Low-dose X-ray Research Articles

Cumulative effects of low X-ray doses on some liver function and proteins of diagnostic technicians working in conventional X-rays

Today X-rays are widely used for diagnostic in medicine using different technics such as computed tomography (CT), fluoroscopy and conventional X-ray. During diagnostic procedures the technicians might expose to low X-ray doses especially those who omit radiation protection tools. The aim of the study was to assess liver function and proteins due to  the cumulative effects of low X-ray doses on diagnostic technicians through measuring  aspartate aminotransferase (AST), alanine aminotransferase (ALT), total proteins, albumin, globulin, serum ferritin (s.ferritin), malondialdehyde (MDA) and glutathione (GSH). Twenty four male diagnostic technicians at Kirkuk hospitals participated, they classified into two groups depending on their working experiences, each group with 12 technicians. Twelve male healthy controls participated to show any alteration of the parameters. The results showed that ALT, AST and s.ferritin increased significantly (p<0.05) for the first group compared to the control while high significant (p<0.001) increasing was recorded for the second group. Total proteins decreased significantly (p<0.05) in the first group and high significant (p<0.001) decreasing in the second group compared with the control group. High significant (p<0.001) decreasing for albumin was recorded in both groups while globulin decreased insignificantly (p>0.05) in the first group and significant (p<0.05) decreases were recorded for the second group. For MDA and GSH high significant (p<0.001) increasing and decreasing respectively, recorded for both groups. The study revealed that low doses of X-ray can change some liver functions and proteins and the number of working years has discernible effects on the cumulative doses in diagnostic technicians.

Strong Shift to ATR-Dependent Regulation of the G2-Checkpoint after Exposure to High-LET Radiation.

The utilization of high linear-energy-transfer (LET) ionizing radiation (IR) modalities is rapidly growing worldwide, causing excitement but also raising concerns, because our understanding of their biological effects is incomplete. Charged particles such as protons and heavy ions have increasing potential in cancer therapy, due to their advantageous physical properties over X-rays (photons), but are also present in the space environment, adding to the health risks of space missions. Therapy improvements and the protection of humans during space travel will benefit from a better understanding of the mechanisms underpinning the biological effects of high-LET IR. There is evidence that high-LET IR induces DNA double-strand breaks (DSBs) of increasing complexity, causing enhanced cell killing, owing, at least partly, to the frequent engagement of a low-fidelity DSB-repair pathway: alternative end-joining (alt-EJ), which is known to frequently induce severe structural chromosomal abnormalities (SCAs). Here, we evaluate the radiosensitivity of A549 lung adenocarcinoma cells to X-rays, α-particles and 56Fe ions, as well as of HCT116 colorectal cancer cells to X-rays and α-particles. We observe the expected increase in cell killing following high-LET irradiation that correlates with the increased formation of SCAs as detected by mFISH. Furthermore, we report that cells exposed to low doses of α-particles and 56Fe ions show an enhanced G2-checkpoint response which is mainly regulated by ATR, rather than the coordinated ATM/ATR-dependent regulation observed after exposure to low doses of X-rays. These observations advance our understanding of the mechanisms underpinning high-LET IR effects, and suggest the potential utility for ATR inhibitors in high-LET radiation therapy.

Noise-robust breathing-phase estimation on marker-free, ultra low dose X-ray projections for real-time tumor localization via surrogate structures

