Detection of prohibited and restricted object X-ray images based on Hi color space segmentation.

BACKGROUND: X-ray imaging plays an important role in security inspection. However, the objects are complex, which makes it difficult to automatically detect prohibited and restricted objects. OBJECTIVE: This study aims to develop and test a detection method based on a new image segmentation scheme to solve the problem of detecting prohibited and restricted objects from pseudo-color X-ray images with complex backgrounds. METHODS: The internal mechanism of the influence of different color spaces on image segmentation effect is explored, and the color space component Hi is studied. Furthermore, the mechanism of the new Hi component and the influence law of its adjustable coefficient are revealed. Additionally, a detection method based on Hi color space segmentation for pseudo-color X-ray images is proposed. The segmentation and detection methods are then tested on actual X-ray images. RESULTS: The results show that hue has the greatest influence on image segmentation effect of the pseudo-color X-ray images. For different pseudo-color X-ray images with complex backgrounds, applying the proposed new Hi color space segmentation method achieves overall accuracy of 0.974 and 1.0 in detecting the gun and knife, respectively. CONCLUSION: The new X-ray image detection method based on the Hi color space segmentation proposed in this paper enables to better solve the complex background problem including object overlap and adhesion and thus more effectively meet the requirements of actual security inspection.

Physical design of photon-counting mode γ-ray large object radiation imaging system.

BACKGROUND: The detectors of existing large object radiation imaging systems generally work under current-integration mode and cannot distinguish effective signals of unreacted photons from interfering signals of electronic noise and scattered photons, therefore, resulting in image quality deterioration. OBJECTIVE: This study aims to design a new photon-counting mode γ-ray large object radiation imaging system. Therefore, interfering signals with lower energy than effective signals can be eliminated by energy analysis. In addition, the system enables to work properly even under 30∼300Ci Co-60 intensity. METHODS: Based on the physical analysis of the system, the design requirements are listed. Following the requirements, the best-performing photon-counting detector based on LYSO and SiPM is used in the system. ZP-SK and (ZP)2-SK filter circuits are designed for Co-60 radiation imaging system with the highest intensity of 100Ci and 300Ci, respectively. Then, a voltage comparator and an FPGA are followed to realize the function of energy analysis and photon counting. RESULTS: The proposed technical solution can improve the Steel Penetration (SP) by at least 60∼70 mmFe compared with the existing current-integration system, which is equivalent to the improvement obtained by increasing the intensity of the radioactive source more than 13 to 20 times. CONCLUSIONS: This study demonstrates the advantages of applying the new photon-counting mode γ-ray large object radiation imaging system to improve the radiation image quality and the penetration ability, which will have enormous potential for future applications.

Association between a changeable lifestyle, sedentary behavior, and suicide risk: A systematic review and meta-analysis.

BACKGROUND: Suicide and self-injury have become increasingly serious public health crises. Yet current evidence about the association between sedentary behavior (SB) and suicide is inconclusive. We explore the relationship between SB and suicide behavior to provide intervention measures to change the risk factors of the latter. METHODS: We searched PubMed, Embase, Cochrane Library, and Web of Science from database inception to September 10, 2023. Adjusted odds ratios (ORs) with 95 % confidence intervals (CIs) were used as effect measures. Subgroup analysis was conducted based on gender, regions and countries, age, and study type. RESULTS: A total of 13 studies were included. According to the meta-analysis of suicide type, compared with individuals without sedentary behavior, individuals with sedentary behavior have a higher risk of suicide attempt (OR = 1.23, 95%CI: 1.15-1.37, p < 0.001), suicide ideation (OR = 1.47, 95%CI:1.28-1.68, p < 0.001) and suicide plan (OR = 1.30, 95%CI:1.16-1.44, p < 0.001). We conducted multiple subgroup analyses for different suicidal behaviors. The analysis found that SB can increase the risk of suicide attempt in different subgroups of different genders, different research centers, Africa, and adolescents; SB can increase the risk of suicide ideation in the subgroups of different genders and ages, different research centers, Asia and Africa; SB can increase the risk of suicide plan in the subgroups of different genders, multi-center study, Africa, and adolescents. LIMITATIONS: Future research should focus on objective SB measurement and explore its dose-response relation and time limit. CONCLUSION: A sedentary lifestyle is associated with suicide behavior risk, with varying effects across age groups and regions, as evidenced in both single-center and multi-center studies.