Influence Of Radiation Dose Research Articles

Gamma irradiation green synthesis of (polyacrylamide/chitosan/silver nanoparticles) hydrogel nanocomposites and their using as antifungal against Candida albicans and anti-cancer modulator

Silver nanoparticles-loaded hydrogel nanocomposites are exploited for medicinal and pharmaceutical applications. Hydrogel nanocomposites were prepared from acrylamide (Am), chitosan (CS) and AgNO3 utilizing gamma rays. Diverse variables were applied in preparation of silver nanoparticles-laoded hydrogel nanocomposites of (PAm/CS)-AgNPs such as influence of radiation dose and influnece of CS concentration. Diverse techniques were utilized to characterize hydrogel nanocomposites; Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and scanning electron microscopy (SEM). Results confirmed formation of silver nanoparticles-loaded hydrogel nanocomposites of (PAm/CS)-AgNPs. Antifungal activity of (PAm/CS)-AgNPs hydrogel nanocomposites on viability of C. albicans was esitmated. Results displayed the efficient microbial inhibition activity of treatment against C. albicans compared to control. Furthermore, (PAm/CS)-AgNPs hydrogel nanocomposite against cervical cancer HeLa cell line was investigated. Cytotoxicity of (PAm/CS)-AgNPs hydrogel nanocomposites on prior cancer cell line empolyed to prohibition of cell growth assesssed by MTT test. HeLa cancer cell is treated by (PAm/CS)-AgNPs for 48 h exposed a potential apoptotic activity by noticeable up-regulation of p53 gene expression. Moreover, anticancer activity was investigated by down-regulation of platelet-based growth variable receptor beta (PDGFR-β), Bcl2, Cathepsine, and MMP-2 gene expression. antioxidant activity was investigated and results showed antioxidant activity of (PAm/CS) hydrogel and (PAm/CS)-AgNPs hydrogel nanocomposite are 87.8% and 62.9%, respectively.

Influence of radiation dose from repeated chest X-ray on cell morphology and proliferation in peripheral blood mononuclear cells an in vitro study

The chest X-ray is a simple technique for routine medical examinations. Patients under investigation (PUI) might be exposed to radiation over the recommended dose due to the necessity of repeated X-rays. The aim of this research was to study the effects of repeated chest X-rays on peripheral blood mononuclear cells (PBMCs). The study determined characteristics of PBMCs by inverted microscope and flow cytometry after single and repeated X-ray exposure doses. The morphology of PBMCs showed cell differentiation to mesenchymal stromal cells throughout the plate and the trend of cells to differentiate in control groups more than single exposure and repeated irradiation. The cell growth of PBMCs was decreased after 10 days following repeated X-ray exposure as compared to controls. The overall results indicated that low-dose radiation from diagnostic X-rays affected PBMCs possibly indicating harmful radiation exposure. Future clinical studies will necessitate a larger sample size to more clearly assess cellular changes.

Influence of radiation dose and predicted tumor invasion depth on local recurrence after definitive chemoradiotherapy for stage 0\u2013I esophageal squamous cell carcinoma: a propensity score-weighted, retrospective, observational study

BackgroundThe optimal radiation dose for treating non-metastatic superficial esophageal squamous cell carcinoma is unknown. In this retrospective observational study, we investigated the influence of radiation dose and pretreatment endoscopic prediction of tumor invasion depth on local recurrence after definitive chemoradiotherapy in patients with superficial esophageal squamous cell carcinoma.MethodsWe analyzed 134 patients with clinical Tis–T1N0M0 esophageal squamous cell carcinoma who underwent chemoradiotherapy at our institution between 2006 and 2019. Patients were grouped into standard-dose (50.0–50.4 Gy) and high-dose (60.0 Gy) radiotherapy groups. The outcomes of interest were local recurrence and major local recurrence (endoscopically unresectable local recurrent tumors). Kaplan–Meier analysis and the log-rank test were used with propensity score and inverse probability of treatment weighting. Cox proportional hazards analysis was performed to identify predictors of local recurrence and major local recurrence.ResultsThe median follow-up times were 52 and 84 months for the standard-dose and high-dose groups, respectively. The adjusted 3-year local recurrence and major local recurrence rates in the standard-dose and high-dose groups were 33.8 and 9.6% (adjusted hazard ratio, 4.00 [95% confidence interval: 1.64–9.73]; adjusted log-rank p = 0.001) and 12.5 and 4.7% (adjusted hazard ratio, 3.13 [95% confidence interval: 0.91–10.81]; adjusted log-rank p = 0.098), respectively. Cox proportional hazards analysis showed that standard-dose radiotherapy and endoscopic findings of deep submucosal invasion are independently associated with local recurrence and major local recurrence.ConclusionsHigh-dose radiotherapy is more beneficial for local tumor control than standard-dose radiotherapy in patients with non-metastatic superficial esophageal squamous cell carcinoma. The use of high-dose radiotherapy may merit consideration for tumors with deep submucosal invasion.

