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Sample records for energy electron dosimetry

  1. Neutron dosimetry at a high-energy electron-positron collider

    NASA Astrophysics Data System (ADS)

    Bedogni, Roberto

    Electron-positron colliders with energy of hundreds of MeV per beam have been employed for studies in the domain of nuclear and sub-nuclear physics. The typical structure of such a collider includes an LINAC, able to produce both types of particles, an accumulator ring and a main ring, whose diameter ranges from several tens to hundred meters and allows circulating particle currents of several amperes per beam. As a consequence of the interaction of the primary particles with targets, shutters, structures and barriers, a complex radiation environment is produced. This paper addresses the neutron dosimetry issues associated with the operation of such accelerators, referring in particular to the DAΦ NE complex, operative since 1997 at INFN-Frascati National Laboratory (Italy). Special attention is given to the active and passive techniques used for the spectrometric and dosimetric characterization of the workplace neutron fields, for radiation protection dosimetry purposes.

  2. Solid water as phantom material for dosimetry of electron backscatter using low-energy electron beams: a Monte Carlo evaluation.

    PubMed

    Chow, James C L; Owrangi, Amir M

    2009-05-01

    This study evaluated the dosimetry of electron backscatter when Solid Water is used to substitute water as phantom in electron radiotherapy. Monte Carlo simulation (EGSnrc-based code) was employed to predict electron energy spectra and depth doses for the 0.5 and 1 cm of Solid Water and water slabs above 3 mm of lead (Pb) layers using electron beams with energies of 4 and 6 MeV. For comparison, Monte Carlo simulations were repeated with Pb layers taken out from the phantoms using the same experimental configuration. Analyses on electron energy spectra for the 4 and 6 MeV electron beams showed that deviations of electron energy distributions between the Solid Water and water phantom were more significant in the high-energy range (i.e., close to the maximal electron energy) than the lower range corresponding to the electron backscatter. These deviations of electron energy spectra varied with depth and were mainly due to the electron fluence or beam attenuation. Dosimetry results from Monte Carlo simulations showed that the Solid Water phantom had lower depth dose compared to water with the same experimental setup. For the 4 MeV electron beams with 0.5 cm of Solid Water, depth doses were 1.8%-3.9% and 2.3%-4.4% lower than those in water, with and without the Pb layer underneath, respectively. Thicker Solid Water of 1 cm resulted in different decreases in depth doses of 1.8%-4.6% (with Pb) and 2.3%-4.4% (without Pb) compared to water. For higher nominal electron beam energy of 6 MeV with 0.5 cm of Solid Water, depth doses decreased 1.7%-2.9% (with Pb) and 1.6%-2.1% (without Pb) compared to water. These decreases in depth doses changed to 1.7%-3.7% (with Pb) and 1.7%-3% (without Pb) when the thickness of Solid Water was increased to 1 cm. The dosimetry data in this study are useful in determining the correction factor when using Solid Water to substitute water for the electron backscatter measurement in electron radiotherapy. PMID:19544774

  3. Solid Water as phantom material for dosimetry of electron backscatter using low-energy electron beams: A Monte Carlo evaluation

    SciTech Connect

    Chow, James C. L.; Owrangi, Amir M.

    2009-05-15

    This study evaluated the dosimetry of electron backscatter when Solid Water is used to substitute water as phantom in electron radiotherapy. Monte Carlo simulation (EGSnrc-based code) was employed to predict electron energy spectra and depth doses for the 0.5 and 1 cm of Solid Water and water slabs above 3 mm of lead (Pb) layers using electron beams with energies of 4 and 6 MeV. For comparison, Monte Carlo simulations were repeated with Pb layers taken out from the phantoms using the same experimental configuration. Analyses on electron energy spectra for the 4 and 6 MeV electron beams showed that deviations of electron energy distributions between the Solid Water and water phantom were more significant in the high-energy range (i.e., close to the maximal electron energy) than the lower range corresponding to the electron backscatter. These deviations of electron energy spectra varied with depth and were mainly due to the electron fluence or beam attenuation. Dosimetry results from Monte Carlo simulations showed that the Solid Water phantom had lower depth dose compared to water with the same experimental setup. For the 4 MeV electron beams with 0.5 cm of Solid Water, depth doses were 1.8%-3.9% and 2.3%-4.4% lower than those in water, with and without the Pb layer underneath, respectively. Thicker Solid Water of 1 cm resulted in different decreases in depth doses of 1.8%-4.6% (with Pb) and 2.3%-4.4% (without Pb) compared to water. For higher nominal electron beam energy of 6 MeV with 0.5 cm of Solid Water, depth doses decreased 1.7%-2.9% (with Pb) and 1.6%-2.1% (without Pb) compared to water. These decreases in depth doses changed to 1.7%-3.7% (with Pb) and 1.7%-3% (without Pb) when the thickness of Solid Water was increased to 1 cm. The dosimetry data in this study are useful in determining the correction factor when using Solid Water to substitute water for the electron backscatter measurement in electron radiotherapy.

  4. Electron Paramagnetic Resonance Retrospective Dosimetry

    SciTech Connect

    Romanyukha, Alex; Trompier, Francois

    2011-05-05

    Necessity for, principles of, and general concepts of the electron paramagnetic resonance (EPR) retrospective dosimetry are presented. Also presented and given in details are examples of EPR retrospective dosimetry applications in tooth enamel, bone, and fingernails with focus on general approaches for solving technical and methodological problems. Advantages, drawbacks, and possible future developments are discussed and an extensive bibliography on EPR retrospective dosimetry is provided.

  5. A diamond detector in the dosimetry of high-energy electron and photon beams

    NASA Astrophysics Data System (ADS)

    Laub, Wolfram U.; Kaulich, Theodor W.; Nüsslin, Fridtjof

    1999-09-01

    A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water phantom with the detector connected to a Unidos electrometer (PTW Freiburg). After a pre-irradiation of about 5 Gy the diamond detector shows a stability in response which is better than that of an ionization chamber. The current of the diamond detector was measured under variation of photon beam dose rate between 0.1 and 7 Gy min-1. Different FSDs were chosen. Furthermore the pulse repetition frequency and the depth of the detector were changed. The electron beam dose rate was varied between 0.23 and 4.6 Gy min-1 by changing the pulse-repetition frequency. The response shows no energy dependence within the covered photon-beam energy range. Between 4 MeV and 18 MeV electron beam energy it shows only a small energy dependence of about 2%, as expected from theory. For smaller electron energies the response increases significantly and an influence of the contact material used for the diamond detector can be surmised. A slight sublinearity of the current and dose rate was found. Detector current and dose rate are related by the expression ipropto(dotD)Delta, where i is the detector current, (dotD) is the dose rate and Delta is a correction factor of approximately 0.963. Depth-dose curves of photon beams, measured with the diamond detector, show a slight overestimation compared

  6. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out.

    PubMed

    Sipilä, Petri; Ojala, Jarkko; Kaijaluoto, Sampsa; Jokelainen, Ilkka; Kosunen, Antti

    2016-01-01

    For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in 60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ± 50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scan-ner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k = 2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established

  7. Dosimetry of very high energy electrons (VHEE) for radiotherapy applications: using radiochromic film measurements and Monte Carlo simulations.

    PubMed

    Subiel, A; Moskvin, V; Welsh, G H; Cipiccia, S; Reboredo, D; Evans, P; Partridge, M; DesRosiers, C; Anania, M P; Cianchi, A; Mostacci, A; Chiadroni, E; Di Giovenale, D; Villa, F; Pompili, R; Ferrario, M; Belleveglia, M; Di Pirro, G; Gatti, G; Vaccarezza, C; Seitz, B; Isaac, R C; Brunetti, E; Wiggins, S M; Ersfeld, B; Islam, M R; Mendonca, M S; Sorensen, A; Boyd, M; Jaroszynski, D A

    2014-10-01

    Very high energy electrons (VHEE) in the range from 100-250 MeV have the potential of becoming an alternative modality in radiotherapy because of their improved dosimetry properties compared with MV photons from contemporary medical linear accelerators. Due to the need for accurate dosimetry of small field size VHEE beams we have performed dose measurements using EBT2 Gafchromic® film. Calibration of the film has been carried out for beams of two different energy ranges: 20 MeV and 165 MeV from conventional radio frequency linear accelerators. In addition, EBT2 film has been used for dose measurements with 135 MeV electron beams produced by a laser-plasma wakefield accelerator. The dose response measurements and percentage depth dose profiles have been compared with calculations carried out using the general-purpose FLUKA Monte Carlo (MC) radiation transport code. The impact of induced radioactivity on film response for VHEEs has been evaluated using the MC simulations. A neutron yield of the order of 10(-5) neutrons cm(-2) per incident electron has been estimated and induced activity due to radionuclide production is found to have a negligible effect on total dose deposition and film response. Neutron and proton contribution to the equivalent doses are negligible for VHEE. The study demonstrates that EBT2 Gafchromic film is a reliable dosimeter that can be used for dosimetry of VHEE. The results indicate an energy-independent response of the dosimeter for 20 MeV and 165 MeV electron beams and has been found to be suitable for dosimetry of VHEE. PMID:25207591

  8. Dosimetry of very high energy electrons (VHEE) for radiotherapy applications: using radiochromic film measurements and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Subiel, A.; Moskvin, V.; Welsh, G. H.; Cipiccia, S.; Reboredo, D.; Evans, P.; Partridge, M.; DesRosiers, C.; Anania, M. P.; Cianchi, A.; Mostacci, A.; Chiadroni, E.; Di Giovenale, D.; Villa, F.; Pompili, R.; Ferrario, M.; Belleveglia, M.; Di Pirro, G.; Gatti, G.; Vaccarezza, C.; Seitz, B.; Isaac, R. C.; Brunetti, E.; Wiggins, S. M.; Ersfeld, B.; Islam, M. R.; Mendonca, M. S.; Sorensen, A.; Boyd, M.; Jaroszynski, D. A.

    2014-10-01

    Very high energy electrons (VHEE) in the range from 100-250 MeV have the potential of becoming an alternative modality in radiotherapy because of their improved dosimetry properties compared with MV photons from contemporary medical linear accelerators. Due to the need for accurate dosimetry of small field size VHEE beams we have performed dose measurements using EBT2 Gafchromic® film. Calibration of the film has been carried out for beams of two different energy ranges: 20 MeV and 165 MeV from conventional radio frequency linear accelerators. In addition, EBT2 film has been used for dose measurements with 135 MeV electron beams produced by a laser-plasma wakefield accelerator. The dose response measurements and percentage depth dose profiles have been compared with calculations carried out using the general-purpose FLUKA Monte Carlo (MC) radiation transport code. The impact of induced radioactivity on film response for VHEEs has been evaluated using the MC simulations. A neutron yield of the order of 10-5 neutrons cm-2 per incident electron has been estimated and induced activity due to radionuclide production is found to have a negligible effect on total dose deposition and film response. Neutron and proton contribution to the equivalent doses are negligible for VHEE. The study demonstrates that EBT2 Gafchromic film is a reliable dosimeter that can be used for dosimetry of VHEE. The results indicate an energy-independent response of the dosimeter for 20 MeV and 165 MeV electron beams and has been found to be suitable for dosimetry of VHEE.

  9. Applicability of Topaz Composites to Electron Dosimetry

    NASA Astrophysics Data System (ADS)

    Bomfim, K. S.; Souza, D. N.

    2010-11-01

    Thermoluminescent dosimetric topaz properties have been investigated and the results have shown that this mineral presents characteristics of a good dosimeter mainly in doses evaluation in radiotherapy with photons beams in radiotherapy. Typical applications of thermoluminescent dosimeters in radiotherapy are: in vivo dosimetry on patients (either as a routine quality assurance procedure or for dose monitoring in special cases); verification of treatment techniques; dosimetry audits; and comparisons among hospitals. The mean aim of this work was to evaluate the efficiency of topaz-Teflon pellets as thermoluminescent dosimeters in high-energy electron beams used to radiotherapy. Topaz-Teflon pellets were used as TLD.

  10. Depth dependence of electron backscatter: an energy spectral and dosimetry study using Monte Carlo simulation.

    PubMed

    Chow, James C L; Owrangi, Amir M

    2009-02-01

    This study investigated the depth dependence of electron backscatter from a layer of lead (Pb) for clinical electron beams. The change in the electron backscatter with variation in the water depth above the Pb was determined. Electron energy spectra and relative depth doses as a function of depth in water over the Pb layer were calculated using a Monte Carlo simulation and studied. Phase-space files for 4 and 9 MeV electron beams (10 x 10 cm2 applicator and cutout) based on the Varian 21 EX linear accelerator were generated using the EGSnrc-based BEAMNRC code. 3 mm of Pb, at depths of 0.5 and 1 cm in water, was irradiated with electrons. The source-to-surface distance is equal to 100 cm. Electron energy spectra and relative depth doses with and without the presence of the Pb layer at different depths in water were determined using the BEAMNRC code. For the 4 MeV electron energy spectra at a depth of 0.5 cm in water, electron backscatter was found to originate at the Pb-water interface and extend to 0.5 cm above the Pb insert. However, at a depth of 1 cm in water, electron backscatter almost disappeared at 0.5 and 1 cm above th ePb insert. This is due to the increased attenuation of the incident 4 MeV electron beam in a thicker layer of water as well as increased attenuation of the electron backscatter above the Pb. This resulted in a 23% decrease in relative dose at a measurement point of 0.5 cm depth, when the depth of the Pb insert was changed from 1 to 0.5 cm. For the electron energy spectra of the 9 MeV beams with a 0.5 cm depth of water, only a small amount of electron backscatter was observed. However, more electron backscatter was found when the water depth was increased to 1 cm. This is because the electron beam energy was decreased more due to the increase in attenuation from the increased depth of water compared to 0.5 cm. Since the electron energy spectrum and relative depth dose above the Pb layer vary with depth of water on top of the Pb, the electron

  11. SU‐C‐105‐05: Reference Dosimetry of High‐Energy Electron Beams with a Farmer‐Type Ionization Chamber

    SciTech Connect

    Muir, B; Rogers, D

    2013-06-15

    Purpose: To investigate gradient effects and provide Monte Carlo calculated beam quality conversion factors to characterize the Farmer‐type NE2571 ion chamber for high‐energy reference dosimetry of clinical electron beams. Methods: The EGSnrc code system is used to calculate the absorbed dose to water and to the gas in a fully modeled NE2571 chamber as a function of depth in a water phantom. Electron beams incident on the surface of the phantom are modeled using realistic BEAMnrc accelerator simulations and electron beam spectra. Beam quality conversion factors are determined using calculated doses to water and to air in the chamber in high‐energy electron beams and in a cobalt‐60 reference field. Calculated water‐to‐air stopping power ratios are employed for investigation of the overall ion chamber perturbation factor. Results: An upstream shift of 0.3–0.4 multiplied by the chamber radius, r-cav, both minimizes the variation of the overall ion chamber perturbation factor with depth and reduces the difference between the beam quality specifier (R{sub 5} {sub 0}) calculated using ion chamber simulations and that obtained with simulations of dose‐to‐water in the phantom. Beam quality conversion factors are obtained at the reference depth and gradient effects are optimized using a shift of 0.2r-cav. The photon‐electron conversion factor, k-ecal, amounts to 0.906 when gradient effects are minimized using the shift established here and 0.903 if no shift of the data is used. Systematic uncertainties in beam quality conversion factors are investigated and amount to between 0.4 to 1.1% depending on assumptions used. Conclusion: The calculations obtained in this work characterize the use of an NE2571 ion chamber for reference dosimetry of high‐energy electron beams. These results will be useful as the AAPM continues to review their reference dosimetry protocols.

  12. Energy correction factors of LiF powder TLDs irradiated in high-energy electron beams and applied to mailed dosimetry for quality assurance networks.

    PubMed

    Marre, D; Ferreira, I H; Bridier, A; Björeland, A; Svensson, H; Dutreix, A; Chavaudra, J

    2000-12-01

    Absorbed dose determination with thermoluminescent dosimeters (TLDs) generally relies on calibration in 60Co gamma-ray reference beams. The energy correction factor fCo(E) for electron beams takes into account the difference between the response of the TLD in the beam of energy E and in the 60Co gamma-ray beam. In this work, fCo(E) was evaluated for an LiF powder irradiated in electron beams of 6 to 20 MeV (Varian 2300C/D) and 10 to 50 MeV (Racetrack MM50), and its variation with electron energy, TLD size and nature of the surrounding medium was also studied for LiF powder. The results have been applied to the ESTRO-EQUAL mailed dosimetry quality assurance network. Monte Carlo calculations (EGS4, PENELOPE) and experiments have been performed for the LiF powder (rho = 1.4 g cm3) (DTL937, Philitech, France), read on a home made reader and a PCL3 automatic reader (Fimel, France). The TLDs were calibrated using Fricke dosimetry and compared with three ionization chambers (NE2571, NACP02, ROOS). The combined uncertainties in the experimental fCo(E) factors determined in this work are less than about 0.4% (1 SD), which is appreciably smaller than the uncertainties up to 1.4% (1 SD) reported for other calculated values in the literature. Concerning the Varian 2300C/D beams, the measured fCo(E) values decrease from 1.065 to 1.049 +/- 0.004 (1 SD) when the energy at depth in water increases from 2.6 to 14.1 MeV; the agreement with Monte Carlo calculations is better than 0.5%. For the Racetrack MM50 pulsed-scanned beams, the average experimental value of fCo(E) is 1.071 +/- 0.005 (1 SD) for a mean electron energy at depth Ez ranging from 4.3 to 36.3 MeV: fCo(E) is up to 2% higher for the MM50 beams than for the 2300C/D beams in the range of the tested energies. The energy correction factor for LiF powder (3 mm diameter and 15 mm length) varies with beam quality and type (pulsed or pulsed-scanning), cavity size and nature of the surrounding medium. The fCo(E) values obtained

  13. SU-D-19A-01: Can Farmer-Type Ionization Chambers Be Used to Improve the Accuracy of Low-Energy Electron Beam Reference Dosimetry?

    SciTech Connect

    Muir, B R; McEwen, M R

    2014-06-01

    Purpose: To investigate the use of cylindrical Farmer-type ionization chambers to improve the accuracy of low-energy electron beam calibration. Historically, these chamber types have not been used in beams with incident energies less than 10 MeV (R{sub 5} {sub 0} < 4.3 cm) because early investigations suggested large (up to 5 %) fluence perturbation factors in these beams, implying that a significant component of uncertainty would be introduced if used for calibration. More recently, the assumptions used to determine perturbation corrections for cylindrical chambers have been questioned. Methods: Measurements are made with cylindrical chambers in Elekta Precise 4, 8 and 18 MeV electron beams. Several chamber types are investigated that employ graphite walls and aluminum electrodes with very similar specifications (NE2571, NE2505/3, FC65-G). Depth-ionization scans are measured in water in the 8 and 18 MeV beams. To reduce uncertainty from chamber positioning, measurements in the 4 MeV beam are made at the reference depth in Virtual Water™. The variability of perturbation factors is quantified by comparing normalized response of various chambers. Results: Normalized ion chamber response varies by less than 0.7 % for similar chambers at average electron energies corresponding to that at the reference depth from 4 or 6 MeV beams. Similarly, normalized measurements made with similar chambers at the reference depth in the 4 MeV beam vary by less than 0.4 %. Absorbed dose calibration coefficients derived from these results are stable within 0.1 % on average over a period of 6 years. Conclusion: These results indicate that the uncertainty associated with differences in fluence perturbations for cylindrical chambers with similar specifications is only 0.2 %. The excellent long-term stability of these chambers in both photon and electron beams suggests that these chambers might offer the best performance for all reference dosimetry applications.

  14. An evaluation of epoxy resin phantom materials for electron dosimetry

    NASA Astrophysics Data System (ADS)

    Nisbet, A.; Thwaites, D. I.

    1998-06-01

    The use of epoxy resin `solid water' (water substitute) phantoms is becoming increasingly common in radiotherapy dosimetry, and depth ionization curves and conversion factors from ionization to dose identical to water have often been assumed. Fluence ratios of water to solid water for WTe (produced by Radiation Physics, St Bartholomew's Hospital, London) and RMI 457 (produced by Radiation Measurements Inc., Middleton, Wisconsin) have therefore been determined and have been found to decrease with energy, which, within measurement uncertainty, can be described with a linear function dependent on mean electron beam energy at the depth of measurement, . The fluence ratios for WTe are very close to unity (i.e. within the measuring uncertainty) for most of the energies examined, the exception being a nominal 20 MeV beam. The results also show that an assumption of unity for the fluence ratios of RMI 457 may introduce a systematic error of the order of 1% in electron beam dosimetry at lower energies. As regards the depth ionization curves measured in the respective solid water materials, these are shown to be in agreement with those measured in water within the limits of the measuring uncertainty.

  15. Practical neutron dosimetry at high energies

    SciTech Connect

    McCaslin, J.B.; Thomas, R.H.

    1980-10-01

    Dosimetry at high energy particle accelerators is discussed with emphasis on physical measurements which define the radiation environment and provide an immutable basis for the derivation of any quantities subsequently required for risk evaluation. Results of inter-laboratory dosimetric comparisons are reviewed and it is concluded that a well-supported systematic program is needed which would make possible detailed evaluations and inter-comparisons of instruments and techniques in well characterized high energy radiation fields. High-energy dosimetry is so coupled with radiation transport that it is clear their study should proceed concurrently.

  16. Energy Metabolism and Human Dosimetry of Tritium

    SciTech Connect

    Galeriu, D.; Takeda, H.; Melintescu, A.; Trivedi, A

    2005-07-15

    In the frame of current revision of human dosimetry of {sup 14}C and tritium, undertaken by the International Commission of Radiological Protection, we propose a novel approach based on energy metabolism and a simple biokinetic model for the dynamics of dietary intake (organic {sup 14}C, tritiated water and Organically Bound Tritium-OBT). The model predicts increased doses for HTO and OBT comparing to ICRP recommendations, supporting recent findings.

