Low-dose X-ray Research Articles

X-ray Doses in Relation to Body Mass, Indication, and Substrate During Pediatric Electrophysiological Procedures on the Heart.

The main goal of this study is to determine typical values of dose area product (DAP) and difference in the effective dose (ED) for pediatric electrophysiological procedures on the heart in relation to patient body mass. This paper also shows DAP and ED in relation to the indication, the arrhythmia substrate determined during the procedure, and in relation to the reason for using radiation. Organ doses are described as well. The subjects were children who have had an electrophysiological study done with a 3D mapping system and X-rays in two healthcare institutions. Children with congenital heart defects were excluded. There were 347 children included. Significant difference was noted between mass groups, while heavier children had higher values of DAP and ED. Median DAP in different mass groups was between 4.00 (IQR 1.00-14.00) to 26.33 (IQR 8.77-140.84) cGycm2. ED median was between 23.18 (IQR 5.21-67.70) to 60.96 (IQR 20.64-394.04) µSv. The highest DAP and ED in relation to indication were noted for premature ventricular contractions and ventricular tachycardia-27.65 (IQR 12.91-75.0) cGycm2 and 100.73 (IQR 53.31-258.10) µSv, respectively. In arrhythmia substrate groups, results were similar, and the highest doses were in ventricular substrates with DAP 29.62 (IQR 13.81-76.0) cGycm2 and ED 103.15 (IQR 60.78-266.99) µSv. Pediatric electrophysiology can be done with very low doses of X-rays when using 3D mapping systems compared to X-rays-based electrophysiology, or when compared to pediatric interventional cardiology or adult electrophysiology.

Dynamic X-ray imaging with screen-printed perovskite CMOS array.

High performance X-ray detector with ultra-high spatial and temporal resolution are crucial for biomedical imaging. This study reports a dynamic direct-conversion CMOS X-ray detector assembled with screen-printed CsPbBr3, whose mobility-lifetime product is 5.2 × 10-4 cm2 V-1 and X-ray sensitivity is 1.6 × 104 µC Gyair-1 cm-2. Samples larger than 5 cm[Formula: see text]10 cm can be rapidly imaged by scanning this detector at a speed of 300 frames per second along the vertical and horizontal directions. In comparison to traditional indirect-conversion CMOS X-ray detector, this perovskite CMOS detector offers high spatial resolution (5.0 lp mm-1) X-ray radiographic imaging capability at low radiation dose (260 nGy). Moreover, 3D tomographic images of a biological specimen are also successfully reconstructed. These results highlight the perovskite CMOS detector's potential in high-resolution, large-area, low-dose dynamic biomedical X-ray and CT imaging, as well as in non-destructive X-ray testing and security scanning.

Effects of low-dose ionizing radiation on the molecular pathways linking neurogenesis and autism spectrum disorders in zebrafish embryos

Prenatal exposure to environmental factors may play an important role in the aetiopathogenesis of autism spectrum disorder (ASD). We aim to investigate the potential effects of low-dose x-rays from dental diagnostic x-rays on neurodevelopment and molecular mechanisms associated with ASD in developing zebrafish embryos. Zebrafish embryos were divided into four groups and exposed using a dental x-ray unit: control, 0.08, 0.15 and 0.30 seconds, which are exemplary exposure settings for periapical imaging. These exposure times were measured as 7.17, 23.17 and 63.83 mSv using optical stimulated luminescence dosimeters. At the end of 72 hours post-fertilization, locomotor activity, oxidant-antioxidant status, and acetylcholine esterase (AChE) activity were analyzed. Expression of genes related to apoptosis (bax, bcl2a, p53), neurogenesis (α1-tubulin, syn2a, neurog1, elavl3) and ASD (eif4eb, adsl2a, shank3) was determined by RT-PCR. Even at reduced doses, developmental toxicity was observed in three groups as evidenced by pericardial edema, yolk sac edema and scoliosis. Deleterious effects of dental x-rays on neurogenesis through impaired locomotor activity, oxidative stress, apoptosis and alterations in genes associated with neurogenesis and ASD progression were more pronounced in the 0.30s exposure group. Based on these results we suggest that the associations between ASD and low-dose ionizing radiation need a closer look.