Influence of Radiation Dose, Photon Energy, and Reconstruction Kernel on rho/z Analysis in Spectral Computer Tomography: A Phantom Study.

The effective atomic number (Zeff) and electron density relative to water (ρe or Rho) of elements can be derived in dual-energy computed tomography (DECT). The aim of this phantom study was to investigate the effect of different photon energies, radiation doses, and reconstruction kernels on Zeff and Rho measured in DECT. An anthropomorphic head phantom including five probes of known composition was scanned under three tube-voltage combinations in DECT: Sn140/100 kV, 140/80 kV and Sn140/80 kV with incremented radiation doses. Raw data were reconstructed with four reconstruction kernels (I30, I40, I50, and I70). Rho and Zeff were measured for each probe for all possible combinations of scan and reconstruction parameters. DECT-based Rho and Zeff closely approached the reference values with a mean and maximum error of 1.7% and 6.8%, respectively. Rho was lower for 140/80 kV compared with Sn140/100 kV and Sn140/80 kV with differences being 0.009. Zeff differed among all tube voltages with the most prominent difference being 0.28 between 140/80 kV and Sn140/100 kV. Zeff was lower in I70 compared with those of I30 and I40 with a difference of 0.07. Varying radiation dose yielded a variation of 0.0002 in Rho and 0.03 in Z, both considered negligible in practice. DECT comprises a feasible method for the extraction of material-specific information. Slight variations should be taken into account when different radiation doses, photon energies, and kernels are applied; however, they are considered small and in practice not crucial for an effective tissue differentiation.

Gamma irradiation a green alternative for hides and leather conservation

In this work bovine hides were treated with 25, 35 and 50 kGy in a Gamma Chamber 5000 self-shielded research irradiator and the influence of radiation dose on hide microbiological load, collagen crosslinking, interfibrillary substances solubility by shrinkage temperature and soluble nitrogen was evaluated in comparison with crude hide and sodium chloride treated hides (raw hides). Pilot level experiments were performed on large hide quantities in a SVST-Co-60/B Multipurpose Gamma Industrial Irradiator at 25 kGy as well as on semi processed leathers e.g. wet-blue, split wet-blue and crust. The evaluation of shrinkage temperature, microbiological load and physico-chemical and mechanical characteristics of gamma irradiated leathers showed that small modifications are induced by 25 kGy gamma irradiation. The scanning electron microscopy images of leather cross sections and Fourier Transform Infrared spectra confirmed minimum structural modifications at molecular level and not at microscopic level. Gamma irradiation allows conservation of high quantities of hides and leathers with impact on final product quality improvement, substantial infection reduction in abattoirs, raw material warehouses or tanneries shops, reduction of total dissolved solids by 40% and of chloride concentration by 78% from wastewaters.

Influence of Radiation Dose and Reconstruction Kernel on Fat Fraction Analysis in Dual-energy CT: A Phantom Study.

The quantitative evaluation of fat tissue, mainly for the determination of liver steatosis, is possible by using dual-energy computed tomography. Different photon energy acquisitions allow for estimation of attenuation coefficients. The effect of variation in radiation doses and reconstruction kernels on fat fraction estimation was investigated. A six-probe-phantom with fat concentrations of 0%, 20%, 40%, 60%, 80%, and 100% were scanned in Sn140/100 kV with radiation doses ranging between 20 and 200 mAs before and after calibration. Images were reconstructed using iterative kernels (I26,Q30,I70). Fat fractions measured in dual-energy computed tomography (DECT) were consistent with the 20%-stepwise varying actual concentrations. Variation in radiation dose resulted in 3.1% variation of fat fraction. Softer reconstruction kernel (I26) underestimated the fat fraction (-9.1%), while quantitative (Q30) and sharper kernel (I70) overestimated fat fraction (10,8% and 13,1, respectively). The fat fraction in DECT approaches the actual fat concentration when calibrated to the reconstruction kerneö. Variation of radiation dose caused an acceptable 3% variation.