  17. [Dosimetry of total skin electron irradiation

    PubMed

    Kontra, Gábor; Horváth, Akos; Bajcsay, András; Németh, György

    2000-07-01

    Elaboration of such a simple technique for total skin electron irradiation which ensures good dose homogeneity and minimal x-ray background dose. MATERIALS AND METHODS: We started large electron field irradiations with the Neptun 10p linear accelerator in the National Institute of Oncology -Budapest in 1986. After the installation of the Siemens Mevatron KD linear accelerator it was possible to introduce the modified Stanford technique. This technique satisfies better the requirements given in the objective. The required field size of 200x75 cm is produced as a result of two fields with 30 degrees angular separation (dual field) at a source skin distance of 465 cm. The patient's body is exposed to six dual electron fields. The electron energy is 6 MeV. Despite the long source skin distance the treatment time is relatively short due to the high dose rate (940 mu/min) capability of our Mevatron KD. The in air dose profiles were measured in miniphantom with semiconductor detector. Depth dose curves were measured in water and in polystyrene phantom with semiconductor detector and with films. RESULTS: The measured dose homogeneity of the 6 MeV energy dual field with 30 degrees angular separation is within +/- 5%in a 200x75cm plane field. The depth of dose maximum of the resulting dose distribution of six dual field irradiation is between 2 mm and 5 mm, while the depth of 80% isodose curve is about 8 mm. The total body x-ray background dose is less than 1% of the skin dose. CONCLUSION: The modified Stanford technique adapted to our Mevatron KD linear accelerator is suitable for total skin electron beam therapy. PMID:12050758

  18. High-energy neutron dosimetry

    NASA Astrophysics Data System (ADS)

    Sutton, Michele Rhea

    2001-12-01

    Fluence-to-dose conversion coefficients for the radiation protection quantity effective dose were calculated for neutrons, photons and protons with energies up to 2 GeV using the MCNPX code. The calculations were performed using the Pacific Northwest National Laboratory versions of the MIRD-V male and female anthropomorphic phantoms modified to include the skin and esophagus. The latest high-energy neutron evaluated cross-section libraries and the recommendations given in ICRP Publication 60 and ICRP Publication 74 were utilized to perform the calculations. Sets of fluence-to- effective dose conversion coefficients are given for anterior-posterior, posterior-anterior, left-lateral, right-lateral and rotational irradiation geometries. This is the first set of dose conversion coefficients over this energy range calculated for the L-LAT irradiation geometry. A unique set of high-energy neutron depth-dose benchmark experiments were performed at the Los Alamos Neutron Science Center/Weapons Neutron Research (LANSCE/WNR) complex. The experiments consisted of filtered neutron beams with energies up to 800 MeV impinging on a 30 x 30 x 30 cm3 tissue-equivalent phantom. The absorbed dose was measured in the phantom at various depths with tissue-equivalent ion chambers. The phantom and the experimental set-up were modeled using MCNPX. Comparisons of the experimental and computational depth- dose distributions indicate that the absorbed dose calculated by MCNPX is within 13% for neutrons with energies up to 750 MeV. This experiment will serve as a benchmark experiment for the testing of high-energy radiation transport codes for the international radiation protection community.

  19. Energy response improvement for photon dosimetry using pulse analysis

    NASA Astrophysics Data System (ADS)

    Zaki, Dizaji H.

    2016-02-01

    During the last few years, active personal dosimeters have been developed and have replaced passive personal dosimeters in some external monitoring systems, frequently using silicon diode detectors. Incident photons interact with the constituents of the diode detector and produce electrons. These photon-induced electrons deposit energy in the detector's sensitive region and contribute to the response of diode detectors. To achieve an appropriate photon dosimetry response, the detectors are usually covered by a metallic layer with an optimum thickness. The metallic cover acts as an energy compensating shield. In this paper, a software process is performed for energy compensation. Selective data sampling based on pulse height is used to determine the photon dose equivalent. This method is applied to improve the energy response in photon dosimetry. The detector design is optimized for the response function and determination of the photon dose equivalent. Photon personal dose equivalent is determined in the energy range of 0.3-6 MeV. The error values of the calculated data for this wide energy range and measured data for 133Ba, 137Cs, 60Co and 241Am-Be sources respectively are up to 20% and 15%. Fairly good agreement is seen between simulation and dose values obtained from our process and specifications from several photon sources.

  20. The use of a portable electronic device in accident dosimetry.

    PubMed

    Beerten, Koen; Vanhavere, Filip

    2008-01-01

    The use of a portable electronic device in accident dosimetry has been investigated. The thermoluminescence properties of a surface-mount alumina-rich ceramic resonator from a USB flash drive were investigated. The following characteristics were verified: the absence of a zero-dose signal, gamma dose response, dose recycling behaviour, fading and optical bleaching. Finally, this component has been successfully used to determine a simulated accident dose (1 d following the irradiation event). It is concluded that it should be possible to perform rapid and reliable accident dose assessments with such components using conventional thermoluminescence dosimetry equipment. PMID:18703583

  1. [Electronic portal image device dosimetry for volumetric modulated arc therapy].

    PubMed

    Tatsumi, Daisaku; Nakada, Ryosei; Ienaga, Akinori; Yomoda, Akane; Inoue, Makoto; Ichida, Takao; Hosono, Masako

    2013-01-01

    Recently electronic portal image devices (EPIDs) have been widely used for quality assurance and dose verification. However there are no reports describing EPID dosimetry for Elekta volumetric modulated arc therapy (VMAT). We have investigated EPID dosimetry during VMAT delivery using a commercial software EPIDose with an Elekta Synergy linac. Dose rate dependence and the linac system sag during gantry rotation were measured. Gamma indices were calculated between measured doses using an EPID and calculation made by a treatment planning system for prostate VMAT test plans. The results were also compared to gamma indices using films and a two-dimensional detector array, MapCHECK2. The pass rates of the gamma analysis with a criterion of 3% and 2 mm for the three methods were over 96% with good consistency. Our results have showed that EPID dosimetry is feasible for Elekta VMAT. PMID:23358333

  2. Small field electron beam dosimetry using MOSFET detector.

    PubMed

    Amin, Md Nurul; Heaton, Robert; Norrlinger, Bern; Islam, Mohammad K

    2011-01-01

    The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth-dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high-sensitivity microMOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber for a range of field sizes from 1 cm diameter to 10 cm × 10 cm for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also per-formed with MOSFET and films in solid water phantom. The MOSFET sensitivity was found to be practically constant over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ± 1% for 100 cGy). An excellent agreement was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 3% with those measured by film dosimetry. Overall results indicate that MOSFET can be utilized to perform dosimetry for small field electron beam. PMID:21330970

  3. Monte Carlo calculations of correction factors for plane-parallel ionization chambers in clinical electron dosimetry

    SciTech Connect

    Araki, Fujio

    2008-09-15

    Recent standard dosimetry protocols recommend that plane-parallel ionization chambers be used in the measurements of depth-dose distributions or the calibration of low-energy electron beams with beam quality R{sub 50}<4 g/cm{sup 2}. In electron dosimetry protocols with the plane-parallel chambers, the wall correction factor, P{sub wall}, in water is assumed to be unity and the replacement correction factor, P{sub repl}, is taken to be unity for well-guarded plane-parallel chambers, at all measurement depths. This study calculated P{sub wall} and P{sub repl} for NACP-02, Markus, and Roos plane-parallel chambers in clinical electron dosimetry using the EGSnrc Monte Carlo code system. The P{sub wall} values for the plane-parallel chambers increased rapidly as a function of depth in water, especially at lower energy. The value around R{sub 50} for NACP-02 was about 10% greater than unity at 4 MeV. The effect was smaller for higher electron energies. Similarly, P{sub repl} values with depth increased drastically at the region with the steep dose gradient for lower energy. For Markus P{sub repl} departed more than 10% from unity close to R{sub 50} due to the narrow guard ring width. P{sub repl} for NACP-02 and Roos was close to unity in the plateau region of depth-dose curves that includes a reference depth, d{sub ref}. It was also found that the ratio of the dose to water and the dose to the sensitive volume in the air cavity for the plane-parallel chambers, D{sub w}/[D{sub air}]{sub pp}, at d{sub ref} differs significantly from that assumed by electron dosimetry protocols.

  4. SU-D-213-06: Dosimetry of Modulated Electron Radiation Therapy Using Fricke Gel Dosimeter

    SciTech Connect

    Gawad, M Abdel; Elgohary, M; Hassaan, M; Emam, M; Desouky, O; Eldib, A; Ma, C

    2015-06-15

    Purpose: Modulated electron radiation therapy (MERT) has been proposed as an effective modality for treatment of superficial targets. MERT utilizes multiple beams of different energies which are intensity modulated to deliver optimized dose distribution. Energy independent dosimeters are thus needed for quantitative evaluations of MERT dose distributions and measurements of absolute doses delivered to patients. Thus in the current work we study the feasibility of Fricke gel dosimeters in MERT dosimetry. Methods: Batches of radiation sensitive Fricke gel is fabricated and poured into polymethyl methacrylate cuvettes. The samples were irradiated in solid water phantom and a thick layer of bolus was used as a buildup. A spectrophotometer system was used for measuring the color changes (the absorbance) before and after irradiation and then we calculate net absorbance. We constructed calibration curves to relate the measured absorbance in terms of absorbed dose for all available electron energies. Dosimetric measurements were performed for mixed electron beam delivery and we also performed measurement for segmented field delivery with the dosimeter placed at the junction of two adjacent electron beams of different energies. Dose measured by our gel dosimetry is compared to that calculation from our precise treatment planning system. We also initiated a Monte Carlo study to evaluate the water equivalence of our dosimeters. MCBEAM and MCSIM codes were used for treatment head simulation and phantom dose calculation. PDDs and profiles were calculated for electron beams incident on a phantom designed with 1cm slab of Fricke gel. Results: The calibration curves showed no observed energy dependence with all studied electron beam energies. Good agreement was obtained between dose calculated and that obtained by gel dosimetry. Monte Carlo results illustrated the tissue equivalency of our Gel dosimeters. Conclusion: Fricke Gel dosimeters represent a good option for the dosimetric

  5. Two-parametric model of electron beam in computational dosimetry for radiation processing

    NASA Astrophysics Data System (ADS)

    Lazurik, V. M.; Lazurik, V. T.; Popov, G.; Zimek, Z.

    2016-07-01

    Computer simulation of irradiation process of various materials with electron beam (EB) can be applied to correct and control the performances of radiation processing installations. Electron beam energy measurements methods are described in the international standards. The obtained results of measurements can be extended by implementation computational dosimetry. Authors have developed the computational method for determination of EB energy on the base of two-parametric fitting of semi-empirical model for the depth dose distribution initiated by mono-energetic electron beam. The analysis of number experiments show that described method can effectively consider random displacements arising from the use of aluminum wedge with a continuous strip of dosimetric film and minimize the magnitude uncertainty value of the electron energy evaluation, calculated from the experimental data. Two-parametric fitting method is proposed for determination of the electron beam model parameters. These model parameters are as follow: E0 - energy mono-energetic and mono-directional electron source, X0 - the thickness of the aluminum layer, located in front of irradiated object. That allows obtain baseline data related to the characteristic of the electron beam, which can be later on applied for computer modeling of the irradiation process. Model parameters which are defined in the international standards (like Ep- the most probably energy and Rp - practical range) can be linked with characteristics of two-parametric model (E0, X0), which allows to simulate the electron irradiation process. The obtained data from semi-empirical model were checked together with the set of experimental results. The proposed two-parametric model for electron beam energy evaluation and estimation of accuracy for computational dosimetry methods on the base of developed model are discussed.

  6. Radiation accident dosimetry on electronic components by OSL.

    PubMed

    Bassinet, C; Trompier, F; Clairand, I

    2010-02-01

    In the event of large-scale radiation accidents and considering a growing terrorism concern, non-invasive and sufficiently accurate retrospective dosimetry methods are necessary to carry out a fast population triage in order to determine which radiation-exposed individuals need medical treatment. Retrospective dosimetry using different electronic components such as resistors, capacitors, and integrated circuits present on mobile phone circuit boards have been considered. Their response has been investigated with luminescence techniques (OSL, IRSL, and TL). The majority of these electronic components exhibit radiation-induced luminescence signals, and the OSL technique seems the most promising for these materials. Results concerning three types of components that present the most interesting OSL characteristics (in terms of signal annealing and sensitivity) and that are the most often present on mobile phone circuit boards are presented. Preheating effects on OSL signal, sensitization, and dose-response curves from 0.7 to 27 Gy for resistors and from 0.7 to 160 Gy for capacitors and integrated circuits, dose recovery tests, and signal stability 10 h after irradiation have been studied and interests and limits of their use evaluated. PMID:20065718

  7. Application of the ICRP/ICRU reference computational phantoms to internal dosimetry: calculation of specific absorbed fractions of energy for photons and electrons.

    PubMed

    Hadid, L; Desbrée, A; Schlattl, H; Franck, D; Blanchardon, E; Zankl, M

    2010-07-01

    The emission of radiation from a contaminated body region is connected with the dose received by radiosensitive tissue through the specific absorbed fractions (SAFs) of emitted energy, which is therefore an essential quantity for internal dose assessment. A set of SAFs were calculated using the new adult reference computational phantoms, released by the International Commission on Radiological Protection (ICRP) together with the International Commission on Radiation Units and Measurements (ICRU). Part of these results has been recently published in ICRP Publication 110 (2009 Adult reference computational phantoms (Oxford: Elsevier)). In this paper, we mainly discuss the results and also present them in numeric form. The emission of monoenergetic photons and electrons with energies ranging from 10 keV to 10 MeV was simulated for three source organs: lungs, thyroid and liver. SAFs were calculated for four target regions in the body: lungs, colon wall, breasts and stomach wall. For quality assurance purposes, the simulations were performed simultaneously at the Helmholtz Zentrum München (HMGU, Germany) and at the Institute for Radiological Protection and Nuclear Safety (IRSN, France), using the Monte Carlo transport codes EGSnrc and MCNPX, respectively. The comparison of results shows overall agreement for photons and high-energy electrons with differences lower than 8%. Nevertheless, significant differences were found for electrons at lower energy for distant source/target organ pairs. Finally, the results for photons were compared to the SAF values derived using mathematical phantoms. Significant variations that can amount to 200% were found. The main reason for these differences is the change of geometry in the more realistic voxel body models. For electrons, no SAFs have been computed with the mathematical phantoms; instead, approximate formulae have been used by both the Medical Internal Radiation Dose committee (MIRD) and the ICRP due to the limitations imposed

  8. Application of the ICRP/ICRU reference computational phantoms to internal dosimetry: calculation of specific absorbed fractions of energy for photons and electrons

    NASA Astrophysics Data System (ADS)

    Hadid, L.; Desbrée, A.; Schlattl, H.; Franck, D.; Blanchardon, E.; Zankl, M.

    2010-07-01

    The emission of radiation from a contaminated body region is connected with the dose received by radiosensitive tissue through the specific absorbed fractions (SAFs) of emitted energy, which is therefore an essential quantity for internal dose assessment. A set of SAFs were calculated using the new adult reference computational phantoms, released by the International Commission on Radiological Protection (ICRP) together with the International Commission on Radiation Units and Measurements (ICRU). Part of these results has been recently published in ICRP Publication 110 (2009 Adult reference computational phantoms (Oxford: Elsevier)). In this paper, we mainly discuss the results and also present them in numeric form. The emission of monoenergetic photons and electrons with energies ranging from 10 keV to 10 MeV was simulated for three source organs: lungs, thyroid and liver. SAFs were calculated for four target regions in the body: lungs, colon wall, breasts and stomach wall. For quality assurance purposes, the simulations were performed simultaneously at the Helmholtz Zentrum München (HMGU, Germany) and at the Institute for Radiological Protection and Nuclear Safety (IRSN, France), using the Monte Carlo transport codes EGSnrc and MCNPX, respectively. The comparison of results shows overall agreement for photons and high-energy electrons with differences lower than 8%. Nevertheless, significant differences were found for electrons at lower energy for distant source/target organ pairs. Finally, the results for photons were compared to the SAF values derived using mathematical phantoms. Significant variations that can amount to 200% were found. The main reason for these differences is the change of geometry in the more realistic voxel body models. For electrons, no SAFs have been computed with the mathematical phantoms; instead, approximate formulae have been used by both the Medical Internal Radiation Dose committee (MIRD) and the ICRP due to the limitations imposed

  9. Dosimetry and processing anomalies due to heterogeneities of materials irradiated with high-energy electrons. Influence of heterogeneities on e-irradiation

    NASA Astrophysics Data System (ADS)

    Okuda, Shuichi; Nakamura, Shigeki; Tabata, Tatsuo; Fukuda, Kyue; Seiyama, Takeyoshi; Okabe, Shigeru

    Nonuniform dose distributions in heterogeneous materials irradiated by high-energy electron beams were mapped by using blue cellophane thin dosimeter strip (20μm thickness). The absorbed doses and dose distributions in solid-state dosimeters and in products irradiated for practical use have been estimated from the measurements. Deviations from uniformity of absorbed doses as large as several tens of percent have been found near material interfaces.

  10. Thin film tritium dosimetry

    DOEpatents

    Moran, Paul R.

    1976-01-01

    The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

  11. Polymer gel dosimetry applied to beta particles, electrons and 300 kV X-rays

    NASA Astrophysics Data System (ADS)

    Amin, Md. Nurul

    Polymer gels were used with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions for beta particles, electron and x-rays beams that are used in radiotherapy. The manufacturing processes and calibration procedures for two dosimeters (hypoxic PAG and normoxic MAGIC gels) were investigated. The response of both gels was energy independent over a range of electron and photon energies commonly used for radiotherapy. However, dose response of both gels was dependent on the temperature at the time of MR scanning, while MAGIC was also dependent on the temperature at the time of irradiation, which had not been previously reported. Results suggest that MAGIC gel is superior to PAG, since it is easier to manufacture and unaffected by oxygen diffusion through wall materials. The potential usefulness of both types of gel in different areas of radiotherapy was studied, including vascular brachytherapy. Results were compared with doses measured using radio- chromic film, confirming that dose distributions for vascular brachytherapy sources with a high dose gradient can be measured using PAG. However, because of the disadvantages of the gel manufacturing process and the need for access to a high-resolution scanner, it was concluded that radio-chromic film would be the method of choice for routine quality assurance in brachytherapy. PAG and MAGIC gels were also used for dosimetry across the junction of 6MV photon and 12MeV electron fields that are often used in radiotherapy. Different photon field configurations were studied, and dose profiles were measured. For each configuration either significant "hot" or "cold spots" were measured, with good agreement between the MAGIC and PAG and radio- chromic film. This work has confirmed the usefulness of gel dosimetry in radiotherapy in general, and in beta and electron dosimetry in particular. In addition, these studies have quantified the advantages of normoxic gels over the hypoxic PAG.

  12. Radiological characterization and water equivalency of genipin gel for x-ray and electron beam dosimetry

    NASA Astrophysics Data System (ADS)

    Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Bosi, Stephen; Davies, Justin B.; Baldock, Clive

    2011-08-01

    The genipin radiochromic gel offers enormous potential as a three-dimensional dosimeter in advanced radiotherapy techniques. We have used several methods (including Monte Carlo simulation), to investigate the water equivalency of genipin gel by characterizing its radiological properties, including mass and electron densities, photon interaction cross sections, mass energy absorption coefficient, effective atomic number, collisional, radiative and total mass stopping powers and electron mass scattering power. Depth doses were also calculated for clinical kilovoltage and megavoltage x-ray beams as well as megavoltage electron beams. The mass density, electron density and effective atomic number of genipin were found to differ from water by less than 2%. For energies below 150 keV, photoelectric absorption cross sections are more than 3% higher than water due to the strong dependence on atomic number. Compton scattering and pair production interaction cross sections for genipin gel differ from water by less than 1%. The mass energy absorption coefficient is approximately 3% higher than water for energies <60 keV due to the dominance of photoelectric absorption in this energy range. The electron mass stopping power and mass scattering power differ from water by approximately 0.3%. X-ray depth dose curves for genipin gel agree to within 1% with those for water. Our results demonstrate that genipin gel can be considered water equivalent for kilovoltage and megavoltage x-ray beam dosimetry. For megavoltage electron beam dosimetry, however, our results suggest that a correction factor may be needed to convert measured dose in genipin gel to that of water, since differences in some radiological properties of up to 3% compared to water are observed. Our results indicate that genipin gel exhibits greater water equivalency than polymer gels and PRESAGE formulations.

  13. Epid Dosimetry

    NASA Astrophysics Data System (ADS)

    Greer, Peter B.; Vial, Philip

    2011-05-01

    Electronic portal imaging devices (EPIDs) were introduced originally for patient position verification. The idea of using EPIDs for dosimetry was realised in the 1980s. Little was published on the topic until the mid 1990's, when the interest in EPIDs for dosimetry increased rapidly and continues to grow. The increasing research on EPID dosimetry coincided with the introduction of intensity modulated radiation therapy (IMRT). EPIDs are well suited to IMRT dosimetry because they are high resolution, two-dimensional (2D) digital detectors. They are also pre-existing on almost all modern linear accelerators. They generally show a linear response to increasing dose. Different types of EPIDs have been clinically implemented, and these have been described in several review papers. The current generation of commercially available EPIDs are indirect detection active matrix flat panel imagers, also known as amorphous silicon (a-Si) EPIDs. Disadvantages of a-Si EPIDs for dosimetry include non-water equivalent construction materials, and the energy sensitivity and optical scatter of the phosphor scintillators used to create optical signal from the megavoltage beam. This report discusses current knowledge regarding a-Si EPIDs for dosimetry.