Passivation of defective states in single crystal MAPbBr3 and their optoelectronic properties study

We fabricated high-quality Methylpropyl lead bromide (MAPbBr3) single crystals (SC) by introducing moderate amount electron-rich amino-terminated polyoxypropylene (PEA) additives via inverse temperature crystallization (ITC) method. The intramolecular vibrations and defective states of prepared MAPbBr3 single crystals were systemically studied by the in situ variable-temperature Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), the synchrotron-based X-ray absorption near edge structure (XANES) et al. We find the proper amount PEA additives would prevent the formation of intermediate states and crystal boundaries, passivating the density of defective states. The X-ray detection properties of single-crystal MAPbBr3 crystals were investigated, using both high dose and low dose X-ray photons at 40 keV in synchrotron beamlines. The photocurrent of optimized PEA-treated MAPbBr3 single crystals demonstrate better performance compared with the as-prepared single crystals. Meanwhile, the decay time of MAPbBr3 single crystal is decreased from 376 ns to 17.1 ns by Time-resolved photoluminescence (TRPL) decay measurement, owing to the defect passivation by 0.5 wt% PEA additives. The PEA-treated single crystals possess much faster decay time than the commercialized Cerium-doped Yttrium Aluminum Garnet (Ce:YAG) scintillator (∼100ns). These results help elucidate the passivation of defective states and contribute paths to manufacture high-quality single crystal perovskites for next-generation optoelectronic devices.

Prediction and analysis of breast cancer based on transfer learning from DDSM mammography images

Breast cancer is a cancer mostly found in women, causing a high morality rate. It appears as a lump in the breast initially, and as cancer cells spread, the other organs are endangered. Research shows that the earlier the breast cancer is detected, the higher rate of recovering will be. The main methods of breast cancer detection are mainly using various physical methods to probe the internal condition of the patients breast. Breast X-ray imaging, also known as mammography, is the most widely used. It uses low-dose X-ray technology to observe the breast tissue and help doctors figure out the exact condition of the patient. With the advancements in deep learning and image recognition, the analysis of mammograms can be previously done by the computer, easing the pressure on doctors. Digital Database for Screening Mammography (DDSM) dataset is a mammography dataset specifically designed for the development of mammography detection models. It contains huge amounts of mammograms and provides the labels corresponding to them. In this study, the performances of normal deep learning model and transfer learning model on the DDSM dataset are compared. Pretrained neural network models are employed and fine-tuned on the DDSM dataset to adapt to the features of mammographic images. Experimental results demonstrate significant improvements through transfer learning, outperforming traditional methods with Convolutional Neural Network (CNN). Finally, the models are evaluated in multiple aspects, conclusions and prospects are analysed based on the results.

General Algorithm Applicability in Determining DBS Lead Orientation: Adapting 2D and 3D X-Ray Techniques for SenSightTM Leads

Introduction: With recent advancements in deep brain stimulation (DBS), directional leads featuring segmented contacts have been introduced, allowing for targeted stimulation of specific brain regions. Given that manufacturers employ diverse markers for lead orientation, our investigation focuses on the adaptability of the 2017 techniques proposed by the Cologne research group for lead orientation determination. Methods: We tailored the two separate 2D and 3D X-ray-based techniques published in 2017 and originally developed for C-shaped markers, to the dual-marker of the Medtronic SenSight™ lead. In a retrospective patient study, we evaluated their feasibility and consistency by comparing the degree of agreement between the two methods. Results: The Bland-Altman plot showed favorable concordance without any noticeable systematic errors. The mean difference was 0.79°, with limits of agreement spanning from 21.4° to −19.8°. The algorithms demonstrated high reliability, evidenced by an intraclass correlation coefficient of 0.99 (p < 0.001). Conclusion: The 2D and 3D algorithms, initially formulated for discerning the circular orientation of a C-shaped marker, were adapted to the marker of the Medtronic SenSight™ lead. Statistical analyses revealed a significant level of agreement between the two methods. Our findings highlight the adaptability of these algorithms to different markers, achievable through both low-dose intraoperative 2D X-ray imaging and standard CT imaging.