PurposeThis paper presents a novel strategy for feature-based breathing-phase estimation on ultra low-dose X-ray projections for tumor motion control in radiation therapy. MethodsCoarse-scaled Curvelet coefficients are identified as motion sensitive but noise-robust features for this purpose. For feature-based breathing-phase estimation, an ensemble strategy with two classifiers is used. This consensus-based estimation substantially increases tracking reliability by rejection of false positives. The algorithm is evaluated on both synthetic and measured phantom data: Monte Carlo simulated ultra low dose projections for a C-arm X-ray and on the basis of 4D-chest-CTs of eight patients on one hand side and real measurements based on a motion phantom. ResultsTo achieve an accuracy of breathing-phase estimation of more than 95% a fluence between 20 and 400 photons per pixel (open field) is required depending on the patient. Furthermore, the algorithm is evaluated on real ultra low dose projections from an XVI R5.0 system (Elekta AB, Stockholm, Sweden) using an additional lead filter to reduce fluence. The classifiers-consensus-based-gating method estimated the correct position of the test projections in all test cases at a fluence of ∼180 photons per pixel and 92% at a fluence of ∼40 photons per pixel. The deposited dose to patient per image is in the range of nGy. ConclusionsA novel method is presented for estimation of breathing-phases for real-time tumor localization at ultra low dose both on a simulation and a phantom basis. Its accuracy is comparable to state of the art X-ray based algorithms while the released dose to patients is reduced by two to three orders of magnitude compared to conventional template-based approaches. This allows for continuous motion control during irradiation without the need of external markers.

Synthesis and Characterization of a New Nanocomposite Film Based on Polyvinyl Alcohol Polymer and Nitro Blue Tetrazolium Dye as a Low Radiation Dosimeter in Medical Diagnostics Application.

Dosimetry is a field of increasing importance in diagnostic radiology. There has been a realization among healthcare professionals that the dose of radiation received by patients via modern medical X-ray examinations could induce acute damage to the skin and eyes. The present study highlights the synthesis of polyvinyl alcohol/nitro blue tetrazolium nanocomposite films (PVA/NBT) for radiation detection depending on chromic, optical, chemical and morphologic changes. First, we synthesized the nanocomposite film-based PVA doped with NBT and the different parameters of the preparation procedure were optimized. Then The films were exposed to different low X-ray doses on the scale of mGy level (0, 2, 4, 10 and 20 mGy). The sensitivity and the performance of the made composite films were evaluated via different characterization methods. Indeed, the response curve based on UV-Vis absorptions revealed a linear increase in absorbance with increased radiation doses (R = 0.998). FTIR analysis showed a clear chemical modification in recorded spectra after irradiation. X-ray diffraction assessment revealed clear structural changes in crystallinity after ionization treatment. SEM analysis showed a clear morphological modification of PVA/NBT films after irradiation. In addition, the prepared PVA/NBT films exhibited excellent pre- and post-irradiation stability in dark and light. Finally, the quantitative colorimetry study confirmed the performance of the prepared films and the different colorimetric coordinates, the total color difference (∆E) and the color strength (K/S) showed a linear increase with increasing X-ray doses. The made nanocomposite PVA/NBT film might offer promising potential for an effective highly sensitive medical dosimeter applied for very low doses in X-ray diagnostic radiology.

Low-dose X-ray enhanced tumor accumulation of theranostic nanoparticles for high-performance bimodal imaging-guided photothermal therapy

BackgroundTheranostic nanoparticles (NPs) have achieved rapid development owing to their capacity for personalized multimodal diagnostic imaging and antitumor therapy. However, the efficient delivery and bulk accumulation of NPs in tumors are still the decisive factors in improving therapeutic effect. It is urgent to seek other methods to alters tumor microenvironment (like vascular permeability and density) for enhancing the efficiency of nanoparticles delivery and accumulation at the tumor site.MethodsHerein, we developed a Raman-tagged hollow gold nanoparticle (termed as HAuNP@DTTC) with surface-enhanced Raman scattering (SERS) property, which could be accumulated efficiently in tumor site with the pre-irradiation of low-dose (3 Gy) X-ray and then exerted highly antitumor effect in breast cancer model.ResultsThe tumor growth inhibition (TGI) of HAuNP@DTTC-induced photothermal therapy (PTT) was increased from 60% for PTT only to 97%, and the lethal distant metastasis of 4T1 breast cancer (such as lung and liver) were effectively inhibited under the X-ray-assisted PTT treatment. Moreover, with the strong absorbance induced by localized surface plasmon resonance in near-infrared (NIR) region, the signals of Raman/photoacoustic (PA) imaging in tumor was also significantly enhanced after the administration of HAuNP@DTTC, indicating it could be used as the Raman/PA imaging and photothermal agent simultaneously under 808 nm laser irradiation.ConclusionsOur studied of the as-prepared HAuNP@DTTC integrated the Raman/PA imaging and PTT functions into the single platform, and showed the good prospects for clinical applications especially with the low-dose X-ray irradiation as an adjuvant, which will be a productive strategy for enhancing drug delivery and accumulation in tumor theranostics.Graphic