Size and volume of kidney stones in computed tomography: Influence of acquisition techniques and image reconstruction parameters

PurposeComputed tomography (CT) is routinely used to assess suspected urolithiasis. Information obtained from CT include presence, location and size of stones, with the latter frequently determining treatment strategy. While there is consensus regarding measurements procedures of kidney stones, influence of radiation dose and reconstruction techniques on stone measurements are unknown. The purpose of this study was to systematically evaluate the influence of these technical determinants on kidney stone size measurements. Method47 kidney stones of different composition were scanned using a 64-row-multi-detector CT in a 3D-printed, semi-anthropomorphic phantom. Reference stone sizes were measured manually with a digital caliper (Man-M). Stones were imaged with 2 and 10 mGy CTDI. Images were reconstructed using filtered-back-projection, hybrid-iterative and model-based-iterative reconstruction algorithms (FBP, HIR, MBIR) in combination with different kernels and denoising levels. All stones underwent semi-automatic, threshold-based segmentation for computation of maximum diameter and volume. Statistics were conducted using ANOVA ± correction for multiple comparisons. ResultsOverall stone size as compared to manual measurements was overestimated in CT (10.0 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05) yet showing a good correlation (R2 = 0.66). Radiation dose and denoising levels did not significantly influence measurements (p > 0.05). MBIR and sharp kernels showed closest agreement with Man-M (9.3 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05). Differences within single stones were as high as 40 % (e.g. Man-M: 5.9 mm, CT: 7.3–12.0 mm). ConclusionsCT-based measurements of kidney stone size appear unaffected by radiation dose and denoising technique, whereas reconstruction algorithms and kernels demonstrate a relevant impact on size measurements. Smallest differences were found using MBIR with a sharp kernel.

Peripheral bronchial luminal conspicuity on dynamic-ventilation computed tomography: association with radiation doses and temporal resolution by using an ex vivo porcine lung phantom.

It is still unclear which image reconstruction algorithm is appropriate for peripheral bronchial luminal conspicuity (PBLC) on dynamic-ventilation computed tomography (DVCT). To assess the influence of radiation doses and temporal resolution (TR) on the association between movement velocity (MV) and PBLC on DVCT. An ex vivo porcine lung phantom with simulated respiratory movement was scanned by 320-row CT at 240 mA and 10 mA. Peak and dip CT density and luminal area adjusted by values at end-inspiration (CTDpeak and CTDdip, luminal area ratio [LAR]) for PBLC and MVs were measured and visual scores (VS) were obtained at 12 measurement points on 13 frame images obtained at half and full reconstructions (TR 340 and 190 ms) during expiration. Size-specific dose estimate (SSDE) was applied to presume radiation dose. VS, CTDpeak, CTDdip, LAR, and their cross-correlation coefficients with MV (CCC) were compared among four methods with combinations of two reconstruction algorithms and two doses. The dose at 10 mA was presumed as 26 mA by SSDE for standard proportion adults. VS, CTDdip, CTDpeak, and LAR with half reconstruction at 10 mA (2.52 ± 0.59, 1.016 ± 0.221, 0.948 ± 0.103, and 0.990 ± 0.527) were similar to those at 240 mA except for VS, and different from those with full reconstruction at both doses (2.24 ± 0.85, 0.830 ± 0.209, 0.986 ± 0.065, and 1.012 ± 0.438 at 240 mA) (P < 0.05). CCC for CTDdip with half reconstruction (-0.024 ± 0.552) at 10 mA was higher compared with full reconstruction (-0.503 ± 0.291) (P < 0.05). PBLC with half reconstruction at 10 mA was comparable to that at 240 mA and better than those with full reconstruction on DVCT.

Reproducibility of CT Radiomic Features within the Same Patient: Influence of Radiation Dose and CT Reconstruction Settings.

