Irradiated Part Research Articles

INFLUENCE OF PHOTOACTIVATED ROSE BENGAL ON MICROCIRCULATION

The study of mean blood velocity changes in rat mesenteric venules (15–30 µm) due to photoactivation (λ = 532 nm, 0,175 W/cm2, 300 s) of i.v. injected Rose Bengal (17 mg/kg) is represented in the article. Using in vivo biomicroscopy the progressive decrease of mean blood velocity both during the laser irradiation and after it was registered. The calculation of thermal effects in the irradiated part of microvessel due to laser absorption by hemoglobin and Rose Bengal showed the rise of temperature was not exceed 0.2оC as compared to initial level. Thus, thermal effect has nearly no significant influence on microvascular disturbances caused by Rose Bengal photoactivation.

Formation of nonlinear optical Na2TeW2O9 crystals and laser irradiation in tungsten–tellurite glasses

The crystallization behavior of 25Na2O–50WO3–25TeO2 glass was examined to develop transparent glass-ceramics containing nonlinear optical Na2TeW2O9 crystals. It was clarified from XRD analysis and Raman scattering spectra that a metastable crystalline phase is formed initially and the stable crystalline phase of Na2TeW2O9 is created through the transformation of the metastable phase. Laser irradiations (continuous wave Yb:YVO4 fiber laser, wavelength of 1080 nm) with the condition of the laser power of P = 0.55 W and scanning speed of S = 2.3 μm/s created the patterning of homogeneous crystals lines. The crystalline phase in the laser irradiated part was proposed to be the metastable crystalline phase from micro-Raman scattering spectra.

Internal mammary lymph nodes radiotherapy of breast cancer in the era of individualized medicine.

Inclusion internal mammary lymph nodes as a part of regional nodal irradiation have a potential to reduce local recurrence, distant recurrence, and improve survival in breast cancer. However, the increased risk of cardiac toxicity and lungs injure associated with internal mammary lymph nodes irradiation has drew more and more attention. Estimating risk of metastasis in internal mammary lymph nodes based on axillary lymph nodes metastasis status is not always reliable: low-risk do not always mean negative in internal mammary lymph nodes and high-risk do not always indicate positive in internal mammary lymph nodes. Inaccurate prediction of in internal mammary lymph nodes metastasis might lead to over- or under-treatment of in internal mammary lymph node. Internal mammary sentinel lymph node biopsy is a minimally invasive technique which has a high potential to accurately evaluate the metastasis status in in internal mammary lymph nodes and improve accuracy of nodal staging. This technique might be a useful tool to guide individualized internal mammary lymph nodes irradiation.

TTC-Pluronic 3D radiochromic gel dosimetry of ionizing radiation

This work reports the first results obtained using a new 3D radiochromic gel dosimeter. The dosimeter is an aqueous physical gel matrix made of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127, PEO-PPO-PEO) doped with a representative of tetrazolium salts, 2, 3, 5-triphenyltetrazolium chloride (TTC). There were several reasons for the choice of Pluronic as a gel forming substrate: (i) the high degree of transparency and colourlessness; (ii) the possibility of gel dosimeter preparation at both high and low temperatures due to the phase behaviour of Pluronic; (iii) the broad temperature range over which the TTC-Pluronic dosimeter is stable; and (iv) the non-toxicity of Pluronic. A reason for the choice of TTC was its ionising radiation-induced transformation to water-insoluble formazan, which was assumed to impact beneficially on the spatial stability of the dose distribution. If irradiated, the TTC-Pluronic gels become red but transparent in the irradiated part, while the non-irradiated part remains crystal clear. The best obtained composition is characterised by <4 Gy dose threshold, a dose sensitivity of 0.002 31 (Gy × cm)–1, a large linear dose range of >500 Gy and a dynamic dose response much greater than 500 Gy (7.5% TTC, 25% Pluronic F-127, 50 mmol dm−3 tetrakis). Temporal and spatial stability studies revealed that the TTC-Pluronic gels (7.5% TTC, 25% Pluronic F-127) were stable for more than one week. The addition of compounds boosting the gels’ dose performance caused deterioration of the gels’ temporal stability but did not impact the stability of the 3D dose distribution. The proposed method of preparation allows for the repeatable manufacture of the gels. There were no differences observed between gels irradiated fractionally and non-fractionally. The TTC-Pluronic dose response might be affected by the radiation source dose rate—this, however, requires further examination.

