Journal articles: 'Electron dose'

1

Solin, J. R. "Electron collision dose enhancement." IEEE Transactions on Nuclear Science 47, no. 6 (2000): 2447–50. http://dx.doi.org/10.1109/23.903791.

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Dubeau, J., and J. Sun. "ELECTRON EYE-LENS OPERATIONAL DOSE COEFFICIENTS." Radiation Protection Dosimetry 188, no. 3 (January 30, 2020): 372–77. http://dx.doi.org/10.1093/rpd/ncz295.

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Abstract In 2012, the International Commission on Radiological Protection issued a recommendation for a reduced annual eye-lens dose limit in the face of mounting evidence of the risk of cataract induction. This led to worldwide research efforts in various areas including the dose simulation in realistic eye-models, the production of dosimeters and the elaboration of protection and operation fluence to eye-lens dose coefficients. In this last case, much efforts have been expanded with regards to photon operational coefficients for Hp (3) but much less for electron radiation. In this work, Hp (3) coefficients for electrons are presented following simulations using MCNP and compared to those that are available in the literature. It is found that, at energies of 1 MeV and less, Hp (3) coefficients depend strongly on the selected electron transport options and on the dose tally volume. The effect of these differences is demonstrated for two beta emitters.

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Kundmann, Michael K., Ondrej L. Krivanek, and J. M. Martin. "Minimum-dose electron energy-loss spectroscopy." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 634–35. http://dx.doi.org/10.1017/s0424820100105230.

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Parallel-detection electron energy-loss spectrometers have greatly reduced the irradiation doses needed to acquire electron energy-loss spectroscopy (EELS) data. This raises the possibility that changes in chemical bonding due to radiation damage, which usually precede changes in composition, may be studied by examining alterations in low-loss and core-edge fine structure with increasing dose.The quality of data attainable with low-doses in parallel-detection EELS is illustrated by Fig. 1, which shows the K-edge region for a thin amorphous carbon film. This spectrum was collected in 2sec with a 1pm-diameter probe at 100kV in (microscope) diffraction mode. A 20cm camera length ensured that virtually all scattered electrons passed through the 3mm entrance aperture of the spectrometer. Spectrum dispersion is 3eV/channel and the energy resolution is ∼1eV/channel as the π* peak is clearly resolved. The total incident current, as determined in image mode (no objective aperture) from the viewing-screen meter, was only 40pA. The total dose for this K-edge spectrum was consequently only 6.4e-/Å2.

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Harmon, RT, S. Meyer, CR Booth, and J. Wilbrink. "Simplifying Minimum Dose Electron Tomography." Microscopy and Microanalysis 15, S2 (July 2009): 626–27. http://dx.doi.org/10.1017/s1431927609095208.

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5

Klein, Holger, and Stéphanie Kodjikian. "Low-dose electron diffraction tomography." Acta Crystallographica Section A Foundations and Advances 74, a2 (August 22, 2018): e312-e313. http://dx.doi.org/10.1107/s2053273318090496.

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Toossi, Mohammad Taghi Bahreyni, Mahdi Ghorbani, Leila Sobhkhiz Sabet, Fateme Akbari, and Mohammad Mehrpouyan. "A Monte Carlo study on dose enhancement and photon contamination production by various nanoparticles in electron mode of a medical linac." Nukleonika 60, no. 3 (July 1, 2015): 489–96. http://dx.doi.org/10.1515/nuka-2015-0087.

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Abstract The aim of this study is the evaluation of electron dose enhancement and photon contamination production by various nanoparticles in the electron mode of a medical linac. MCNPX Monte Carlo code was used for simulation of Siemens Primus linac as well as a phantom and a tumor loaded with nanoparticles. Electron dose enhancement by Au, Ag, I and Fe2O3 nanoparticles of 7, 18 and 30 mg/ml concentrations for 8, 12 and 14 MeV electrons was calculated. The increase in photon contamination due to the presence of the nanoparticles was evaluated as well. The above effects were evaluated for 500 keV and 10 keV energy cut-offs defined for electrons and photons. For 500 keV energy cut-off, there was no significant electron dose enhancement. However, for 10 keV energy cut-off, a maximum electron dose enhancement factor of 1.08 was observed for 30 mg/ml of gold nanoparticles with 8 MeV electrons. An increase in photon contamination due to nanoparticles was also observed which existed mainly inside the tumor. A maximum photon dose increase factor of 1.07 was observed inside the tumor with Au nanoparticles. Nanoparticles can be used for the enhancement of electron dose in the electron mode of a linac. Lower energy electron beams, and nanoparticles with higher atomic number, can be of greater benefit in this field. Photons originating from nanoparticles will increase the photon dose inside the tumor, and will be an additional advantage of the use of nanoparticles in radiotherapy with electron beams.