Hair Follicle Damage after 100 mGy Low-Dose Fractionated X-Ray Irradiation and the Protective Effects of TEMPOL, a Stable Nitroxide Radical, against Radiation.

The effects of long-term low-dose X-ray irradiation on the outer root sheath (ORS) cells of C3H/He mice were investigated. Mice were irradiated with a regime of 100 mGy/day, 5 days/week, for 12 weeks (Group X) and the results obtained were compared to those in a non-irradiated control (Group C). Potential protection against ORS cells damage induced by this exposure was investigated by adding the stable nitroxide radical 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) at 1 mM to the drinking water of mice (Group X + TEMPOL). The results obtained were compared with Group C and a non-irradiated group treated with TEMPOL (Group C + TEMPOL). After fractionated X-ray irradiation, skin was removed and ORS cells were examined by hematoxylin and eosin staining and electron microscopy for an abnormal nuclear morphology and nuclear condensation changes. Fractionated X-irradiated mice had an increased number of ORS cells with an abnormal nuclear morphology as well as nuclear condensation changes. Sections were also immunohistochemically examined for the presence of TdT-mediated dUTP nick-end labeling (TUNEL), 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), vascular endothelial growth factor (VEGF), nitrotyrosine, heme oxygenase 1 (HO-1), and protein gene product 9.5 (PGP 9.5). Significant increases were observed in TUNEL, 8-OHdG, and 4-HNE levels in ORS cells from mice in Group X. Electron microscopy also showed irregular shrunken ORS cells in Group X. These changes were prevented by the presence of TEMPOL in the drinking water of the irradiated mice. TEMPOL alone had no significant effects. These results suggest that fractionated doses of radiation induced oxidative damage in ORS cells; however, TEMPOL provided protection against this damage, possibly as a result of the rapid reaction of this nitroxide radical with the reactive oxidants generated by fractionated X-ray irradiation.

Low-dose X-ray radiation induces an adaptive response: A potential countermeasure to galactic cosmic radiation exposure.

Space exploration involves many dangers including galactic cosmic radiation (GCR). This class of radiation includes high-energy protons and heavy ionizing ions. NASA has defined GCR as a carcinogenic risk for long-duration space missions. To date, no clear strategy has been developed to counter chronic GCR exposure. We hypothesize that preconditioning cells with low levels of radiation will be protective from subsequent higher radiation exposures. H9C2 cells were pretreated with 0.1 to 1.0Gy X-rays. The challenge radiation exposure consisted of either 8Gy X-rays or 75cGy of GCR, using a five-ion GCRsim protocol. A cell doubling time assay was used to determine cell viability. An 8Gy X-ray challenge alone significantly (P<0.05) increased cell doubling time compared to the no-radiation control group. Low-dose radiation pre-treatment ameliorated the 8Gy X-ray-induced increases in cell doubling time. A 75cGy GCR challenge alone significantly increased cell doubling time compared to the no-radiation group. Following the 75cGy challenge, only the 0.5 and 1.0Gy pre-treatment ameliorated the 75cGy-induced increases in cell doubling time. DNA damage or pathological oxidant stress will delay replicative functions and increase cell doubling time. Our results suggested that pretreatment with low-dose X-rays induced an adaptive response which offered a small but significant protection against a following higher radiation challenge. Although perhaps not a practical countermeasure, these findings may serve to offer insight into cell signalling pathways activated in response to low-dose irradiation and targeted for countermeasure development.