  14. Epid Dosimetry

    SciTech Connect

    Greer, Peter B.; Vial, Philip

    2011-05-05

    Electronic portal imaging devices (EPIDs) were introduced originally for patient position verification. The idea of using EPIDs for dosimetry was realised in the 1980s. Little was published on the topic until the mid 1990's, when the interest in EPIDs for dosimetry increased rapidly and continues to grow. The increasing research on EPID dosimetry coincided with the introduction of intensity modulated radiation therapy (IMRT). EPIDs are well suited to IMRT dosimetry because they are high resolution, two-dimensional (2D) digital detectors. They are also pre-existing on almost all modern linear accelerators. They generally show a linear response to increasing dose. Different types of EPIDs have been clinically implemented, and these have been described in several review papers. The current generation of commercially available EPIDs are indirect detection active matrix flat panel imagers, also known as amorphous silicon (a-Si) EPIDs. Disadvantages of a-Si EPIDs for dosimetry include non-water equivalent construction materials, and the energy sensitivity and optical scatter of the phosphor scintillators used to create optical signal from the megavoltage beam. This report discusses current knowledge regarding a-Si EPIDs for dosimetry.

  15. Electron paramagnetic resonance dosimetry: Methodology and material characterization

    NASA Astrophysics Data System (ADS)

    Hayes, Robert Bruce

    Electron Paramagnetic Resonance (EPR) methodologies for radiation dose reconstruction are investigated using various dosimeter materials. Specifically, methodologies were developed and used that were intended to improve the accuracy and precision of EPR dosimetric techniques, including combining specimen rotation during measurement, use of an internal manganese standard, instrument stabilization techniques and strict measurement protocols. Characterization and quantification of these improvements were preformed on three specific EPR dosimeter materials. The dosimeter materials investigated using these optimized EPR techniques were Walrus teeth, human tooth enamel and alanine dosimeters. Walrus teeth showed the least desirable properties for EPR dosimetry yielding large native signals and low sensitivity (EPR signal per unit dose). The methods for tooth enamel and alanine resulted in large improvements in precision and accuracy. The minimum detectable dose (MDD) found for alanine was approximately 30 mGy (three standard deviations from the measured zero dose value). This is a sensitivity improvement of 5 to 10 over other specialized techniques published in the literature that offer MDD's in the range of 150 mGy to 300 mGy. The accuracy of the method on tooth enamel was comparable to that typically reported in the literature although the measurement precision was increased by about 7. This improvement in measurement precision enables various applications including dose vs. depth profile analysis and a more nondestructive testing evaluation (where the whole sample need not be additively irradiated in order to calibrate its radiation response). A nondestructive evaluation of numerous samples showed that the method could reconstruct the same doses to within 10 mGy of those evaluated destructively. Doses used for this assessment were in the range of 100 to 250 mGy. The method had sufficient stability to measure tooth enamel samples exhibiting extreme anisotropy with a

  16. Superficial dosimetry imaging of Čerenkov emission in electron beam radiotherapy of phantoms

    NASA Astrophysics Data System (ADS)

    Zhang, Rongxiao; Fox, Colleen J.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2013-08-01

    Čerenkov emission is generated from ionizing radiation in tissue above 264 keV energy. This study presents the first examination of this optical emission as a surrogate for the absorbed superficial dose. Čerenkov emission was imaged from the surface of flat tissue phantoms irradiated with electrons, using a range of field sizes from 6 cm × 6 cm to 20 cm × 20 cm, incident angles from 0° to 50°, and energies from 6 to 18 MeV. The Čerenkov images were compared with the estimated superficial dose in phantoms from direct diode measurements, as well as calculations by Monte Carlo and the treatment planning system. Intensity images showed outstanding linear agreement (R2 = 0.97) with reference data of the known dose for energies from 6 to 18 MeV. When orthogonal delivery was carried out, the in-plane and cross-plane dose distribution comparisons indicated very little difference (±2-4% differences) between the different methods of estimation as compared to Čerenkov light imaging. For an incident angle 50°, the Čerenkov images and Monte Carlo simulation show excellent agreement with the diode data, but the treatment planning system had a larger error (OPT = ±1˜2%, diode = ±2˜3%, TPS = ±6-8% differences) as would be expected. The sampling depth of superficial dosimetry based on Čerenkov radiation has been simulated in a layered skin model, showing the potential of sampling depth tuning by spectral filtering. Taken together, these measurements and simulations indicate that Čerenkov emission imaging might provide a valuable method of superficial dosimetry imaging from incident radiotherapy beams of electrons.

  17. Superficial dosimetry imaging of Čerenkov emission in electron beam radiotherapy of phantoms.

    PubMed

    Zhang, Rongxiao; Fox, Colleen J; Glaser, Adam K; Gladstone, David J; Pogue, Brian W

    2013-08-21

    Čerenkov emission is generated from ionizing radiation in tissue above 264 keV energy. This study presents the first examination of this optical emission as a surrogate for the absorbed superficial dose. Čerenkov emission was imaged from the surface of flat tissue phantoms irradiated with electrons, using a range of field sizes from 6 cm × 6 cm to 20 cm × 20 cm, incident angles from 0° to 50°, and energies from 6 to 18 MeV. The Čerenkov images were compared with the estimated superficial dose in phantoms from direct diode measurements, as well as calculations by Monte Carlo and the treatment planning system. Intensity images showed outstanding linear agreement (R(2) = 0.97) with reference data of the known dose for energies from 6 to 18 MeV. When orthogonal delivery was carried out, the in-plane and cross-plane dose distribution comparisons indicated very little difference (± 2-4% differences) between the different methods of estimation as compared to Čerenkov light imaging. For an incident angle 50°, the Čerenkov images and Monte Carlo simulation show excellent agreement with the diode data, but the treatment planning system had a larger error (OPT = ± 1~2%, diode = ± 2~3%, TPS = ± 6-8% differences) as would be expected. The sampling depth of superficial dosimetry based on Čerenkov radiation has been simulated in a layered skin model, showing the potential of sampling depth tuning by spectral filtering. Taken together, these measurements and simulations indicate that Čerenkov emission imaging might provide a valuable method of superficial dosimetry imaging from incident radiotherapy beams of electrons. PMID:23880473

  18. Superficial Dosimetry Imaging of Čerenkov Emission in Electron Beam Radiotherapy of Phantoms

    PubMed Central

    Zhang, Rongxiao; Fox, Colleen J.; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2014-01-01

    Čerenkov emission is generated from ionizing radiation in tissue above 264keV energy. This study presents the first examination of this optical emission as a surrogate for the absorbed superficial dose. Čerenkov emission was imaged from the surface of flat tissue phantoms irradiated with electrons, using a range of field sizes from 6cm×6cm to 20cm×20cm, incident angles from 0 to 50 degrees, and energies from 6 to 18 MeV. The Čerenkov images were compared with estimated superficial dose in phantoms from direct diode measurements, as well as calculations by Monte Carlo and the treatment planning system. Intensity images showed outstanding linear agreement (R2=0.97) with reference data of the known dose for energies from 6MeV to 18MeV. When orthogonal delivery was done, the in-plane and cross-plane dose distribution comparisons indicated very little difference (±2~4% differences) between the different methods of estimation as compared to Čerenkov light imaging. For an incident angle 50 degrees, the Čerenkov images and Monte Carlo simulation show excellent agreement with the diode data, but the treatment planning system (TPS) had at a larger error (OPT=±1~2%, Diode=±2~3%, TPS=±6~8% differences) as would be expected. The sampling depth of superficial dosimetry based on Čerenkov radiation has been simulated in layered skin model, showing the potential of sampling depth tuning by spectral filtering. Taken together, these measurements and simulations indicate that Čerenkov emission imaging might provide a valuable way to superficial dosimetry imaging from incident radiotherapy beams of electrons. PMID:23880473

  19. Dosimetry quality assurance in Martin Marietta Energy Systems` centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm{sup 2} filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  20. Dosimetry quality assurance in Martin Marietta Energy Systems' centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm[sup 2] filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  1. Limitations of silicon diodes for clinical electron dosimetry.

    PubMed

    Song, Haijun; Ahmad, Munir; Deng, Jun; Chen, Zhe; Yue, Ning J; Nath, Ravinder

    2006-01-01

    This work investigates the relevance of several factors affecting the response of silicon diode dosemeters in depth-dose scans of electron beams. These factors are electron energy, instantaneous dose rate, dose per pulse, photon/electron dose ratio and electron scattering angle (directional response). Data from the literature and our own experiments indicate that the impact of these factors may be up to +/-15%. Thus, the different factors would have to cancel out perfectly at all depths in order to produce true depth-dose curves. There are reports of good agreement between depth-doses measured with diodes and ionisation chambers. However, our measurements with a Scantronix electron field detector (EFD) diode and with a plane-parallel ionisation chamber show discrepancies both in the build-up and in the low-dose regions, with a ratio up to 1.4. Moreover, the absolute sensitivity of two diodes of the same EFD model was found to differ by a factor of 3, and this ratio was not constant but changed with depth between 5 and 15% in the low-dose regions of some clinical electron beams. Owing to these inhomogeneities among diodes even of the same model, corrections for each factor would have to be diode-specific and beam-specific. All these corrections would have to be determined using parallel plane chambers, as recommended by AAPM TG-25, which would be unrealistic in clinical practice. Our conclusion is that in general diodes are not reliable in the measurement of depth-dose curves of clinical electron beams. PMID:16772305

  2. Ion beam energy spectrum calculation via dosimetry data deconvolution.

    SciTech Connect

    Harper-Slaboszewicz, Victor Jozef; Sharp, Andrew Clinton

    2010-10-01

    The energy spectrum of a H{sup +} beam generated within the HERMES III accelerator is calculated from dosimetry data to refine future experiments. Multiple layers of radiochromic film are exposed to the beam. A graphic user interface was written in MATLAB to align the film images and calculate the beam's dose depth profile. Singular value regularization is used to stabilize the unfolding and provide the H{sup +} beam's energy spectrum. The beam was found to have major contributions from 1 MeV and 8.5 MeV protons. The HERMES III accelerator is typically used as a pulsed photon source to experimentally obtain photon impulse response of systems due to high energy photons. A series of experiments were performed to explore the use of Hermes III to generate an intense pulsed proton beam. Knowing the beam energy spectrum allows for greater precision in experiment predictions and beam model verification.

  3. Personnel neutron dosimetry at Department of Energy facilities

    SciTech Connect

    Brackenbush, L.W.; Endres, G.W.R.; Selby, J.M.; Vallario, E.J.

    1980-08-01

    This study assesses the state of personnel neutron dosimetry at DOE facilities. A survey of the personnel dosimetry systems in use at major DOE facilities was conducted, a literature search was made to determine recent advances in neutron dosimetry, and several dosimetry experts were interviewed. It was concluded that personnel neutron dosimeters do not meet current needs and that serious problems exist now and will increase in the future if neutron quality factors are increased and/or dose limits are lowered.

  4. Simultaneous measurements of pure scintillation and Cerenkov signals in an integrated fiber-optic dosimeter for electron beam therapy dosimetry.

    PubMed

    Yoo, Wook Jae; Shin, Sang Hun; Jeon, Dayeong; Hong, Seunghan; Kim, Seon Geun; Sim, Hyeok In; Jang, Kyoung Won; Cho, Seunghyun; Lee, Bongsoo

    2013-11-18

    For real-time dosimetry in electron beam therapy, an integrated fiber-optic dosimeter (FOD) is developed using a water-equivalent dosimeter probe, four transmitting optical fibers, and a multichannel light-measuring device. The dosimeter probe is composed of two inner sensors, a scintillation sensor and a Cerenkov sensor, and each sensor has two different channels. Accordingly, we measured four separate light signals from each channel in the dosimeter probe, simultaneously, and then obtained the scintillation and Cerenkov signals using a subtraction method. To evaluate the performance of the integrated FOD, we measured the light signals according to the irradiation angle of the electron beam, the depth variation of the solid water phantom, and the electron beam energy. In conclusion, we demonstrated that the pure scintillation and Cerenkov signals obtained by an integrated FOD system based on a subtraction method can be effectively used for calibrating the conditions of high-energy electron beams in radiotherapy. PMID:24514292

  5. An alternative method using microwave power saturate in fingernail/electron paramagnetic resonance dosimetry.

    PubMed

    Choi, Hoon; Park, Byeongryong; Choi, Muhyun; Lee, Byungil; Lee, Cheol Eui

    2014-06-01

    An alternative method for fingernail/electron paramagnetic resonance (EPR) dosimetry valid at low doses (0-3 Gy) is suggested in this paper. The method consisted of two steps. The first step involved dehydrating fingernail clippings to remove their water content by heating them at 70 °C for 72 h. As the water content in the fingernails decreased, the variability of the EPR signals improved. The second step involved measuring and fitting the EPR signals at successive microwave power levels. A newly derived value known as 'curvature', which was based on the conventional peak-to-peak amplitudes of the EPR signals, was applied for the dosimetry. This method could be used as an alternative method in cases of low-radiation exposure doses (<3 Gy) or where use of the conventional dosimetry method is not proper for a fingernail sample. PMID:24876339

  6. Handbook for the Department of Energy Laboratory Accreditation Program for personnel dosimetry systems

    SciTech Connect

    Not Available

    1986-12-01

    The program contained in this Handbook provides a significant advance in the field of radiation protection through a structured means for assuring the quality of personnel dosimetry performance. Since personnel dosimetry performance is directly related to the assurance of worker safety, it has been of key interest to the Department of Energy. Studies conducted over the past three decades have clearly demonstrated a need for personnel dosimetry performance criteria, related testing programs, and improvements in dosimetry technology. In responding to these needs, the DOE Office of Nuclear Safety (EH) has developed and initiated a DOE Laboratory Accreditation Program (DOELAP) which is intended to improve the quality of personnel dosimetry through (1) performance testing, (2) dosimetry and calibration intercomparisons, and (3) applied research. In the interest of improving dosimetry technology, the DOE Laboratory Accreditation Program (DOELAP) is also designed to encourage cooperation and technical interchange between DOE laboratories. Dosimetry intercomparison programs have been scheduled which include the use of transport standard instruments, transport standard radioactive sources and special dosimeters. The dosimeters used in the intercomparison program are designed to obtain optimum data on the comparison of dosimetry calibration methodologies and capabilities. This data is used in part to develop enhanced calibration protocols. In the interest of overall calibration update, assistance and guidance for the calibration of personnel dosimeters is available through the DOELAP support laboratories. 20 refs., 1 tab.

  7. Effect of electron contamination of a 6 MV x-ray beam on near surface diode dosimetry

    NASA Astrophysics Data System (ADS)

    Edwards, C. R.; Mountford, P. J.; Moloney, A. J.

    2006-12-01

    In critical organ in vivo x-ray dosimetry, the relative contaminating electron contribution to the total dose and total detector response outside the field will be different to the corresponding contributions at the central axis detector calibration position, mainly due to the effects of shielding in the linear accelerator head on the electron and x-ray energy spectrum. To investigate these contributions, the electron energy response of a Scanditronix PFD diode was measured using electrons with mean energies from 0.45 to 14.6 MeV, and the Monte Carlo code MCNP-4C was used to calculate the electron energy spectra on the central axis, and at 1 and 10 cm outside the edge of a 4 × 4, 10 × 10 and a 15 × 15 cm2 6 MV x-ray field. The electron contribution to the total dose varied from about 8% on the central axis of the smallest field to about 76% at 10 cm outside the edge of the largest field. The electron contribution to the total diode response varied from about 7-8% on the central axis of all three fields to about 58% at 10 cm outside the edge of the smallest field. The results indicated that a near surface x-ray dose measurement with a diode outside the treatment field has to be interpreted with caution and requires knowledge of the relative electron contribution specific to the measurement position and field size.

  8. Polymer gel dosimetry of an electron beam in the presence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Vandecasteele, J.; De Deene, Y.

    2013-06-01

    The effect of a strong external magnetic field on 4 MeV electron beam was measured with polymer gel dosimetry. The measured entrance dose distribution was compared with a calculated fluence map. The magnetic field was created by use of two permanent Neodymium (NdFeB) magnets that were positioned perpendicular to the electron beam. The magnetic field between the magnets was measured with Hall sensors. Based on the magnetic field measurement and the law of Biot-Savart, the magnetic field distribution was extrapolated. Electron trajectories were calculated using a relativistic Lorentz force operator. Although the simplified computational model that was applied, the shape and position of the calculated entrance fluence map are found to be in good agreement with the measured dose distribution in the first layer of the phantom. In combination with the development of low density polymer gel dosimeters, these preliminary results show the potential of 3D gel dosimetry in MRI-linac applications.

  9. Thermoluminescence characteristics of flat optical fiber in radiation dosimetry under different electron irradiation conditions

    NASA Astrophysics Data System (ADS)

    Alawiah, A.; Intan, A. M.; Bauk, S.; Abdul-Rashid, H. A.; Yusoff, Z.; Mokhtar, M. R.; Wan Abdullah, W. S.; Mat Sharif, K. A.; Mahdiraji, G. A.; Mahamd Adikan, F. R.; Tamchek, N.; Noor, N. M.; Bradley, D. A.

    2013-05-01

    Thermoluminescence (TL) flat optical fibers (FF) have been proposed as radiation sensor in medical dosimetry for both diagnostic and radiotherapy applications. A flat optical fiber with nominal dimensions of (3.226 × 3.417 × 0.980) mm3 contains pure silica SiO2 was selected for this research. The FF was annealed at 400°C for 1 h before irradiated. Kinetic parameters and dosimetric glow curve of TL response were studied in FF with respect to electron irradiation of 6 MeV, 15 MeV and 21 MeV using linear accelerator (LINAC) in the dose range of 2.0-10.0 Gy. The TL response was read using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader used includes; initial preheat temperature of 80°C, maximum readout temperature is 400°C and the heating rate of 30°Cs-1. The proposed FF shows excellent linear radiation response behavior within the clinical relevant dose range for all of these energies, good reproducibility, independence of radiation energy, independence of dose rate and exhibits a very low thermal fading. From these results, the proposed FF can be used as radiation dosimeter and favorably compares with the widely used of LiF:MgTi dosimeter in medical radiotherapy application.

  10. An image-based skeletal dosimetry model for the ICRP reference newborn—internal electron sources

    NASA Astrophysics Data System (ADS)

    Pafundi, Deanna; Rajon, Didier; Jokisch, Derek; Lee, Choonsik; Bolch, Wesley

    2010-04-01

    In this study, a comprehensive electron dosimetry model of newborn skeletal tissues is presented. The model is constructed using the University of Florida newborn hybrid phantom of Lee et al (2007 Phys. Med. Biol. 52 3309-33), the newborn skeletal tissue model of Pafundi et al (2009 Phys. Med. Biol. 54 4497-531) and the EGSnrc-based Paired Image Radiation Transport code of Shah et al (2005 J. Nucl. Med. 46 344-53). Target tissues include the active bone marrow (surrogate tissue for hematopoietic stem cells), shallow marrow (surrogate tissue for osteoprogenitor cells) and unossified cartilage (surrogate tissue for chondrocytes). Monoenergetic electron emissions are considered over the energy range 1 keV to 10 MeV for the following source tissues: active marrow, trabecular bone (surfaces and volumes), cortical bone (surfaces and volumes) and cartilage. Transport results are reported as specific absorbed fractions according to the MIRD schema and are given as skeletal-averaged values in the paper with bone-specific values reported in both tabular and graphic format as electronic annexes (supplementary data). The method utilized in this work uniquely includes (1) explicit accounting for the finite size and shape of newborn ossification centers (spongiosa regions), (2) explicit accounting for active and shallow marrow dose from electron emissions in cortical bone as well as sites of unossified cartilage, (3) proper accounting of the distribution of trabecular and cortical volumes and surfaces in the newborn skeleton when considering mineral bone sources and (4) explicit consideration of the marrow cellularity changes for active marrow self-irradiation as applicable to radionuclide therapy of diseased marrow in the newborn child.

  11. A portable electronic system for radiation dosimetry using electrets

    NASA Astrophysics Data System (ADS)

    Cruvinel, P. E.; Mascarenhas, S.; Cameron, J.

    1990-02-01

    An electret dosimeter with a cylindrical active volume has been introduced by Mascarenhas and collaborators [Proc. 10th Anniversary Conf. 1969-1979, Associacâo Brasileira de Fisicos em Medicina, p. 488; Topics Appl. Phys. 33 (1987) 321] for possible use in personnel and area monitoring. The full energy response curve as well as the degree of reproducibility and accuracy of the dosimeter are reported in a previous report [O. Guerrini, Master Science Thesis, São Carlos, USP-IFQSC (1982)]. For dimensions similar to those of the common pen dosimeter, the electret has a total surface charge of the order of 10 -9 C and it has a readout sensitivity of the order of 10 -5 Gy with a useful range of 5 × 10 -2 Gy. In this paper we describe a portable electronic system to measure X and γ-rays using a cylindrical electret ionization chamber. It uses commercially available operational amplifiers, and charge measurements can also be made by connecting a suitable capacitor in the feedback loop. With this system it is possible to measure equivalent surface charges up to (19.99±0.01) on the dosimeter. The readout doses are shown on a 3 {1}/{2} digit liquid crystal display (LCD). We have used complementary metal oxide semiconductor (CMOS) and bipolar metal oxide semiconductor (BiMOS) operatonal amplifier devices in the system's design. This choice provides small power consumption and is ideal for battery powered instruments. Furthermore the instrument is ideally suited for in situ measurements of X and γ radiation using a cylindrical electret ionization chamber.