Cytotoxicity and radiosensitizing potency of Moscatilin in cancer cells at low radiation doses of X-ray and UV-C

Moscatilin (stilbenoid) is a plant-derived anticancer compound, and it has mostly been isolated from threatened wild Dendrobium species. The present study attempts to evaluate the cytotoxicity of Moscatilin on several cancer cell lines through MTT assay. Additionally, it also aims towards estimating and comparing the radiosensitivity, cell-cycle progression, and apoptotic/necrotic effect induced by Moscatilin on different cell lines. The effects of Moscatilin was compared with another significant stilbenoid anticancer agent, Resveratrol (a structural analog of Moscatilin), whose presence has also been reported in Dendrobiums. Considering the threatened nature of this genus, crude extracts of a tropical and epiphytic Dendrobium species, viz., Dendrobium ovatum, prepared from in vitro seedlings were also tested towards cytotoxicity and radiosensitization efficacy. Moscatilin functioned as an effective radiosensitizer at 5 µg/ml along with 1 Gy X-ray and 200 J/m2 UV-C radiations. It was also able to perturb cell cycle both at replicative and post-replicative phases with the aforementioned combination. Moscatilin, in unison with radiation, triggered immunogenic death specifically on cancer cells starting from Pyroptosis, terminating in Necroptosis. Moscatilin, when used singly, could evoke immunogenic cell death. Analyses of Damage-Associated Molecular Patterns released during radiation and Moscatilin treatment would aid in ascertaining the mode of cell death. Moscatilin is a potential radiosensitizer and must be tested for preclinical and clinical trials to combat cancer.

LiF Nanoparticles Enhance Targeted Degradation of Organic Material under Low Dose X-ray Irradiation

The targeted irradiation of structures by X-rays has seen application in a variety of fields. Herein, the use of 5–10 nm LiF nanoparticles to locally enhance the degradation of an organic thin film, diindenoperylene, under hard X-ray irradiation, at relatively low ionizing radiation doses, is shown. X-ray reflectivity analysis indicated that the film thickness increased 12.04 Å in air and 11.34 Å in a helium atmosphere, under a radiation dose of ∼65 J/cm2 for 3 h illumination with a bi-layer structure that contained submonolayer coverage of thermally evaporated LiF. This was accompanied by significant modification of the surface topography for the organic film, which initially formed large flat islands. Accelerated aging experiments suggested that localized heating was not a major mechanism for the observed changes, suggesting a photochemical mechanism due to the formation of reactive species from LiF under irradiation. As LiF has a tendency to form active defects under radiation across the energy spectrum, this could could open a new direction to explore the efficacy of LiF or similar optically active materials that form electrically active defects under irradiation in various applications that could benefit from enhanced activity, such as radiography or targeted X-ray irradiation therapies.

Evaluation of vertebral bone strength with a finite element method using low dose computed tomography imaging