Proton beam radiotherapy as part of comprehensive regional nodal irradiation for locally advanced breast cancer

PurposeThis study evaluates acute toxicity outcomes in breast cancer patients treated with adjuvant proton beam therapy (PBT). MethodsFrom 2011 to 2016, 91 patients (93 cancers) were treated with adjuvant PBT targeting the intact breast/chest wall and comprehensive regional nodes including the axilla, supraclavicular fossa, and internal mammary lymph nodes. Toxicity was recorded weekly during treatment, one month following treatment, and then every 6months according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Charts were retrospectively reviewed to verify toxicities, patient parameters, disease and treatment characteristics, and disease-related outcomes. ResultsMedian follow-up was 15.5months. Median PBT dose was 50.4 Gray relative biological effectiveness (GyRBE), with subsequent boost as clinically indicated (N=61, median 10 GyRBE). Chemotherapy, when administered, was given adjuvantly (N=42) or neoadjuvantly (N=46). Grades 1, 2, and 3 dermatitis occurred in 23%, 72%, and 5%, respectively. Eight percent required treatment breaks owing to dermatitis. Median time to resolution of dermatitis was 32days. Grades 1, 2, and 3 esophagitis developed in 31%, 33%, and 0%, respectively. ConclusionsPBT displays acceptable toxicity in the setting of comprehensive regional nodal irradiation.

Effects of electron beam irradiation on physicochemical properties of corn flour and improvement of the gelatinization inhibition

The properties and viscosity-reduction mechanism of corn flour irradiated by electron beam have not been understood properly. Here, we investigate the effects of electron beam irradiation (EBI) on the gelatinization and physicochemical properties of corn flour irradiated by 0–5.40kGy of electron beam. The total starch and crude fiber contents of corn flour decreased significantly (P<0.05) after EBI treatment, while the moisture and reducing sugar contents increased significantly (P<0.05). EBI caused perforations on the corn flour particle surfaces, and the irradiated parts of the particles would gradually peel off and afford smooth surfaces, spherical structures, and smaller sizes. Molecular chains of corn flour broke owing to EBI. After irradiation, the pasting peak viscosity decreased dramatically (P<0.01) from 1251.74 to 7.16Pa·s, showing that the gelatinization of corn flour was completely inhibited. Thus, EBI can be used to inhibit the gelatinization of corn flour, which may be beneficial for industrial and food formulations.

Thermal analysis of thin-walled deployable composite boom in simulated space environment

This paper seeks to investigate thermal behaviour of a thin-walled deployable composite boom (DCB) in a space environment using ground thermal-vacuum test and FEA methods. Thermal tests simulating a space environment include three key conditions, namely ultra-high level of vacuum (lower than 10−5Pa), heat sink (−180°C) that is realized using black panels with the liquid-nitrogen cooling system and thermal loading that is achieved through infrared lamps. The thermal tests of the DCB under seven typical heat fluxes were conducted to characterize heat transfer mechanisms and to obtain temperature fields. The basic heat transfer methods for the DCB in a space environment were surface radiation, cavity radiation and heat conduction. These led to significant temperature difference and gradient occurring on the irradiated and shadowed parts of the DCB at nighttime and daytime. FE models were established to predict temperature fields and thermally induced deformation. Good correlation was achieved between experimental and numerical results.