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Fragopoulou, M., M. Zamani, S. Siskos, T. Laopoulos, V. Konstantakos, and G. Sarrabayrouse. "A Study of the Response of Depleted Type p-MOSFETs to Electron Doses." HNPS Proceedings 24 (April 1, 2019): 153. http://dx.doi.org/10.12681/hnps.1859.

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A study of depleted pMOSFETs characteristics performed with electrons, at energies ranging from 6 to 15 MeV delivered by Linac medical accelerator. The depleted pMOSFETs present high sensitivity to electron doses. Linear threshold voltage shift with dose was measured for all the electron’s energies studied. A small decrease of the response was observed with dose rate during irradiations which can be attributed to ELDRS effects.

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8

Song, Jiamei, Biying Song, Liqi Zou, Christopher Allen, Hidetaka Sawada, Fucai Zhang, Xiaoqing Pan, Angus I. Kirkland, and Peng Wang. "Fast and Low-dose Electron Ptychography." Microscopy and Microanalysis 24, S1 (August 2018): 224–25. http://dx.doi.org/10.1017/s1431927618001617.

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9

Voelkl, Edgar, Rodney Herring, Benjamin Bammes, and David Hoyle. "Low Dose Electron Holography: First Steps." Microscopy and Microanalysis 21, S3 (August 2015): 1951–52. http://dx.doi.org/10.1017/s1431927615010533.

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10

D'Alfonso, A. J., L. J. Allen, H. Sawada, and A. I. Kirkland. "Dose-dependent high-resolution electron ptychography." Journal of Applied Physics 119, no. 5 (February 7, 2016): 054302. http://dx.doi.org/10.1063/1.4941269.

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11

Zhang, Yue, Peng-Han Lu, Enzo Rotunno, Filippo Troiani, J. Paul van Schayck, Amir H. Tavabi, Rafal E. Dunin-Borkowski, Vincenzo Grillo, Peter J. Peters, and Raimond B. G. Ravelli. "Single-particle cryo-EM: alternative schemes to improve dose efficiency." Journal of Synchrotron Radiation 28, no. 5 (August 26, 2021): 1343–56. http://dx.doi.org/10.1107/s1600577521007931.

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Imaging of biomolecules by ionizing radiation, such as electrons, causes radiation damage which introduces structural and compositional changes of the specimen. The total number of high-energy electrons per surface area that can be used for imaging in cryogenic electron microscopy (cryo-EM) is severely restricted due to radiation damage, resulting in low signal-to-noise ratios (SNR). High resolution details are dampened by the transfer function of the microscope and detector, and are the first to be lost as radiation damage alters the individual molecules which are presumed to be identical during averaging. As a consequence, radiation damage puts a limit on the particle size and sample heterogeneity with which electron microscopy (EM) can deal. Since a transmission EM (TEM) image is formed from the scattering process of the electron by the specimen interaction potential, radiation damage is inevitable. However, we can aim to maximize the information transfer for a given dose and increase the SNR by finding alternatives to the conventional phase-contrast cryo-EM techniques. Here some alternative transmission electron microscopy techniques are reviewed, including phase plate, multi-pass transmission electron microscopy, off-axis holography, ptychography and a quantum sorter. Their prospects for providing more or complementary structural information within the limited lifetime of the sample are discussed.

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12

McMullan, G., A. T. Clark, R. Turchetta, and A. R. Faruqi. "Enhanced imaging in low dose electron microscopy using electron counting." Ultramicroscopy 109, no. 12 (November 2009): 1411–16. http://dx.doi.org/10.1016/j.ultramic.2009.07.004.