  12. The application of thermoluminescence dosimetry in X-ray energy discrimination.

    PubMed

    Nelson, V K; Holloway, L; McLean, I D

    2015-12-01

    Clinical dosimetry requires an understanding of radiation energy to accurately determine the delivered dose. For many situations this is known, however there are also many situations where the radiation energy is not well known, thus limiting dosimetric accuracy. This is the case in personnel dosimetry where thermo luminescent (TL) dosimetry is the method of choice. Traditionally beam energy characteristics in personnel dosimetry are determined through discrimination with the use of various filters fitted within a radiation monitor. The presence of scattered and characteristic radiation produced by these metallic filters, however, can compromise the results. In this study the TL response of five materials TLD100, TLD100H, TLD200, TLD400 and TLD500, was measured at various X-ray energies. The TL sensitivity ratio for various combinations of materials as a function of X-ray energy was calculated. The results indicate that in personal dosimetry a combination of three or more TL detector system has a better accuracy of estimation of effective radiation energy of an X-ray beam than some of the current method of employed for energy estimation and has the potential to improve the accuracy in dose determination in a variety of practical situations. The development of this method also has application in other fields including quality assurance of the orthovoltage therapy machines, dosimetry intercomparisons of kilovoltage X-ray beams, and measurement of the dose to critical organs outside a treatment field of a megavoltage therapy beam. PMID:26330215

  13. Calculation of electron and isotopes dose point kernels with fluka Monte Carlo code for dosimetry in nuclear medicine therapy

    SciTech Connect

    Botta, F.; Mairani, A.; Battistoni, G.; Cremonesi, M.; Di Dia, A.; Fasso, A.; Ferrari, A.; Ferrari, M.; Paganelli, G.; Pedroli, G.; Valente, M.

    2011-07-15

    Purpose: The calculation of patient-specific dose distribution can be achieved by Monte Carlo simulations or by analytical methods. In this study, fluka Monte Carlo code has been considered for use in nuclear medicine dosimetry. Up to now, fluka has mainly been dedicated to other fields, namely high energy physics, radiation protection, and hadrontherapy. When first employing a Monte Carlo code for nuclear medicine dosimetry, its results concerning electron transport at energies typical of nuclear medicine applications need to be verified. This is commonly achieved by means of calculation of a representative parameter and comparison with reference data. Dose point kernel (DPK), quantifying the energy deposition all around a point isotropic source, is often the one. Methods: fluka DPKs have been calculated in both water and compact bone for monoenergetic electrons (10{sup -3} MeV) and for beta emitting isotopes commonly used for therapy ({sup 89}Sr, {sup 90}Y, {sup 131}I, {sup 153}Sm, {sup 177}Lu, {sup 186}Re, and {sup 188}Re). Point isotropic sources have been simulated at the center of a water (bone) sphere, and deposed energy has been tallied in concentric shells. fluka outcomes have been compared to penelope v.2008 results, calculated in this study as well. Moreover, in case of monoenergetic electrons in water, comparison with the data from the literature (etran, geant4, mcnpx) has been done. Maximum percentage differences within 0.8{center_dot}R{sub CSDA} and 0.9{center_dot}R{sub CSDA} for monoenergetic electrons (R{sub CSDA} being the continuous slowing down approximation range) and within 0.8{center_dot}X{sub 90} and 0.9{center_dot}X{sub 90} for isotopes (X{sub 90} being the radius of the sphere in which 90% of the emitted energy is absorbed) have been computed, together with the average percentage difference within 0.9{center_dot}R{sub CSDA} and 0.9{center_dot}X{sub 90} for electrons and isotopes, respectively. Results: Concerning monoenergetic electrons

  14. Calculation of electron and isotopes dose point kernels with fluka Monte Carlo code for dosimetry in nuclear medicine therapy

    SciTech Connect

    Botta, F; Di Dia, A; Pedroli, G; Mairani, A; Battistoni, G; Fasso, A; Ferrari, A; Ferrari, M; Paganelli, G; Valente, M

    2011-06-01

    The calculation of patient-specific dose distribution can be achieved by Monte Carlo simulations or by analytical methods. In this study, fluka Monte Carlo code has been considered for use in nuclear medicine dosimetry. Up to now, fluka has mainly been dedicated to other fields, namely high energy physics, radiation protection, and hadrontherapy. When first employing a Monte Carlo code for nuclear medicine dosimetry, its results concerning electron transport at energies typical of nuclear medicine applications need to be verified. This is commonly achieved by means of calculation of a representative parameter and comparison with reference data. Dose point kernel (DPK), quantifying the energy deposition all around a point isotropic source, is often the one.Methods: fluka DPKs have been calculated in both water and compact bone for monoenergetic electrons (10–3 MeV) and for beta emitting isotopes commonly used for therapy (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, and 188Re). Point isotropic sources have been simulated at the center of a water (bone) sphere, and deposed energy has been tallied in concentric shells. fluka outcomes have been compared to penelope v.2008 results, calculated in this study as well. Moreover, in case of monoenergetic electrons in water, comparison with the data from the literature (etran, geant4, mcnpx) has been done. Maximum percentage differences within 0.8·RCSDA and 0.9·RCSDA for monoenergetic electrons (RCSDA being the continuous slowing down approximation range) and within 0.8·X90 and 0.9·X90 for isotopes (X90 being the radius of the sphere in which 90% of the emitted energy is absorbed) have been computed, together with the average percentage difference within 0.9·RCSDA and 0.9·X90 for electrons and isotopes, respectively.Results: Concerning monoenergetic electrons, within 0.8·RCSDA (where 90%–97% of the particle energy is deposed), fluka and penelope agree mostly within 7%, except for 10 and 20 keV electrons (12% in water, 8

  15. Skeletal dosimetry in a voxel-based rat phantom for internal exposures to photons and electrons

    SciTech Connect

    Xie Tianwu; Han Dao; Liu Yang; Sun Wenjuan; Liu Qian

    2010-05-15

    Purpose: The skeleton makes a significant contribution to the whole body absorbed dose evaluation of rats, since the bone marrow and bone surface in the skeleton express high radiosensitivity and are considered to be important dose-limiting tissues. The bone marrow can be categorized as red bone marrow (RBM) and yellow bone marrow (YBM). It is important to investigate the bone marrow in skeletal dosimetry. Methods: Cryosectional color images of the skeleton of a 156 g rat were segmented into mineral bone (including cortical bone and trabecular bone), RBM, and YBM. These three tissue types were identified at 40 different bone sites and integrated into a previously developed voxel-based rat computational phantom. Photon and electron skeletal absorbed fractions were then calculated using the MCNPX Monte Carlo code. Results: Absorbed fraction (AF) and specific absorbed fraction (SAF) for mineral bone, RBM, and YBM at the 40 different bone sites were established for monoenergetic photon and electron sources placed in 18 organs and seven bone sites. Discrete photon energy was varied from 0.01 to 5.0 MeV in 21 discrete steps, while 21 discrete electron energies were studied, from 0.1 to 10.0 MeV. The trends and values found were consistent with the results of other researchers [M. G. Stabin, T. E. Peterson, G. E. Holburn, and M. A. Emmons, ''Voxel-based mouse and rat models for internal dose calculations,'' J. Nucl. Med. 47, 655-659 (2006)]. S-factors for the radionuclides {sup 169}Er, {sup 143}Pr, {sup 89}Sr, {sup 32}P, and {sup 90}Y, located in 18 organs and seven bone sites for the skeleton, were calculated and are provided in detail. Conclusions: For internal dose calculations, the AF data reveal that the mineral bone in the rat skeletal system is responsible for significant attenuation of gamma rays, especially at low energies. The photon SAF curves of RBM show that, for photon energies greater than 0.6 MeV, there is an increase in secondary photons emitted from the

  16. US Department of Energy Laboratory Accredition Program (DOELAP) for personnel dosimetry systems

    SciTech Connect

    Cummings, F.M.; Carlson, R.D.; Loesch, R.M.

    1993-12-31

    Accreditation of personnel dosimetry systems is required for laboratories that conduct personnel dosimetry for the U.S. Department of Energy (DOE). Accreditation is a two-step process which requires the participant to pass a proficiency test and an onsite assessment. The DOE Laboratory Accreditation Program (DOELAP) is a measurement quality assurance program for DOE laboratories. Currently, the DOELAP addresses only dosimetry systems used to assess the whole body dose to personnel. A pilot extremity DOELAP has been completed and routine testing is expected to begin in January 1994. It is expected that participation in the extremity program will be a regulatory requirement by January 1996.

  17. Practical considerations for electron beam small field size dosimetry

    SciTech Connect

    Sharma, Subhash C.; Johnson, Martin W.; Gossman, Michael S. . E-mail: GossmanMS@erlanger.org

    2005-06-30

    Special care of superficial lesions surrounding critical structures, such as an eye, may require tight margins. When this is the case, small megavoltage electron treatment fields and nonstandard treatment distances become necessary. When the field size is found to be less than the practical range of the electron beam, dosimetric measurements should be performed. This research includes data proving that very small electron fields can be employed for treatment with appropriate beam flatness and penumbra. This is accomplished by first coning down the incident beam to a small field size, then secondly by adding a single lead sheet to the patient's skin surface. The aperture of the sheet is required to be greater than 2 x 2 cm{sup 2} in size, and must be cut properly to adequately confine the treatment area.

  18. Progress on standardization of electron beam dosimetry for radiation processing

    NASA Astrophysics Data System (ADS)

    Chenghua, Li; Yanli, Zhang; Ruicao, Pang; Zhimian, Liu; Xuan, Xia; Jingmin, Wu

    1993-10-01

    The high dose standards and dissemination system of electron beams are being established at NIM. The graphite and/ or water calorimeters and liquid chemical dosimeter are to be accepted as standards. The transfer dosimeter selected are alanine/ESR dosimeter and radiochromic film (FWT - 60). Several kinds of radiochromic films, undyed cellulose triacetate, polyethylene and blue cellophane will be recommended as working dosimeter. A series of intercomparison studies are conducted between calorimeter and dichromate dosimeter. Agreement is found within 2%. Water calorimeters and dichromate dosimeters are used to make absolute dosimetric measurements of electron beams. These calibrated beams are then used to calibrate several types of dosimeters, such as alanine, radiochromic films, undyed and dyed polyethylene. Preliminary studies show that water calorimeter and dichromate dosimeter are reproducible and sufficiently accurate for electron beam calibration. The estimated overall uncertainty of the measurement is better than 5% at 95% confidence level.

  19. A new electronic neutron dosimeter (END) for reliable personal dosimetry

    NASA Astrophysics Data System (ADS)

    Ing, H.; Cousins, T.; Andrews, H. R.; Machrafi, R.; Voevodskiy, A.; Kovaltchouk, V.; Clifford, E. T. H.; Robins, M.; Larsson, C.; Hugron, R.; Brown, J.

    2008-04-01

    Tests of existing electronic neutron dosimeters by military and civilian groups have revealed significant performance limitations. To meet the operational requirements of emergency response personnel to a radiological/nuclear incident as well as those in the nuclear industry, a new END has been developed. It is patterned after a unique commercial neutron spectral dosemeter known as the N-probe. It uses a pair of small special scintillators on tiny photomultiplier tubes. Special electronics were designed to minimize power consumption to allow for weeks of operation on a single charge. The size, performance, and data analysis for the END have been designed to meet/exceed international standards for electronic neutron dosimeters. Results obtained with the END prototype are presented.

  20. A comparison of electronic portal dosimetry verification methods for use in stereotactic radiotherapy.

    PubMed

    Millin, Anthony E; Windle, Rebecca S; Lewis, D Geraint

    2016-01-01

    Three methods of transit dosimetry using Electronic Portal Imaging Devices (EPIDs) were investigated for use in routine in-vivo dosimetry for cranial stereotactic radiosurgery and radiotherapy. The approaches examined were (a) A full Monte Carlo (MC) simulation of radiation transport through the linear accelerator and patient; (b) Calculation of the expected fluence by a treatment planning system (TPS); (c) Point doses calculated along the central axis compared to doses calculated using parameters acquired using the EPID. A dosimetric comparison of each of the three methods predicted doses at the imager plane to within ±5% and a gamma comparison for the MC and TPS based approaches showed good agreement for a range of dose and distance to agreement criteria. The MC technique was most time consuming, followed by the TPS calculation with the point dose calculation significantly quicker than the other methods. PMID:26748961

  1. Comparative dosimetry study of three UK centres implementing total skin electron treatment through external audit

    PubMed Central

    Gonzalez, R; McGovern, M; Greener, A

    2015-01-01

    Objective: This article describes the external audit measurements conducted in two UK centres implementing total skin electron beam therapy (TSEBT) and the results obtained. Methods: Measurements of output, energy, beam flatness and symmetry at a standard distance (95 or 100 cm SSD) were performed using a parallel plate chamber in solid water. Similarly, output and energy measurements were also performed at the treatment plane for single and dual fields. Clinical simulations were carried out using thermoluminescent dosemeters (TLDs) and Gafchromic® film (International Specialty Products, Wayne, NJ) on an anthropomorphic phantom. Results: Extended distance measurements confirmed that local values for the beam dosimetry at Centres A and B were within 2% for outputs and 1-mm agreement of the expected depth at which the dose is 50% of the maximum for the depth–dose curve in water (R50,D) value. Clinical simulation using TLDs) showed an agreement of −1.6% and −6.7% compared with the expected mean trunk dose for each centre, respectively, and a variation within 10% (±1 standard deviation) across the trunk. The film results confirmed that the delivery of the treatment technique at each audited centre complies with the European Organisation for Research and Treatment of Cancer recommendations. Conclusion: This audit methodology has proven to be a successful way to confirm the agreement of dosimetric parameters for TSEBT treatments at both audited centres and could serve as the basis for an audit template to be used by other audit groups. Advances in knowledge: TSEBT audits are not established in the UK owing to a limited number of centres carrying out the treatment technique. This article describes the audits performed at two UK centres prior to their clinical implementation. PMID:25761213

  2. A modified Fricke gel dosimeter for fast electron blood dosimetry

    NASA Astrophysics Data System (ADS)

    Del Lama, L. S.; de Góes, E. G.; Sampaio, F. G. A.; Petchevist, P. C. D.; de Almeida, A.

    2014-12-01

    It has been suggested for more than forty years that blood and blood components be irradiated before allogeneic transfusions for immunosuppressed patients in order to avoid the Transfusion-Associated Graft-versus-Host Disease (TA-GVHD). Whole blood, red blood cells, platelets and granulocytes may have viable T cells and should be irradiated before transfusion for different patient clinical conditions. According to international guides, absorbed doses from 25 up to 50 Gy should be delivered to the central middle plane of each blood bag. Although gamma and X-rays from radiotherapy equipments and dedicated cell irradiators are commonly used for this purpose, electron beams from Linear Accelerators (LINACs) could be used as well. In this work, we developed a methodology able to acquire dosimetric data from blood irradiations, especially after fast electrons exposures. This was achieved using a proposed Fricke Xylenol Gel (FXGp) dosimeter, which presents closer radiological characteristics (attenuation coefficients and stopping-powers) to the whole blood, as well as complete absorbed dose range linearity. The developed methodology and the FXGp dosimeter were also able to provide isodose curves and field profiles for the irradiated samples.

  3. ELECTRON PARAMAGNETIC RESONANCE DOSIMETRY FOR A LARGE-SCALE RADIATION INCIDENT

    PubMed Central

    Swartz, Harold M.; Flood, Ann Barry; Williams, Benjamin B.; Dong, Ruhong; Swarts, Steven G.; He, Xiaoming; Grinberg, Oleg; Sidabras, Jason; Demidenko, Eugene; Gui, Jiang; Gladstone, David J.; Jarvis, Lesley A.; Kmiec, Maciej M.; Kobayashi, Kyo; Lesniewski, Piotr N.; Marsh, Stephen D.P.; Matthews, Thomas P.; Nicolalde, Roberto J.; Pennington, Patrick M.; Raynolds, Timothy; Salikhov, Ildar; Wilcox, Dean E.; Zaki, Bassem I.

    2013-01-01

    With possibilities for radiation terrorism and intensified concerns about nuclear accidents since the recent Fukushima Daiichi event, the potential exposure of large numbers of individuals to radiation that could lead to acute clinical effects has become a major concern. For the medical community to cope with such an event and avoid overwhelming the medical care system, it is essential to identify not only individuals who have received clinically significant exposures and need medical intervention but also those who do not need treatment. The ability of electron paramagnetic resonance to measure radiation-induced paramagnetic species, which persist in certain tissues (e.g., teeth, fingernails, toenails, bone, and hair), has led this technique to become a prominent method for screening significantly exposed individuals. Although the technical requirements needed to develop this method for effective application in a radiation event are daunting, remarkable progress has been made. In collaboration with General Electric, and through funding committed by the Biomedical Advanced Research and Development Authority, electron paramagnetic resonance tooth dosimetry of the upper incisors is being developed to become a Food and Drug Administration-approved and manufacturable device designed to carry out triage for a threshold dose of 2 Gy. Significant progress has also been made in the development of electron paramagnetic resonance nail dosimetry based on measurements of nails in situ under point-of-care conditions, and in the near future this may become a second field-ready technique. Based on recent progress in measurements of nail clippings, we anticipate that this technique may be implementable at remotely located laboratories to provide additional information when the measurements of dose on site need to be supplemented. We conclude that electron paramagnetic resonance dosimetry is likely to be a useful part of triage for a large-scale radiation incident. PMID:22850230

  4. Emergency Dosimetry Using Ceramic Components in Personal Electronic Devices

    NASA Astrophysics Data System (ADS)

    Kouroukla, E. C.; Bailiff, I. K.; Terry, I.

    2014-02-01

    The rapid assessment of radiation dose to members of the public exposed to significant levels of ionizing radiation during a radiological incident presents a significant difficulty in the absence of planned radiation monitoring. However, within most personal electronic devices components such as resistors with alumina substrates can be found that have potentially suitable properties as solid state dosimeters using luminescence measurement techniques. The suitability of several types of ceramic-based components (e.g., resonators, inductors and resistors) has been previously examined using optically stimulated luminescence (OSL) and thermoluminescence (TL) techniques to establish their basic characteristics for the retrospective determination of absorbed dose. In this paper, we present results obtained with aluminum oxide surface mount resistors extracted from mobile phones that further extend this work. Very encouraging results have been obtained related to the measurement of luminescence sensitivity, dose response, reusability, limit of detection, signal reproducibility and known-dose recovery. However, the alumina exhibits a rapid loss of the latent luminescence signal with time following irradiation attributed to athermal (or anomalous) fading. The issues related to obtaining a reliable correction protocol for this loss and the detailed examinations required of the fading behavior are discussed.

  5. Transit Dosimetry for Patient Treatment Verification with an Electronic Portal Imaging Device

    NASA Astrophysics Data System (ADS)

    Berry, Sean L.

    The complex and individualized photon fluence patterns constructed during intensity modulated radiation therapy (IMRT) treatment planning must be verified before they are delivered to the patient. There is a compelling argument for additional verification throughout the course of treatment due to the possibility of data corruption, unintentional modification of the plan parameters, changes in patient anatomy, errors in patient alignment, and even mistakes in identifying the correct patient for treatment. Amorphous silicon (aSi) Electronic Portal Imaging Devices (EPIDs) can be utilized for IMRT verification. The goal of this thesis is to implement EPID transit dosimetry, measurement of the dose at a plane behind the patient during their treatment, within the clinical process. In order to achieve this goal, a number of the EPID's dosimetric shortcomings were studied and subsequently resolved. Portal dose images (PDIs) acquired with an aSi EPID suffer from artifacts related to radiation backscattered asymmetrically from the EPID support structure. This backscatter signal varies as a function of field size (FS) and location on the EPID. Its presence can affect pixel values in the measured PDI by up to 3.6%. Two methods to correct for this artifact are offered: discrete FS specific correction matrices and a single generalized equation. The dosimetric comparison between the measured and predicted through-air dose images for 49 IMRT treatment fields was significantly improved (p << .001) after the application of these FS specific backscatter corrections. The formulation of a transit dosimetry algorithm followed the establishment of the backscatter correction and a confirmation of the EPID's positional stability with linac gantry rotation. A detailed characterization of the attenuation, scatter, and EPID response behind an object in the beam's path is necessary to predict transit PDIs. In order to validate the algorithm's performance, 49 IMRT fields were delivered to a

  6. WE-E-BRE-01: An Image-Based Skeletal Dosimetry Model for the ICRP Reference Adult Female - Internal Electron Sources

    SciTech Connect

    O'Reilly, S; Maynard, M; Marshall, E; Bolch, W; Sinclair, L; Rajon, D; Wayson, M

    2014-06-15

    Purpose: Limitations seen in previous skeletal dosimetry models, which are still employed in commonly used software today, include the lack of consideration of electron escape and cross-fire from cortical bone, the modeling of infinite spongiosa, the disregard of the effect of varying cellularity on active marrow self-irradiation, and the lack of use of the more recent ICRP definition of a 50 micron surrogate tissue region for the osteoprogenitor cells - shallow marrow. These limitations were addressed in the present dosimetry model. Methods: Electron transport was completed to determine specific absorbed fractions to active marrow and shallow marrow of the skeletal regions of the adult female. The bone macrostructure was obtained from the whole-body hybrid computational phantom of the UF series of reference phantoms, while the bone microstructure was derived from microCT images of skeletal region samples taken from a 45 year-old female cadaver. The target tissue regions were active marrow and shallow marrow. The source tissues were active marrow, inactive marrow, trabecular bone volume, trabecular bone surfaces, cortical bone volume and cortical bone surfaces. The marrow cellularity was varied from 10 to 100 percent for active marrow self-irradiation. A total of 33 discrete electron energies, ranging from 1 keV to 10 MeV, were either simulated or modeled analytically. Results: The method of combining macro- and microstructure absorbed fractions calculated using MCNPX electron transport was found to yield results similar to those determined with the PIRT model for the UF adult male in the Hough et al. study. Conclusion: The calculated skeletal averaged absorbed fractions for each source-target combination were found to follow similar trends of more recent dosimetry models (image-based models) and did not follow current models used in nuclear medicine dosimetry at high energies (due to that models use of an infinite expanse of trabecular spongiosa)

  7. Comparison between thermoluminescence and electronic dosimetry results at the Belgian Nuclear Research Centre.

    PubMed

    Vanhavere, F; Coeck, M

    2001-01-01

    At the Belgian Nuclear Research Centre, SCK.CEN, the official dose of record is measured by thermoluminescence dosemeters (TLDs), read out on a monthly basis. The workers who frequently enter controlled areas also wear an electronic dosemeter (ED), in addition, as an ALARA tool. In this paper the dose values registered by both dosimetry systems during 1 year are compared. Special attention was given to the determination of the background radiation. The general agreement was good, although the TLD gave slightly higher values. An exercise like this yielded useful information on the storage and use of dosemeters by personnel and on the lowest limit of detection obtained with both systems. PMID:11586711

  8. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  9. SU-E-QI-15: Single Point Dosimetry by Means of Cerenkov Radiation Energy Transfer (CRET)

    SciTech Connect

    Volotskova, O; Jenkins, C; Xing, L

    2014-06-15

    Purpose: Cerenkov light is generated when a charged particles with energy greater then 250 keV, moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons during the static megavoltage linear accelerator (LINAC) operational mode. Recently, Cerenkov radiation gained considerable interest as possible candidate as a new imaging modality. Optical signals generated by Cerenkov radiation may act as a surrogate for the absorbed superficial radiation dose. We demonstrated a novel single point dosimetry method for megavoltage photon and electron therapy utilizing down conversion of Cerenkov photons. Methods: The custom build signal characterization system was used: a sample holder (probe) with adjacent light tight compartments was connected via fiber-optic cables to a photon counting photomultiplier tube (PMT). One compartment contains a medium only while the other contains medium and red-shifting nano-particles (Q-dots, nanoclusters). By taking the difference between the two signals (Cerenkov photons and CRET photons) we obtain a measure of the down-converted light, which we expect to be proportional to dose as measured with an adjacent ion chamber. Experimental results are compared to Monte Carlo simulations performed using the GEANT4 code. Results: The signal correlation between CR signal, CRET readings and dose produced by LINAC at a single point were investigated. The experimental results were compared with simulations. The dose linearity, signal to noise ratio and dose rate dependence were tested with custom build CRET based probe. Conclusion: Performance characteristics of the proposed single point CRET based probe were evaluated. The direct use of the induced Cerenkov emission and CRET in an irradiated single point volume as an indirect surrogate for the imparted dose was investigated. We conclude that CRET is a promising optical based dosimetry method that offers advantages over those already proposed.