Cone-beam x-ray luminescence computed tomography (CB-XLCT) prototype development and performance evaluation.

This study developed a prototype for a rotational cone-beam x-ray luminescence computed tomography (CB-XLCT) system, considering its potential application in pre-clinical theranostic imaging. A geometric calibration method applicable to both imaging chains (XL and CT) was also developed to enhance image quality. The results of systematic performance evaluations were presented to assess the feasibility of commercializing XLCT technology. Monte Carlo GATE simulation was performed to determine the optimal imaging conditions for nanophosphor particles (NPs) irradiated by 70 kV x-rays. We acquired a low-dose transmission x-ray tube and designed a prone positioning platform and a rotating gantry, using mice as targets from commercial small animalμ-CT systems. We then employed the image cross-correlation (ICC) automatic geometric calibration method to calibrate XL and CT images. The performance of the system was evaluated through a series of phantom experiments with a linearity of 0.99, and the contrast-to-noise ratio (CNR) between hydroxyl-apatite (HA) and based epoxy resin is 19.5. The XL images of the CB-XLCT prototype achieved a Dice similarity coefficient (DICE) of 0.149 for a distance of 1 mm between the two light sources. Finally, the final XLCT imaging results were demonstrated using the Letter phantoms with NPs. In summary, the CB-XLCT prototype developed in this study showed the potential to achieve high-quality imaging with acceptable radiation doses for small animals. The performance of CT images was comparable to current commercial machines, while the XL images exhibited promising results in phantom imaging, but further efforts are needed for biomedical applications.

Improved effectiveness of X-PDT against human triple-negative breast cancer cells through the use of liposomes co-loaded with protoporphyrin IX and perfluorooctyl bromide.

In this study, we utilized X-ray-induced photodynamic therapy (X-PDT) against triple-negative breast cancer (TNBC) cells. To achieve this, we developed a liposome delivery system that co-loaded protoporphyrin IX (PPIX) and perfluorooctyl bromide (PFOB) in a rational manner. Low-dose X-ray at 2 Gy was employed to activate PPIX for the generation of reactive oxygen species (ROS), and the co-loading of PFOB provided additional oxygen to enhance ROS production. The resulting highly toxic ROS effectively induced cell death in TNBC. In vitro X-PDT effects, including intracellular ROS generation, cell viability, and apoptosis/necrosis assays in TNBC cells, were thoroughly investigated. Our results indicate that the nanocarriers effectively induced X-PDT effects with very low-dose radiation, making it feasible to damage cancer cells. This suggests the potential for the effective utilization of X-PDT in treating hypoxic cancers, including TNBC, with only a fraction of conventional radiotherapy.

Low-dose X-ray stimulated NO-releasing nanocomposites for closed-loop dual-mode cancer therapy.

X-ray-excited photodynamic therapy (X-PDT) employs X-rays as an energy source, overcoming the light penetration limitations of traditional photodynamic therapy (PDT) but is constrained by high-energy radiation and the hypoxic tumor microenvironment. Low-dose X-ray-excited photodynamic therapy and reduction of mitochondrial oxygen consumption can serve as significant breakthroughs in overcoming these barriers. In this study, NaLuF4:Tb/Gd (15%/5%)@NaYF4 (ScNP) nanoparticles adsorbing the photosensitizer MC540 and loaded with α-(nitrate ester) acid (NEAA) were prepared as low X-ray dose triggered nano-scintillators. The final product obtained was NaLuF4:Tb/Gd (15%/5%)@NaYF4@mSiO2@MC540@NEAA (ScNP-MS@MC540@NEAA) nanocomposites, which exhibited intense green luminescence. X-PDT generates cytotoxic reactive oxygen species (ROS) with minimal ionizing radiation damage. Simultaneously, NEAA reacts with glutathione (GSH) to generate nitric oxide (NO) for gaseous treatment of the damaged mitochondrial respiratory chain to reduce oxygen consumption and alleviate hypoxia, enhancing the X-PDT efficacy and realizing a closed-loop treatment. The superoxide ions (˙O2-) can rapidly react with NO produced to form the highly cytotoxic reactive nitrogen species (RNS) peroxynitrite anion (ONOO-), which exhibits higher cytotoxicity compared to ROS. Furthermore, GSH scavenges toxic ROS and maintains the physiological function of tumor cells. It can induce cancer cell overoxidation and nitrosative stress. This work describes a low-dose X-ray-triggered X-PDT system with total radiation of 50 mGy, which involves GSH consumption, self-supplied NO, mitochondrial damage alleviation, and hypoxia relief to generate ROS and RNS, forming a closed-loop anti-hypoxia dual-mode system with synergistically enhanced anti-tumor effects, without significant biological side effects. It provides a promising platform for deep-seated tumor X-PDT with considerable application prospects.