Harvesting, sensing and regulating light based on photo-thermal effect of Cu@CuO mesh

A system of light harvesting, sensing and regulating was designed based on the photo-thermal and Seebeck effect of flexible CuO nanostructures. Cu@CuO meshes were prepared via self-oxidation of Cu mesh and utilized as the photo-thermal material. Upon irradiation by visible light, the temperature of the Cu@CuO mesh dramatically increases. The temperature difference between the irradiated and non-irradiated parts of the Cu@CuO mesh produced a measurable voltage output due to the Seebeck effect. The generated voltage was then converted into a digital signal to control a rotary neutral-density disc to filter the received light. This enabled regulation of the intensity of the incident light at a selected region. This system is cost effective and has potential applications in greenhouses, factories and smart buildings to minimize energy consumption and improve wellbeing.

Experimental Study on Microwave Assisted Hard Rock Cutting of Granite

This paper describes the influence of high-power microwave irradiation on the forces needed to cut granite with a conical pick. Granite samples have been irradiated with 24 kW at 2450 MHz with an open ended waveguide. The effect of microwave treatment was assessed by linear cutting tests with a conical pick.Microwave irradiation lead to an extensive network of cracks. The linear cutting tests provide a comparison of treated and non-treated parts and show that peak as well as average forces needed for cutting this very hard and abrasive material are reduced significantly. The average cutting force is reduced from 7.06 to 6.39 kN, equalling 10 %, from the untreated to the irradiated part, respectively.

レーザ加熱を利用したかん合に関する研究

Laser shrink fitting for shaft coupling was developed as application of laser forming. The coupling of the pipe of stainless steel and bar of carbon steel is made by laser shrink fitting. A bar is inserted into a pipe, and the pipe surface of the bar-inserted-part is irradiated and heated by 1kw class laser. Metallographic structure of the laser irradiated part of the pipe and bar is not changed. The fitted part of the pipe is shrunk in both circumferential and axial direction. The residual stress on the surface of the fitted pipe is a compressive one in the circumferential and axial direction. The tensile strength of the fitted part is nearly equal to the tensile strength of base metal of stainless steel pipe.

Role of the overall treatment time of radiotherapy with 10×3Gy for outcomes in patients with metastatic spinal cord compression.

Radiotherapy alone still is the most commonly delivered treatment modality for metastatic spinal cord compression (MSCC). MSCC is an emergency situation, which requires treatment as soon as possible. When radiotherapy is performed with the most commonly used approach 10×3Gy (30Gy in 10 fractions) over 2weeks, the question has been asked whether an overall treatment time (OTT) of 14-15days including two weekends without irradiation leads to worse outcomes than OTT of 12days (beginning of radiotherapy on a Monday resulting in only one weekend break)? A total of 412 patients with MSCC were included in this retrospective study. Ninety-two patients receiving 10×3Gy over 12days were compared to 320 patients with an OTT of 14-15days. Ten additional factors were investigated. On multivariate analysis, functional outcome was associated with tumour type (P<0.001), time developing motor deficits (P<0.001), ambulatory status (P=0.018) and performance score (P<0.001); OTT had no significant impact (P=0.40). On univariate analysis of local control of MSCC (freedom from recurrence in irradiated spinal parts), no factor was significant including OTT (P=0.66). On multivariate analysis, visceral metastases (P<0.001), tumour type (P<0.001), time developing motor deficits (P<0.001), ambulatory status (P<0.001) and performance score (P<0.001) were associated with survival, OTT not even on univariate analysis (P=0.55). Since an OTT of 14-15days had no negative impact on outcomes compared to 12days, compensation in form of an additional radiation fraction or continuation of radiotherapy during weekends is not required, if radiotherapy cannot be started on a Monday.