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13

Mittelberger, Andreas, Christian Kramberger, and Jannik C. Meyer. "Software electron counting for low-dose scanning transmission electron microscopy." Ultramicroscopy 188 (May 2018): 1–7. http://dx.doi.org/10.1016/j.ultramic.2018.02.005.

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14

Pla, Marina, Ervin B. Podgorsak, and Conrado Pla. "Electron dose rate and photon contamination in electron arc therapy." Medical Physics 16, no. 5 (September 1989): 692–97. http://dx.doi.org/10.1118/1.596328.

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15

Acar, Hilal, Mustafa Caglar, and Ayse Y. Altinok. "Experimental validatıon of peripheral dose distribution of electron beams for eclipse electron Monte Carlo algorithm." Journal of Radiotherapy in Practice 17, no. 3 (July 23, 2018): 279–88. http://dx.doi.org/10.1017/s1460396917000784.

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AbstractAimThe accuracy of two calculation algorithms of the Varian Eclipse treatment planning system (TPS), the electron Monte Carlo algorithm (eMC) and general Gaussian pencil beam algorithm (GGPB) for calculating peripheral dose distribution of electron beams was investigated.MethodsPeripheral dose measurements were carried out for 6, 9, 12, 15, 18 and 22 MeV electron beams using parallel plate ionisation chamber and EBT3 film in the slab phantom. Measurements were performed for 6×6, 10×10 and 25×25 cm2 cone sizes at dmax of each energy up to 20 cm beyond the field edges. The measured and TPS calculated data were compared.ResultsThe TPS underestimated the out-of-field doses. The difference between measured and calculated doses increase with the cone size. For ionisation chamber measurement, the largest deviation between calculated and measured doses is <4·29% using the eMC, but can increase up to 8·72% of the distribution using GGPB. For film measurement, the minimum gamma analysis passing rates between measured and calculated dose distributions for all field sizes and energies used in this study were 91·2 and 74·7% for eMC and GGPB, respectively.FindingsThe use of GGPB for planning large field treatments with 6 MeV could lead to inaccuracies of clinical significance.

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16

Shi, Jun-Wen, Yee-Min Jen, Shyh-An Yeh, and Jia-Ming Wu. "Delivering total skin electron therapy using regular electron cones." International Journal of Modern Physics B 34, no. 22n24 (August 28, 2020): 2040162. http://dx.doi.org/10.1142/s0217979220401621.

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This study presents a technique requiring relatively simple supporting devices and protection accessories for treating conditions like mycosis fungoides in which a uniform radiation dose to the whole body can be achieved by using the regular largest electron cone instead of HDRe[Formula: see text] mode in one treatment course. The regular cone total skin electron therapy technique presented in this study is able to deliver a uniform radiation dose to the patient’s skin surface. The result is satisfying when compared with the High Dose Rate e[Formula: see text] (HDRe[Formula: see text]) Stanford Six Field Technique.

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17

Mehta, Kishor, Pier-Giorgio Fuochi, András Kovács, Marco Lavalle, and Peter Hargittai. "Dose distribution in electron-irradiated PMMA: effect of dose and geometry." Radiation Physics and Chemistry 55, no. 5-6 (August 1999): 773–79. http://dx.doi.org/10.1016/s0969-806x(99)00302-3.

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18

Maigné, Alan, and Matthias Wolf. "Low-dose electron energy-loss spectroscopy using electron counting direct detectors." Microscopy 67, suppl_1 (November 9, 2017): i86—i97. http://dx.doi.org/10.1093/jmicro/dfx088.

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19

Nicholls, Daniel, Juhan Lee, Houari Amari, Andrew Stevens, B. Mehdi Layla, and Nigel Browning. "Distributing the Electron Dose to Minimise Electron Beam Damage in Scanning Transmission Electron Microscopy." Microscopy and Microanalysis 26, S2 (July 30, 2020): 3070–71. http://dx.doi.org/10.1017/s1431927620023727.

