Dosimetric Analysis of a Laser Accelerated Electron Beam and Optimization of FBX Chemical Dosimeter

AbstractBackgroundIn radiotherapy, electron beam irradiation is an effective modality for superficial tumours. Electron beams have good coverage of tumours which involve the skin, however there is an issue about electron scattering and tissue heterogeneity. This subsequently demands dosimetric analysis of electron beam behaviour, particularly in the treatment of lesions on the scalp requiring the application of treatment to scalp curvatures. There are various methods which are used to treat scalp malignancies including photons and electrons, but, the later needs precise dosimetry before each session of treatment. The purpose of the study was to undertake a detailed analysis of the dosimetry of electron beams when applied to the curved surface of the scalp using Gafchromic® EBT2 films.Methods and materialsA rando phantom and Gafchromic® EBT2 films were used for dosimetric analysis. A gafchromic calibration curve was plotted and an in-treatment beam dosimetric analysis was carried out using dosimetry films placed on the scalp. Electron behaviour was assessed by introducing five electron fields in particular curvature regions of scalp.ResultThere was an acceptable dose range through all five fields and hotspots occurred in the curved borders. In our study, skin doses and doses at the field junctions, with no gaps, were between 78–97% and 80–97%, respectively.ConclusionsElectron beams are a good modality for treating one flat field, but in the special topography of the scalp, whole scalp treatment requires precise field matching and dosimetry. In undertaking this detailed dosimetric analysis using a rando phantom and Gafchromic® EBT2 films, it is concluded that this method requires further detailed analysis before using in clinics.

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A dosimetric analysis comparing electron beam with the MammoSite brachytherapy applicator for intact breast boost

Physica Medica ◽

10.1016/j.ejmp.2009.08.004 ◽

2010 ◽

Vol 26 (2) ◽

pp. 80-87 ◽

Cited By ~ 7

Author(s):

A.P. Shah ◽

J.B. Strauss ◽

M.C. Kirk ◽

S.S. Chen ◽

A. Dickler

Keyword(s):

Electron Beam ◽

Dosimetric Analysis

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Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065079 ◽

1971 ◽

Vol 29 ◽

pp. 204-205

Author(s):

G. G. Shaw

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Aluminum Alloy ◽

Electron Beam ◽

Pure Aluminum ◽

Ion Milling ◽

Transmission Electron ◽

Fiber Matrix ◽

Ion Erosion ◽

Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

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Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053188 ◽

1982 ◽

Vol 40 ◽

pp. 78-79

Author(s):

Kenneth H. Downing ◽

Robert M. Glaeser

Keyword(s):

Electron Beam ◽

Fatty Acid ◽

Inelastic Scattering ◽

Temperature Dependence ◽

Structural Damage ◽

Direct Result ◽

Second Step ◽

Strong Temperature Dependence ◽

Electron Dose ◽

Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

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Lithography below 100 nm

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074367 ◽

1983 ◽

Vol 41 ◽

pp. 96-99

Author(s):

L. D. Jackel

Keyword(s):

Spatial Distribution ◽

Electron Beam ◽

Electron Scattering ◽

Electron Beam Lithography ◽

Substrate Material ◽

Local Electron ◽

Electron Dose ◽

Positive Resist ◽

Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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Domain Formation in Synthetic Quartz

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064839 ◽

1971 ◽

Vol 29 ◽

pp. 156-157

Author(s):

Joseph J. Comer

Keyword(s):

Electron Beam ◽

Room Temperature ◽

Domain Formation ◽

Synthetic Quartz ◽

Transmission Electron ◽

Black Spots ◽

Diffraction Mode ◽

Domain Boundaries ◽

Kikuchi Lines ◽

Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

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