Extra Radiation Research Articles

Optimizing prone CT use for suspected interstitial lung abnormalities.

We investigated whether supine chest CT alone suffices for diagnosing ILAs, thereby reducing the need for prone chest CT. Patients who underwent prone chest CT for suspected ILAs from January 2021 to July 2023, with matching supine CT within 1 year, were retrospectively evaluated. Five multinational thoracic radiologists independently rated ILA suspicion and fibrosis scores (1 to 5-point) and ILA extent (1-100%) using supine CT first, then combined supine-prone CT after a 1-month washout. We categorized ILA suspicion and fibrosis scores into four diagnostic groups; normal, non-fibrotic, indeterminate-type, and fibrotic ILAs. The areas under the receiver operating characteristic curve (AUCs) of ILA suspicion scores, inter-reader agreement on diagnostic categories, and intra-reader/inter-reader reliability for ILA extent were evaluated. This study included 69 patients (mean age 67.2 ± 7.2 years; 36 women), with 23 age- and sex-matched patients in each group: normal, non-fibrotic ILAs, and fibrotic ILAs. The pooled AUC for ILA suspicion and inter-reader agreement on diagnostic categories improved for non-fibrotic ILAs with prone CT (AUC 0.76 to 0.92, p < 0.001; Fleiss kappa 0.25 to 0.51, p = 0.004), but not for fibrotic ILAs (AUC 0.94 to 0.99, p = 0.06; Fleiss kappa 0.63 to 0.72, p = 0.08). ILA extent was 1-2% smaller with prone CT for both ILA types (p < 0.001). For fibrotic ILAs, supine CT alone exhibited substantial diagnostic accuracy and inter-reader agreement, while the diagnosis of non-fibrotic ILAs benefited from adding prone CT. Supine CT alone slightly overestimated extent regardless of ILA type. Question Prone CT is recommended when interstitial lung abnormalities (ILAs) are suspected on supine CT, but its benefits remain underexplored. Findings Supine CT alone sufficed for diagnosing fibrotic ILAs, while prone CT improved non-fibrotic ILA diagnosis and reduced extent overestimation for both types. Clinical relevance Omitting prone CT reduces extra time, space, and radiation exposure without compromising the diagnosis of fibrotic ILAs, which have higher rates of progression and mortality risks, enhancing patient comfort and simplifying patient management.

A quality improvement project addressing motion artefact on CTPAs in a district general hospital setting: A complete cycle resulting in changed practice.

Introduction: A still breath hold from the patient is one of the key requirements for a diagnostic computed tomography pulmonary angiogram (CTPA). It is important for the timely identification and treatment of patients with life threatening pulmonary emboli (PEs). Motion artefact on CTPA can cause blurring, double borders, shading and streaking in the lungs, which can either obscure PEs or create artefact that mimics PEs. This risks patient harm from delayed diagnoses, missed PEs, false positives and extra radiation and contrast exposure due to repeat studies. Methods: We devised local standards and methodology for assessing the presence and degree of motion artefact on CTs. The study consisted of initial data collection, implementation of changes to clinical practice, and subsequent repeat data collection 3 months after implementation of interventions. For each data collection round, 100 consecutive inpatient and emergency CTPAs performed in a UK District General Hospital were retrospectively identified and images reviewed to categorise each as having either: ‘no significant’, ‘minor’ or ‘major’ motion artefact. There were no exclusions. Interventions after initial data collection included a multidisciplinary meeting with radiographers, department assistants, and radiologists to devise changes to workflow and practices to build in 'rehearsal' of a breath-hold and explanation of breathing instructions with patients before scanning. A prompting phrase for this was added to our CTPA scanning protocol. Results: Initial results demonstrated that 50% of CTPA showed either minor or major motion artefact, while 50% showed no significant motion artefact. For 2% with minor motion, a clinical reason for why this was unavoidable was provided. Therefore 52% of studies met the proposed local standards. In total, 45% of CTPA were assessed to have minor motion and 5% had major motion artefact (non-diagnostic). 18% of CTPA were positive for PE. Following implementation of changes to practice, repeat data collection demonstrated that 67% of CTPA showed no significant motion artefact. 3% with minor motion provided a clinical reason why this was unavoidable. Therefore 70% of studies met the proposed standard. The increase in compliance with local standards was statistically significant (p=0.00906). Conclusion: Our interventions improved compliance with local standards from 52% to 70%. We recommend rehearsal of breath-holding with patients before CTPA scans as a quick and easy way to improve the diagnostic quality of scans. A prompting phrase within the CTPA scanning protocol has proven effective.