Micromachining and micro-magnetization of Pr-Fe-B magnets fabricated using pulsed laser deposition for MEMS applications

For MEMS actuators that use permanent magnets, such as micro linear motors, micromachining and micro-magnetization of the magnets are needed in order to enhance and concentrate the magnetic field. This paper examines these processing technologies for magnets fabricated by pulsed laser deposition (PLD magnets). Magnets of this type can be more than a hundred microns thick, which makes them suitable for high power MEMS actuators. For the micromachining, we utilized molds with micro-grooves. These were filled with magnetic material deposited using Pr2.0Fe14B target, and then polished to decrease the surface roughness of the magnets to a few tens of μm. As a result, a linear array of magnets, each 100μm wide and 50μm high, was realized. For the micro-magnetization, partial magnetization reversal due to weakening of the coercivity as a result of laser heating while applying an external magnetic field was examined. To limit the magnetization reversal to the irradiated parts, heat conduction to the non-irradiated parts was restricted by using a thermally insulating glass mold, which was fabricated by micromachining. As a result, micro-magnetized magnets with a pole pitch of 200μm were realized. The average measured magnetic flux density at a distance of 100μm from the surface of the magnets was 43mT (p-p), which corresponds to 88% of the value obtained by simulation.

Development of a Control Method for Conduction and Magnetism in Molecular Crystals

AbstractThis study concerns development of a non-destructive method to control conduction and magnetism of molecular solids such as single crystals of charge-transfer complexes. The method is named “optical doping”, where appropriate irradiation is utilized under ambient conditions. Owing to this feature, it can be applied to a wide range of substances while measuring the properties during the control. In addition, the method adds unique conduction and magnetic properties to common insulators. Unlike other doping methods, optical doping only affects the properties and/or structures of the irradiated part of a sample while leaving the rest of the sample unchanged. There are two patterns in the optical doping. Irreversible optical doping produces junction-structures on the single molecular crystals, which exhibit characteristic behavior of semiconductor devices such as diodes and varistors. Reversible optical doping produces “giant photoconductors” and “photomagnetic conductors” by realizing unprecedented metallic photoconduction. In the latter case, localized spins are also excited to produce a Kondo system, where carriers and localized spins interact with each other. Not only the control of conduction and magnetism, the optical doping has realized the observation of physical properties in molecular crystals hardly observed under any thermodynamic condition.

A.60 - A simplified intensity-modulated radiotherapy technique for the breast to reduce posterior part of the axilla irradiation

A.60 - A simplified intensity-modulated radiotherapy technique for the breast to reduce posterior part of the axilla irradiation

Modeling cell response to low doses of photon irradiation--Part 1: on the origin of fluctuations.

Intra- and inter-individual variability is a well-known aspect of biological responses of cells observed at low doses of radiation, whichever the phenomenon considered (adaptive response, bystander effects, genomic instability, etc.). There is growing evidence that low-dose phenomena are related to cell mechanisms other than DNA damage and misrepair, meaning that other cellular structures may play a crucial role. Therefore, in this study, a series of calculations at low doses was carried out to study the distribution of specific energies from different irradiation doses (3, 10 and 30 cGy) in targets of different sizes (0.1, 1 and 10 μm) corresponding to the dimensions of different cell structures. The results obtained show a strong dependence of the probability distributions of specific energies on the target size: targets with dimensions comparable to those of the cell show a Gaussian-like distribution, whereas very small targets are very likely to not be hit. A statistical analysis showed that the level of fluctuations in the fraction of aberrant cells is only related to the fraction of aberrant cells and the number of irradiated cells, regardless of, for instance, the heterogeneity in cell response.

