X-ray Radiation Dose Research Articles

TV-based conjugate gradient method and discrete L-curve for few-view CT reconstruction of X-ray in vivo data.

High-resolution, three-dimensional (3D) imaging of soft tissues requires the solution of two inverse problems: phase retrieval and the reconstruction of the 3D image from a tomographic stack of two-dimensional (2D) projections. The number of projections per stack should be small to accommodate fast tomography of rapid processes and to constrain X-ray radiation dose to optimal levels to either increase the duration of in vivo time-lapse series at a given goal for spatial resolution and/or the conservation of structure under X-ray irradiation. In pursuing the 3D reconstruction problem in the sense of compressive sampling theory, we propose to reduce the number of projections by applying an advanced algebraic technique subject to the minimisation of the total variation (TV) in the reconstructed slice. This problem is formulated in a Lagrangian multiplier fashion with the parameter value determined by appealing to a discrete L-curve in conjunction with a conjugate gradient method. The usefulness of this reconstruction modality is demonstrated for simulated and in vivo data, the latter acquired in parallel-beam imaging experiments using synchrotron radiation.

Sensitivity and fading of pMOS dosemeters irradiated with X-ray radiation doses from 1 to 100 cGy.

In this paper, the results of pMOS dosemeters sensitivity to X-ray radiation and 28-d fading at room temperature are presented. Two types of dosemeters were used, which differ in gate oxide layer thickness. The sensitivity of pMOS dosemeters with gate oxide layer thickness of 1 µm was followed in the dose intervals of 1 to 10 cGy and 10 to 100 cGy, whereas that of 400 nm was in the interval of 10 to 100 cGy. The sensitivity was characterised by the threshold voltage shift, which was determined as a function of absorbed radiation dose and time after irradiation. Linear dependence between threshold voltage shift and absorbed radiation dose was established, as well as that considerable fading occurs during the first few days after irradiation. The mechanisms responsible for threshold voltage shift during irradiation and latter annealing have been also discussed.

Loss of EGF-dependent cell proliferation ability on radioresistant cell HepG2-8960-R.

Acquired radioresistance of cancer cells interferes with radiotherapy and increases the probability of cancer recurrence. HepG2-8960-R, which is one of several clinically relevant radioresistant (CRR) cell lines, has a high tolerance to the repeated clinically relevant doses of X-ray radiation. In this study, HepG2-8960-R had slightly lower cell proliferation ability than HepG2 in the presence of FBS. In particular, epidermal growth factor (EGF) hardly enhanced cell proliferation and DNA synthesis in HepG2-8960-R. Additionally, EGF could not induce the activation of Erk1/2, because the expression of EGF receptor (EGFR) protein decreased in HepG2-8960-R in accordance with the methylation of the EGFR promoter region. Therefore, cetuximab did not inhibit HepG2-8960-R cell proliferation. Our study showed that HepG2-8960-R had radioresistant and cetuximab-resistant abilities.

How alkali-metal and silver ions affect the formation of structural defects in silicate glasses after x-irradiation

This article discusses how x-irradiation affects the formation of silver clusters, based on spectroluminescent studies. Increasing the x-ray irradiation dose increases the optical density of the test glasses in the 300–450-nm region and causes an absorption band to appear in the 300-nm region in the case of glasses that contain Na+. Replacing Na+ with Li+ substantially increases the absorption in the 250–300-nm region, while replacing Na+ with K+ displaces the absorption band into the 313-nm region. Intense luminescence was observed in the 450–820-nm region in all the test glasses after x-irradiation. These results are explained by taking into account the change of the structure of the glass and the physicochemical properties when various alkali oxides are introduced. An analysis of the luminescence properties of the test glasses made it possible to assume that negatively charged clusters of silver and complexes of the form Agn-Me were formed, where Me=Li+, Na+, K+.