Gravitational waves from more attractive dark binaries

The detection of gravitational waves (GWs) has led to a deeper understanding of binaries of ordinary astrophysical objects, including neutron stars and black holes. In this work, we point out that binary systems may also exist in a dark sector with astrophysical-mass macroscopic dark matter. These “dark binaries”, when coupled to an additional attractive long-range dark force, may generate a stochastic gravitational wave background (SGWB) with a characteristic spectrum different from ordinary binaries. We find that the SGWB from planet-mass dark binaries is detectable by space- and ground-based GW observatories. The contribution to the SGWB today is smaller from binaries that merge before recombination than after, avoiding constraints on extra radiation degrees of freedom while potentially leaving a detectable GW signal at high frequencies up to tens of GHz.

Design of compact low‐profile single‐layer filtering antenna based on half‐mode patches

AbstractIn this paper, a single‐layer filtering antenna based on half‐mode patches is proposed. It consists of a main driven patch and a parasitic patch. A U‐shaped slot is first etched on the main driven patch to generate a new resonant mode and a radiation null simultaneously. Four pairs of shorting pins are introduced on the main driven patch to raise its operating frequency to near that of the U‐shaped slot, thus broadening the impedance bandwidth (IBW). Additionally, a parasitic patch is introduced near the driven patch to introduce an extra half‐TM10 mode and an extra radiation null, significantly enhancing the IBW and the upper‐edge selectivity of the antenna. A prototype was fabricated and tested for validation. It achieves a peak realized gain of 6.55 dBi and −10‐dB IBW of 8.8%, and exhibits good out‐of‐band rejection performance while maintaining a low profile of 0.017 λ0 and a compact transverse size of 0.29 λ02.

F(R) gravity dark energy model of an interaction between dark radiation and dark matter

In this work, we will study the late-time dynamic evolution of the F(R) gravity dark energy model of an interaction between dark radiation and dark matter. We explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decaying into dark radiation. The decay process is controlled by its rate Q=αHρdm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q=\\alpha H\\rho _{dm}$$\\end{document}, where α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} is the (constant) dimensionless parameter quantifying the strength of the decay mechanism, for the weak coupling between dark matter and dark radiation α≪1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha \\ll 1$$\\end{document}. We will solve the field equations numerically by using the statefinder function yH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$y_{H}$$\\end{document} to appropriately represent the field equation. The F(R) gravity model we consider is described by a nearly R2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^{2}$$\\end{document}-model at early epochs and at late-time the model mimic the Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda $$\\end{document}-Cold-Dark-Matter model (ΛCDM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda CDM$$\\end{document}), and we fine tune the parameters to achieve viability and compatibility with the latest Planck constraints at late-time. Furthermore, we consider the behavior of several well-known statefinder quantities, we find that statefinder diagnostic and Om diagnostic can not only break the degeneracy of different parameter values in the F(R) gravity dark energy model, but also effectively distinguish the difference between the F(R) gravity model and the ΛCDM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda CDM$$\\end{document} model. At last, we compared the theoretical results with the SNIa data.

Coronary calcification on invasive angiography and the Agatston score—a single-center experience

Aim: The pattern and severity of coronary artery calcification (CAC) can influence prognosis and outcome in percutaneous coronary intervention. An objective assessment of CAC during invasive angiography may provide additional prognostic information. This study aimed to assess the correlation between the angiographic Birmingham calcium score (BCS) and the Agatston coronary calcium score (CCS) performed as part of single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI). Methods: In this retrospective observational study, patients undergoing SPECT-MPI and invasive coronary angiography as part of their routine management were included. BCS was calculated by reviewing angiography images in retrospect by an observer blinded to the SPECT-MPI calcium score. Spearman’s correlation was used to analyze the correlation between BCS and SPECT-MPI. Receiver operating characteristic curve was used to detect cut-off for BCS that would detect clinically significant CAC [&gt; 400 Agatston units (AU)]. Kaplan-Meier was used to report on outcomes at 5 years follow-up. Results: In this cohort of 151 patients, there was a positive correlation between BCS and CCS [Spearman correlation coefficient (r) = 0.558, P &lt; 0.001]. Cumulative BCS of 1 was able to identify clinically significant CAC [area under the curve 0.788, 95% confidence interval (CI) 0.714–0.863]. Cumulative BCS ≥ 3 was associated with major adverse outcomes at 5 years follow-up (log rank P = 0.013). Conclusion: BCS correlates well with established higher CCS. Application of BCS during invasive coronary angiography will aid risk stratification, management, and follow-up with no extra patient involvement, radiation, or costs.