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20

Acharya, Santhosh, Ganesh Sanjeev, Nagesh Bhat, and Yerol Narayana. "Dose Rate Effect of Pulsed Electron Beam on Micronucleus Frequency in Human Peripheral Blood Lymphocytes." Archives of Industrial Hygiene and Toxicology 61, no. 1 (March 1, 2010): 77–83. http://dx.doi.org/10.2478/10004-1254-61-2010-1982.

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Dose Rate Effect of Pulsed Electron Beam on Micronucleus Frequency in Human Peripheral Blood LymphocytesThe micronucleus assay in human peripheral blood lymphocytes is a sensitive indicator of radiation damage and could serve as a biological dosimeter in evaluating suspected overexposure to ionising radiation. Micronucleus (MN) frequency as a measure of chromosomal damage has also extensively been employed to quantify the effects of radiation dose rate on biological systems. Here we studied the effects of 8 MeV pulsed electron beam emitted by Microtron electron accelerator on MN induction at dose rates between 35 Gy min-1 and 352.5 Gy min-1. These dose rates were achieved by varying the pulse repetition rate (PRR). Fricke dosimeter was employed to measure the absorbed dose at different PRR and to ensure uniform dose distribution of the electron beam. To study the dose rate effect, blood samples were irradiated to an absorbed dose of (4.7±0.2) Gy at different rates and cytogenetic damage was quantified using the micronucleus assay. The obtained MN frequency showed no dose rate dependence within the studied dose rate range. Our earlier dose effect study using 8 MeV electrons revealed that the response of MN was linear-quadratic. Therefore, in the event of an accident, dose estimation can be made using linear-quadratic dose response parameters, without adding dose rate as a correction factor.

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21

Tunio, Mutahir, Zaeem Ahmed, Asad Zameer, Shoukat Ali, Kamran A. Awan, and Basit Khan. "Single Institutional Experience of Electron Conformal Therapy (ECT) and Modulated Electron Therapy (MET) for Post-mastectomy Chest Wall Irradiation." Journal of Radiotherapy in Practice 12, no. 2 (August 1, 2012): 173–79. http://dx.doi.org/10.1017/s146039691200012x.

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AbstractObjective: Two opposed tangential photon beams followed by scar boost with electrons is a common technique for post-mastectomy radiotherapy to the chest wall. However with current advances in x-rays (conformal and intensity modulated radiotherapy), the electrons have gained less attention; and most of the centres are using the conventional electron therapy techniques. Here we share our experience of electron conformal therapy (ECT) and modulated electron therapy (MET) for post-mastectomy scar boost.Materials and methods: For post-mastectomy chest wall irradiation, 25 patients were treated with ECT and MET in five steps (a) virtual simulation and image acquisition using CT scanner Siemens® followed by (b) data transfer to Coherence Siemens® for contouring of skin, clinical target volume (CTV), planning target volume (PTV) and organs at risk (OARs), followed by (c) forward and reverse planning applying segmented fields using Prowess Panther treatment planning system (TPS) Siemens® and shaping of fields on beam’s eye view (BEV), (d) data transfer to computer assisted fabrication device (Autimo 2D) for lead cut outs and wax blocks and finally (e) quality assurance (QA) and modified treatment delivery.Results: Apart from energy selection and tumor delineation, the ECT and MET showed maximal sparing of OARs (< 70% of prescribed dose), and improved dose conformity compared to single energy single field plans. Phantom and in vivo dosimetric measurements showed excellent agreement with calculated doses with difference ±2%. Conformity improved little beyond allowing three energies due to energy overlap and field-size constraints and conformity improvement was found at the expanse of dose heterogeneity within the PTV.Conclusions: ECT and MET is time saving and can be utilised for treating superficial targets to improve the treatment outcome and with better QA; however, efforts are required to design commercially available eMLC (electron multileaf collimators) in modern linear accelerators.

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22

Franciszek Kukolowicz, Pawel, Malgorzata Gil-Ulkowska, and Wojciech Bulski. "The effective dose (Deff) for electron beams." Radiotherapy and Oncology 74, no. 2 (February 2005): 211–15. http://dx.doi.org/10.1016/j.radonc.2004.09.012.

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23

Prestwich, William V., and Fred Kus. "Radial dose profiles for pencil electron beams." Radiation Physics and Chemistry 50, no. 6 (December 1997): 535–43. http://dx.doi.org/10.1016/s0969-806x(97)00093-5.