BackgroundFocusing on compression fractures of bone by finite elements, we evaluated bone strength based on the computed tomography-based finite element method. However, the exposure dose is an issue. We aimed to investigate the quantity of reduction of the radiation dose with respect to the reference dose by comparing the calculation results of compression fractures of the vertebral body using experimental data obtained from the spine of a pig. MethodsComputed tomography images of a self-made phantom that enclosed the lower lumbar vertebra of edible wild pigs were obtained under baseline-dose conditions using various lower tube currents. Images obtained under reference-dose conditions were reconstructed using the filtered back-projection method, whereas images obtained under low-dose conditions were reconstructed using both the filtered back-projection method and the iterative reconstruction method. Computer simulations involving the creation of finite element models using all images were implemented for the compression load calculation for vertebral body parts. Based on the calculated results, images of the low-dose and reference-dose conditions were compared. ResultsUsing pigs’ lower lumbar vertebrae, finite element model analysis of low-dose X-ray computed tomography images showed that equivalent results can be obtained with a dose of approximately 40% of the standard radiographic reference doses. As for the compression stress intensity, the same results as those under reference-dose conditions were obtained using the iterative reconstruction method in combination with computed tomography-based finite element method. ConclusionsThe combination of the iterative reconstruction method with the computed tomography-based finite element method is an effective image reconstruction method for achieving dose reduction.

Garetosmab Reduces Flare-ups in Patients With Fibrodysplasia Ossificans Progressiva

Abstract Background: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare, autosomal dominant disorder driven by mutations in ACVR1 that render it responsive to Activin A. FOP is characterized by progressive heterotopic ossification (HO) and distressing inflammatory events called “flare-ups.” Flare-ups can precede new HO; however, limited prospective data exists on this phenomenon. Garetosmab (GAR), an investigational human monoclonal antibody against Activin A, blocks formation of new HO in FOP. Methods: This is a post-hoc analysis of LUMINA-1 (NCT03188666) a phase 2, randomized, double-blind, placebo-controlled study, which evaluated the safety and efficacy of GAR (10 mg/kg/week IV) versus placebo (PBO) in adult patients with FOP over 28 weeks. Patient-reported flare-ups were collected via a patient diary and severity level was reported as mild, moderate or severe. Clinician-reported flare-ups were collected as adverse events in the trial. HO lesions were imaged by 18F-NaF positron emission tomography (PET) and whole-body low-dose X-ray computed tomography (CT). Results: There was a two-fold higher proportion of patients who reported one or more flare-ups on PBO 17/24 (71%) compared with GAR 7/20 (35%). Clinicians reported a four-fold higher proportion of patients experiencing one or more flare-ups on PBO 10/24 (42%) compared with GAR 2/20 (10%). Overall rates of flare-up events were two-fold higher on PBO vs. GAR (1.4 vs. 0.65 events/patient/28 weeks) for patient-reported events and eight-fold higher on PBO vs. GAR by clinician report (0.83 vs. 0.10 events/patient/28 weeks). Most flare-ups occurred on the extremities and back; pain was the most commonly reported symptom. Patient-reported flare-ups on PBO were more frequently reported as severe (29.4%) compared with GAR (7.7%). Among subjects with at least 12 weeks of follow-up from start of patient-reported flare-up, development of new HO near the site was 5/27 (18.5%) on PBO and (0%) on GAR. Of all new HO lesions, 41% on PBO and 0% on GAR occurred with spatial and temporal relation to flare-up. Conclusions: Approximately two-thirds of patients on PBO reported flare-ups over 28 weeks. GAR was associated with reductions in frequency and severity of flare-ups. Fewer than 20% of patient-reported flare-ups were associated with new HO, indicating frequent discordance of these phenomena, and compatible with previous reports. GAR’s ability to reduce patient- and clinician-reported flare-ups, as well as new HO lesions may provide an important therapeutic option.

Ultrafiltration Extract of Radix Angelica Sinensis and Radix Hedysari Attenuates Risk of Low-Dose X-Ray Radiation-Induced Myocardial Fibrosis In Vitro.