Interpretable deep learning analysis on correction of motion blur X-ray images to ensure the efficiency and reliability of clinical decisions

Motion blur X-rays often lead to repeated imaging and extra radiation exposure. This study introduces an interpretable deep learning method to ensure AI prediction efficiency and reliability and uses the correction of motion blur X-ray images as a case study. A deep learning model that integrates Enhanced Super-Resolution Generative Adversarial Network (ESRGAN) and EfficientNet-B3 is trained to correct motion-blurred images with interpretable analysis. ESRGAN corrects motion-blurred images and EfficientNet-B3 tackles the disease recognition. The accuracy on public datasets reaches 0.97 and clinical motion blur X-rays improves from 0.4 to 0.74 with an 85% increase. The results are analyzed using image quality metrics and interpretative methods to confirm the effectiveness and reliability of the proposed method. The proposed method ensures accuracy and reliability in disease recognition and improves the quality of X-ray images, which are verified with actual clinical data. This approach alleviates the workload of radiologists, reduces radiation exposure risks for patients, and holds promise for wider applications in medical imaging. To the best of our knowledge, this is the first study combining deep learning with interpretability to ensure the deblurring task of medical images with potential applications in CT and MRI.

Design of a compact filtering antenna with multi-adjustable radiation nulls

ABSTRACT A compact filtering antenna with multi-adjustable radiation nulls is designed. Initially, a conventional aperture-coupled antenna is crafted by fine-tuning positions of the gap and radiation patch, achieving a radiation null. Additionally, an aperture-coupled filtering antenna is created by cascading a resonator with a microstrip feedline. Subsequently, the integration of the aperture-coupled antenna and the filtering antenna results in a dual-slot aperture cross-coupling filtering antenna, with two radiation nulls at both ends of the passband. Finally, a pair of slot lines is etched on the radiation patch, introducing an extra radiation null to enhance selectivity further. The measured results show that the proposed filtering antenna has a bandwidth from 2.44 to 2.64 GHz for |S 11|<−10 dB, a peak gain of 5.5 dBi, and three radiation nulls at 2.3, 2.75, and 3.15 GHz enhancing the selectivity.

The Value of Axial Imaging to Check Reduction after Anterior Approach Open Reduction for Developmental Dysplasia of the Hip

Background: There are still many controversies regarding the diagnosis and management of developmental dysplasia of the hip (DDH). Axial imaging is routinely used after closed or open reduction to confirm reduction has occurred. In this study, we aimed to determine the rate of early re-dislocation or failure of reduction after anterior approach open reduction (AOR), to establish whether there is a true need for routinely performing post-operative axial imaging.&#x0D; Methods: We retrospectively reviewed radiographs, operation notes and post-operative CT scan images of our AOR cases from September 2018 to June 2020. The CT scan images were reviewed to check the post-operative reduction and congruency. The ‘posterior neckline’ and the ‘modified Shenton line’ were used to assess reduction. The related literature was also reviewed.&#x0D; Results: Thirty patients were included. The post-operative CT scans confirmed that all cases had reduced congruent hips. The CT scans did not change future treatment plans for any patient in this cohort and did not predict late re-dislocation.&#x0D; Conclusions: The rate of early re-dislocation or failure of reduction after AOR was negligible. Traditional routine axial imaging after this operation is therefore unjustified and has no value in predicting possible late re-dislocations. It also comes at the cost of extra radiation to the child and expense for the health system. We recommend stopping the routine use of post-operative axial imaging and using it selectively for specific indications, including teratologic and neuromuscular hips, bilateral DDH, and after revision surgery, in addition to closed reductions and medial approach open reduction.