  10. Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy

    SciTech Connect

    Adolfsson, Emelie; Alm Carlsson, Gudrun; Grindborg, Jan-Erik; Gustafsson, Haakan; Lund, Eva; Carlsson Tedgren, Aasa

    2010-09-15

    Purpose: To investigate experimentally the energy dependence of the detector response of lithium formate EPR dosimeters for photon energies below 1 MeV relative to that at {sup 60}Co energies. High energy photon beams are used in calibrating dosimeters for use in brachytherapy since the absorbed dose to water can be determined with high accuracy in such beams using calibrated ion chambers and standard dosimetry protocols. In addition to any differences in mass-energy absorption properties between water and detector, variations in radiation yield (detector response) with radiation quality, caused by differences in the density of ionization in the energy imparted (LET), may exist. Knowledge of an eventual deviation in detector response with photon energy is important for attaining high accuracy in measured brachytherapy dose distributions. Methods: Lithium formate EPR dosimeters were irradiated to known levels of air kerma in 25-250 kV x-ray beams and in {sup 137}Cs and {sup 60}Co beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free in air into values of mean absorbed dose to the detectors were made using EGSnrc MC simulations and x-ray energy spectra measured or calculated for the actual beams. The signals from the detectors were measured using EPR spectrometry. Detector response (the EPR signal per mean absorbed dose to the detector) relative to that for {sup 60}Co was determined for each beam quality. Results: Significant decreases in the relative response ranging from 5% to 6% were seen for x-ray beams at tube voltages {<=}180 kV. No significant reduction in the relative response was seen for {sup 137}Cs and 250 kV x rays. Conclusions: When calibrated in {sup 60}Co or MV photon beams, corrections for the photon energy dependence of detector response are needed to achieve the highest accuracy when using lithium formate EPR dosimeters for measuring absorbed doses around brachytherapy sources emitting photons in the energy

  11. Experimental assessment of gold nanoparticle-mediated dose enhancement in radiation therapy beams using electron spin resonance dosimetry.

    PubMed

    Wolfe, T; Guidelli, E J; Gómez, J A; Baffa, O; Nicolucci, P

    2015-06-01

    In this work, we aim to experimentally assess increments of dose due to nanoparticle-radiation interactions via electron spin resonance (ESR) dosimetry performed with a biological-equivalent sensitive material.We employed 2-Methyl-Alanine (2MA) in powder form to compose the radiation sensitive medium embedding gold nanoparticles (AuNPs) 5 nm in diameter. Dosimeters manufactured with 0.1% w/w of AuNPs or no nanoparticles were irradiated with clinically utilized 250 kVp orthovoltage or 6 MV linac x-rays in dosimetric conditions. Amplitude peak-to-peak (App) at the central ESR spectral line was used for dosimetry. Dose-response curves were obtained for samples with or without nanoparticles and each energy beam. Dose increments due to nanoparticles were analyzed in terms of absolute dose enhancements (DEs), calculated as App ratios for each dose/beam condition, or relative dose enhancement factors (DEFs) calculated as the slopes of the dose-response curves.Dose enhancements were observed to present an amplified behavior for small doses (between 0.1-0.5 Gy), with this effect being more prominent with the kV beam. For doses between 0.5-5 Gy, dose-independent trends were observed for both beams, stable around (2.1   ±   0.7) and (1.3   ±   0.4) for kV and MV beams, respectively. We found DEFs of (1.62   ±   0.04) or (1.27   ±   0.03) for the same beams. Additionally, we measured no interference between AuNPs and the ESR apparatus, including the excitation microwaves, the magnetic fields and the paramagnetic radicals.2MA was demonstrated to be a feasible paramagnetic radiation-sensitive material for dosimetry in the presence of AuNPs, and ESR dosimetry a powerful experimental method for further verifications of increments in nanoparticle-mediated doses of biological interest. Ultimately, gold nanoparticles can cause significant and detectable dose enhancements in biological-like samples irradiated at both kilo

  12. Dosimetry of low energy proton beams for use in spacecraft parts testing

    NASA Technical Reports Server (NTRS)

    Miller, C. G.

    1975-01-01

    Thermoluminescent Dosimeters tes (TLD) were used to measure proton fluences consisting of 5MeV or lower energies. The results were at variance with the corresponding gamma measurements. The results of experiments on low energy proton dosimetry using LiF-in-teflon microrods (TLD-700 or LiF-7), are presented.

  13. Validation of total skin electron irradiation (TSEI) technique dosimetry data by Monte Carlo simulation.

    PubMed

    Nevelsky, Alexander; Borzov, Egor; Daniel, Shahar; Bar-Deroma, Rachel

    2016-01-01

    Total skin electron irradiation (TSEI) is a complex technique which requires many nonstandard measurements and dosimetric procedures. The purpose of this work was to validate measured dosimetry data by Monte Carlo (MC) simulations using EGSnrc-based codes (BEAMnrc and DOSXYZnrc). Our MC simulations consisted of two major steps. In the first step, the incident electron beam parameters (energy spectrum, FWHM, mean angular spread) were adjusted to match the measured data (PDD and profile) at SSD = 100 cm for an open field. In the second step, these parameters were used to calculate dose distributions at the treatment distance of 400 cm. MC simulations of dose distributions from single and dual fields at the treatment distance were performed in a water phantom. Dose distribution from the full treatment with six dual fields was simulated in a CT-based anthropomorphic phantom. MC calculations were compared to the available set of measurements used in clinical practice. For one direct field, MC calculated PDDs agreed within 3%/1 mm with the measurements, and lateral profiles agreed within 3% with the measured data. For the OF, the measured and calculated results were within 2% agreement. The optimal angle of 17° was confirmed for the dual field setup. Dose distribution from the full treatment with six dual fields was simulated in a CT-based anthropomorphic phantom. The MC-calculated multiplication factor (B12-factor), which relates the skin dose for the whole treatment to the dose from one calibration field, for setups with and without degrader was 2.9 and 2.8, respectively. The measured B12-factor was 2.8 for both setups. The difference between calculated and measured values was within 3.5%. It was found that a degrader provides more homogeneous dose distribution. The measured X-ray contamination for the full treatment was 0.4%; this is compared to the 0.5% X-ray contamination obtained with the MC calculation. Feasibility of MC simulation in an anthropomorphic phantom

  14. Electronic energy states

    NASA Technical Reports Server (NTRS)

    1976-01-01

    One-electron wave functions are reviewed and approximate solutions of two-electron systems are given in terms of these one-electron functions. The symmetry effects associated with electron spin are reviewed and the effects of electron exchange on energy levels of the two-electron system are given. The coupling of electronic orbital and spin angular momentum is considered next and the Lande interval rule for Russell-Saunders or LS coupling is derived. The configurations possible for various multi-electron LS couplings are enumerated (examples from the first two rows of the periodic table are given), and the meaning of the spectroscopic nomenclature is discussed, particularly with respect to the degeneracies of the electron states involved. Next the nomenclature, symmetries, and degeneracies for electron states of diatomic molecules are discussed, and some examples for N2, O2, and NO are presented. The electronic partition functions and derivative thermodynamic properties are expressed in terms of these energies and degeneracies, and examples are given for some of the simple gas species encountered in the earth's atmosphere.

  15. Monte Carlo calculations for reference dosimetry of electron beams with the PTW Roos and NE2571 ion chambers

    SciTech Connect

    Muir, B. R. Rogers, D. W. O.

    2013-12-15

    beam quality conversion factors is obtained without explicitly correcting for gradient effects. The inadequacy of R{sub 50} to uniquely specify beam quality for the accurate selection of k{sub Q} factors is discussed. Systematic uncertainties in beam quality conversion factors are analyzed for the NE2571 chamber and amount to between 0.4% and 1.2% depending on assumptions used. Conclusions: The calculated beam quality conversion factors for the PTW Roos chamber obtained here are in good agreement with literature data. These results characterize the use of an NE2571 ion chamber for reference dosimetry of electron beams even in low-energy beams.

  16. Characterization of the water-equivalent material WTe for use in electron beam dosimetry

    NASA Astrophysics Data System (ADS)

    McEwen, M. R.; Du Sautoy, A. R.

    2003-07-01

    This paper describes the characterization of the water-equivalent material WTe (produced by St Bartholomew's Hospital, London). The use of epoxy resin phantoms offers a number of advantages over water for radiotherapy dosimetry in terms of robustness and ease of use, but the published uncertainties in the fluence corrections for such phantoms significantly increase the overall uncertainty in the measurement of absorbed dose to water at the reference point. Depth-ionization data were obtained in water and WTe for electron beams in the range 4 MeV to 16 MeV and it was found that the measured fluence in the WTe phantom was approximately 0.4% higher than in a water phantom at the same depth. For measurements only at the reference depth this difference was less, with the fluence in the WTe phantom being 0.2% higher. The standard uncertainty on this value is estimated to be +/-0.12%, which represents a significant improvement over previous measurements. It was also found that the range scaling factor is not equal to unity, as previously recommended for this material, but that the data was best fitted by the relation 1 mm WTe = 1.01 mm water (with an uncertainty of +/-0.2%). The results obtained confirm previous investigations of WTe as to its suitability for reference ion chamber dosimetry in the radiotherapy clinic. However, the recommendation is still to use a water phantom wherever possible.

  17. Review of the results of the in vivo dosimetry during total skin electron beam therapy

    PubMed Central

    Guidi, Gabriele; Gottardi, Giovanni; Ceroni, Paola; Costi, Tiziana

    2013-01-01

    This work reviews results of in vivo dosimetry (IVD) for total skin electron beam (TSEB) therapy, focusing on new methods, data emerged within 2012. All quoted data are based on a careful review of the literature reporting IVD results for patients treated by means of TSEB therapy. Many of the reviewed papers refer mainly to now old studies and/or old guidelines and recommendations (by IAEA, AAPM and EORTC), because (due to intrinsic rareness of TSEB-treated pathologies) only a limited number of works and reports with a large set of numerical data and proper statistical analysis is up-to-day available in scientific literature. Nonetheless, a general summary of the results obtained by the now numerous IVD techniques available is reported; innovative devices and methods, together with areas of possible further and possibly multicenter investigations for TSEB therapies are highlighted. PMID:24936333

  18. Internal Photon and Electron Dosimetry of the Newborn Patient – A Hybrid Computational Phantom Study

    PubMed Central

    Wayson, Michael; Lee, Choonsik; Sgouros, George; Treves, S. Ted; Frey, Eric; Bolch, Wesley E.

    2013-01-01

    Objective Estimates of radiation absorbed dose to organs of the nuclear medicine patient are a requirement for administered activity optimization and for stochastic risk assessment. Pediatric patients, and in particular the newborn child, represent that portion of the patient population where such optimization studies are most crucial owing to the enhanced tissue radiosensitivities and longer life expectancies of this patient subpopulation. In cases where whole-body CT imaging is not available, phantom-based calculations of radionuclide S values – absorbed dose to a target tissue per nuclear transformation in a source tissue – are required for dose and risk evaluation. In this study, a comprehensive model of electron and photon dosimetry of the reference newborn child is presented based on a high-resolution hybrid-voxel phantom from the University of Florida patient model series. Methods Values of photon specific absorbed fraction (SAF) were assembled for the both the reference male and female newborn using the radiation transport code MCNPX v2.6. Values of electron specific absorbed fraction were assembled in a unique and time-efficient manner whereby the collisional and radiative components of organ dose – for both self and cross dose terms – were computed separately. Dose to the newborn skeletal tissues were assessed via fluence-to-dose response functions reported for the first time in this study. Results Values of photon and electron specific absorbed fractions were used to assemble a complete set of S values for some 16 radionuclides commonly associated with molecular imaging of the newborn. These values were then compared to those available in the OLINDA/EXM software. S value ratios for organ self-dose ranged from 0.46 to 1.42, while similar ratios for organ cross-dose varied from a low of 0.04 to a high of 3.49. These large discrepancies are due in large part to the simplistic organ modeling in the stylized newborn model used in the OLINDA

  19. Internal photon and electron dosimetry of the newborn patient—a hybrid computational phantom study

    NASA Astrophysics Data System (ADS)

    Wayson, Michael; Lee, Choonsik; Sgouros, George; Treves, S. Ted; Frey, Eric; Bolch, Wesley E.

    2012-03-01

    Estimates of radiation absorbed dose to organs of the nuclear medicine patient are a requirement for administered activity optimization and for stochastic risk assessment. Pediatric patients, and in particular the newborn child, represent that portion of the patient population where such optimization studies are most crucial owing to the enhanced tissue radiosensitivities and longer life expectancies of this patient subpopulation. In cases where whole-body CT imaging is not available, phantom-based calculations of radionuclide S values—absorbed dose to a target tissue per nuclear transformation in a source tissue—are required for dose and risk evaluation. In this study, a comprehensive model of electron and photon dosimetry of the reference newborn child is presented based on a high-resolution hybrid-voxel phantom from the University of Florida (UF) patient model series. Values of photon specific absorbed fraction (SAF) were assembled for both the reference male and female newborn using the radiation transport code MCNPX v2.6. Values of electron SAF were assembled in a unique and time-efficient manner whereby the collisional and radiative components of organ dose--for both self- and cross-dose terms—were computed separately. Dose to the newborn skeletal tissues were assessed via fluence-to-dose response functions reported for the first time in this study. Values of photon and electron SAFs were used to assemble a complete set of S values for some 16 radionuclides commonly associated with molecular imaging of the newborn. These values were then compared to those available in the OLINDA/EXM software. S value ratios for organ self-dose ranged from 0.46 to 1.42, while similar ratios for organ cross-dose varied from a low of 0.04 to a high of 3.49. These large discrepancies are due in large part to the simplistic organ modeling in the stylized newborn model used in the OLINDA/EXM software. A comprehensive model of internal dosimetry is presented in this study for

  20. Monte Carlo calculations of correction factors for plastic phantoms in clinical photon and electron beam dosimetry.

    PubMed

    Araki, Fujio; Hanyu, Yuji; Fukuoka, Miyoko; Matsumoto, Kenji; Okumura, Masahiko; Oguchi, Hiroshi

    2009-07-01

    The purpose of this study is to calculate correction factors for plastic water (PW) and plastic water diagnostic-therapy (PWDT) phantoms in clinical photon and electron beam dosimetry using the EGSnrc Monte Carlo code system. A water-to-plastic ionization conversion factor k(pl) for PW and PWDT was computed for several commonly used Farmer-type ionization chambers with different wall materials in the range of 4-18 MV photon beams. For electron beams, a depth-scaling factor c(pl) and a chamber-dependent fluence correction factor h(pl) for both phantoms were also calculated in combination with NACP-02 and Roos plane-parallel ionization chambers in the range of 4-18 MeV. The h(pl) values for the plane-parallel chambers were evaluated from the electron fluence correction factor phi(pl)w and wall correction factors P(wall,w) and P(wall,pl) for a combination of water or plastic materials. The calculated k(pl) and h(pl) values were verified by comparison with the measured values. A set of k(pl) values computed for the Farmer-type chambers was equal to unity within 0.5% for PW and PWDT in photon beams. The k(pl) values also agreed within their combined uncertainty with the measured data. For electron beams, the c(pl) values computed for PW and PWDT were from 0.998 to 1.000 and from 0.992 to 0.997, respectively, in the range of 4-18 MeV. The phi(pl)w values for PW and PWDT were from 0.998 to 1.001 and from 1.004 to 1.001, respectively, at a reference depth in the range of 4-18 MeV. The difference in P(wall) between water and plastic materials for the plane-parallel chambers was 0.8% at a maximum. Finally, h(pl) values evaluated for plastic materials were equal to unity within 0.6% for NACP-02 and Roos chambers. The h(pl) values also agreed within their combined uncertainty with the measured data. The absorbed dose to water from ionization chamber measurements in PW and PWDT plastic materials corresponds to that in water within 1%. Both phantoms can thus be used as a

  1. Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak

    SciTech Connect

    Rasouli, C.; Pourshahab, B.; Rasouli, H.; Hosseini Pooya, S. M.; Orouji, T.

    2014-05-15

    In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points – three TLDs per point – to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

  2. Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak

    NASA Astrophysics Data System (ADS)

    Rasouli, C.; Pourshahab, B.; Hosseini Pooya, S. M.; Orouji, T.; Rasouli, H.

    2014-05-01

    In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points - three TLDs per point - to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

  3. Electron energies in metals

    SciTech Connect

    Mahan, G.D. Tennessee Univ., Knoxville, TN . Dept. of Physics and Astronomy)

    1991-07-10

    The modern era of electron-electron interactions began a decade ago. Plummer's group initiated a program of using angular resolved photoemission to examine the band structure of the simple metals. Beginning with aluminum, and carrying on to sodium and potassium, they always found that the occupied energy bands were much narrower than expected. For example, the compressed energy bands for metallic potassium suggest a band effective mass of m* = 1.33m{sub e}. This should be compared to the band mass found from optical conductivity m*/m{sub e} = 1.01 {plus minus} 0.01. The discrepancy between these results is startling. It was this great difference which started my group doing calculations. Our program was two-fold. On one hand, we reanalyzed the experimental data, in order to see if Plummer's result was an experimental artifact. On the other hand, we completely redid the electron-electron self-energy calculations for simple metals, using the most modern choices of local-field corrections and vertex corrections. Our results will be reported in these lectures. They can be summarized as following: Our calculations give the same effective masses as the older calculations, so the theory is relatively unchanged; Our analysis of the experiments suggests that the recent measurements of band narrowing are an experimental artifact. 38 refs., 9 figs.

  4. Alanine-EPR as a transfer standard dosimetry system for low energy X radiation

    NASA Astrophysics Data System (ADS)

    Khoury, H. J.; da Silva, E. J.; Mehta, K.; de Barros, V. S.; Asfora, V. K.; Guzzo, P. L.; Parker, A. G.

    2015-11-01

    The purpose of this paper is to evaluate the use of alanine-EPR as a transfer standard dosimetry system for low energy X radiation, such as that in RS-2400, which operates in the range from 25 to 150 kV and 2 to 45 mA. Two types of alanine dosimeters were investigated. One is a commercial alanine pellets from Aérial-Centre de Ressources Technologiques, France and one was prepared in our laboratory (LMRI-DEN/UFPE). The EPR spectra of the irradiated dosimeters were recorded in the Nuclear Energy Department of UFPE, using a Bruker EMX10 EPR spectrometer operating in the X-band. The alanine-EPR dosimetry system was calibrated in the range of 20-220 Gy in this X-ray field, against an ionization chamber calibrated at the relevant X-ray energy with traceability to PTB. The results showed that both alanine dosimeters presented a linear dose response the same sensitivity, when the EPR signal was normalized to alanine mass. The total uncertainty in the measured dose was estimated to be about 3%. The results indicate that it is possible to use the alanine-EPR dosimetry system for validation of a low-energy X ray irradiator, such as RS-2400.

