed for advancing plasmonic gas sensing technologies.

• Book : 15(1)
• Pub. Date : 2025
• Page : pp.1-9
• Keyword :

Abstract

Multi-material, multi-layered systems such as AlGaN/GaN high electron mobility transistors (HEMTs) contain residual mechanical stresses that arise from sharp contrasts in device geometry and materials parameters. These stresses, which can be either tensile or compressive, are difficult to detect and eliminate because of their highly localized nature. We propose that their high-stored internal energy makes potential sites for defect nucleation sites under radiation, particularly if their locations coincide with the electrically sensitive regions of a transistor. In this study, we validate this hypothesis with molecular dynamic simulation and experiments exposing both pristine and annealed HEMTS to 2.8 MeV Au⁺³ irradiation. Our unique annealing process uses mechanical momentum of electrons, also known as the electron wind force (EWF) to mitigate the residual stress at room temperature. High-resolution transmission electron microscopy and cathodoluminescence spectra reveal the reduction of point defects and dislocations near the two-dimensional electron gas region of EWF-treated devices compared to pristine devices. The EWF-treated HEMTs showed relatively higher resilience with approximately 10% less degradation of drain saturation current and ON-resistance and 5% less degradation of peak transconductance. Both mobility and carrier concentration of the EWF-treated devices were less impacted compared to the pristine devices. Our results suggest that the lower density of nanoscale stress localization contributed to the improved radiation tolerance of the EWF-treated devices. Intriguingly, the EWF is found to modulate the defect distribution by moving the defects to electrically less sensitive regions in the form of dislocation networks, which act as sinks for the radiation induced defects and this assisted faster dynamic annealing.

• Book : 58(4)
• Pub. Date : 2025
• Page : pp.045105
• Keyword :

• Book : 603()
• Pub. Date : 2025
• Page : pp.155384
• Keyword :

• Book : 226()
• Pub. Date : 2025
• Page : pp.112237
• Keyword :

• Book : 211()
• Pub. Date : 2025
• Page : pp.110966
• Keyword :

• Book : 226()
• Pub. Date : 2025
• Page : pp.112343
• Keyword :

• Book : 211()
• Pub. Date : 2025
• Page : pp.111005
• Keyword :

• Book : 226()
• Pub. Date : 2025
• Page : pp.112285
• Keyword :