Evaluating delivered radiation dose in intraoperative radiotherapy for breast cancer using TLD

The extra radiation that it delivers has been questioned by patients, physicians, and the public for early breast cancer patients of intraoperative radiotherapy (IORT). This investigation concerns a left breast Rando phantom with a lumpectomy cavity of 30 cm3 of left breast of Rando phantom made of polymethylmethacrylate (PMMA). Thermoluminescent dosimetry (TLD) was used to evaluate the extra radiation dose or air kerma (kair) rate under IORT from 20 Gy, 50 kV of an Xoft Axxent system. TLDs were first calibrated using 50 kV photons, and then inserted at phantom positions that were close to the positions of the represented organs and tissues. Equivalent doses (DT) delivered to the organ at risks (OAR) were evaluated according to ICRP 103. Entrance surface doses (ESD) or skin doses (Dskin) varied markedly among positions close to the lumpectomy cavity. The dose was 20 Gy at the surface of a balloon applicator and kair varied from 6.40 ± 0.92 Gy down to 1.20 ± 0.30 mGy along the left-right axis of the 17th slice of Rando. These experimental results are compared with those in the literature. The shielding effect of the tungsten-impregnated rubber was also evaluated. This study supports recommendations to patients, relatives, physicians and radiologists concerning IORT.

Natural lighting of interiors and sun protection of premises with roof lighting system

The article describes the contemporary issues of natural lighting of interiors of civil and industrial buildings. The major attention is given to the roof lighting system of the buildings in question, as far as this system provides not only increased levels of natural lighting, but sometimes an undesirable heat gains, due to prolonged insolation period and hence, extra solar radiation. It is noted, that this reason leads to design and construct the means of natural lighting in such a way, that to provide interiors with sufficient natural illumination and efficient sun protection at the same time. Some principal conclusions and recommendations were made as a result of analytic studies, presented in the article. For example, it was competently proved that the best solar standing solution for roof lighting installations are sheds, or sawtooth roof structure. The worst solution, to protect interiors from solar overheating are roof skylights. These skylights require extra sun protection in form of jalousies, blinds, etc. The same additional solar shading, though to less extend, is needed to provide additional sun protection for roof monitors.

ALTERNATIVE METHOD OF PHOTOPOLYMERIZATION OF COMPOSITE RESIN SPECIMEN FOR FLEXURAL STRENGTH TEST

The flexural resistence is one of the most used test in researchs of mechanical characterization of resin composites for dental restoration. ISO 4049 photopolymerization technique performed static application stages of light tip. To polymerize the entire area of ​​the specimen some areas must receive extra radiation. These areas with extra radiation are called overlap areas. In an attempt to remedy this problem, this research compared the ISO method with a new method using constant movement (CM) during photopolymerization. Twenty specimens (SPs) were produced with 25 x 2 x 2 mm, for each group, 10 specimens being polymerized by the static technique recommended by the ISO-4049 and 10 specimens polymerized by the CM technique for each LED curing light used. After Tukey's statistical analysis, it was found that there was no statistical difference in relation to flexural strength (FS) and for the flexural modulus of elasticity (EF). However, the standard deviation of both FS and EF were much lower in MC than in ISO. Therefore, the photopolymerization by CM of the samples for the flexural strength test proved to be a possible solution to the problem of overlap of the technique proposed by ISO. Keywords: Flexural Strength, Elastic Modulus, Composite Resin, Photopolymerization.

Development and evaluation of ultrasound image tracking technology based on Mask R-CNN applied to respiratory motion compensation system.

For respiration induced tumor displacement during a radiation therapy, a common method to prevent the extra radiation is image-guided radiation therapy. Moreover, mask region-based convolutional neural networks (Mask R-CNN) is one of the state-of-the-art (SOTA) object detection frameworks capable of conducting object classification, localization, and pixel-level instance segmentation. We developed a novel ultrasound image tracking technology based on Mask R-CNN for stable tracking of the detected diaphragm motion and applied to the respiratory motion compensation system (RMCS). For training Mask R-CNN, 1800 ultrasonic images of the human diaphragm are collected. Subsequently, an ultrasonic image tracking algorithm was developed to compute the mean pixel coordinates of the diaphragm detected by Mask R-CNN. These calculated coordinates are then utilized by the RMCS for compensation purposes. The tracking similarity verification experiment of mask ultrasonic imaging tracking algorithm (M-UITA) is performed. The correlation between the input signal and the signal tracked by M-UITA was evaluated during the experiment. The average discrete Fréchet distance was less than 4 mm. Subsequently, a respiratory displacement compensation experiment was conducted. The proposed method was compared to UITA, and the compensation rates of three different respiratory signals were calculated and compared. The experimental results showed that the proposed method achieved a 6.22% improvement in compensation rate compared to UITA. This study introduces a novel method called M-UITA, which offers high tracking precision and excellent stability for monitoring diaphragm movement. Additionally, it eliminates the need for manual parameter adjustments during operation, which is an added advantage.