Design improvement and performance evaluation of solar photocatalytic reactor for industrial effluent treatment

This work reports the details of the design components and materials used in a linear compound parabolic trough reactor constructed with an aim to use the photocatalyst for solar photocatalytic applications. A compound parabolic trough reactor has been designed and engineered to exploit both UV and visible part of the solar irradiation. The developed compound parabolic trough reactor could receive almost 88% of UV radiation along with a major part of visible radiation. The performance of the reactor has been evaluated in terms of degradation of a probe pollutant using the parameters such as rate constant, residence time and photonic efficiency. An attempt has been made to assess the performance in different ranges of solar spectrum. Finally the developed reactor has been employed for the photocatalytic treatment of a paper mill effluent using Degussa P25 as the photocatalyst. The paper mill effluent collected from Nagaon paper mill, Assam, India has been treated under both batch mode and continuous mode using Degussa P25 photocatalyst under artificial and natural solar radiation, respectively. The photocatalytic degradation kinetics of the paper mill effluent has been determined using the reduction in total organic carbon (TOC) values of the effluent.

TH-AB-201-02: Fluoroscopy-Guided Radiation Dose; Best Correlated to Patient Thickness

Purpose: To survey a radiation dose index of peripheral and trunk fluoroscopic interventional procedures at a tertiary care pediatric hospital. These results allow the correlation of a patient dose index to the patient thickness, age, weight, and body mass index (BMI) to be analyzed. Methods: Radiation dose structured reports were retrospectively collected for pediatric and adult interventional fluoroscopic cases. Kerma Area Product (KAP), air Kerma (AK), fluoroscopy time (FT), thickness of body part irradiated, patient’s age, height, and weight were collected. Cumulative AK was divided by fluoroscopy time to normalize the dose index by the complexity of the case. This index for each study was analyzed as a function of thickness of body part irradiated, patient age, weight, and BMI. Non-parametric correlation coefficients along with the 95% confidence intervals were computed to investigate which parameter correlates best with patient dose. Results: A total of 522 cases were included in the study. The patients’ irradiated body part thicknesses, ages, masses, and heights ranged from 1–35 cm, 0.01–61 years, 1.4–145.5 kg, and 37.5–190 cm respectively. The FT and AK of the cases ranged from 0.1–100 min and 0.1–2756 mGy respectively. The correlation with 95% confidence interval of AK/FT to each patient parameter is listed in the supporting document. Each patient parameter is statistically correlated with patient dose (p-value < 0.0001), however the correlation with patient thickness statistically provides the highest correlation whereas the three other parameters are of similar, lower correlation. Conclusion: Fluoroscopy-guided patient dose indices should be reported as a function of patient thickness irradiated as opposed to the patient’s age, weight, or BMI. If the thickness of the patient is unknown, our results suggest that any of the other three patient charateristics could be used. K Strauss serves as a consultant to Philips Healthcare upon their request. R Nachabe is a paid employee of Phillips Healthcare.

Polymorphic Crystallization and Thermodynamic Phase Transition between the Polymorphs of a Photochromic Diarylethene

We synthesized a photochromic diarylethene, 1,2-bis(2-methyl-5-(4-hexyloxyphenyl)-3-thienyl)perfluorocyclopentene (1a), and found that it has two types of crystals, a needle-like α-crystal and a plate-like β-crystal. From X-ray crystallographic analysis, the space groups of the α- and β-crystals were determined to be P1̅ and C2/c, respectively. The molecular conformation and packing of two crystal forms are quite different. The α- and β-crystals can be obtained individually by recrystallization from acetone at different temperatures. The solvent-mediated phase transition from the α-crystal to the β-crystal was found to occur in the acetone solution at room temperature. Moreover, the thermodynamic phase transition from α-form to β-form was found to take place above 88 °C, as confirmed by differential scanning calorimetry measurement, optical microscopic observation under crossed Nicols, and powder X-ray diffraction measurement. The phase transition from α-form to β-form was also observed at 78 °C by photochromic reaction of 1a, and the phase transition proceeded from the UV irradiated part to the nonirradiated part.

Tagged MRI based cardiac motion modeling and toxicity evaluation in breast cancer radiotherapy.