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24

Lawrence, C. B., J. McKeown, and E. B. Svendsen. "Real-time confirmation of electron-beam dose." Radiation Physics and Chemistry 52, no. 1-6 (June 1998): 543–47. http://dx.doi.org/10.1016/s0969-806x(98)00092-9.

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25

Calderon, Hector, Jeffrey Rimer, Francisco Robles-Hernandez, and Christian Kisielowski. "Low Dose Electron Microscopy of Amonium Urates." Microscopy and Microanalysis 26, S2 (July 30, 2020): 2230–31. http://dx.doi.org/10.1017/s1431927620020887.

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26

Chow, James C. L., and Grigor N. Grigorov. "Peripheral dose outside applicators in electron beams." Physics in Medicine and Biology 51, no. 12 (May 31, 2006): N231—N240. http://dx.doi.org/10.1088/0031-9155/51/12/n01.

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27

Kodjikian, Stéphanie, and Holger Klein. "Low-dose electron diffraction tomography (LD-EDT)." Ultramicroscopy 200 (May 2019): 12–19. http://dx.doi.org/10.1016/j.ultramic.2019.02.010.

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28

Kumar, P., C. Watts, T. Svimonishvili, M. Gilmore, and E. Schamiloglu. "The Dose Effect in Secondary Electron Emission." IEEE Transactions on Plasma Science 37, no. 8 (August 2009): 1537–51. http://dx.doi.org/10.1109/tps.2009.2022970.

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29

Mittendorfer, Josef, and Markus Niederreiter. "Intrinsic dose characteristics in electron beam irradiation." Radiation Physics and Chemistry 177 (December 2020): 109124. http://dx.doi.org/10.1016/j.radphyschem.2020.109124.

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30

Fullem, T. Z., K. C. Fazel, J. A. Geuther, and Y. Danon. "Therapeutic Dose from a Pyroelectric Electron Accelerator." Radiation Research 172, no. 5 (November 2009): 643–47. http://dx.doi.org/10.1667/rr1876.1.

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31

Deshmukh, P. R., and W. S. Khokle. "On dose correction in electron beam lithography." Journal of Applied Physics 64, no. 1 (July 1988): 421–23. http://dx.doi.org/10.1063/1.341445.

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32

Shortt, K. R., C. K. Ross, A. F. Bielajew, and D. W. O. Rogers. "Electron beam dose distributions near standard inhomogeneities." Physics in Medicine and Biology 31, no. 3 (March 1, 1986): 235–49. http://dx.doi.org/10.1088/0031-9155/31/3/003.

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33

Meigooni, A. S., and I. J. Das. "Parametrisation of depth dose for electron beams." Physics in Medicine and Biology 32, no. 6 (June 1, 1987): 761–68. http://dx.doi.org/10.1088/0031-9155/32/6/008.

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34

Shiu, Almon S., Samuel Tung, Kenneth R. Hogstrom, John W. Wong, Russell L. Gerber, William B. Harms, James A. Purdy, Randall K. Ten Haken, Daniel L. McShan, and Benedick A. Fraass. "Verification data for electron beam dose algorithms." Medical Physics 19, no. 3 (May 1992): 623–36. http://dx.doi.org/10.1118/1.596808.

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35

Faddegon, B. A., and I. Blevis. "Electron spectra derived from depth dose distributions." Medical Physics 27, no. 3 (March 2000): 514–26. http://dx.doi.org/10.1118/1.598919.

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36

Kirby, Thomas H., Robert J. Gastorf, William F. Hanson, Lawrence W. Berkley, William F. Gagnon, John D. Hazle, and Robert J. Shalek. "Electron beam central axis depth dose measurements." Medical Physics 12, no. 3 (May 1985): 357–61. http://dx.doi.org/10.1118/1.595696.

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37

Yu, C. X., T. R. Mackie, and J. W. Wong. "Photon dose calculation incorporating explicit electron transport." Medical Physics 22, no. 7 (July 1995): 1157–65. http://dx.doi.org/10.1118/1.597611.