The risk of radiation-induced heart damage (RIHD) is a growing concern since recent advances in radiation therapy (RT) for cancer treatments have significantly improved the number of survivors. Radiation-induced myocardial fibrosis (RIMF) is the final pathological condition of RIHD and main change leading to serious cardiovascular complications following RT. The aim of this study was to investigate the effect of ultrafiltration extract of Radix Angelica Sinensis and Radix Hedysari (RAS-RH) on the proliferation, apoptosis, and reactive oxygen species (ROS) of cardiac fibroblasts after X-irradiation in vitro. The RAS-RH extract was from the Danggui Buxue decoction (DBD) in TCM. Primary cardiac fibroblasts were irradiated with 1 Gy X-ray to evaluate the effect of RAS-RH on the expression levels of cell proliferation, apoptosis, ROS, and fibrotic molecules. Our data demonstrated that X-irradiation at 1 Gy resulted in the proliferation of cardiac fibroblasts; RAS-RH attenuated the myocardial fibrosis. Furthermore, X-ray radiation reduced the apoptosis of cardiac fibroblasts; RAS-RH accelerated the apoptosis of these cells after irradiation. In addition, the damage driven by ROS in primary cardiac fibroblasts after irradiation was weakened by RAS-RH and the expression of TGF-β1, Col1, and α-SMA increased after irradiation; RAS-RH decreased the expression of these makers. Overall, these data indicate that low-dose X-ray irradiation boosts myocardial fibrosis, and the effect of RAS-RH protects against fibrosis via attenuating the proliferation and accelerating the apoptosis of myocardial fibroblasts after X-irradiation.

АНАЛИЗ ЭФФЕКТОВ НИЗКИХ ДОЗ РАДИАЦИИ НА МЕЗЕНХИМАЛЬНЫЕ СТВОЛОВЫЕ КЛЕТКИ ЧЕЛОВЕКА

Purpose: The aim of the study was to study the effect of low X-ray doses on human mesenchymal stem cells (MSCs) in long-term cultivation in vitro.
 Material and methods: MSCs of the mucosal gum tissue of human were used. Cells were irradiated using an RUST-M1 X-ray unit (Russia) at doses of 50, 80, 100, 250 and 1000 mGy (dose rate40 mGy/min) and then cultivated according to standard methods. Immunological characteristics and viability of MSCs were evaluated on a FACSCanto II flow cytometer (Becton Dickinson CA, USA) for early and late passengers. Proliferative activity (PA) was evaluated using an xCelligence real-time cell analyzer (ACEA Biosciencs, Inc.).
 Results: It was shown that the proliferative activity (PA) of MSCs of the mucosal gum tissue which were irradiated at dose 50 mGy is comparable with the control group in long-term cultivation while doses of 100 and 250 mGy showed a decrease of PA. Also non-irradiated MSCs showed a significant decrease of the PA during cultivation in a conditioned medium from cells that received dose of 1000 mGy and an increase of PA during cultivation in a conditioned medium of cells that received doses of 50, 100 and 250 mGy. The cells were previously irradiated at dose 250 mGy showed adaptive response during cultivation in conditioned medium from cells that received dose of 1000 mGy.
 Сonclusion: The assessment of the effects of low radiation doses was focused on the bystander effect in the presented study. It was noted after adding conditioned media from irradiated cells to previously irradiated and non-irradiated MSCs. The bystander effects for low and high doses are different and their biological meaning requires further study. The phenomenon of adaptive response was shown after addition conditioned media from cells irradiated at dose 1000 mGy to pre-irradiated MSCs received a dose of 250 mGy. The obtained result leads to the conclusion that the effects of low doses can be positive. Thus, the results of study mainly correspond to the threshold nonlinear concept, according to which the effect is not proportional to the received radiation dose.

Assessment of pedicle size in patients with scoliosis using EOS 2D imaging: a validity and reliability study