Radiomics Based on Single-Phase CTA for Distinguishing Left Atrial Appendage Thrombus from Circulatory Stasis in Patients with Atrial Fibrillation before Ablation.

Differentiation of left atrial appendage thrombus (LAAT) and left atrial appendage (LAA) circulatory stasis is difficult when based only on single-phase computed tomography angiography (CTA) in routine clinical practice. Radiomics provides a promising tool for their identification. We retrospectively enrolled 204 (training set: 144; test set: 60) atrial fibrillation patients before ablation, including 102 LAAT and 102 circulatory stasis patients. Radiomics software was used to segment whole LAA on single-phase CTA images and extract features. Models were built and compared via a multivariable logistic regression algorithm and area under of the receiver operating characteristic curves (AUCs), respectively. For the radiomics model, radiomics clinical model, radiomics radiological model, and combined model, the AUCs were 0.82, 0.86, 0.90, 0.93 and 0.82, 0.82, 0.84, 0.85 in the training set and the test set, respectively (p < 0.05). One clinical feature (rheumatic heart disease) and four radiological features (transverse diameter of left atrium, volume of left atrium, location of LAA, shape of LAA) were added to the combined model. The combined model exhibited excellent differential diagnostic performances between LAAT and circulatory stasis without increasing extra radiation exposure. The single-phase, CTA-based radiomics analysis shows potential as an effective tool for accurately detecting LAAT in patients with atrial fibrillation before ablation.

Validation of Opportunistic Artificial Intelligence-Based Bone Mineral Density Measurements in Coronary Artery Calcium Scans

BackgroundPreviously we reported a manual method of measuring thoracic vertebral bone mineral density (BMD) using quantitative CT in noncontrast cardiac CT scans used for coronary artery calcium (CAC) scoring. In this report, we present validation studies of an artificial intelligence–based automated BMD measurement (AutoBMD) that recently received FDA approval as an opportunistic add-on to CAC scans. MethodsA deep learning model was trained to detect vertebral bodies. Subsequently, signal processing techniques were developed to detect intervertebral discs and the trabecular components of the vertebral body. The model was trained using 132 CAC scans comprising 7,649 slices. To validate AutoBMD, we used 5,785 cases of manual BMD measurements previously reported from CAC scans in the Multi-Ethnic Study of Atherosclerosis. ResultsMean ± SD for AutoBMD and manual BMD were 166.1 ± 47.9 mg/cc and 163.1 ± 46 mg/cc, respectively (P = .006). Multi-Ethnic Study of Atherosclerosis cases were 47.5% male and 52.5% female, with age 62.2 ± 10.3. A strong correlation was found between AutoBMD and manual measurements (R = 0.85, P < .0001). Accuracy, sensitivity, specificity, positive predictive value and negative predictive value for AutoBMD-based detection of osteoporosis were 99.6%, 96.7%, 97.7%, 99.7% and 99.8%, respectively. AutoBMD averaged 15 seconds per report versus 5.5 min for manual measurements (P < .0001). ConclusionsAutoBMD is an FDA-approved, artificial intelligence–enabled opportunistic tool that reports BMD with Z-scores and T-scores and accurately detects osteoporosis and osteopenia in CAC scans, demonstrating results comparable to manual measurements. No extra cost of scanning and no extra radiation to patients, plus the high prevalence of asymptomatic osteoporosis, make AutoBMD a promising candidate to enhance patient care.