Substantial radiation reduction in pediatric and adult congenital heart disease interventions with a novel X-ray imaging technology

BackgroundPediatric catheterization exposes patients to varying radiation doses. Concerns over the effects of X-ray radiation dose on the patient population have increased in recent years. This study aims at quantifying the patient radiation dose reduction after the introduction of an X-ray imaging technology using advanced real time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in a pediatric and adult population with congenital heart disease. MethodsPatient and radiation dose data was retrospectively collected (July 2012–February 2013) for 338 consecutive patients treated with a system using state of the art image processing and reference acquisition chain (referred as “reference system”). The same data was collected (March–October 2013) for 329 consecutive patients treated with the new imaging technology (Philips AlluraClarity, referred as “new system”). Patients were divided into three weight groups: A) below 10kg, B) 10–40kg, and C) over 40kg. Radiation dose was quantified using dose area product (DAP), while procedure complexity using fluoroscopy time, procedure duration and volume of contrast medium. ResultsThe new system provides significant patient dose reduction compared to the reference system. Median DAP values were reduced in group A) from 140.6cGy·cm2 to 60.7cGy·cm2, in group B) from 700.0cGy·cm2 to 202.2cGy·cm2 and in group C) from 4490.4cGy·cm2 to 1979.8cGy·cm2 with reduction of 57%, 71% and 56% respectively (p<0.0001 for all groups). ConclusionsDespite no other changes in procedural approach, the novel X-ray imaging technology provided substantial radiation dose reduction of 56% or higher.

Effect of annealing temperature and X-ray irradiation on the performance of tetraphenylporphyrin/p-type silicon hybrid solar cell

Hybrid organic–inorganic heterojunction solar cell, Au/tetraphenylporphyrin (TPP)/p-Si/Al, was fabricated. The TPP films were deposited by thermal evaporation technique onto p-type silicon single crystal wafer. The current–voltage characteristics of the heterojunction diode have been studied at a temperature range of 298 – 390K and the voltage applied during measurements varied from -1.5 to 2V. The device showed a rectification behavior like a diode under different temperatures. It was found that the conduction mechanisms of the diode are controlled by the thermionic emission at forward voltage bias ⩽0.5V and the single trap level space charge limited conduction (SCLC) mechanism at forward voltage bias >0.5V. Dependence of the I–V characteristics on temperature, illumination and X-ray irradiation dose of 50kGy for such a device have been studied. The dependence of photovoltaic parameters on annealing temperatures, illumination conditions and irradiation dose has been estimated. The calculated parameters are: series and shunt resistances, ideality factor, barrier potential, open-circuit voltage, short-circuit current, fill factor and efficiency.

Laser-Free RF-Gun as a Combined Source of Thz and Ps-Sub-Ps X-Rays

A coherent, mm-sub-mm-wave source driven by a RF electron gun is proposed for wide research applications as well as auxiliary inspection and screening, safe imaging, cancer diagnostics, surface defectoscopy, and enhanced time-domain spectroscopy. It allows generation of high peak and average THz-sub-THz radiation power provided by beam pre-bunching and chirping in the RF gun followed by microbunching in magnetic compressor, and resonant Cherenkov radiation of an essentially flat beam in a robust, ∼inch-long, planar, mm-sub-mm gap structure. The proof-of-principle has been successfully demonstrated in Phase I on a 5 MeV beam of L-band thermionic injector of Idaho Accelerator Center. The system can also deliver an intense, ps-sub-ps bursts of low-to-moderate dose of relativistic electrons and X-ray radiation produced by the same beam required for pulsed radiolysis as well as to enhance screening efficiency, throughput and safety.