Background Results of recent phantom studies show that variation in CT acquisition parameters and reconstruction techniques may make radiomic features largely nonreproduceable and of limited use for prognostic clinical studies. Purpose To investigate the effect of CT radiation dose and reconstruction settings on the reproducibility of radiomic features, as well as to identify correction factors for mitigating these sources of variability. Materials and Methods This was a secondary analysis of a prospective study of metastatic liver lesions in patients who underwent staging with single-energy dual-source contrast material-enhanced staging CT between September 2011 and April 2012. Technique parameters were altered, resulting in 28 CT data sets per patient that included different dose levels, section thicknesses, kernels, and reconstruction algorithm settings. By using a training data set (n = 76), reproducible intensity, shape, and texture radiomic features (reproducibility threshold, R2 ≥ 0.95) were selected and correction factors were calculated by using a linear model to convert each radiomic feature to its estimated value in a reference technique. By using a test data set (n = 75), the reproducibility of hierarchical clustering based on 106 radiomic features measured with different CT techniques was assessed. Results Data in 78 patients (mean age, 60 years ± 10; 33 women) with 151 liver lesions were included. The percentage of radiomic features deemed reproducible for any variation of the different technical parameters was 11% (12 of 106). Of all technical parameters, reconstructed section thickness had the largest impact on the reproducibility of radiomic features (12.3% [13 of 106]) if only one technical parameter was changed while all other technical parameters were kept constant. The results of the hierarchical cluster analysis showed improved clustering reproducibility when reproducible radiomic features with dedicated correction factors were used (ρ = 0.39-0.71 vs ρ = 0.14-0.47). Conclusion Most radiomic features are highly affected by CT acquisition and reconstruction settings, to the point of being nonreproducible. Selecting reproducible radiomic features along with study-specific correction factors offers improved clustering reproducibility. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Sosna in this issue.

The effects of electron beam radiation on material properties and degradation of commercial PBAT/PLA blend

ABSTRACTThis work investigates the potential application of e‐beam radiation for sterilization of food packaging made of commercial polyester blend of poly(butylene adipate‐co‐terephthalate) and polylactide known under the trade name Ecovio 23B1. Ecovio film was irradiated at doses of 5, 13, and 26 kGy and the effect of sterilization on the microorganism inactivation ability was performed. The influence of radiation doses on structural and packaging properties such as tensile strength, barrier, and migration properties was also studied. 1H NMR and FTIR analysis revealed no significant changes in the polymer structure, however, the molar mass of irradiated samples decreased with increasing radiation dose. This result indicated the occurrence of degradation process during radiation, which was confirmed by the thermal analysis and accelerated enzymatic degradation. The packaging properties did not changed significantly and the overall migration for 10% ethanol, isooctane, and MPPO was below the limit for all of the studied samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48462.

942 - Influence of Radiation dose on Undergoing Esophagectomy for Locally Advanced Esophageal Cancer

942 - Influence of Radiation dose on Undergoing Esophagectomy for Locally Advanced Esophageal Cancer

Physicochemical, microbiological and sensory acceptance alterations of strawberries caused by gamma radiation and storage time

Abstract Consumer demand for food similar to one unprocessed has justified new studies seeking reduced changes in its physicochemical characteristics, the sensory acceptance and the microbiological safety. Irradiation increases the shelf life of foods, according to data in the literature. This study evaluated possible changes during the storage of non-irradiated and irradiated strawberries, the last treated at doses of 1, 2, 3 and 4 kGy, all of them stored at 8 ± 1 °C. The pH, total titratable acidity, ascorbic acid content, weight loss, firmness, the microbiota of natural contaminants and sensory acceptance of strawberries were analyzed. Influence of radiation dose and storage period on the physicochemical characteristics, microbiological quality and sensory acceptance of strawberries were observed. Although control strawberry presented better results for the ascorbic acid content, for firmness and for weight loss, it should be emphasized the effect of irradiation on inactivating mesophilic aerobics and markedly reducing of molds and yeasts. In addition, irradiated strawberries at 2 kGy presented the same hedonic mean on acceptance tests during 12 days of storage. It is suggested to use the 2 kGy dose as an alternative for strawberry conservation, since only minor changes were observed in the product during the 12 days of storage and it was the treatment that obtained better microbiological quality and maintenance of sensory acceptance during the storage period studied. Therefore, irradiation is a method that may be a substitute and could be used along with conventional methods, providing strawberries quality with a longer shelf life.