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38

Kovács, A., and A. Miller. "Electron dose determination by ethanol-monochlorobenzene dosimeter." International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry 28, no. 5-6 (January 1986): 531–33. http://dx.doi.org/10.1016/1359-0197(86)90183-9.

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39

Miller, Arne. "Polystyrene calorimeter for electron beam dose measurements." Radiation Physics and Chemistry 46, no. 4-6 (September 1995): 1243–46. http://dx.doi.org/10.1016/0969-806x(95)00361-z.

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40

Kuznetsov, P. I. "Dependence of bremsstrahlung dose on electron energy." Soviet Atomic Energy 69, no. 2 (August 1990): 667–69. http://dx.doi.org/10.1007/bf02046346.

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41

Van Cappellen, Eric, Christian Maunders, Ingrid Kieft, Maarten Bischoff, Felix Van Uden, Mikhail Ovsyanko, Boy Markus, et al. "Spectra optimizes the use of electron dose." Microscopy and Microanalysis 27, S1 (July 30, 2021): 1066–67. http://dx.doi.org/10.1017/s1431927621004025.

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Pradère, Philippe, and Edwin L. Thomas. "Shot-noise simulations of HREM images of polymer crystals." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 342–43. http://dx.doi.org/10.1017/s0424820100153683.

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High Resolution Electron Microscopy (HREM) is a very powerful technique for the study of crystal defects at the molecular level. Unfortunately polymer crystals are beam sensitive and are destroyed almost instantly under the typical HREM imaging conditions used for inorganic materials. Recent developments of low dose imaging at low magnification have nevertheless permitted the attainment of lattice images of very radiation sensitive polymers such as poly-4-methylpentene-1 and enabled molecular level studies of crystal defects in somewhat more resistant ones such as polyparaxylylene (PPX) [2].With low dose conditions the images obtained are very noisy. Noise arises from the support film, photographic emulsion granularity and in particular, the statistical distribution of electrons at the typical doses of only few electrons per unit resolution area. Figure 1 shows the shapes of electron distribution, according to the Poisson formula :

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Isoda, Seiji, Kimitsugu Saitoh, Sakumi Moriguchi, and Takashi Kobayashi. "Application of Imaging Plate to High-Voltage Electron Microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 168–69. http://dx.doi.org/10.1017/s0424820100179592.

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On the observation of structures by high resolution electron microscopy, recording materials with high sensitivity and high quality is awaited, especially for the study of radiation sensitive specimens. Such recording material should be easily combined with the minimum dose system and cryoprotection method. Recently a new recording material, imaging plate, comes to be widely used in X-ray radiography and also in electron microscopy, because of its high sensitivity, high quality and the easiness in handling the images with a computer. The properties of the imaging plate in 100 to 400 kV electron microscopes were already discussed and the effectiveness was revealed.It is demanded to study the applicability of the imaging plate to high voltage electron microscopy. The quality of the imaging plate was investigated using an imaging plate system (JEOL EM-HSR100) equipped in a new Kyoto 1000kV electron microscope. In the system both the imaging plate and films can be introduced together into the camera chamber. Figure 1 shows the effect of accelerating voltage on read-out signal intensities from the imaging plate. The characteristic of commercially available imaging plates is unfortunately optimized for 100 to 200 keV electrons and then for 600 to 1000 keV electrons the signal is reduced. In the electron dose range of 10−13 to 10−10 C/cm2, the signal increases linearly with logarithm of electron dose in all acceralating volatges.

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Fragopoulou, M., S. Stoulos, M. Zamani, E. Benton, D. O'Sullivan, S. Siskos, T. Laopoulos, V. Konstantakos, and G. Sarrabayrouse. "A study of the response of depleted type p-MOSFETs to electron dose." HNPS Proceedings 21 (March 8, 2019): 84. http://dx.doi.org/10.12681/hnps.2009.

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The p-MOSFET dosimeter studied in this work has been manufactured at LAAS- CNRS Laboratory in Toulouse France, for applications in personal and space dosimetry. They are proposed for proton, heavy ions and electron and photon dose measurements. The current study investigates the sensitivity of this new type of Metal-Oxide-Semiconductor field effect transistor (MOSFET) to electrons. The sensitivity of the new MOSFET based dosemeters to electrons is linear for wide dose ranges. The influence of the electrons energy on the dosemeters response is also investigated.