Total Ionizing Dose X-ray Radiation Effects on MWCNT/PMMA Thin Film Composites

Multiwalled carbon nanotube (MWCNT) and poly(methyl methacrylate) (PMMA) composites are a new class of nanomaterial composites that have potential to be deployed as sensing elements for various applications including ionizing radiation detection. In this paper, we present an investigation of the ionizing radiation effects on electrical resistance of this composite both from a dose and dose rate standpoint. The solution blending method was used in synthesizing the MWCNT/PMMA composites. The synthesized thin film composites were cast on an interdigitated electrode to perform radiation sensing experiments. A 160-kV X-ray radiation source was used to study the ionizing radiation effects on the synthesized composite. A carbon black/PMMA composite was synthesized and subjected to the same dose and dose rate experiments as the MWCNT/PMMA thin film composite and a comparison was made. We have observed a very good repeatable quasi-linear response curve for radiation dose and dose rate measurement with the MWCNT/PMMA composite. Post radiation exposure recovery time of MWCNT/PMMA composite and heat treatment technique to accelerate recovery time have also been studied and the results are presented. The results suggest that simple sensor elements based on relatively economical MWCNT may be useful for the detection of ionizing radiation.

4종 해충의 발육과 생식에 대한 전자빔과 X-ray의 억제선량

This study investigated inhibitory doses of electron beam and X-ray irradiation by comparing their effects on the development and reproduction of four insect pests (Myzus persicae, Tetranychus urticae, Liriomyza trifolii, and Frankliniella intonsa). When M. persicae nymphs were irradiated with 100 Gy of electron beam and 30 Gy of X-ray beam, offspring production by adults that developed from the treated nymphs was completely inhibited. When M. persicae adults were irradiated with 200 Gy of electron beam and 50 Gy of X-ray beam, emergence of the generation was inhibited. However, these two ionizing radiations did not affect adult longevity. When T. urticae eggs were irradiated with 150 Gy of electron beam and 50 Gy of X-ray beam, egg hatching was completely inhibited. When L. trifolii pupae were irradiated, the emergence rate decreased with increasing doses of X-ray irradiation. After F. intonsa adults were irradiated with 250 Gy of electron beam and 200 Gy of X-ray beam, egg hatching of the generation was completely suppressed.

Assessment of Ge-doped optical fibres subjected to x-ray irradiation

We have reported the thermoluminescence (TL) response of five different diameters ~120, 241, 362, 483, and 604 μm of 6 mol percent Ge-doped optical fibres. The perfomance of the Ge-doped optical fibre are compared with commercially available TLD-100 chips (LiF:Mg,Ti) in terms of their sensitivity and minimum detectable dose (MDD). The irradiation was performed using X-ray machine (Model ISO 'Narrow Spectrum Series') provided by the Malaysian Nuclear Agency (MNA) at 60 kV X-ray irradiation in low doses ranging from 1-10 mGy. The results show the linear TL dose response from the fibres up to 10 mGy. The smallest diameter of 120 pm optical fibre shows the highest TL dose response compared to above mentioned fibres. The minimum detectable dose (MDD) is 0.82, 0.20, 0.14, 0.08, and 0.13 mGy for Ge-doped with diameters of 120, 241, 362, 483 and 604 μm. All TL materials show the MDD value within the delivered dose 0.01-1.00 mGy subjected to x-ray irradiation. The Ge-doped fibre with diameter of 483 pm was matched the MDD value of TLD-100 chips that equivalent to 0.08 mGy at the same irradiation. We have observed that among the five different diameters of optical fibre, 120 μm shows the best results and its better response than TLD-100 chips (by a factor of 5). The linear response at low dose levels makes this optical fibre most suitable for medical application.