The Fractal Dimensions of Carbon-Black-Filled Polymers and Elastomers. Part 2. The Fractal Dimensions of Carbon-Black-Filled Systems

Values of the fractal dimensions, characterising the internal structure and mechanisms of structure formation of dispersed systems, were obtained. The obtained dependences for individual clusters and images as a whole are linear in log–log coordinates. The slope of the dependences varies in the range 1.38–1.82. The obtained dependences can be divided into two groups: for systems with a low filler content (up to 10%) and for systems with a high filler content (over 15%), and accordingly with relatively low (up to 1.5) and high fractal dimensions and different (cluster–cluster and cluster–particle) mechanisms of formation of fractal structures. The influence of radiation dose (7–60 Mrad) on the structure and fractal dimensions of systems was investigated. Using the concept of fractal dimensions, the combined state of carbon black aggregates is described. It is shown that the fractal dimensions of dispersed systems filled with carbon black depend on their preparation and exposure to external effects.

Evaluation of polybutadiene rubbers using FTIR spectra

Radiation dosimetry for medical and industrial purposes has increasingly evolved over the last few decades with the introduction of various new detectors. Depending on the properties exhibited for radiation dosimetry, some detectors present their applications in a specific area. From a physics point of view, an ideal dosimeter should be able to measure absorbed dose. In this work, synthetic materials based on polybutadiene rubbers (PBR) were proposed as a new class of radiation detectors. The influence of radiation dose on their properties has been investigated for application in radiation dosimetry. The rubber samples were exposed to absorbed doses from 10 Gy up to 250 Gy, using a 60 Co Gamma Cell-220 system. Their responses were carried out with a Fourier Transform Infrared (FTIR) Spectrometer to investigate the presence of absorbance peaks. The results suggested the existence of a relationship between the absorbed doses and the absorbance peaks associated with stretching (1300-1200 cm -1 ), deformation (1450-1340 cm -1 ) and vibration (1500-1400 cm -1 ) processes in the material.

Influence of radiation dose in computed tomography on antioxidant enzyme activity in rabbit erythrocytes

The objective of this study was to assess the radiation dose in computed tomography examinations of rabbits using different examination protocols and to correlate these values with the activity of antioxidant enzymes in their red blood cells following irradiation. The presented results revealed that a single, routine computed tomography scan exposure led to a different response of the activity of antioxidant enzymes in red blood cells regarding both dose and time. The results indicate that there is a dose threshold that is about 25 mGy. Doses below that level do not produce any significant changes in the level of antioxidant enzymes activity. On the other hand, the level just above that threshold had a significant impact on the antioxidant defence, but in a relatively short time period (2 hours after exposure), compared to the higher dose that requires a longer adaptive period.

Sequential boost in neoadjuvant irradiation for T3N0-1 rectal cancer: long-term results from a single-center experience.

To evaluate the influence of radiation dose on tumor regression grade (TRG) and sphincter preservation rate in a series of cT3N0-1 rectal cancer patients treated with neoadjuvant chemoradiotherapy (CT-RT) with or without a sequential radiation boost. Between May 2002 and September 2013, 116 cases were eligible for retrospective evaluation. Radiotherapy was delivered for a total dose of 45 Gy (no boost arm) or 50.4 Gy (boost arm). TRG was evaluated with the Dworak scale. Median follow-up was 62 months (range, 12-138 months). The 5-year overall survival and local control rates were 72% and 93%, respectively. Fifty-five patients (47%) were treated with a sequential radiation boost and 61 (53%) without a boost. Eighty patients (72%) presented T3N0 disease and 32 (28%) T3N1 disease. Concomitant capecitabine was administered in 92 cases (79%) and intravenous 5-fluorouracil in 24 cases (21%). Sphincter preservation was performed in 82% of patients in the boost arm and 66% in the no-boost arm. A higher TRG was related to a longer interval between neoadjuvant treatment and surgery (p&lt;0.001). The probability of a TRG ≥2 was 2.5 times higher in the boost arm. A gain in local control, estimated at 4% during the first 3 years after CT-RT, favored the boost arm. The long-term results from our single-center experience confirm literature data on the role of a sequential boost in tumor response after neoadjuvant CT-RT in a series of cT3N0-1 rectal cancer patients.

Impact of radiation dose and iterative reconstruction on pulmonary nodule measurements at chest CT: a phantom study.