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Beketov, E. E., E. V. Isaeva, N. V. Nasedkina, I. A. Zamulaeva, O. N. Matchuk, L. N. Ulyanenko, E. P. Malakhov, et al. "Acquired resistance of B16 tumor cells to protons after prolonged fractional electron irradiation." "Radiation and Risk" Bulletin of the National Radiation and Epidemiological Registry 29, no. 4 (2020): 69–83. http://dx.doi.org/10.21870/0131-3878-2020-29-4-69-83.

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Cancer radiotherapy effectiveness largely depends on tumor cells radiosensitivity. Inherent or acquired radioresistance of tumor cells is important challenge in radiation therapy. Response of tumor cells to fractionated radiation therapy has been investigated by many research groups. At present time the use of protons for cancer research and treatment has expanded rapidly. In this connection research on sensitivity of tumor cells to proton beam therapy is an urgent task. The aim of the study was to assess sensitivity of irradiated with electrons or protons B16 melanoma cells to the next electron beam or proton beam irradiation at comparable total doses. Studies with the use of stable tumor cell lines with acquired radioresistance may be useful for the develop-ment of effective treatment plan tailored to the patients with relapses or metastases that have oc-curred after prior unsuccessful radiotherapy with standard types of radiation. Protons were pro-vided by Prometeus installation scanning beam and the electron beam of the accelerator Novac-11. Cells radiosensitivity was measured by clonogenic assay. The resistance of cells first irradiat-ed with protons and electrons to the next irradiation with protons and electrons was estimated by clonogenic assay. DNA damages, cell size, proliferative activity and cell cycle phase distribution were also evaluated. The study demonstrated that fractionated irradiation of B16 cells with elec-trons at the total dose of 60 Gy causes significant reduction of cells radiosensitivity to the next ir-radiation with protons, radiosensitivity of irradiated cells to the second irradiation with electrons remains the same. In contrast, the first fractionated irradiation of cells with protons at the total dose of 50 Gy does not affect the radiosensitivity of the cells to the next irradiation with electrons or protons.

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Kuruoğlu, Furkan, Özgür Yavuzçetin, and Ayşe Erol. "Electron Beam Dose and PMMA Thickness Dependent Circularity and Diameter Analysis of Au Nanodots." Current Nanoscience >15, no. 5 (July 19, 2019): 486–91. http://dx.doi.org/10.2174/1573413714666181114104255.

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Background: The electrical and optical properties of nanoparticle-based devices depend on the shape, dimension and uniformity of these particles. Methods: In this work, we fabricated ordered Au nanodots using electron beam lithography and thermal evaporation. Au nanodot diameter and circularity varied with a changed exposure dose and resist thickness. Electron beam dose ranged from 5 fC to 200 fC for single dot patterns. Commonly used PMMA thin films of thicknesses 60 nm and 100 nm coated samples were used for investigating the resist thickness dependency with varying dose exposure. Results: The analyses of patterns show that the diameter and circularity of the Au nanodots ranged from smaller to larger diameters and from lower to higher circularities with increasing dose and resist thickness. Conclusion: The distributions of the nanodot diameter began to show Gaussian behavior at larger electron doses. Besides, single circularity value became dominant up to the medium doses and then a homogeneous distribution was observed with the increasing dose.

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Armstrong, David A., Suichu Luo, and David C. Joy. "Re-examining mechanisms of radiation damage in organic specimens." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 812–13. http://dx.doi.org/10.1017/s0424820100177192.

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Radiation damage to organic specimens is the major limiting factor in high resolution electron microscopy studies of biological systems. Electron beam irradiation compromises resolution by altering chemical microstructure, resulting in local mass loss and volume shrinkage in a specimen. All significant mass loss is thought to occur prior to a total incident dose of 50 electrons/ square angstrom If this is the case it is hard to reconcile the observation that images must be recorded at doses of less than 100 el/Å in order to avoid excessive mass loss and shrinkage while microanalytical (EDS and EELS) studies of the same tissue are routinely carried out at doses of 104 - 105el/Å2. Also, since most workers typically use either low dose (for imaging) or high dose (for microapalysis) there are apparently no studies in the literature which attempt to follow the process of radiation damage between these two extremes.We have chosen to investigate mass loss in polymer embedding resins such as are routinely used for TEM imaging as well as for X ray microanalytical applications.