PurposeFree-hand pedicle screw insertion methods are widely used for screw insertion during scoliosis surgery. Preoperative knowledge about the pedicle size helps to maximize screw containment and minimize the risk of pedicle breach. Radiographs taken by a biplanar low-dose X-ray device (EOS) have no divergence in the vertical plane. The criterion validity and reliability of preoperative EOS images for pedicle size measurements in patients with idiopathic scoliosis (IS) was investigated in this study.MethodsSixteen patients who underwent surgical treatment for IS were prospectively included. Intra- and extracortical pedicle height and width measurements on EOS images were compared with reconstructed intra-operative 3D images of the isthmus of included pedicles. Secondly, intra- and interobserver reliability of pedicle size measurements on EOS images was determined.ResultsThe total number of analyzed pedicles was 203. The correlation between the EOS and 3D scan measurements was very strong for the intra- and extracortical pedicle height and strong for the intra- and extracortical pedicle width. There are, however, significant, but likely clinically irrelevant differences (mean absolute differences < 0.43 mm) between the two measure methods for all four measurements except for extracortical pedicle height. For pedicles classified as Nash–Moe 0, no significant differences in intra- and extracortical pedicle width were observed. Both intra- and interobserver reliability was excellent for all pedicle size measurements on EOS images.ConclusionThe results of this study indicate a good validity and reliability for pedicle size measurements on EOS radiographs. Therefore, EOS radiographs may be used for a preoperative estimation of pedicle size and subsequent screw diameter in patients with IS.

Persistent DNA Double-Strand Breaks After Repeated Diagnostic CT Scans in Breast Epithelial Cells and Lymphocytes.

DNA double-strand break (DSB) induction and repair have been widely studied in radiation therapy (RT); however little is known about the impact of very low exposures from repeated computed tomography (CT) scans for the efficiency of repair. In our current study, DSB repair and kinetics were investigated in side-by-side comparison of RT treatment (2 Gy) with repeated diagnostic CT scans (≤20 mGy) in human breast epithelial cell lines and lymphoblastoid cells harboring different mutations in known DNA damage repair proteins. Immunocytochemical analysis of well known DSB markers γH2AX and 53BP1, within 48 h after each treatment, revealed highly correlated numbers of foci and similar appearance/disappearance profiles. The levels of γH2AX and 53BP1 foci after CT scans were up to 30% of those occurring 0.5 h after 2 Gy irradiation. The DNA damage repair after diagnostic CT scans was monitored and quantitatively assessed by both γH2AX and 53BP1 foci in different cell types. Subsequent diagnostic CT scans in 6 and/or 12 weeks intervals resulted in elevated background levels of repair foci, more pronounced in cells that were prone to genomic instability due to mutations in known regulators of DNA damage response (DDR). The levels of persistent foci remained enhanced for up to 6 months. This “memory effect” may reflect a radiation-induced long-term response of cells after low-dose x-ray exposure.

Planarian stem cells specify fate yet retain potency during the cell cycle.

Planarian whole-body regeneration is enabled by stem cells called neoblasts. At least some neoblasts are individually pluripotent. Neoblasts are also heterogeneous, with subpopulations of specialized neoblasts having different specified fates. Fate specification in neoblasts is regulated by fate-specific transcription factor (FSTF) expression. Here, we find that FSTF expression is common in neoblast S/G2/M cell-cycle phases but less common in G1. We find that specialized neoblasts can divide to produce progeny with asymmetric cell fates, suggesting that they could retain pluripotency. Furthermore, no known neoblast class was present in all neoblast colonies, suggesting that pluripotency is not the exclusive property of any known class. We tested this possibility with single-cell transplantations, which indicate that at least some specialized neoblasts are likely clonogenic. On the basis of these findings, we propose a model for neoblast pluripotency in which neoblasts can undergo specialization during the cell cycle without loss of potency.

Direct conversion X-ray sensing nature of bismuth (III) iodide thick films

In this work, Bismuth (III) iodide (BiI3) thick film-based direct conversion X-ray sensor was fabricated for low-dose (mGy) X-ray detection since it exhibits high attenuation against 70 keV X-ray photon energy that is about 4.70 cm2/g. Prior to the device fabrication, commercial BiI3 powder was characterized for their phase, morphology, and optical properties. Nanocrystalline BiI3 film with ~211 µm thickness was coated on wet-etch-derived interdigitated electrode by the glass rod sliding technique using Poly(vinylidene fluoride co-hexafluoropropylene) as a binder. The photocurrent induced under the illumination of X-ray was measured for four different doses 7.97, 5.05, 2.56, and 1.28 mGy, then the observed photocurrent characteristics were applied to estimate sensitivity of the device and it was found to be 0.053, 0.045, 0.037, and 0.030 nC/mGy cm3, respectively. The response rate of our sensor was found to be linear with the exposed X-ray doses and it offers the applicability of BiI3 thick film in the direct conversion X-ray sensor fabrication for real-time applications.

