Search results for "DOSIMETRY"
showing 10 items of 297 documents
Use of aluminum nitride for UV radiation dosimetry
2007
Abstract An investigation of AlN ceramics for applications in UV radiation detection shows the advantages of using the 480 nm emission band for optically stimulated luminescence signal detection instead of the previously used 400 nm emission band since the rate of decrease of the response signal at room temperature is lower than that of the 400 nm band, and its excitation region falls in the UV-B range.
Discrimination of LINAC photon and sunlight contributions in watch glass analyzed by means of thermoluminescence
2012
Abstract The research described in this paper shows how to extract from the glow curves of watch glasses exposed to LINAC photons and sunlight a contribution sensitive to LINAC photons dose. As first step, the dependence of the TL signal due to sunlight on the exposure duration was studied and a signal saturation was observed after about 20 weeks. The comparison of TL signals due to solar light and to LINAC photons highlights a partial overlap of the two signals. Here, two different analysis procedures of glow curves (general order kinetics deconvolution and principal components analysis) are reported to point out components which depend differently on LINAC photon radiation dose. For both …
Evaluation of high-energy brachytherapy source electronic disequilibrium and dose from emitted electrons
2009
Purpose: The region of electronic disequilibrium near photon-emitting brachytherapysources of high-energy radionuclides ( C 60 o , C 137 s , I 192 r , and Y 169 b ) and contributions to total dose from emitted electrons were studied using the GEANT4 and PENELOPEMonte Carlo codes. Methods: Hypothetical sources with active and capsule materials mimicking those of actual sources but with spherical shape were examined. Dose contributions due to sourcephotons, x rays, and bremsstrahlung; source β − , Auger electrons, and internal conversionelectrons; and water collisional kerma were scored. To determine if conclusions obtained for electronic equilibrium conditions and electrondose contribution t…
SU-FF-T-15: Comparison of Various Monte Carlo Codes for Brachytherapy Source Dosimetry
2009
Purpose: Monte Carlo simulations are used for dosimetric evaluation of brachytherapysources. Various investigators had demonstrated good agreement between the measured and simulated data while some others have shown discrepancies between the two methods. These discrepancies were attributed to the errors in cross section data, differences in phantom and source geometry and composition. However, the exact causes of these differences have not yet fully explored. The goal of this project is to verify the differences among the widely available Monte Carlo codes for brachytherapysourcedosimetry.Material and method: These investigations are based on VariSource 192 Ir , Model VS2000, IsoAid Advanta…
Dosimetric characterization of Ir-192 LDR elongated sources
2008
Ir-192 wires have been used in low-dose-rate brachytherapy for many years. Commercially available treatment planning systems approximate the dose rate distribution of the straight or curved wires applying the superposition principle using one of the following methods: (i) The wire is modeled as a set of point sources, (ii) the wire is modeled as a set of small straight segment wires, (iii) the values of the parameters and functions of the American Association of Physicists in Medicine (AAPM) Task Group 43 protocol are obtained for wire lengths between 3 and 7 cm assuming some simplifications. The dose rate distributions obtained using these methods for linear wires of different lengths and …
Monte Carlo and experimental derivation of TG43 dosimetric parameters for CSM-type Cs-137 sources
2004
In this study, complete dosimetric datasets for the CSM2 and CSM3 Cs-137 sources were obtained using the Monte Carlo GEANT4 code. The application of this calculation method was experimentally validated with thermoluminescent dosimetry (TLD). Functions and parameters following the TG43 formalism are presented: the dose rate constant, the radial dose functional, and the anisotropy function. In addition, to aid the quality control process on treatment planning systems, a two-dimensional (2D) rectangular dose rate table (the traditional along-away table), coherent with the TG43 dose calculation formalism, is given. The data given in this study complement existing information for both sources on…
Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams.
2020
The beam quality correction factor k Q for megavoltage photon beams has been calculated for eight PTW (Freiburg, Germany) ionization chambers (Farmer chambers PTW30010, PTW30011, PTW30012, and PTW30013, Semiflex 3D chambers PTW31021, PTW31010, and PTW31013, and the PinPoint 3D chamber PTW31016). Simulations performed on the widely used NE-2571 ionization chamber have been used to benchmark the results. The Monte Carlo code PENELOPE/penEasy was used to calculate the absorbed dose to a point in water and the absorbed dose to the active air volume of the chambers for photon beams in the range 4 to 24 MV. Of the nine ionization chambers analysed, only five are included in the current version of…
Monte Carlo calculation of dose rate distributions around the Walstam CDC.K-type137Cs sources
2001
Basic dosimetric data for the Walstam CDC.K-type low dose rate 137Cs sources in water have been calculated using Monte Carlo techniques. These sources, CDC.K1 -K3 and CDC.K4, are widely used in a range of applicators and moulds for the treatment of intracavitary and superficial cancers. Our purpose is to improve existing data about these sources using the Monte Carlo simulation code GEANT3. Absolute dose rate distributions in water have been calculated around these sources and are presented as conventional 2D Cartesian look-up tables. Also the AAPM Task Group 43 formalism for dose calculation has been applied. The calculated dose rate constant for the CDC.K1-K3 source is A = 1.106 +/- 0.001…
Low Energy Protons at RADEF - Application to Advanced eSRAMs
2014
A low energy proton facility has been developed at RADEF, Jyvskyl, Finland. The proton energy selection, calibration and dosimetry are described. The first experiment with external users was performed using two memory test vehicles fabricated with 28 nm technology. Examples of single event upset measurements in the test vehicles embedded SRAMs (eSRAMs) as a function of proton energy are provided.
Improvement of the LET sensitivity in ESR dosimetry for -photons and thermal neutrons through gadolinium addition
2007
Abstract We investigated the ESR response of new materials, alanine and ammonium tartrate to which gadolinium was added. The addition of gadolinium enhances sensitivity for Co 60 γ -photons because of its high atomic number ( Z = 64 ) and an enhancement of sensitivity for thermal neutrons because of its high thermal neutron cross section and high linear energy transfer (LET) secondary particles produced after the reaction with neutrons. In particular, in this paper we analyzed the microwave power saturation properties of dosimeters of alanine and ammonium tartrate with or without gadolinium exposed to different LET beams. The power saturation trends of dosimeters exposed to photons and to t…