  5. Determination of RW3-to-water mass-energy absorption coefficient ratio for absolute dosimetry.

    PubMed

    Seet, Katrina Y T; Hanlon, Peta M; Charles, Paul H

    2011-12-01

    The measurement of absorbed dose to water in a solid-phantom may require a conversion factor because it may not be radiologically equivalent to water. One phantom developed for the use of dosimetry is a solid water, RW3 white-polystyrene material by IBA. This has a lower mass-energy absorption coefficient than water due to high bremsstrahlung yield, which affects the accuracy of absolute dosimetry measurements. In this paper, we demonstrate the calculation of mass-energy absorption coefficient ratios, relative to water, from measurements in plastic water and RW3 with an Elekta Synergy linear accelerator (6 and 10 MV photon beams) as well as Monte Carlo modeling in BEAMnrc and DOSXYZnrc. From this, the solid-phantom-to-water correction factor was determined for plastic water and RW3. PMID:21960410

  6. Pre-treatment verification of intensity modulated radiation therapy plans using a commercial electronic portal dosimetry system.

    PubMed

    Roxby, Kathleen J; Crosbie, Jeffrey C

    2010-03-01

    We commissioned a commercially available portal dosimetry system for quality assurance of intensity modulated radiation therapy (IMRT) treatment plans. The system included gamma analysis software to compare the measured and predicted fluence maps from individual IMRT fields. The portal dosimetry system was tested using six head and neck IMRT patient plans, and we demonstrated that the accuracy of the alignment of measured and predicted images improved by retracting and repositioning the electronic portal imaging device (EPID) at each new gantry angle. The mean gamma score (fraction of pixels passing the gamma criteria) for the six test plans (after initial testing and using the EPID retracting and repositioning method) was 0.987 (2SD = 0.018), using gamma criteria of a dose difference of 2% of the maximum field dose and 2 mm distance to agreement. The mean gamma score was 0.989 (2SD = 0.017) for 24 head and neck IMRT patient plans carried out with portal dosimetry. Using gamma criteria of 2% maximum field dose and 2 mm distance to agreement, a gamma score tolerance of 0.980 is a useful way of highlighting only those fields requiring further analysis. Portal dosimetry is a quick way of assessing individual field fluence distributions and can be integrated into an IMRT quality assurance programme. PMID:20237893

  7. Measurement of absorbed dose to water around an electronic brachytherapy source. Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film

    NASA Astrophysics Data System (ADS)

    Adolfsson, Emelie; White, Shane; Landry, Guillaume; Lund, Eva; Gustafsson, Håkan; Verhaegen, Frank; Reniers, Brigitte; Carlsson Tedgren, Åsa; Alm Carlsson, Gudrun

    2015-05-01

    Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film. Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water. Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison. This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies (192Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.

  8. Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

    SciTech Connect

    Di Venanzio, C.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Falco, M. D.; Bagala, P.; Santoni, R.; Pimpinella, M.

    2013-02-15

    Purpose: To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. Methods: A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. Results: During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1{sigma}) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below {+-}0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy/min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. Conclusions: The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

  9. Standard Practice for Dosimetry of Proton Beams for use in Radiation Effects Testing of Electronics

    SciTech Connect

    McMahan, Margaret A.; Blackmore, Ewart; Cascio, Ethan W.; Castaneda, Carlos; von Przewoski, Barbara; Eisen, Harvey

    2008-07-25

    Representatives of facilities that routinely deliver protons for radiation effect testing are collaborating to establish a set of standard best practices for proton dosimetry. These best practices will be submitted to the ASTM International for adoption.

  10. Improving quantitative dosimetry in 177Lu-DOTATATE SPECT by energy window-based scatter corrections

    PubMed Central

    Lagerburg, Vera; Klausen, Thomas L.; Holm, Søren

    2014-01-01

    Purpose Patient-specific dosimetry of lutetium-177 (177Lu)-DOTATATE treatment in neuroendocrine tumours is important, because uptake differs across patients. Single photon emission computer tomography (SPECT)-based dosimetry requires a conversion factor between the obtained counts and the activity, which depends on the collimator type, the utilized energy windows and the applied scatter correction techniques. In this study, energy window subtraction-based scatter correction methods are compared experimentally and quantitatively. Materials and methods 177Lu SPECT images of a phantom with known activity concentration ratio between the uniform background and filled hollow spheres were acquired for three different collimators: low-energy high resolution (LEHR), low-energy general purpose (LEGP) and medium-energy general purpose (MEGP). Counts were collected in several energy windows, and scatter correction was performed by applying different methods such as effective scatter source estimation (ESSE), triple-energy and dual-energy window, double-photopeak window and downscatter correction. The intensity ratio between the spheres and the background was measured and corrected for the partial volume effect and used to compare the performance of the methods. Results Low-energy collimators combined with 208 keV energy windows give rise to artefacts. For the 113 keV energy window, large differences were observed in the ratios for the spheres. For MEGP collimators with the ESSE correction technique, the measured ratio was close to the real ratio, and the differences between spheres were small. Conclusion For quantitative 177Lu imaging MEGP collimators are advised. Both energy peaks can be utilized when the ESSE correction technique is applied. The difference between the calculated and the real ratio is less than 10% for both energy windows. PMID:24525900

  11. Tooth Retrospective Dosimetry Using Electron Paramagnetic Resonance: Influence of Irradiated Dental Composites

    PubMed Central

    Desmet, Céline M.; Djurkin, Andrej; Dos Santos-Goncalvez, Ana Maria; Dong, Ruhong; Kmiec, Maciej M.; Kobayashi, Kyo; Rychert, Kevin; Beun, Sébastien; Leprince, Julian G.; Leloup, Gaëtane; Levêque, Philippe; Gallez, Bernard

    2015-01-01

    In the aftermath of a major radiological accident, the medical management of overexposed individuals will rely on the determination of the dose of ionizing radiations absorbed by the victims. Because people in the general population do not possess conventional dosimeters, after the fact dose reconstruction methods are needed. Free radicals are induced by radiations in the tooth enamel of victims, in direct proportion to dose, and can be quantified using Electron Paramagnetic Resonance (EPR) spectrometry, a technique that was demonstrated to be very appropriate for mass triage. The presence of dimethacrylate based restorations on teeth can interfere with the dosimetric signal from the enamel, as free radicals could also be induced in the various composites used. The aim of the present study was to screen irradiated composites for a possible radiation-induced EPR signal, to characterize it, and evaluate a possible interference with the dosimetric signal of the enamel. We investigated the most common commercial composites, and experimental compositions, for a possible class effect. The effect of the dose was studied between 10 Gy and 100 Gy using high sensitivity X-band spectrometer. The influence of this radiation-induced signal from the composite on the dosimetric signal of the enamel was also investigated using a clinical L-Band EPR spectrometer, specifically developed in the EPR center at Dartmouth College. In X-band, a radiation-induced signal was observed for high doses (25-100 Gy); it was rapidly decaying, and not detected after only 24h post irradiation. At 10 Gy, the signal was in most cases not measurable in the commercial composites tested, with the exception of 3 composites showing a significant intensity. In L-band study, only one irradiated commercial composite influenced significantly the dosimetric signal of the tooth, with an overestimation about 30%. In conclusion, the presence of the radiation-induced signal from dental composites should not

  12. High-energy neutron dosimetry with superheated drop detectors.

    PubMed

    d'Errico, F; Agosteo, S; Sannikov, A V; Silari, M

    2002-01-01

    A systematic analysis of the response of dichlorodifluoromethane superheated drop detectors was performed in the 46-133 MeV energy range. Experiments with quasi-monoenergetic neutron beams were performed at the Université Catholique de Leuvain-la-Neuve, Belgium and the Svedberg Laboratory, Sweden, while tests in a broad field were performed at CERN. To determine the response of the detectors to the high-energy beams, the spectra of incident neutrons were folded over functions modelled after the cross sections for the production of heavy ions from the detector elements. The cross sections for fluorine and chlorine were produced in this work by means of the Monte Carlo high-energy transport code HADRON based on the cascade exciton model of nuclear interactions. The new response data permit the interpretation of measurements at high-energy accelerators and on high-altitude commercial flights, where a 30-50% under-response had been consistently recorded with respect to neutron dose equivalent. The introduction of a 1 cm lead shell around the detectors effectively compensates most of the response defect. PMID:12382936

  13. A new approach in the design of electronic portal imaging devices for portal dosimetry in radiotherapy.

    PubMed

    Badel, J N; Partouche-Sebban, D; Abraham, I; Carrie, C

    2014-09-01

    A CCD-based EPID using new crystal-assembly X-ray (CAX) converters is investigated for radiotherapy dosimetry. The proposed EPID design consists in replacing the common phosphor X-ray converters of current CCD-based EPIDs with high-stopping-power CAX converters. A Test Imaging Device (TID), consisting of a 30-mm-thick CAX converter made of Bismuth Germanate (BGO), coupled to a highly sensitive CCD camera, was used to evaluate the accessible imaging and dosimetric performance of the proposed design. The system response to dose and its dependence on photon beam energy were investigated. The effects of ghosting, dose rate, field size and phantom thickness were evaluated as well. The same measurements were also performed with our clinically used aSi-EPID so that comparisons of performance could be directly inferred. The TID displayed no detectable ghosting or sensitivity to dose rate. Its response to MU exposure was found to be linear within about ±1%. The level of glare induced in the TID and the aSi-EPID were equivalent. The TID resolution was higher than that of the aSi-EPID on the axis, but was found to decrease with off-axis distance. Finally, the image quality, assessed on the basis of signal-to-noise ratio in low dose radiographs of the larynx of a patient, was higher for the TID. The imaging performance accessible with the TID proved to be satisfying and its dosimetric capability was found to be superior to that of the current aSi-EPID. PMID:24767869

  14. Dosimetry for electron Intra-Operative RadioTherapy: Comparison of output factors obtained through alanine/EPR pellets, ionization chamber and Monte Carlo-GEANT4 simulations for IORT mobile dedicate accelerator

    NASA Astrophysics Data System (ADS)

    Marrale, Maurizio; Longo, Anna; Russo, Giorgio; Casarino, Carlo; Candiano, Giuliana; Gallo, Salvatore; Carlino, Antonio; Brai, Maria

    2015-09-01

    In this work a comparison between the response of alanine and Markus ionization chamber was carried out for measurements of the output factors (OF) of electron beams produced by a linear accelerator used for Intra-Operative Radiation Therapy (IORT). Output factors (OF) for conventional high-energy electron beams are normally measured using ionization chamber according to international dosimetry protocols. However, the electron beams used in IORT have characteristics of dose per pulse, energy spectrum and angular distribution quite different from beams usually used in external radiotherapy, so the direct application of international dosimetry protocols may introduce additional uncertainties in dosimetric determinations. The high dose per pulse could lead to an inaccuracy in dose measurements with ionization chamber, due to overestimation of ks recombination factor. Furthermore, the electron fields obtained with IORT-dedicated applicators have a wider energy spectrum and a wider angular distribution than the conventional fields, due to the presence of electrons scattered by the applicator's wall. For this reason, a dosimetry system should be characterized by a minimum dependence from the beam energy and from angle of incidence of electrons. This become particularly critical for small and bevelled applicators. All of these reasons lead to investigate the use of detectors different from the ionization chamber for measuring the OFs. Furthermore, the complete characterization of the radiation field could be accomplished also by the use of Monte Carlo simulations which allows to obtain detailed information on dose distributions. In this work we compare the output factors obtained by means of alanine dosimeters and Markus ionization chamber. The comparison is completed by the Monte Carlo calculations of OFs determined through the use of the Geant4 application "iort _ therapy" . The results are characterized by a good agreement of response of alanine pellets and Markus

  15. The use of gel dosimetry for verification of electron and photon treatment plans in carcinoma of the scalp.

    PubMed

    Trapp, J V; Partridge, M; Hansen, V N; Childs, P; Bedford, J; Warrington, A P; Leach, M O; Webb, S

    2004-05-01

    In recent years there has been a large amount of research into the potential use of radiation sensitive gels for three-dimensional verification of clinical radiotherapy doses. In this paper we report the use of a MAGIC gel dosimeter (Fong et al 2001 Phys. Med. Biol. 46 3105) for the verification of a specific patient's radiation therapy dose distribution. A 69-year-old male patient presented with a squamous cell carcinoma extending approximately 180 degrees across the top of the scalp (anterior to posterior) and from just over midline to 90 degrees left of the skull. The patient's treatment was commenced using two electron fields. For gel dosimetry, phantoms were produced in which the outer surface spatially corresponded to the outer contours of the patient's anatomy in the region of irradiation. The phantoms were treated with either electrons or intensity modulated radiation therapy (IMRT) with photons. The results identified a hot spot between the matched electron fields and confirmed the more homogeneous dose distribution produced by the IMRT planning system. The IMRT plan was then clinically implemented. The application of a clinical dose to a phantom shaped to a specific patient as well as the ability to select a slice at will during phantom imaging means that gel dosimetry can no longer be considered to simply have potential alone, but is now in fact a useful dosimetric tool. PMID:15152920

  16. The use of gel dosimetry for verification of electron and photon treatment plans in carcinoma of the scalp

    NASA Astrophysics Data System (ADS)

    Trapp, J. V.; Partridge, M.; Hansen, V. N.; Childs, P.; Bedford, J.; Warrington, A. P.; Leach, M. O.; Webb, S.

    2004-05-01

    In recent years there has been a large amount of research into the potential use of radiation sensitive gels for three-dimensional verification of clinical radiotherapy doses. In this paper we report the use of a MAGIC gel dosimeter (Fong et al 2001 Phys. Med. Biol. 46 3105) for the verification of a specific patient's radiation therapy dose distribution. A 69-year-old male patient presented with a squamous cell carcinoma extending approximately 180° across the top of the scalp (anterior to posterior) and from just over midline to 90° left of the skull. The patient's treatment was commenced using two electron fields. For gel dosimetry, phantoms were produced in which the outer surface spatially corresponded to the outer contours of the patient's anatomy in the region of irradiation. The phantoms were treated with either electrons or intensity modulated radiation therapy (IMRT) with photons. The results identified a hot spot between the matched electron fields and confirmed the more homogeneous dose distribution produced by the IMRT planning system. The IMRT plan was then clinically implemented. The application of a clinical dose to a phantom shaped to a specific patient as well as the ability to select a slice at will during phantom imaging means that gel dosimetry can no longer be considered to simply have potential alone, but is now in fact a useful dosimetric tool.

  17. Dosimetry at the sub-cellular scale of Auger-electron emitter 99mTc in a mouse single thyroid follicle.

    PubMed

    Taborda, A; Benabdallah, N; Desbrée, A

    2016-02-01

    The Auger-electrons emitted by (99m)Tc have been recently associated with the induction of thyroid stunning in in vivo experiments in mice, making the dosimetry at the sub-cellular level of (99m)Tc a pertinent and pressing subject. The S-values for (99m)Tc were calculated using MCNP6, which was first validated for studies at the sub-cellular scale and for low energies electrons. The calculation was then performed for (99m)Tc within different cellular compartments in a single mouse thyroid follicle model, considering the radiative and non-radiative transitions of the (99m)Tc radiation spectrum. It was shown that the contribution of the (99m)Tc Auger and low energy electrons to the absorbed dose to the follicular cells' nucleus is important, being at least of the same order of magnitude compared to the emitted photons' contribution and cannot be neglected. The results suggest that Auger-electrons emitted by (99m)Tc play a significant role in the occurrence of the thyroid stunning effect in mice. PMID:26704702

  18. Water-equivalent plastic scintillation detectors for high-energy beam dosimetry: I. Physical characteristics and theoretical consideration.

    PubMed

    Beddar, A S; Mackie, T R; Attix, F H

    1992-10-01

    A minimally perturbing plastic scintillation detector has been developed for the dosimetry of high-energy beams in radiotherapy. The detector system consists of two identical parallel sets of radiation-resistant optical fibre bundles, each connected to independent photomultiplier tubes (PMTs). One fibre bundle is connected to a miniature water equivalent plastic scintillator and so scintillation as well as Cerenkov light generated in the fibres is detected at its PMT. The other 'background' bundle is not connected to the scintillator and so only Cerenkov light is detected by its PMT. The background signal is subtracted to yield only the signal from the scintillator. The water-equivalence of plastic scintillation detectors is studied for photon and electron beams in the radiotherapy range. Application of Burlin cavity theory shows that the energy dependence of such detectors is expected to be better than the commonly used systems (ionization chambers, LiF thermoluminescent dosimeters, film and Si diodes). It is also shown that they are not affected by temperature variations and exhibit much less radiation damage than either photon or electron diode detectors. PMID:1438554

  19. Department of Energy standard for the performance testing of personnel dosimetry systems

    SciTech Connect

    Not Available

    1986-12-01

    This standard is intended to be used in the Department of Energy Laboratory Accreditation Program (DOELAP) for personnel dosimetry systems. It is based on the American National Standards Institute's (ANSI) ''Criteria for Testing Personnel Dosimetry Performance,'' ANSI N13.11-1983, recommendations made to DOE in ''Guidelines for the Calibration of Personnel Dosimeters,'' Pacific Northwest Laboratory (PNL)-4515 and comments received during peer review by DOE and DOE contractor personnel. The recommendations contained in PNL-4515 were based on an evaluation of ANSI N13.11 conducted for the Office of Nuclear Safety, DOE, by PNL. Parts of ANSI N13.11 that did not require modification were used essentially intact in this standard to maintain consistency with nationally recognized standards. Modifications to this standard have resulted from several DOE/DOE contractor reviews and a pilot testing session. An initial peer review by selected DOE and DOE contractor representatives on technical content was conducted in 1983. A review by DOE field offices, program offices, and contractors was conducted in mid-1984. A pilot performance testing session sponsored by the Office of Nuclear Safety was conducted in early 1985 by the Radiological and Environmental Sciences Laboratory, Idaho Falls. Results of the pilot test were reviewed in late 1985 by a DOE and DOE contractor committee. 11 refs., 4 tabs.

  20. Potential of discrete Gaussian edge feathering method for improving abutment dosimetry in eMLC-delivered segmented-field electron conformal therapy

    SciTech Connect

    Eley, John G.; Hogstrom, Kenneth R.; Matthews, Kenneth L.; Parker, Brent C.; Price, Michael J.

    2011-12-15

    Purpose: The purpose of this work was to investigate the potential of discrete Gaussian edge feathering of the higher energy electron fields for improving abutment dosimetry in the planning volume when using an electron multileaf collimator (eMLC) to deliver segmented-field electron conformal therapy (ECT). Methods: A discrete (five-step) Gaussian edge spread function was used to match dose penumbras of differing beam energies (6-20 MeV) at a specified depth in a water phantom. Software was developed to define the leaf eMLC positions of an eMLC that most closely fit each electron field shape. The effect of 1D edge feathering of the higher energy field on dose homogeneity was computed and measured for segmented-field ECT treatment plans for three 2D PTVs in a water phantom, i.e., depth from the water surface to the distal PTV surface varied as a function of the x-axis (parallel to leaf motion) and remained constant along the y-axis (perpendicular to leaf motion). Additionally, the effect of 2D edge feathering was computed and measured for one radially symmetric, 3D PTV in a water phantom, i.e., depth from the water surface to the distal PTV surface varied as a function of both axes. For the 3D PTV, the feathering scheme was evaluated for 0.1-1.0-cm leaf widths. Dose calculations were performed using the pencil beam dose algorithm in the Pinnacle{sup 3} treatment planning system. Dose verification measurements were made using a prototype eMLC (1-cm leaf width). Results: 1D discrete Gaussian edge feathering reduced the standard deviation of dose in the 2D PTVs by 34, 34, and 39%. In the 3D PTV, the broad leaf width (1 cm) of the eMLC hindered the 2D application of the feathering solution to the 3D PTV, and the standard deviation of dose increased by 10%. However, 2D discrete Gaussian edge feathering with simulated eMLC leaf widths of 0.1-0.5 cm reduced the standard deviation of dose in the 3D PTV by 33-28%, respectively. Conclusions: A five-step discrete Gaussian edge

  1. Pencil beam approach for correcting the energy dependence artifact in film dosimetry for IMRT verification.

    PubMed

    Kirov, Assen S; Caravelli, Gregory; Palm, Asa; Chui, Chen; LoSasso, Thomas

    2006-10-01

    The higher sensitivity to low-energy scattered photons of radiographic film compared to water can lead to significant dosimetric error when the beam quality varies significantly within a field. Correcting for this artifact will provide greater accuracy for intensity modulated radiation therapy (IMRT) verification dosimetry. A procedure is developed for correction of the film energy-dependent response by creating a pencil beam kernel within our treatment planning system to model the film response specifically. Film kernels are obtained from EGSnrc Monte Carlo simulations of the dose distribution from a 1 mm diameter narrow beam in a model of the film placed at six depths from 1.5 to 40 cm in polystyrene and solid water phantoms. Kernels for different area phantoms (50 x 50 cm2 and 25 x 25 cm2 polystyrene and 30 x 30 cm2 solid water) are produced. The Monte Carlo calculated kernel is experimentally verified with film, ion chamber and thermoluminescent dosimetry (TLD) measurements in polystyrene irradiated by a narrow beam. The kernel is then used in convolution calculations to, predict the film response in open and IMRT fields. A 6 MV photon beam and Kodak XV2 film in a polystyrene phantom are selected to test the method as they are often used in practice and can result in large energy-dependent artifacts. The difference in dose distributions calculated with the film kernel and the water kernel is subtracted from film measurements to obtain a practically film artifact free IMRT dose distribution for the Kodak XV2 film. For the points with dose exceeding 5 cGy (11% of the peak dose) in a large modulated field and a film measurement inside a large polystyrene phantom at depth of 10 cm, the correction reduces the fraction of pixels for which the film dose deviates from dose to water by more than 5% of the mean film dose from 44% to 6%. PMID:17089835

  2. Pencil beam approach for correcting the energy dependence artifact in film dosimetry for IMRT verification

    SciTech Connect

    Kirov, Assen S.; Caravelli, Gregory; Palm, Aasa; Chui, Chen; LoSasso, Thomas

    2006-10-15

    The higher sensitivity to low-energy scattered photons of radiographic film compared to water can lead to significant dosimetric error when the beam quality varies significantly within a field. Correcting for this artifact will provide greater accuracy for intensity modulated radiation therapy (IMRT) verification dosimetry. A procedure is developed for correction of the film energy-dependent response by creating a pencil beam kernel within our treatment planning system to model the film response specifically. Film kernels are obtained from EGSnrc Monte Carlo simulations of the dose distribution from a 1 mm diameter narrow beam in a model of the film placed at six depths from 1.5 to 40 cm in polystyrene and solid water phantoms. Kernels for different area phantoms (50x50 cm{sup 2} and 25x25 cm{sup 2} polystyrene and 30x30 cm{sup 2} solid water) are produced. The Monte Carlo calculated kernel is experimentally verified with film, ion chamber and thermoluminescent dosimetry (TLD) measurements in polystyrene irradiated by a narrow beam. The kernel is then used in convolution calculations to predict the film response in open and IMRT fields. A 6 MV photon beam and Kodak XV2 film in a polystyrene phantom are selected to test the method as they are often used in practice and can result in large energy-dependent artifacts. The difference in dose distributions calculated with the film kernel and the water kernel is subtracted from film measurements to obtain a practically film artifact free IMRT dose distribution for the Kodak XV2 film. For the points with dose exceeding 5 cGy (11% of the peak dose) in a large modulated field and a film measurement inside a large polystyrene phantom at depth of 10 cm, the correction reduces the fraction of pixels for which the film dose deviates from dose to water by more than 5% of the mean film dose from 44% to 6%.