Low dose whole Lung Therapy for patients with SARS-CoV-2&#x0D; disease (COVID-19) Pneumonitis

In this article provides an overview of publications by foreign authors of the novel coronavirus (SARS-CoV-2) and introduce a&#x0D; modified treatment method for COVID-19-associated pneumonia. X-ray therapy was used to treat pneumonia during the first half&#x0D; of the 20th century. Fifteen studies report that approximately 700 cases of bacterial (lobar and bronchopneumonia), sulfanilamide&#x0D; non-responsive, interstitial, and atypical pneumonia were effectively treated by low doses of X-rays, leading to disease resolution, based on clinical symptoms, objective disease biomarkers, and mortality incidence. The capacity of the X-ray treatment to reduce mortality was similar to serum therapy and sulfonamide treatment during the same time period. The mechanism by which the X-ray treatment acts upon pneumonia involves the induction of an anti-inflammatory phenotype that leads to a rapid reversal of clinical symptoms. The capacity of low doses of X-rays to suppress inflammatory responses is a significant new concept for treatment COVID-19 pneumonitis. Low dose whole lung irradiation may be a potential solution in the present time. International research organization and the International Geriatric Radiotherapy Group (http://www.igrg.org) proposed a simple and practical protocol for Low dose whole lung irradiation to allow participation of all countries in the world regardless of their resources and made available to the whole world community for treatment COVID-19 pneumonitis.

Benign and malignant breast tumors classification based on texture analysis and backpropagation neural network

Breast cancer is a leading cause of death in women due to cancer. According to WHO in 2018, it is estimated that 627.000 women died from breast cancer, that is approximately 15 % of all cancer deaths among women [3]. Early detection is a very important factor to reduce mortality by 25-30 %. Mammography is the most commonly used technique in detecting breast cancer using a low-dose X-ray system in the examination of breast tissue that can reduce false positives. A Computer-Aided Detection (CAD) system has been developed to effectively assist radiologists in detecting masses on mammograms that indicate the presence of breast tumors. The type of abnormality in mammogram images can be seen from the presence of microcalcifications and the presence of mass lesions. In this research, a new approach was developed to improve the performance of CAD System for classifying benign and malignant tumors. Areas suspected of being masses (RoI) in mammogram images were detected using an adaptive thresholding method and mathematical morphological operations. Wavelet decomposition is performed on the Region of Interest (RoI) and the feature extraction process is performed using a GLCM method with 4 statistical features, namely, contrast, correlation, entropy, and homogeneity. Classification of benign and malignant tumors using the MIAS database provided an accuracy of 95.83 % with a sensitivity of 95.23 % and a specificity of 96.49 %. A comparison with other methods illustrates that the proposed method provides better performance.

ATP-Responsive Smart Hydrogel Releasing Immune Adjuvant Synchronized with Repeated Chemotherapy or Radiotherapy to Boost Antitumor Immunity.

Certain chemotherapeutics and forms of ionizing radiation can induce immunogenic cell death (ICD). If there simultaneously exist immune adjuvants within the tumor, such antitumor immunity would be further amplified. However, as clinical chemo/radiotherapies are usually repeatedly given at low individual doses, it would be impractical to administrate immune adjuvants into tumors at each dose of chemo/radiotherapies. Thus, a smart hydrogel is developed that releases immune adjuvants in response to repeatedly applied chemo-/radiotherapies. Herein, alginate is conjugated with an adenosine triphosphate (ATP)-specific aptamer, which is hybridized with immunoadjuvant CpG oligonucleotide. Upon intratumoral injection, alginate-based hydrogel is formed in situ. Interestingly, low doses of oxaliplatin or X-rays, while inducing ICD of tumor cells, could trigger release of ATP, which competitively binds with ATP-specific aptamer to trigger CpG release. Therefore, the smart hydrogel could release the immune adjuvant synchronized with low-dose repeated chemo/radiotherapies, achieving remarkable synergistic responses in eliminating established tumors, as well as immune memory to reject re-challenged tumors. Moreover, repeated radiotherapies assisted by the smart hydrogel could inhibit distant tumor metastases, especially in combination with immune checkpoint blockade. The study presents a conceptually new strategy to boost cancer immunotherapy coherent with repeated low-dose chemo-/radiotherapies following a clinically relevant manner.