The effect of low dose X-ray radiation on the bone ingrowth onto prosthesis interface

The effect of low dose X-ray radiation on the bone ingrowth onto prosthesis interface

Abstract 4921: X-ray irradiation induced bio luminescence: Ex vivo and endoscopic imaging of radiobioluminescence

Abstract Accurate dose delivery to malignant tissue in radiotherapy is essential for enhancing the treatment efficacy while minimizing morbidity of surrounding normal tissues. Advances in therapeutic strategies and diagnosis technologies along with our understanding of the biology of tumor response to radiation therapy have paved way to allow nearly 60% of current cancer patients to be treated with Radiation Therapy. The confluence of molecular imaging and nanotechnology fields are bridging physics and medicine and are quickly making strides in opening new avenues and therapeutic strategies that complement radiation therapy- with a distinct footprint in immunotherapy, adoptive cell therapy, and targeted chemotherapy. Incorporating optical imaging in radiation therapy in my laboratory, endogenous bioluminescence resulting from whole body irradiation in different organs, which is distinct from the cherenkov radiation, is described here. Mice were subjected to 5 - 10 Gy X-ray irradiation doses using commercially available X-RAD 320 irradiator (1Gy/min; F2 beam hardening filter 1.5mm Al, 0.25mm Cu, 0.75mm Sn; Precision X-ray inc, USA). The endogenous bioluminescence in response to irradiation, described here as radiobioluminescence, was captured using cooled CCD camera from live subjects, and from the excised organs/tissues. Significant increase (up to 100 fold) in the amounts of photons released as bioluminescence was detected during 5 -10 min capture from the mice subjected to irradiation compared to that of the control. The GI tract contributed significant portion of this radiobioluminescence and was confirmed both by ex-vivo and minimally invasive rectal endoscopic imaging. Other organs and tissues displaying such robust increase in radiobioluminescence include skin, and fat depots. The role, evaluation, and future assessment of nutrients, nutriceuticals, microbiome, and metabolites during the course of radiation therapy become highlighted with these findings. Thus such molecular imaging methodologies and modalities described will be useful tools in radiation treatment design and process. Citation Format: Rao V. Papineni. X-ray irradiation induced bio luminescence: Ex vivo and endoscopic imaging of radiobioluminescence. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4921. doi:10.1158/1538-7445.AM2014-4921

Modulation of radiation-induced alterations in oxidative stress and cytokine expression in lung tissue by Panax ginseng extract.

We investigated the modulating effect of Panax ginseng extract (PGE) on radiation-induced lung injury (RILI) by measuring early changes in oxidative stress levels, cytokine expression, and the histopathology of mouse lung tissue treated with high dose of X-ray radiation. The mice were pretreated with 25, 50, and 100-mg/kg doses of PGE orally for four consecutive days, and their thoraces were then exposed to 15-Gy X-ray radiation 1 h after the last administration of PGE on day 4. The pretreatments with 50 and 100 mg/kg PGE led to significant reductions in the elevation of lipid peroxidation levels at 2 and 10 days, respectively, after irradiation. The mice pretreated with PGE exhibited dose-dependent reductions in the irradiation-induced production of tumor necrosis factor α and transforming growth factor β1 cytokines 10 days after irradiation, with these reductions nearly reaching the control levels after the 100-mg/kg dose. Furthermore, together with providing significant protection against reductions in catalase activity and glutathione content, pretreatment with 100 mg/kg PGE resulted in a marked attenuation of the severity of inflammatory changes in lung tissue 10 days after irradiation. A high pretreatment dose of PGE may be a useful pharmacological approach for protection against RILI.

Effect of multiple short highly energetic X-ray pulses on the synthesis of endoglucanase by a mutant strain of Trichoderma reesei-M7

Bioconversion of cellulose-containing substrate to glucose represents an important area of modern biotechnology. Enzymes for the degradation of the polysaccharide part of biomass have been produced, mostly by fungi belonging to genus Trichoderma. Studies were carried out with the mutant strain Trichoderma reesei-M7, a cellulase producer. Spores of the enzyme producer were irradiated with different doses of characteristic X-ray radiation from metallic tungsten (mainly the W Kα1 and Kα2 lines) with a high dose rate. The latter is a specific property of the dense plasma focus (DPF) device, which has pulsed operation and thus gives short and highly energetic pulses of multiple types of rays and particles. In this case, we focused our study on the influence of hard X-rays. The doses of X-rays absorbed by the spores varied in the range of approximately 5–11,000 mSv measured with thermoluminescent dosimeters (TLD). The influence of the applied doses in combination with exceptionally high dose rates (in the order of tens of millisieverts per microsecond) on the activity of the produced endoglucanase, amount of biomass and extra-cellular protein, was studied in batch cultivation conditions. In the dose range of 200–1200 mSv, some enhancement of endoglucanase activity was obtained: around 18%–32%, despite the drop of the biomass amount, compared with the untreated material.