  3. The Department of Energy Laboratory Accreditation Program in personnel dosimetry: Results of the pilot performance test

    SciTech Connect

    Carlson, R.D.; Gesell, T.F.

    1986-10-01

    A complete pilot test of the Department of Energy Laboratory Accreditation Program (DOELAP) has been conducted. Six Department of Energy (DOE) and DOE contractor personnel dosimetry programs were involved in the pilot test. Nine dosimeter types were tested, including three separate neutron dosimeters. Both film dosimeter and thermoluminescent dosimeter (TLD) types were represented for low-energy photon, high-energy photon, and beta categories. TLD-albedo and track-etch dosimeter types were represented for neutron categories. As a group, the participants met the test criteria in only 38% of the categories. The test data showed, however, that Participant F had a serious calibration problem that distorted the overall results. The other five participants met the test criteria in 48% of the categories. The most difficult categories appeared to be the low-energy photon accident category, the low-energy photon + beta mixture categories, and the neutron categories. Most participants had difficulty in any category that required a low-energy photon irradiation.

  4. Design and evaluation of a 1.1-GHz surface coil resonator for electron paramagnetic resonance-based tooth dosimetry.

    PubMed

    Sugawara, Hirotaka; Hirata, Hiroshi; Petryakov, Sergey; Lesniewski, Piotr; Williams, Benjamin B; Flood, Ann Barry; Swartz, Harold M

    2014-06-01

    This paper describes an optimized design of a surface coil resonator for in vivo electron paramagnetic resonance (EPR)-based tooth dosimetry. Using the optimized resonator, dose estimates with the standard error of the mean of approximately 0.5 Gy were achieved with irradiated human teeth. The product of the quality factor and the filling factor of the resonator was computed as an index of relative signal intensity in EPR tooth dosimetry by the use of 3-D electromagnetic wave simulator and radio frequency circuit design environment (ANSYS HFSS and Designer). To verify the simulated results of the signal intensity in our numerical model of the resonator and a tooth sample, we experimentally measured the radiation-induced signals from an irradiated tooth with an optimally designed resonator. In addition to the optimization of the resonator design, we demonstrated the improvement of the stability of EPR spectra by decontamination of the surface coil resonator using an HCl solution, confirming that contamination of small magnetic particles on the silver wire of the surface coil had degraded the stability of the EPR spectral baseline. PMID:24845300

  5. First application of total skin electron beam irradiation in Greece: setup, measurements and dosimetry.

    PubMed

    Platoni, K; Diamantopoulos, S; Panayiotakis, G; Kouloulias, V; Pantelakos, P; Kelekis, N; Efstathopoulos, E

    2012-04-01

    Total Skin Electron Beam (TSEB) irradiation is considered as the treatment of choice for cutaneous T-cell lymphoma internationally, for either curative purposes or palliative care. An attempt for the first application of this external radiation therapy technique in Greece took place at the Radiation Therapy Unit of 2(nd) Department of Radiology of University of Athens at University General Hospital "Attikon". TSEB modality was developed on a linear accelerator VARIAN Clinac 2100C. To create a uniform and sufficiently large field (≈200 cm × 80 cm) at SSD=380 cm, two symmetrical 6 MeV electron beams are combined with 17.5° tilts concerning the horizontal direction. An immobilization system was constructed to support patient during treatment and to modulate the composite electron field. Irradiation procedure demands a standing patient that takes, in total, six treatment positions. For the confirmation of treatment suitability and the determination of physical features of the clinical electron field, specific measurements were carried out using a parallel-plate ionization chamber and TLDs at water equivalent plastic and anthropomorphic phantoms. Measurements at the referred conditions showed a homogeneous total field with intensity variation of ±2% in the longitudinal axis and ±4% at horizontal axis. The mean energy of the composite field (E¯(o)) is 3.4 MeV, the most probable energy (E(p,0)) is 4.4 MeV and the half-value depth in water (R(50)) is 1.5 g/cm(2). The maximum X-ray background of the TSEB field is 2.1% at head and feet. The above results lead us to conclude that TSEB treatment using "Six-dual-field" technique can be applied in our department safely. PMID:21515082

  6. Calorimetric approach for 3D dosimetry of high intensity therapeutic electron beams

    NASA Astrophysics Data System (ADS)

    Lamanna, E.; Fiorillo, A. S.; Vena, R.; Berdondini, A.; Bettuzzi, M.; Brancaccio, R.; Casali, F.; Morigi, M. P.; Bilokon, H.; Barca, G.; Castrovillari, F.; Siaka, Y. F. T.

    2009-12-01

    The technique of High Dose Rate Intra-Operative Radiation Therapy (HDR-IORT) consists in the delivery of irradiation immediately after the removal of a cancerous mass, where the same incision is used to focalize the radiation to the tumour bed. Given its particular characteristics, IORT requires dose measurements that are different from those requested in external radiotherapy treatments. The main reason lies in the fact that in this case a single high dose must be delivered to a target volume whose extension and depth will be determined directly during the operation. Because of this peculiar characteristics, until now there is not a dosimetric system able to detect the electron beam giving at once a realtime response and an extensive spatial measure of the absorbed dose. Within the framework of a research project of the INFN (Italian National Institute of Nuclear Physics), we proposed a new system to overcome the problems, Dosiort. The final set-up is a solid phantom having a density approximately 1 g/cm3 with sensitive layers of scintillating fibres at fixed positions in a calorimetric configuration for the containment of electrons of energy 4-12 MeV. The prototype will be able to define the physical and geometrical characteristics of the electron beam (energy, isotropy, homogeneity, etc) and to measure the parameters needed to select the energy, the intensity and the Monitor Units (MU) for the exposition: percentage Depth Dose; beam profiles; isodose curves; values of dose per MU. In this work we present the results obtained by using two orthogonal layers of the calorimetric phantom Dosiort, in particular we report the measurement of the dynamic range of the read-out system and the first qualitative study of the results which can be extracted from the measurements taken in a test beam.

  7. Analysis of low energy electrons

    NASA Technical Reports Server (NTRS)

    Sharp, R. D.

    1973-01-01

    Simultaneous observations of low energy electrons in the plasma sheet and in the auroral zone were analyzed. Data from the MIT plasma experiment on the OGO-3 satellite and from the Lockheed experiment on the OV1-18 satellite were processed and compared. The OV1-18 carried thirteen magnetic electron spectrometers designed to measure the intensity, angular, and energy distributions of the auroral electrons and protons in the energy range below 50 keV. Two computer programs were developed for reduction of the OV1-18 data. One program computed the various plasma properties at one second intervals as a function of Universal Time and pitch angle; the other program produced survey plots showing the outputs of the various detectors on the satellite as a function of time on a scale of approximately 100 seconds per cm. The OV1-18 data exhibit the high degree of variability associated with substorm controlled phenomena.

  8. Neutron dosimetry in linear electron accelerator during radiotherapy treatment: simulation and experiment

    NASA Astrophysics Data System (ADS)

    Manfredotti, Claudio; Nastasi, U.; Ongaro, C.; Stasi, E.; Zanini, Alessandro

    1995-03-01

    In the electron linear accelerators used for radiotherapy by high energy electrons or gamma rays, there is a non negligible production of neutrons by photodisintegration or electrodisintegration reactions on the high Z components of the head machine (target, flattening filter, collimators). At the Experimental Physics Department of Torino University, Torino, Italy an experimental and theoretical evaluation has been performed on the undesired neutron production in the MD Class Mevatron Siemens accelerator used at the Radiotherapy Department of S. Giovanni Battista A.S. Hospital for cancer therapy by a 15 MV gamma ray beam. A simulation of the total process has been carried out, using EGS4 MonteCarlo computer code for the evaluation of photoneutron spectra and MCNP code for the neutron transport in the patient's body. The geometrical description both of the accelerator head in EGS4 and of the anthropomorphous phantom in MCNP have been highly optimized. Experimental measurements have been carried out by bubble detectors BD 100R appropriately allocated inside a new phantom in polyetylene and plexiglass, especially designed for this purpose.

  9. Boron dose determination for BNCT using Fricke and EPR dosimetry

    SciTech Connect

    Wielopolski, L.; Ciesielski, B.

    1995-02-01

    In Boron Neutron Capture Therapy (BNCT) the dominant dose delivered to the tumor is due to {alpha} and {sup 7}Li charged particles resulting from a neutron capture by {sup 10}B and is referred to herein as the boron dose. Boron dose is directly attributable to the following two independent factors, one boron concentration and the neutron capture energy dependent cross section of boron, and two the energy spectrum of the neutrons that interact with boron. The neutron energy distribution at a given point is dictated by the incident neutron energy distribution, the depth in tissue, geometrical factors such as beam size and patient`s dimensions. To account for these factors can be accommodated by using Monte Carlo theoretical simulations. However, in conventional experimental BNCT dosimetry, e.g., using TLDs or ionization chambers, it is only possible to estimate the boron dose. To overcome some of the limitations in the conventional dosimetry, modifications in ferrous sulfate dosimetry (Fricke) and Electron Paramagnetic Resonance (EPR) dosimetry in alanine, enable to measure specifically boron dose in a mixed gamma neutron radiation fields. The boron dose, in either of the dosimeters, is obtained as a difference between measurements with boronated and unboronated dosimeters. Since boron participates directly in the measurements, the boron dosimetry reflects the true contribution, integral of the neutron energy spectrum with boron cross section, of the boron dose to the total dose. Both methods are well established and used extensively in dosimetry, they are presented briefly here.

  10. Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range

    PubMed Central

    Lessard, François; Archambault, Louis; Plamondon, Mathieu; Després, Philippe; Therriault-Proulx, François; Beddar, Sam; Beaulieu, Luc

    2012-01-01

    Purpose: Photon dosimetry in the kilovolt (kV) energy range represents a major challenge for diagnostic and interventional radiology and superficial therapy. Plastic scintillation detectors (PSDs) are potentially good candidates for this task. This study proposes a simple way to obtain accurate correction factors to compensate for the response of PSDs to photon energies between 80 and 150 kVp. The performance of PSDs is also investigated to determine their potential usefulness in the diagnostic energy range. Methods: A 1-mm-diameter, 10-mm-long PSD was irradiated by a Therapax SXT 150 unit using five different beam qualities made of tube potentials ranging from 80 to 150 kVp and filtration thickness ranging from 0.8 to 0.2 mmAl + 1.0 mmCu. The light emitted by the detector was collected using an 8-m-long optical fiber and a polychromatic photodiode, which converted the scintillation photons to an electrical current. The PSD response was compared with the reference free air dose rate measured with a calibrated Farmer NE2571 ionization chamber. PSD measurements were corrected using spectra-weighted corrections, accounting for mass energy-absorption coefficient differences between the sensitive volumes of the ionization chamber and the PSD, as suggested by large cavity theory (LCT). Beam spectra were obtained from x-ray simulation software and validated experimentally using a CdTe spectrometer. Correction factors were also obtained using Monte Carlo (MC) simulations. Percent depth dose (PDD) measurements were compensated for beam hardening using the LCT correction method. These PDD measurements were compared with uncorrected PSD data, PDD measurements obtained using Gafchromic films, Monte Carlo simulations, and previous data. Results: For each beam quality used, the authors observed an increase of the energy response with effective energy when no correction was applied to the PSD response. Using the LCT correction, the PSD response was almost energy independent, with

  11. Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range

    SciTech Connect

    Lessard, Francois; Archambault, Louis; Plamondon, Mathieu; and others

    2012-09-15

    Purpose: Photon dosimetry in the kilovolt (kV) energy range represents a major challenge for diagnostic and interventional radiology and superficial therapy. Plastic scintillation detectors (PSDs) are potentially good candidates for this task. This study proposes a simple way to obtain accurate correction factors to compensate for the response of PSDs to photon energies between 80 and 150 kVp. The performance of PSDs is also investigated to determine their potential usefulness in the diagnostic energy range. Methods: A 1-mm-diameter, 10-mm-long PSD was irradiated by a Therapax SXT 150 unit using five different beam qualities made of tube potentials ranging from 80 to 150 kVp and filtration thickness ranging from 0.8 to 0.2 mmAl + 1.0 mmCu. The light emitted by the detector was collected using an 8-m-long optical fiber and a polychromatic photodiode, which converted the scintillation photons to an electrical current. The PSD response was compared with the reference free air dose rate measured with a calibrated Farmer NE2571 ionization chamber. PSD measurements were corrected using spectra-weighted corrections, accounting for mass energy-absorption coefficient differences between the sensitive volumes of the ionization chamber and the PSD, as suggested by large cavity theory (LCT). Beam spectra were obtained from x-ray simulation software and validated experimentally using a CdTe spectrometer. Correction factors were also obtained using Monte Carlo (MC) simulations. Percent depth dose (PDD) measurements were compensated for beam hardening using the LCT correction method. These PDD measurements were compared with uncorrected PSD data, PDD measurements obtained using Gafchromic films, Monte Carlo simulations, and previous data. Results: For each beam quality used, the authors observed an increase of the energy response with effective energy when no correction was applied to the PSD response. Using the LCT correction, the PSD response was almost energy independent, with

  12. Monte Carlo techniques for scattering foil design and dosimetry in total skin electron irradiations.

    PubMed

    Ye, Sung-Joon; Pareek, Prem N; Spencer, Sharon; Duan, Jun; Brezovich, Ivan A

    2005-06-01

    Total skin electron irradiation (TSEI) with single fields requires large electron beams having good dose uniformity, dmax at the skin surface, and low bremsstrahlung contamination. To satisfy these requirements, energy degraders and scattering foils have to be specially designed for the given accelerator and treatment room. We used Monte Carlo (MC) techniques based on EGS4 user codes (BEAM, DOSXYZ, and DOSRZ) as a guide in the beam modifier design of our TSEI system. The dosimetric characteristics at the treatment distance of 382 cm source-to-surface distance (SSD) were verified experimentally using a linear array of 47 ion chambers, a parallel plate chamber, and radiochromic film. By matching MC simulations to standard beam measurements at 100 cm SSD, the parameters of the electron beam incident on the vacuum window were determined. Best match was achieved assuming that electrons were monoenergetic at 6.72 MeV, parallel, and distributed in a circular pattern having a Gaussian radial distribution with full width at half maximum = 0.13 cm. These parameters were then used to simulate our TSEI unit with various scattering foils. Two of the foils were fabricated and experimentally evaluated by measuring off-axis dose uniformity and depth doses. A scattering foil, consisting of a 12 x 12 cm2 aluminum plate of 0.6 cm thickness and placed at isocenter perpendicular to the beam direction, was considered optimal. It produced a beam that was flat within +/-3% up to 60 cm off-axis distance, dropped by not more than 8% at a distance of 90 cm, and had an x-ray contamination of <3%. For stationary beams, MC-computed dmax, Rp, and R50 agreed with measurements within 0.5 mm. The MC-predicted surface dose of the rotating phantom was 41% of the dose rate at dmax of the stationary phantom, whereas our calculations based on a semiempirical formula in the literature yielded a drop to 42%. The MC simulations provided the guideline of beam modifier design for TSEI and estimated the

  13. Limitations of current dosimetry for intracavitary accelerated partial breast irradiation with high dose rate iridium-192 and electronic brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Raffi, Julie A.

    illustrate the limitations of TG-43 dosimetry for intracavitary APBI. TG-43 dose calculations overestimate the dose for regions approaching the lung and breast surface and underestimate the dose for regions in and beyond less-attenuating media such as lung tissue, and for lower energies, breast tissue as well.

  14. Current internal-dosimetry practices at US Department of Energy facilities

    SciTech Connect

    Traub, R.J.; Murphy, B.L.; Selby, J.M.; Vallario, E.J.

    1985-04-01

    The internal dosimetry practice at DOE facilities were characterized. The purpose was to determine the size of the facilities' internal dosimetry programs, the uniformity of the programs among the facilities, and the areas of greatest concern to health physicists in providing and reporting accurate estimates of internal radiation dose and in meeting proposed changes in internal dosimetry. The differences among the internal-dosimetry programs are related to the radioelements in use at each facility and, to some extent, the number of workers at each facility. The differences include different frequencies in the use of quality control samples, different minimum detection levels, different methods of recording radionuclides, different amounts of data recorded in the permanent record, and apparent differences in modeling the metabolism of radionuclides within the body. Recommendations for improving internal-dosimetry practices include studying the relationship between air-monitoring/survey readings and bioassay data, establishing uniform methods for recording bioassay results, developing more sensitive direct-bioassay procedures, establishing a mechanism for sharing information on internal-dosimetry procedures among DOE facilities, and developing mathematical models and interactive computer codes that can help quantify the uptake of radioactive materials and predict their distribution in the body. 19 refs., 8 tabs.

  15. Complete radiative terms for the electron/electronic energy equation

    SciTech Connect

    Stanley, S.A.; Carlson, L.A.

    1994-10-01

    A derivation of the radiative terms in the electron/electronic energy equation is presented, properly accounting for the effects of absorption and emission of radiation on the individual energy modes of the gas. This electron/electronic energy equation with the complete radiative terms has successfully been used to model the radiation-dominated precursor ahead of the bow shock of a hypersonic vehicle entering the Earth`s atmosphere. 8 refs.

  16. Liquid scintillator for 2D dosimetry for high-energy photon beams

    SciTech Connect

    Poenisch, Falk; Archambault, Louis; Briere, Tina Marie; Sahoo, Narayan; Mohan, Radhe; Beddar, Sam; Gillin, Michael T.

    2009-05-15

    Complex radiation therapy techniques require dosimetric verification of treatment planning and delivery. The authors investigated a liquid scintillator (LS) system for application for real-time high-energy photon beam dosimetry. The system was comprised of a transparent acrylic tank filled with liquid scintillating material, an opaque outer tank, and a CCD camera. A series of images was acquired when the tank with liquid scintillator was irradiated with a 6 MV photon beam, and the light data measured with the CCD camera were filtered to correct for scattering of the optical light inside the liquid scintillator. Depth-dose and lateral profiles as well as two-dimensional (2D) dose distributions were found to agree with results from the treatment planning system. Further, the corrected light output was found to be linear with dose, dose rate independent, and is robust for single or multiple acquisitions. The short time needed for image acquisition and processing could make this system ideal for fast verification of the beam characteristics of the treatment machine. This new detector system shows a potential usefulness of the LS for 2D QA.

  17. Thermo electronic laser energy conversion

    NASA Technical Reports Server (NTRS)

    Hansen, L. K.; Rasor, N. S.

    1976-01-01

    The thermo electronic laser energy converter (TELEC) is described and compared to the Waymouth converter and the conventional thermionic converter. The electrical output characteristics and efficiency of TELEC operation are calculated for a variety of design variables. Calculations and results are briefly outlined. It is shown that the TELEC concept can potentially convert 25 to 50 percent of incident laser radiation into electric power at high power densities and high waste heat rejection temperatures.

  18. Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

    PubMed Central

    Alves, G.G.; Kinoshita, A.; de Oliveira, H.F.; Guimarães, F.S.; Amaral, L.L.; Baffa, O.