Super-Resolution in Low Dose X-ray CT via Focal Spot Mitigation With Generative Diffusion Networks

Super-Resolution in Low Dose X-ray CT via Focal Spot Mitigation With Generative Diffusion Networks

Plastic scintillation fiber with europium complexes for low-dose X-ray detection and long-distance imaging

This work produces a new type of plastic scintillation fiber with excellent performances to realize X-ray detection and imaging.

PCOS Detection and Breast Cancer Detection

Polycystic Ovary Syndrome (PCOS) is a prevalent endocrine disorder that affects people with ovaries, typically during their reproductive years. Detecting PCOS is crucial for timely intervention and management. PCOS detection involves a multifaceted approach, encompassing both clinical and laboratory methods. Clinical assessment of PCOS often begins with a comprehensive medical history, physical examination, and evaluation of symptoms, such as irregular menstruation, excess hair growth, and acne. Transvaginal ultrasound is commonly employed to visualize the ovaries and identify the characteristic cysts. Blood tests, measuring hormone levels like testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), aid in the diagnosis. Additionally, insulin resistance and glucose tolerance tests may be conducted, as PCOS is frequently associated with metabolic disturbances. Breast Cancer Detection: Breast cancer is a significant global health concern, and early detection is essential for improved prognosis and survival rates. Various techniques are employed for breast cancer detection, combining clinical assessment, imaging, and biopsy procedures. Clinical breast examination involves a physical assessment by a healthcare professional to identify any palpable lumps, changes in breast shape, or skin abnormalities. Mammography, a low-dose X-ray, is a primary imaging modality for breast cancer screening. Other imaging techniques, such as ultrasound and magnetic resonance imaging (MRI), are used for supplemental evaluation. In cases where abnormalities are detected, a biopsy is performed to confirm the presence of cancer cells. Biopsies may include fine-needle aspiration, core needle biopsy, or surgical biopsy, providing definitive evidence of malignancy. Advances in technology, such as digital mammography and the development of artificial intelligence algorithms for image analysis, continue to enhance the precision and efficiency of breast cancer detection, thereby contributing to early diagnosis and effective treatment.

Information sharing promotes bacterial diversity in oligotrophic environment with low-dose X-ray radiation based on modeling and simulation of agent-based model

It remains unclear why bacterial diversity was formed and maintained in oligotrophic environment (OE) with low-dose X-ray radiation (LDXR) due to violation of the competitive exclusion principle in ecology. Based on microbial ecology, bioinformatics, cybernetics, experimental phenomena and data, a new hypothesis was proposed to elucidate information sharing mechanisms driving bacterial community succession with high diversity in OE with LDXR. According to hypothesis, a valid agent-based model (ABM) of cellular automation (CA) was developed to quantitatively describe the hypothesis, and the agent-based simulation sufficiently proved that as the bacterial individuals conduct cooperation to indiscriminately share information of substrate positions with each other in OE with LDXR, it can effectively increase the survival probabilities of all bacterial species, alleviate interspecific competition, and prevent any bacterial species from being dominant, which is beneficial to the coexistence of most species and promotes bacterial diversity during community succession. The results of agent-based simulation are highly similar to the observed phenomena and data in the experiments, therefore sufficiently confirm the proposed hypothesis.This study could not only lay the theoretical foundation for understanding of the crucial role information sharing plays in formation and maintenance of bacterial diversity but also offer effective guidance for bacterial prevention and control as well as other ecological engineering applications.