We aimed to identify the impact of radiation dose and iterative reconstruction (IR) on measurement of pulmonary nodules by chest computed tomography (CT). CT scans were performed on a chest phantom containing various nodules (diameters of 3, 5, 8, 10, and 12 mm; +100, -630 and -800 HU for each diameter) at 80, 100, 120 kVp and 10, 20, 50, 100 mAs (a total of 12 radiation dose settings). Each CT was reconstructed using filtered back projection, iDose4, and iterative model reconstruction (IMR). Thereafter, two radiologists measured the diameter and attenuation of the nodules. Noise, contrast-to-noise ratio and signal-to-noise ratio of CT images were also obtained. Influence of radiation dose and reconstruction algorithm on measurement error and objective image quality metrics was analyzed using generalized estimating equations. The 80 kVp, 10 mAs CT scan was not feasible for the measurement of 3 mm sized simulated ground-glass nodule (GGN); otherwise, diameter measurement error was not significantly influenced by radiation dose (P > 0.05). IR did not have a significant impact on diameter measurement error for simulated solid nodules (P > 0.05). However, for simulated GGNs, IMR was associated with significantly decreased relative diameter measurement error (P < 0.001). Attenuation measurement error was not significantly influenced by either radiation dose or reconstruction algorithm (P > 0.05). Objective image quality was significantly better with IMR (P < 0.05). Nodule measurements were not affected by radiation dose except for 3 mm simulated GGN on 80 kVp, 10 mAs dose setting. However, for GGNs, IMR may help reduce diameter measurement error while improving image quality.

Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study.

Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis-particularly in younger patients-might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiation dose and MBIR in the MDCT assessment of airway WT. An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo(TM), GE Healthcare) were used to reconstruct CT images of the airways. For each kV-mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV-mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV-mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose levels. For FBP, the relative bias and the angular standard deviation of the measured WT increased steeply with decreasing radiation dose. Except for the smallest airway, MBIR enabled significant reduction in both the relative bias and angular standard deviation of the WT, particularly at low radiation dose levels; the SSQ was reduced by 50%-96% by using MBIR. The optimal reconstruction algorithm was found to be MBIR for the seven airways being assessed, and the combined use of MBIR and optimal kV-mAs selection resulted in a radiation dose reduction of 37%-83% compared with a reference scan protocol with a dose level of 1 mGy. The quantification accuracy of airway WT is strongly influenced by radiation dose and reconstruction algorithm. The MBIR algorithm potentially allows the desired WT quantification accuracy to be achieved with reduced radiation dose, which may enable a wider clinical use of MDCT for the assessment of airway WT, particularly for younger patients who may be more sensitive to exposures with ionizing radiation.

Comparison of the Results of Creep and Micro-Indentation Creep to Irradiated HDPE

The main goal of this paper is to compare measurements of creep behavior of Crosslinking polymer materials. Creep properties have been measured by two methods, first is micro-indentation with Depth Sensing Indention (DSI) and the second method is long-term creep test in room temperature. By using of these principally different methods can be better analyzed the influence of radiation netting, and therefore better suggest an appropriate dose of radiation with respect to use of polymer material in practice. The evaluation criteria for DSI test is index CIT [%]. The evaluation criteria for the standard creep test is value of average elongation at the end of the test. Comparison of these two values shows slight influence of radiation dose with using the standard creep test instead of using micro-indentation creep test, which shows very slight influence of radiation dose on material.

Effect of kappa-carrageenan on the properties of poly(vinyl alcohol) hydrogel prepared by application of gamma radiation

Synthesis of hydrogels from aqueous solution of poly(vinyl alcohol) (PVA) and kappa-carrageenan (KC) has been performed with radiation processing technology using Co-60 gamma source. As investigation on the influence of radiation dose and concentration of KC on gel content, swelling properties, and thermal behaviors of hydrogel has been performed. Gel content obtains a maximum value at 25 kGy radiation dose. Equilibrium water content of hydrogel decreases with increased radiation dose but it increases with increased concentration of KC. The water absorption of hydrogel is fast up to 5 hours and it becomes a maximum value at 24 hours. It increases with increased concentration of KC in the feed solution. The water absorption of hydrogel increases from 210 to 410% for the increment of KC content from 0 to 2.0% at the radiation dose 25 kGy. Thermo-gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that thermal degradation reduces with increased concentration of KC in PVA hydrogel. Scanning electron microscopy (SEM) was used to investigate the surface morphology of PVA/KC blend hydrogel. The hydrogel was applied to absorb dye (methyl violet) from aqueous solution. Langmuir and Freundlich models were applied to study the dye adsorption pattern.