Implications for Primordial Black Holes from Cosmological Constraints on Scalar-induced Gravitational Waves

Sufficiently large scalar perturbations in the early universe can create overdense regions that collapse into primordial black holes (PBHs). This process is accompanied by the emission of scalar-induced gravitational waves that behave like an extra radiation component, thus contributing to the relativistic degrees of freedom (N eff). We show that the cosmological constraints on N eff can be used to pose stringent limits on PBHs created from this particular scenario as well as the relevant small-scale curvature perturbation (). We show that the combination of cosmic microwave background (CMB), baryon acoustic oscillation, and Big Bang nucleosynthesis data sets can exclude supermassive PBHs with peak mass M • ∈ [5 × 105, 5 × 1010] M ⊙ as the major component of dark matter, while the detailed constraints depend on the shape of the PBHs’ mass distribution. A future CMB mission such as CMB-S4 can greatly broaden this constraint window to M • ∈ [8 × 10−5, 5 × 1010] M ⊙, covering substellar masses. These limits on PBHs correspond to a tightened constraint on on scales of k ∈ [10, 1022] Mpc−1, much smaller than those probed by direct CMB and large-scale structure power spectra.

Thermal friction as a solution to the Hubble and large-scale structure tensions

Thermal friction offers a promising solution to the Hubble and the large-scale structure (LSS) tensions. This additional friction acts on a scalar field in the early universe and extracts its energy density into dark radiation, the cumulative effect being similar to that of an early dark energy (EDE) scenario. The dark radiation automatically redshifts at the minimal necessary rate to improve the Hubble tension. On the other hand, the addition of extra radiation to the Universe can mitigate the LSS tension. We explore this model in light of cosmic microwave background (CMB), baryon acoustic oscillation, and type Ia supernova data, including the SH0ES ${H}_{0}$ measurement and the Dark Energy Survey Y1 data release in our analysis. Our results indicate a preference for the regime where the scalar field converts to dark radiation at very high redshifts ($z\ensuremath{\gtrsim}{10}^{5}$), asymptoting effectively to an extra self-interacting radiation species rather than an EDE-like injection. In this limit, thermal friction can ease both the Hubble and the LSS tensions, but not resolve them. We find the source of this preference to be the incompatibility of the CMB data with the linear density perturbations of the dark radiation when injected at redshifts close to matter-radiation equality.

PO-1548 Role of extra corporeal radiation in bone tumors

PO-1548 Role of extra corporeal radiation in bone tumors

Bulk-Plasmon-Mediated Free-Electron Radiation Beyond the Conventional Formation Time.

Free-electron radiation is a fundamental photon emission process that is induced by fast-moving electrons interacting with optical media. Historically, it has been understood that, just like any other photon emission process, free-electron radiation must be constrained within a finite time interval known as the "formation time," whose concept is applicable to both Cherenkov radiation and transition radiation, the two basic mechanisms describing radiation from a bulk medium and from an interface, respectively. Here, this work reveals an alternative mechanism of free-electron radiation far beyond the previously defined formation time. It occurs when a fast electron crosses the interface between vacuum and a plasmonic medium supporting bulk plasmons. While emitted continuously from the crossing point on the interface-thus consistent with the features of transition radiation-the extra radiation beyond the conventional formation time is supported by a long tail of bulk plasmons following the electron's trajectory deep into the plasmonic medium. Such a plasmonic tail mixes surface and bulk effects, and provides a sustained channel for electron-interface interaction. These results also settle the historical debate in Ferrell radiation, regarding whether it is a surface or bulk effect, from transition radiation or plasmonic oscillation.

Tuning spin-orbit coupling and realizing inverse persistent spin helix by an extra above-barrier radiation in a GaAs/Al0.3Ga0.7As heterostructure.

A persistent spin helix with equal strength of the Rashba and Dresselhaus spin-orbit coupling (SOC) is expected for future spintronic devices due to the suppression of spin relaxation. In this work we investigate the optical tuning of the Rashba and Dresselhaus SOC by monitoring the spin-galvanic effect (SGE) in a GaAs/Al0.3Ga0.7As two dimensional electron gas. An extra control light above the bandgap of the barrier is introduced to tune the SGE excited by a circularly polarized light below the bandgap of GaAs. We observe different tunability of the Rashba- and Dresselhaus-related SGE currents and extract the ratio of the Rashba and Dresselhaus coefficients. It decreases monotonously with the power of the control light and reaches a particular value of ∼-1, implying the formation of the inverse persistent spin helix state. By analyzing the optical tuning process phenomenologically and microscopically, we reveal greater optical tunability of the Rashba SOC than that of the Dresselhaus SOC.