Ultra-flexible and highly sensitive scintillation screen based on perovskite quantum dots for non-flat objects X-ray imaging

A flexible and highly sensitive scintillation screen is urgently expected for X-ray imaging technology, especially for non-flat, flexible objects in medical and industrial applications. Here, we report a sandwich structure of polymer-perovskite quantum dots-polymer (PPP) scintillation screen. The outer polymer layer provides high mechanical stability and encapsulation for the internal perovskite quantum dots active layer. The relative light output remains 93 ± 0.5% of its initial value after bending cycles up to 600 with a bending radius down to 2.5 mm. This PPP scintillation screen exhibits ultra-sensitivity to low energy X-ray with a detection limit of 1.57nGyair/s and fast decay time of 63.7ns. Well-resolved X-ray images are recorded with a common digital camera with a spatial resolution of 5.35 lp/mm at MTF = 0.3 under the exposure dose of 12 μGyair, which is much lower than the requirement of medical applications. These features demonstrate that this flexible scintillation screen can be applied for non-flat X-ray imaging applications under low-dose X-ray exposure.

Accelerated 3D image reconstruction with a morphological pyramid and noise-power convergence criterion

Model-based iterative reconstruction (MBIR) for cone-beam CT (CBCT) offers better noise-resolution tradeoff and image quality than analytical methods for acquisition protocols with low x-ray dose or limited data, but with increased computational burden that poses a drawback to routine application in clinical scenarios. This work develops a comprehensive framework for acceleration of MBIR in the form of penalized weighted least squares optimized with ordered subsets separable quadratic surrogates. The optimization was scheduled on a set of stages forming a morphological pyramid varying in voxel size. Transition between stages was controlled with a convergence criterion based on the deviation between the mid-band noise power spectrum (NPS) measured on a homogeneous region of the evolving reconstruction and that expected for the converged image, computed with an analytical model that used projection data and the reconstruction parameters. A stochastic backprojector was developed by introducing a random perturbation to the sampling position of each voxel for each ray in the reconstruction within a voxel-based backprojector, breaking the deterministic pattern of sampling artifacts when combined with an unmatched Siddon forward projector. This fast, forward and backprojector pair were included into a multi-resolution reconstruction strategy to provide support for objects partially outside of the field of view. Acceleration from ordered subsets was combined with momentum accumulation stabilized with an adaptive technique that automatically resets the accumulated momentum when it diverges noticeably from the current iteration update. The framework was evaluated with CBCT data of a realistic abdomen phantom acquired on an imaging x-ray bench and with clinical CBCT data from an angiography robotic C-arm (Artis Zeego, Siemens Healthineers, Forchheim, Germany) acquired during a liver embolization procedure. Image fidelity was assessed with the structural similarity index (SSIM) computed with a converged reconstruction. The accelerated framework provided accurate reconstructions in 60 s (SSIM = 0.97) and as little as 27 s (SSIM = 0.94) for soft-tissue evaluation. The use of simple forward and backprojectors resulted in 9.3× acceleration. Accumulation of momentum provided extra ∼3.5× acceleration with stable convergence for 6–30 subsets. The NPS-driven morphological pyramid resulted in initial faster convergence, achieving similar SSIM with 1.5× lower runtime than the single-stage optimization. Acceleration of MBIR to provide reconstruction time compatible with clinical applications is feasible via architectures that integrate algorithmic acceleration with approaches to provide stable convergence, and optimization schedules that maximize convergence speed.