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak.

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points--three TLDs per point--to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

방사선 조사 및 Paraquat투여를 한 생쥐 간에 대한 홍삼의 보호 효과

방사선과 paraquat에 의해서 유도된 간 손상에 대한 홍삼추출물의 보호효과를 비교 연구하였다. ICR계 생쥐에게 X선의 5Gy조사와 paraquat투여 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하였다. 대조군은 생리적 식염수를 투여하고 방사선조사군은 생리적 식염수를 투여하면서 5Gy를 조사하였다. 홍삼추출물 투여군은 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하면서 5Gy를 조사하였다. Paraquat투여군은 7일 전부터 홍삼추출물(200mg/kg/day)을 투여하면서 paraquat(30mg/kg/day)를 투여하였다. 그리고 각각의 실험군에서 간조직의 H2O2, catalase, MDA를 측정하였다. 그 결과 방사선조사군과 paraquat투여군보다 홍삼추출물 투여군에서 catalase함량이 유의성 있게 증가하여 간의 보호효과가 있었으며 H2O2와 MDA함량도 유의성 있게 감소하였다. 홍삼추출물은 간 조직에 대한 방사선조사 및 paraquat투여로부터 매우 우수한 방호제라고 할 수가 있다. The protective effects of Red Ginseng on liver damage induced by linac X-ray and paraquat were investigated. To one group of ICR male mice were given in Red Ginseng(200mg/kg/day for 7days, orally) before 5Gy(1.01Gy/min) dose of linac X-ray irradiation. To another group were given in Red Ginseng (200mg/kg/day for 7days, orally) before paraquat(30mg/kg/day, orally) was Radiation irradiation group were given with saline(0.1ml) and 5Gy. Contrast group were given with saline(0.1ml). The levels of H2O2, catalase and MDA in liver tissue were measured. In Red Ginseng to paraquat(RG+PQ) group and Red Ginseng(RG+Rad) group than irradiation group(Rad), the catalase level were significantly increased, and the catalase levels were appeared at radiation protection. The Red Ginseng was significantly decreased to MDA and H2O2 level to paraquat(RG+PQ) group and Red Ginseng(RG+Rad) group than irradiation group(Rad). Therefore, Red Ginseng was very excellent protector on radiation and paraquat of liver in mice.

Combination of hypomorphic mutations of the Drosophila homologues of aryl hydrocarbon receptor and nucleosome assembly protein family genes disrupts morphogenesis, memory and detoxification.

Aryl hydrocarbon receptor is essential for biological responses to endogenous and exogenous toxins in mammals. Its Drosophila homolog spineless plays an important role in fly morphogenesis. We have previously shown that during morphogenesis spineless genetically interacts with CG5017 gene, which encodes a nucleosome assembly factor and may affect cognitive function of the fly. We now demonstrate synergistic interactions of spineless and CG5017 in pathways controlling oxidative stress response and long-term memory formation in Drosophila melanogaster. Oxidative stress was induced by low doses of X-ray irradiation of flies carrying hypomorphic mutation of spineless, mutation of CG5017, and their combination. To determine the sensitivity of these mutants to pharmacological modifiers of the irradiation effect, we irradiated flies growing on standard medium supplemented by radiosensitizer furazidin and radioprotector serotonin. The effects of irradiation were investigated by analyzing leg and antenna morphological structures and by using real-time PCR to measure mRNA expression levels for spineless, Cyp6g1 and Gst-theta genes. We also examined long-term memory in these mutants using conditioned courtship suppression paradigm. Our results show that the interaction of spineless and CG5017 is important for regulation of morphogenesis, long-term memory formation, and detoxification during oxidative stress. Since spineless and CG5017 are evolutionary conserved, these results must be considered when evaluating the risk of combining similar mutations in other organisms, including humans.