Monitoring of Curve Progression in Patients with Adolescent Idiopathic Scoliosis Using 3-D Ultrasound

ObjectiveTo investigate whether 3D ultrasound can provide comparable results to conventional X-ray examination in assessing curve progression in AIS patients. Methods136 AIS subjects (42 males and 94 females; 10-18 years of age, mean of 14.1 ± 1.9 years) with different severities of scoliosis (Cobb angle ranged from 10-85 degrees, mean of 24.3 ± 14.4 degrees) were included. Each subject underwent bi-planar low-dose X-ray EOS® and 3D ultrasound system scanning with the same posture on the same date. Subjects underwent the second assessment at routine clinical follow-up. Manual measurement of scoliotic curvature on ultrasound coronal projection images and posterior-anterior radiographs were presented as ultrasound curve angle (UCA) and radiographic Cobb angle (RCA), respectively. RCA and UCA increments of five degrees or more represented a scoliosis progression detected by X-ray assessment and 3D ultrasound assessment, respectively. ResultsThe sensitivity and specificity for UCA measurement for detecting scoliosis progression were 0.93 and 0.90, respectively. The negative likelihood ratio of the diagnostic test for scoliosis progression by the 3D ultrasound imaging system was 0.08. ConclusionThe 3D ultrasound imaging method is a valid technique to detect coronal curve progression as compared to conventional radiography in follow-up of AIS. Substituting conventional radiography by 3D ultrasound is effective in reducing the radiation dose to be suffered by AIS patients during their follow-up examinations.

Nanozyme-Coated Bacteria Hitchhike on CD11b+ Immune Cells to Boost Tumor Radioimmunotherapy.

Bacterial-based delivery strategies have recently emerged as a unique research direction in the field of drug delivery. However, bacterial vectors are quickly phagocytosed by immune cells after entering the bloodstream. Taking advantage of this phenomenon, herein, this work seeks to harness the potential of immune cells to delivery micron-sized bacterial vectors, and find that inactivated bacterial can accumulate at tumor-site after intravenous injection through CD11b+ cells hitchhiking. To this end, this work then designs a gold-platinum bimetallic nanozyme coated bacterial vector (Au-Pt@VNP20009, APV). Utilizing strong tumor inflammatory response induced by low dose X-rays, this work further heightens the ability of CD11b+ immune cells to assist APV hitchhiking for tumor-targeted delivery, which can significantly relieve tumor hypoxia and immunosuppression, and inhibit tumor growth and metastasis. This work elucidates the potential mechanisms of bacterial vector targeted delivery, opening up new horizons for bacterial vector delivery strategies and clinical tumor radioimmunotherapy.

Analisa Pengukuran Entrance Surface Dose (ESD) Menggunakan Optically Stimulated Luminescence Dosimeter (OSLD) Pada Pasien Anak