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Anam, Choirul, Djarwani S. Soejoko, Freddy Haryanto, Sitti Yani, and Geoff Dougherty. "Electron contamination for 6 MV photon beams from an Elekta linac: Monte Carlo simulation." Journal of Physics and Its Applications 2, no. 2 (May 28, 2020): 97–101. http://dx.doi.org/10.14710/jpa.v2i2.7771.

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In external beam radiotherapy, the photons from a linear accelerator (linac) machine undergo multiple interactions, not only in the patient but also in the linac head and the air column between the linac head and the patient. Electrons are released from these interactions and contaminate the beams. The current study evaluates electron contamination for 6 MV photon beams from an Elekta linac using Monte Carlo simulation. The linac head was simulated by the BEAMnrc code and the absorbed dose in a phantom was calculated using the DOSXYZnrc code. The parameters of the initial electron beams on the target, such as mean energy and radial intensity distribution, were determined by matching the calculated dose distributions with the measured dose (at 10 x 10 cm2 field size and 90 cm source-skin distance). The central axis depth-dose curves of electron contamination were calculated for various field sizes from 5 x 5 cm2 to 40 x 40 cm2. We investigated the components that generated the electron contamination for a field size of 10 x 10 cm2. The optimal initial electron beam energy was 6.3 MeV with a full-width half maximum (FWHM) of the radial intensity distribution of 1.0 mm. These parameters were found to be in good agreement with the measured data. Electron contamination increased as the field size increased. At a depth of 1.0 mm and field sizes of 5 x 5, 10 x 10, 20 x 20, 30 x 30, and 40 x 40 cm2, the doses from electron contamination were 3.71, 5.19, 14.39, 18.97 and 20.89 %, respectively. Electron contamination decreased with increased depth. At a depth of 15 mm, the electron contamination was about 1 %. It was mainly generated in the air column between the linac head and the phantom (3.65 %), the mirror (0.99 %), and the flattening filter (0.59 %) (for the depth of 1.0 mm and the field size of 10 x 10 cm2).

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Moribayashi, Kengo. "Effect of Recombination between a Molecular Ion and an Electron on Radial Dose in the Irradiation of a Heavy Ion." Applied Physics Research 8, no. 1 (January 29, 2016): 138. http://dx.doi.org/10.5539/apr.v8n1p138.

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<p class="1Body">This paper discusses the effect of recombination between a molecular ion and a free electron on radial dose in the irradiation of a heavy ion through simulations. This irradiation produces molecular ions and free electrons due to the heavy ion impact ionization. The composition electric field, which is formed from these molecular ions, traps some of free electrons and these trapped free electrons increase radial dose near the heavy ion path. These trapped electrons also cause the recombination and that the recombination enhances radial dose.</p>

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Hansen, Joyce M., Niki Fidopiastis, Trabue Bryans, Michelle Luebke, and Terri Rymer. "Radiation Sterilization: Dose Is Dose." Biomedical Instrumentation & Technology 54, s1 (June 1, 2020): 45–52. http://dx.doi.org/10.2345/0899-8205-54.s3.45.

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Abstract In the radiation sterilization arena, the question often arises as to whether radiation resistance of microorganisms might be affected by the energy level of the radiation source and the rate of the dose delivered (kGy/time). The basis for the question is if the microbial lethality is affected by the radiation energy level and/or the rate the dose is delivered, then the ability to transfer dose among different radiation sources could be challenged. This study addressed that question by performing a microbial inactivation study using two radiation sources (gamma and electron beam [E-beam]), two microbial challenges (natural product bioburden and biological indicators), and four dose rates delivered by three energy levels (1.17 MeV [gamma], 1.33 MeV [gamma], and 10 MeV [high-energy E-beam]). Based on analysis of the data, no significant differences were seen in the rate of microbial lethality across the range of radiation energies evaluated. In summary, as long as proof exists that the specified dose is delivered, dose is dose.

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Journal articles on the topic 'Electron dose'

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