Cytotoxic properties of radionuclide-conjugated Cetuximab without and in combination with external irradiation in head and neck cancer cells in vitro

Purpose: Epidermal growth factor receptor (EGFR) is critically involved in progression and therapy resistance of squamous cell carcinoma (SCC). Albeit EGFR targeting could improve the effect of radiotherapy on patients’ outcome, the clinical results failed to meet expectations from preclinical studies. In this work, we evaluated the potential of the radionuclide Yttrium-90 (90Y) bound to Cetuximab (90Y-Cetuximab) as novel targeting approach for SCC cells in vitro.Materials and methods: FaDu and A431 cell lines were used. EGFR subcellular localization, clonogenic survival, radiation-induced γH2AX foci and EGFR signaling were examined. Cells were treated with DTPA, DTPA-Cetuximab, 90Y and 90Y-Cetuximab alone or in combination with external X-ray irradiation.Results: Dose- and cell line-dependently, 90Y-Cetuximab mediated a significant reduction in clonogenicity relative to unbound 90Y. Combined 2-Gy external radiation plus 2-Gy equivalent dose of 90Y-Cetuximab was more effective than equivalent doses of 90Y and X-ray radiation. Analogous effects were observed in the number of residual radiation-induced foci. Additionally, EGFR, ERK1/2 and AKT phosphorylation showed alterations upon different treatments.Conclusions: Our findings show that Cetuximab-conjugated 90Y has a significant potential to eradicate human SCC cells. A combination of radioimmunotherapeutic compounds and external radiotherapy might be a promising treatment strategy for clinical application.

ESR investigation of sucrose radicals produced by 0.25−4.5 Gy doses of X-ray irradiation

We investigated stable radicals produced by 0.25−4.5 Gy doses of X-ray irradiation of sucrose. Electron spin resonance (ESR) is able to observe the signal from sucrose irradiated at 0.25 Gy. The ESR signal intensity of the radicals is related to the accumulated dose, and it increases linearly with increasing absorbed dose. In addition, we examined the effect of dose rate (0.50−1.5 Gy/min) on the signal intensity of the irradiated sucrose. The stable radical production did not exhibit dose rate dependence. In addition, the peak corresponding to the irradiated glucose was observed to increase more with increasing absorbed dose than the peak corresponding to irradiated fructose. Therefore, the present ESR results regarding the 0.25−4.5 Gy irradiation of sucrose provide new insights into a possible sucrose ESR dosimeter.

Model-based Iterative Reconstruction: A Promising Algorithm for Today's Computed Tomography Imaging

Because of its fast image acquisition and the rich diagnostic information it provides, computed tomography (CT) has gradually become a popular imaging modality among clinicians. Because CT scanners emit x-rays, the increased use of CT in clinical applications inevitably leads to increased medical radiation dose to the population. Because of the well-known cancer-inducing effects of high dose x-ray radiation, this increased dose has caused concerns among policy makers and general public that CT patients may be at a higher risk of developing cancer. Over the years, CT manufacturers have developed a variety of strategies to address this issue, the latest being a model-based iterative reconstruction (MBIR) algorithm. MBIR is an advanced CT algorithm that incorporates modeling of several key parameters that were omitted in earlier algorithms to reduce computational requirement and speed up scans. This review article examines the latest literature in the clinical CT field and discusses the general principles of MBIR, its dose and noise reduction potentials, its imaging characteristics, and its limitations. MBIR algorithm and its application in today's CT imaging will greatly reduce the radiation dose to patients and improve image quality for clinicians.