The surface dose of radiation in conventional diagnostic radiology exams, also known as the entrance surface dose (ESD), is measured to ensure optimal radiation protection for patients. This study aimed to determine and analyze the doses received by pediatric patients who underwent a chest X-ray examination while being treated in the NICU and PICU rooms at Hermina Karawang Hospital. The research involved measuring the radiation dose in pediatric patients using the OSLD nanoDot. This susceptible device can detect low-dose X-ray radiation exposure, especially in pediatric patients. The study was conducted from September to December 2022 and included 35 patients aged 0 to 5. The results of the ESD measurements received by pediatric patients at Hermina Karawang Hospital in the 0-1 year age group were found to be in line with the DRL (Diagnostic Reference Levels) of the United Kingdom (UK) and Austria, which recommend a range of 0.05 – 0.055 mGy. The average ESD value for this age group was 0.05 mGy. Similarly, for the 1-5 year age group, an average ESD value of 0.048 mGy was obtained, below the UK and Austria DRL range of 0.05 – 0.069 mGy. These results indicate that the ESD received by pediatric patients during thoracic examination at Hermina Karawang Hospital is close to the DRL values recommended by the UK and Austria. However, it is essential to note that regardless of the dose received, it must always be justified and optimized to prevent unnecessary radiation exposure. Keywords: ESD, OSLD, unnecessary exposure, paediatric radiation protection, radiation exposure

Low-dose X-ray induced long afterglow NIR luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions

The low-dose X-ray induced long afterglow near infrared (NIR) luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions was investigated. The structure analysis shows the good formation of Zn1–xCdxGa2O4 spinel solid solutions, which possesses a cubic spinel structure with Fd3m space group. The formation of Zn1–xCdxGa2O4 spinel solid solutions induces the obvious increase of long afterglow near infrared luminescence excited by low-dose X-ray. When the content of doped Cd2+ reaches 0.1, the low-dose X-ray induced long afterglow NIR luminescence is the maximum. More importantly, only 5 s X-ray irradiation can induce more than 6 h NIR afterglow emission, of which the afterglow luminescent intensity is still 5 times stronger than the background intensity after 6 h. The thermoluminescent results show that under the 5 s exposure of X-ray, the trap density of Zn0.9Cd0.1Ga2O4:Cr3+ is much higher than that of ZnGa2O4:Cr3+. The replacement of Cd2+ ions with large radius at Zn2+ sites causes the increase of defects and dislocations, which results in the obvious increase of trap concentrations. And the addition of high-z number elements Cd2+ would enhance the X-ray absorption of the solid solutions, which thus can be easily excited by low-dose X-ray. Zn0.9Cd0.1Ga2O4:1%Cr3+ solid solution is a potential candidate of low-dose X-ray induced long afterglow luminescent materials.

A Deep Convolutional Gated Recurrent Unit for CT Image Reconstruction.

Computed tomography (CT) is one of the most important medical imaging technologies in use today. Most commercial CT products use a technique known as the filtered backprojection (FBP) that is fast and can produce decent image quality when an X-ray dose is high. However, the FBP is not good enough on low-dose X-ray CT imaging because the CT image reconstruction problem becomes more stochastic. A more effective reconstruction technique proposed recently and implemented in a limited number of CT commercial products is an iterative reconstruction (IR). The IR technique is based on a Bayesian formulation of the CT image reconstruction problem with an explicit model of the CT scanning, including its stochastic nature, and a prior model that incorporates our knowledge about what a good CT image should look like. However, constructing such prior knowledge is more complicated than it seems. In this article, we propose a novel neural network for CT image reconstruction. The network is based on the IR formulation and constructed with a recurrent neural network (RNN). Specifically, we transform the gated recurrent unit (GRU) into a neural network performing CT image reconstruction. We call it "GRU reconstruction." This neural network conducts concurrent dual-domain learning. Many deep learning (DL)-based methods in medical imaging are single-domain learning, but dual-domain learning performs better because it learns from both the sinogram and the image domain. In addition, we propose backpropagation through stage (BPTS) as a new RNN backpropagation algorithm. It is similar to the backpropagation through time (BPTT) of an RNN; however, it is tailored for iterative optimization. Results from extensive experiments indicate that our proposed method outperforms conventional model-based methods, single-domain DL methods, and state-of-the-art DL techniques in terms of the root mean squared error (RMSE), the peak signal-to-noise ratio (PSNR), and the structure similarity (SSIM) and in terms of visual appearance.