Recent research showed radiation for breast cancer can increase heart risks (1, 2). In Ref. (2), it has been noted that for every Gy of radiation a women’s heart risk rises 7.4%. However, the correlation between radiation dose and heart tissue damage is still an open problem. A more accurate model of heart damage will significantly improve the heart safety for patients underwent radiotherapy. Modern radiation treatment planning systems (TPS) use computed tomography (CT) images for dose calculation and evaluation. For evaluation of heart toxicity from radiotherapy, the dose-volume histogram (DVH), which is generated by overlying radiation dose distribution on heart delineations in CT images, is widely used. However, there are three major factors that deteriorate the accuracy of TPS-calculated heart dose distribution. First conventional CT is a fundamentally static imaging modality without the capability to capture and depict the cardiac motion. Instead, heart is usually blurred in CT images due to the motion artifacts. Second, without special contrast dye, CT provides limited contrast between blood in heart chambers and the surrounding myocardium. The heart region in TPS is actually a mixture of myocardium and blood, although only the radiation dose to the myocardium is accountable for heart risks. Finally, there is significant intra- and inter-fractional heart motion. As heart beats involuntarily during and between radiation treatments, myocardium deforms and moves non-rigidly against the fixed radiation beam so that the static dose distribution calculated in CT based TPS does not reflect the accurate radiation dose distribution in heart. There is also concern on the choice of the heart function for the evaluation of radiation damage. Based on radiation beam geometry, only part of the heart will receive clinically significant level of radiation during breast cancer treatment. It is possible that the global heart function remains stable temporarily while cells in the irradiated part of the myocardium lose part or all of their functions. In this case, regional heart function, which can be derived from regional heart wall motion and strain analysis, is a better indication of heart damage corresponding to radiation dose. Although cardiac MRI is widely used in radiology for the diagnosis of heart disease, its application in radiation treatment planning is limited. For multiple reasons, it is not practical to use MRI directly for radiation treatment planning of breast cancer patients. However, via multimodality deformable image registration (DIR) between MRI and CT, MRI images may play a more critical role in the evaluation of the heart damage from whole breast radiation. Tagged MRI (tMRI) (3) is a relatively new imaging protocol that has been implemented in the detection and diagnosis of regional heart functional loss. tMRI methods record regional heart wall motion information as they create identifiable landmark bands (tags) in the myocardium to establish dense point to point correspondence between images. ECG-gated tMRI image sets can be acquired at different phases of the cardiac cycle using the corresponding pulse sequence. The 4D (3D plus time) cardiac motion model can be retrieved by image registration between tMRIs at different phases. In the following sessions, we use tMRI as an example to explain how additional heart function information in MRI is retrieved. It is our objective to demonstrate the additional information retrieved from MRI can help the evaluation and protection of heart risks for breast cancer patients, and we want to discuss the possibility of using MRI to establish a more accurate correlation between regional heart functional loss and radiation dose.

Measurements of the Fe3+ diffusion coefficient in Fricke Xylenol gel using optical density measurements

In Fricke dosimetry, optical density measurements are performed some time after dosimeter irradiation. Values of the diffusion coefficient of Fe3+ in Fricke Xylenol gel (FXG) are necessary for determining the spatial distribution of the absorbed dose from measurements of the optical density. Five sets of FXG dosimeters, kept at different constant temperatures, were exposed to collimated 6MV photons. The optical density profile, proportional to the Fe3+ concentration, at the boundary between irradiated and non-irradiated parts of each dosimeter was measured periodically over a period of 60h. By comparing the experimental data with a function that accounts for the unobserved initial concentration profile of Fe3+ in the FXG, we obtained diffusion coefficients 0.30±0.05, 0.40±0.05, 0.50±0.05, 0.60±0.05 and 0.80±0.05mm2/h for the temperatures 283.0±0.5, 286.0±0.5, 289.0±0.5, 292.0±0.5, and 296.0±0.5K, respectively. The activation energy of Fe3+ diffusion in the gel, 0.54±0.06eV, was determined from the temperature dependence of the diffusion coefficients.