    2015-01-01

    Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses. PMID:26017344

  19. Conditions for reliable time-resolved dosimetry of electronic portal imaging devices for fixed-gantry IMRT and VMAT

    SciTech Connect

    Yeo, Inhwan Jason; Patyal, Baldev; Mandapaka, Anant; Jung, Jae Won; Yi, Byong Yong; Kim, Jong Oh

    2013-07-15

    Purpose: The continuous scanning mode of electronic portal imaging devices (EPID) that offers time-resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time-resolved dosimetry of intensity-modulated radiation therapy (IMRT) beams.Methods: The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 Multiplication-Sign 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 Multiplication-Sign 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 Multiplication-Sign 10 cm. Time-resolved ion chamber measurements at isocenter and time-resolved and integrating EPID measurements were performed for all beams. The time-resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two-dimensional, time-resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time-resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared.Results: For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time-resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame

  20. Conditions for reliable time-resolved dosimetry of electronic portal imaging devices for fixed-gantry IMRT and VMAT

    PubMed Central

    Yeo, Inhwan Jason; Jung, Jae Won; Patyal, Baldev; Mandapaka, Anant; Yong Yi, Byong; Oh Kim, Jong

    2013-01-01

    Purpose: The continuous scanning mode of electronic portal imaging devices (EPID) that offers time-resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time-resolved dosimetry of intensity-modulated radiation therapy (IMRT) beams. Methods: The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 × 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 × 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 × 10 cm. Time-resolved ion chamber measurements at isocenter and time-resolved and integrating EPID measurements were performed for all beams. The time-resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two-dimensional, time-resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time-resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared. Results: For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time-resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame acquisition rate, thereby causing no frame missing

  1. Housing Electrons: Relating Quantum Numbers, Energy Levels, and Electron Configurations.

    ERIC Educational Resources Information Center

    Garofalo, Anthony

    1997-01-01

    Presents an activity that combines the concepts of quantum numbers and probability locations, energy levels, and electron configurations in a concrete, hands-on way. Uses model houses constructed out of foam board and colored beads to represent electrons. (JRH)

  2. Experimental determination of the effective point of measurement for various detectors used in photon and electron beam dosimetry

    NASA Astrophysics Data System (ADS)

    Khee Looe, Hui; Harder, Dietrich; Poppe, Björn

    2011-07-01

    The subject of this study is the 'shift of the effective point of measurement', Δz, well known as a method of correction compensating for the 'displacement effect' in photon and electron beam dosimetry. Radiochromic EBT 1 films have been used to measure the 'true' TPR curves of 6 and 15 MV photons and 6 and 9 MeV electrons in the solid water-equivalent material RW3. For the Roos and Markus chambers, the cylindrical 'PinPoint', 'Semiflex' and 'Rigid-Stem' chambers, the 2D-Array and the E-type silicon diode (all from PTW-Freiburg), the positions of the effective points of measurement have been determined by direct or indirect comparison between their TPR curves and those of the EBT 1 film. Both for the Roos and Markus chambers, we found Δz = (0.4 ± 0.1) mm, which confirms earlier experimental and Monte Carlo results, but means a shortcoming of the 'water-equivalent window thickness' formula. For the cylindrical chambers, the ratio Δz/r was observed to increase with r, confirming a recent Monte Carlo prediction by Tessier (2010 E2-CN-182, Paper no 147, IDOS, Vienna) as well as the experimental observations by Johansson et al (1978 IAEA Symp. Proc. (Vienna) IAEA-SM-222/35 pp 243-70). According to a theoretical consideration, the shift of the effective point of measurement from the reference point of the detector is caused by a gradient of the fluence of the ionizing particles. As the experiments have shown, the value of Δz depends on the construction of the detector, but remains invariant under changes of radiation quality and depth. Other disturbances, which do not belong to the class of 'gradient effects', are not corrected by shifting the effective point of measurement.

  3. Space radiation dosimetry

    SciTech Connect

    Hanser, F.A.; Dichter, B.K. ||

    1993-12-31

    Dosimetry is the measurement of the energy deposited in matter by various forms of radiation. In space the radiation is primarily energetic electrons, protons and heavier ions from planetary radiation belts, solar flares, and interstellar cosmic rays. Experimentally, dose is frequently obtained by summing the individual energy deposits in a solid state detector. If the detector is calibrated and the sensitive mass is known, the energy sum can be converted directly to accumulated radiation dose in Gy (J/kg). Such detectors can also be used to provide an approximate separation of dose into the components due to electrons, protons, and heavier ions, which is useful if it is desired to convert the measured dose into a biological effective dose (Sv) for manned spaceflight purposes. The output can also be used to provide an essentially instantaneous dose rate for use as warning devices. This is the primary type of space radiation dosimeter to be discussed here. The MOS-type dosimeter is another solid state sensor which can be of small size and low power. These devices integrate the total dose once through, can not separate particle types, and are not suitable for instantaneous dose rate measurement at low levels. There are several additional methods of measuring space radiation dose using scintillators, etc., but are not discussed in detail. In this paper emphasis is given to descriptions of active solid state detector instruments which have successfully worked in space. Some results of in-orbit dose measurements are presented.

  4. SU-E-T-188: Film Dosimetry Verification of Monte Carlo Generated Electron Treatment Plans

    SciTech Connect

    Enright, S; Asprinio, A; Lu, L

    2014-06-01

    Purpose: The purpose of this study was to compare dose distributions from film measurements to Monte Carlo generated electron treatment plans. Irradiation with electrons offers the advantages of dose uniformity in the target volume and of minimizing the dose to deeper healthy tissue. Using the Monte Carlo algorithm will improve dose accuracy in regions with heterogeneities and irregular surfaces. Methods: Dose distributions from GafChromic{sup ™} EBT3 films were compared to dose distributions from the Electron Monte Carlo algorithm in the Eclipse{sup ™} radiotherapy treatment planning system. These measurements were obtained for 6MeV, 9MeV and 12MeV electrons at two depths. All phantoms studied were imported into Eclipse by CT scan. A 1 cm thick solid water template with holes for bonelike and lung-like plugs was used. Different configurations were used with the different plugs inserted into the holes. Configurations with solid-water plugs stacked on top of one another were also used to create an irregular surface. Results: The dose distributions measured from the film agreed with those from the Electron Monte Carlo treatment plan. Accuracy of Electron Monte Carlo algorithm was also compared to that of Pencil Beam. Dose distributions from Monte Carlo had much higher pass rates than distributions from Pencil Beam when compared to the film. The pass rate for Monte Carlo was in the 80%–99% range, where the pass rate for Pencil Beam was as low as 10.76%. Conclusion: The dose distribution from Monte Carlo agreed with the measured dose from the film. When compared to the Pencil Beam algorithm, pass rates for Monte Carlo were much higher. Monte Carlo should be used over Pencil Beam for regions with heterogeneities and irregular surfaces.

  5. Computational dosimetry

    SciTech Connect

    Siebert, B.R.L.; Thomas, R.H.

    1996-01-01

    The paper presents a definition of the term ``Computational Dosimetry`` that is interpreted as the sub-discipline of computational physics which is devoted to radiation metrology. It is shown that computational dosimetry is more than a mere collection of computational methods. Computational simulations directed at basic understanding and modelling are important tools provided by computational dosimetry, while another very important application is the support that it can give to the design, optimization and analysis of experiments. However, the primary task of computational dosimetry is to reduce the variance in the determination of absorbed dose (and its related quantities), for example in the disciplines of radiological protection and radiation therapy. In this paper emphasis is given to the discussion of potential pitfalls in the applications of computational dosimetry and recommendations are given for their avoidance. The need for comparison of calculated and experimental data whenever possible is strongly stressed.

  6. Electron correlation energies in atoms

    NASA Astrophysics Data System (ADS)

    McCarthy, Shane Patrick

    This dissertation is a study of electron correlation energies Ec in atoms. (1) Accurate values of E c are computed for isoelectronic sequences of "Coulomb-Hooke" atoms with varying mixtures of Coulombic and Hooke character. (2) Coupled-cluster calculations in carefully designed basis sets are combined with fully converged second-order Moller-Plesset perturbation theory (MP2) computations to obtain fairly accurate, non-relativistic Ec values for the 12 closed-shell atoms from Ar to Rn. The complete basis-set (CBS) limits of MP2 energies are obtained for open-shell atoms by computations in very large basis sets combined with a knowledge of the MP2/CBS limit for the next larger closed-shell atom with the same valence shell structure. Then higher-order correlation corrections are found by coupled-cluster calculations using basis sets that are not quite as large. The method is validated for the open-shell atoms from Al to Cl and then applied to get E c values, probably accurate to 3%, for the 4th-period open-shell atoms: K, Sc-Cu, and Ga-Br. (3) The results show that, contrary to quantum chemical folklore, MP2 overestimates |Ec| for atoms beyond Fe. Spin-component scaling arguments are used to provide a simple explanation for this overestimation. (4) Eleven non-relativistic density functionals, including some of the most widely-used ones, are tested on their ability to predict non-relativistic, electron correlation energies for atoms and their cations. They all lead to relatively poor predictions for the heavier atoms. Several novel, few-parameter, density functionals for the correlation energy are developed heuristically. Four new functionals lead to improved predictions for the 4th-period atoms without unreasonably compromising accuracy for the lighter atoms. (5) Simple models describing the variation of E c with atomic number are developed.

  7. Energy Efficient Electronics Cooling Project

    SciTech Connect

    Steve O'Shaughnessey; Tim Louvar; Mike Trumbower; Jessica Hunnicutt; Neil Myers

    2012-02-17

    Parker Precision Cooling Business Unit was awarded a Department of Energy grant (DE-EE0000412) to support the DOE-ITP goal of reducing industrial energy intensity and GHG emissions. The project proposed by Precision Cooling was to accelerate the development of a cooling technology for high heat generating electronics components. These components are specifically related to power electronics found in power drives focused on the inverter, converter and transformer modules. The proposed cooling system was expected to simultaneously remove heat from all three of the major modules listed above, while remaining dielectric under all operating conditions. Development of the cooling system to meet specific customer's requirements and constraints not only required a robust system design, but also new components to support long system functionality. Components requiring further development and testing during this project included pumps, fluid couplings, cold plates and condensers. All four of these major categories of components are required in every Precision Cooling system. Not only was design a key area of focus, but the process for manufacturing these components had to be determined and proven through the system development.

  8. On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Andreo, Pedro; Burns, David T.; Salvat, Francesc

    2012-04-01

    . 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µen/ρ)graphite,air for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication).

  9. ESR dosimetry for atomic bomb survivors and radiologic technologists

    NASA Astrophysics Data System (ADS)

    Tatsumi-Miyajima, Junko

    1987-06-01

    An individual absorbed dose for atomic bomb (A-bomb) survivors and radiologic technologists has been estimated using a new personal dosimetry. This dosimetry is based on the electron spin resonance (ESR) spectroscopy of the CO 33- radicals, which are produced in their teeth by radiation. Measurements were carried out to study the characteristics of the dosimetry; the ESR signals of the CO 33- radicals were stable and increased linearly with the radiation dose. In the evaluation of the absorbed dose, the ESR signals were considered to be a function of photon energy. The absorbed doses in ten cases of A-bomb victims and eight cases of radiologic technologists were determined. For A-bomb survivors, the adsorbed doses, which were estimated using the ESR dosimetry, were consistent with the ones obtained using the calculations of the tissue dose in air of A-bomb, and also with the ones obtained using the chromosome measurements. For radiologic technologists, the absorbed doses, which were estimated using the ESR dosimetry, agreed with the ones calculated using the information on the occupational history and conditions. The advantages of this method are that the absorbed dose can be directly estimated by measuring the ESR signals obtained from the teeth of persons, who are exposed to radiation. Therefore, the ESR dosimetry is useful to estimate the accidental exposure and the long term cumulative dose.

  10. Review of the near-earth space radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Guo, Jianming; Chen, Xiaoqian; Li, Shiyou

    2016-07-01

    The near-earth space radiation environment has a great effect to the spacecraft and maybe do harm to the astronaut's health. Thus, how to measure the radiation has become a serious challenge. In order to provide sufficient protection both for astronauts and for instruments on-board, dose equivalent and linear energy transfer should be measured instead of merely measuring total radiation dose. This paper reviews the methods of radiation measurement and presents a brief introduction of dosimetry instruments. The method can be divided into two different kinds, i.e., positive dosimetry and passive dosimetry. The former usually includes electronic devices which can be used for data storage and can offer simultaneous monitoring on space radiation. The passive dosimetry has a much simple structure, and need extra operation after on-orbit missions for measuring. To get more reliable data of radiation dosimetry, various instruments and methods had been applied in the spacecrafts and the manned spacecrafts in particular. The outlook of the development in the space radiation dosimetry measurement is also presented.

  11. Low-energy x-ray dosimetry studies (6 to 16 keV) at SSRL beamline 1-5

    NASA Astrophysics Data System (ADS)

    Ipe, N. E.; Chatterji, S.; Fassò, A.; Kase, K. R.; Seefred, R.; Olko, P.; Bilski, P.; Soares, C.

    1997-07-01

    Synchrotron radiation facilities provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory (SSRL) are described. Polish lithium fluoride thermoluminescent dosemeters (TLDs), MTS-N(LiF:Mg, Ti- 0.4 mm thick), MCP-N (LiF:Mg, Cu, P - 0.4 mm thick) were exposed free in air to monochromatic x-rays (6-16 keV). These exposures were monitored with an SSRL ionization chamber. The responses (counts/Gy) of MTS-N and MCP-N were generally found to increase with increasing energy. The response at 16 keV is about 3 and 4 times higher than the response at 6 keV for MTS-N and MCP-N, respectively. Irradiation at 6 keV indicates a fairly linear dose response for both type of TLDs over a dose range of 0.01 to 0.4 Gy. In addition there appears to be no significant difference in responses between irradiating the TLDs from the front and the back sides. The energy response of the PTW ionization chamber type 23342 relative to the SSRL ionization chamber is within ±4.5% between 6 and 16 keV. Both the TLDs and the PTW ionization chamber can also be used for beam dosimetry.

  12. Mass, energy, and the electron

    SciTech Connect

    Mulligan, Bernard . E-mail: mulligan.3@osu.edu

    2006-08-15

    The two-component solutions of the Dirac equation currently in use are not separately a particle equation or an antiparticle equation. We present a unitary transformation that uncouples the four-component, force-free Dirac equation to yield a two-component spinor equation for the force-free motion of a relativistic particle and a corresponding two-component, time-reversed equation for an antiparticle. The particle-antiparticle nature of the two equations is established by applying to the solutions of these two-component equations criteria analogous to those applied for establishing the four-component particle and antiparticle solutions of the four-component Dirac equation. Wave function solutions of our two-component particle equation describe both a right and a left circularly polarized particle. Interesting characteristics of our solutions include spatial distributions that are confined in extent along directions perpendicular to the motion, without the artifice of wave packets, and an intrinsic chirality (handedness) that replaces the usual definition of chirality for particles without mass. Our solutions demonstrate that both the rest mass and the relativistic increase in mass with velocity of the force-free electron are due to an increase in the rate of Zitterbewegung with velocity. We extend this result to a bound electron, in which case the loss of energy due to binding is shown to decrease the rate of Zitterbewegung.

  13. Response of LiF:Mg,Ti thermoluminescent dosimeters at photon energies relevant to the dosimetry of brachytherapy (<1 MeV)

    SciTech Connect

    Tedgren, Aasa Carlsson; Hedman, Angelica; Grindborg, Jan-Erik; Carlsson, Gudrun Alm

    2011-10-15

    Purpose: High energy photon beams are used in calibrating dosimeters for use in brachytherapy since absorbed dose to water can be determined accurately and with traceability to primary standards in such beams, using calibrated ion chambers and standard dosimetry protocols. For use in brachytherapy, beam quality correction factors are needed, which include corrections for differences in mass energy absorption properties between water and detector as well as variations in detector response (intrinsic efficiency) with radiation quality, caused by variations in the density of ionization (linear energy transfer (LET) -distributions) along the secondary electron tracks. The aim of this work was to investigate experimentally the detector response of LiF:Mg,Ti thermoluminescent dosimeters (TLD) for photon energies below 1 MeV relative to {sup 60}Co and to address discrepancies between the results found in recent publications of detector response. Methods: LiF:Mg,Ti dosimeters of formulation MTS-N Poland were irradiated to known values of air kerma free-in-air in x-ray beams at tube voltages 25-250 kV, in {sup 137}Cs- and {sup 60}Co-beams at the Swedish Secondary Standards Dosimetry Laboratory. Conversions from air kerma free-in-air into values of mean absorbed dose in the dosimeters in the actual irradiation geometries were made using EGSnrc Monte Carlo simulations. X-ray energy spectra were measured or calculated for the actual beams. Detector response relative to that for {sup 60}Co was determined at each beam quality. Results: An increase in relative response was seen for all beam qualities ranging from 8% at tube voltage 25 kV (effective energy 13 keV) to 3%-4% at 250 kV (122 keV effective energy) and {sup 137}Cs with a minimum at 80 keV effective energy (tube voltage 180 kV). The variation with effective energy was similar to that reported by Davis et al.[Radiat. Prot. Dosim. 106, 33-43 (2003)] with our values being systematically lower by 2%-4%. Compared to the

  14. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    PubMed Central

    Rezaee, Mohammad; Hunting, Darel J.; Sanche, Léon

    2015-01-01

    Purpose The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by 125I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results For a single decay of 125I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm3 volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should be considered in the

  15. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    SciTech Connect

    Rezaee, Mohammad Hunting, Darel J.; Sanche, Léon

    2014-07-15

    Purpose: The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods: Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by{sup 125}I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results: For a single decay of{sup 125}I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm{sup 3} volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions: Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should

  16. Dosimetry for infant exposures to electronic article surveillance system: posture, physical dimension and anatomy.

    PubMed

    Li, Congsheng; Wu, Tongning

    2015-04-01

    The use of electronic article surveillance (EAS) systems has become popular in many public sites. As a consequence, concern has risen about infant exposure to magnetic fields (MFs) from this kind of device. To evaluate infant exposure to MFs of an EAS system (operating at 125 kHz and 13.56 MHz), we numerically compared dosimetric results among adult, child and infant models. Results revealed that postures insignificantly influenced dosimetric results if there was a similar cross-sectional area under exposure. Although safety limits are unlikely to be exceeded, the infant has higher SAR values for brain and central nervous system tissues compared with adult (1.5x at 125 kHz and 112x at 13.56 MHz), which deserve further investigation. Infant's specific anatomy (e.g., non-proportionally large head and high fat content) did not induce higher SAR values. The numerical models developed in the study (stroller and postured infant models) could be freely used for nonprofit academic research. PMID:25756750

  17. Is electron beam intraoperative radiotherapy (ELIOT) safe in pregnant women with early breast cancer? In vivo dosimetry to assess fetal dose.

    PubMed

    Galimberti, Viviana; Ciocca, Mario; Leonardi, Maria Cristina; Zanagnolo, Vanna; Paola, Baratella; Manuela, Sargenti; Sahium, Rafaela Cecilio; Lazzari, Roberta; Gentilini, Oreste; Peccatori, Fedro; Veronesi, Umberto; Orecchia, Roberto

    2009-01-01

    Electron beam intraoperative radiotherapy (ELIOT) is a new technique permitting breast radiotherapy to be completed in a single session. Since ELIOT is associated with much reduced irradiation to nontarget tissues, we carried out a study on nonpregnant breast cancer patients to estimate doses to the uterus during ELIOT to better evaluate the possible use of ELIOT in pregnant breast cancer patients. We performed in vivo dosimetry with thermoluminescence radiation detectors (TLDs) in 15 premenopausal patients receiving ELIOT to the breast (prescribed dose 21 Gy) using two mobile linear accelerators. The TLDs were positioned subdiaphragmatically on the irradiated side, at the medial pubic position, and within the uterus. A shielding apron (2 mm lead equivalent) was placed over the viscera from the subcostal to the subpubic region. TLDs showed mean doses of 3.7 mGy (range 1-8.5 mGy) at subdiaphragm, 0.9 mGy (range 0.3-2 mGy) pubic, and 1.7 mGy (range 0.6-3.2 mGy) in utero, for beam energies in the range 5-9 MeV. These findings indicate that ELIOT with a mobile linear accelerator and shielding apron would be safe for the fetus, as doses of a few mGy are not associated with measurable increased risk of fetal damage, and the threshold dose for deterministic effects is estimated at 100-200 mGy. We conclude that studies on the use of ELIOT in pregnant women treated with conservative breast surgery are justified. PMID:18941842

  18. The mapping of electronic energy distributions using experimental electron density.

    PubMed

    Tsirelson, Vladimir G

    2002-08-01

    It is demonstrated that the approximate kinetic energy density calculated using the second-order gradient expansion with parameters of the multipole model fitted to experimental structure factors reproduces the main features of this quantity in a molecular or crystal position space. The use of the local virial theorem provides an appropriate derivation of approximate potential energy density and electronic energy density from the experimental (model) electron density and its derivatives. Consideration of these functions is not restricted by the critical points in the electron density and provides a comprehensive characterization of bonding in molecules and crystals. PMID:12149553

  19. Single track nanodosimetry of low energy electrons

    NASA Astrophysics Data System (ADS)

    Bantsar, A.; Grosswendt, B.; Pszona, S.; Kula, J.

    2009-02-01

    Auger-electron-emitting radionuclides (for instance, 125I) with a predominant energy spectrum below 3 keV are an active area of research towards the clinical application of radiopharmaceuticals. Hence, the necessity for an adequate description of the effects of radiation by low-energy electrons on nanometric biological targets seems to be unquestionable. Experimental nanodosimetry for low-energy electrons has been accomplished with a device named JET COUNTER. The present paper describes, for the first time, nanodosimetric experiments in nanometer-sized cavities of nitrogen using low energy electrons ranging from 100 eV to 2 keV.

  20. Ion storage dosimetry

    NASA Astrophysics Data System (ADS)

    Mathur, V. K.

    2001-09-01

    The availability of a reliable, accurate and cost-effective real-time personnel dosimetry system is fascinating to radiation workers. Electronic dosimeters are contemplated to meet this demand of active dosimetry. The development of direct ion storage (DIS) dosimeters, a member of the electronic dosimeter family, for personnel dosimetry is also an attempt in this direction. DIS dosimeter is a hybrid of the well-established technology of ion chambers and the latest advances in data storage using metal oxide semiconductor field effect transistor (MOSFET) analog memory device. This dosimeter is capable of monitoring legal occupational radiation doses of gamma, X-rays, beta and neutron radiation. Similar to an ion chamber, the performance of the dosimeter for a particular application can be optimized through the selection of appropriate wall materials. The use of the floating gate of a MOSFET as one of the electrodes of the ion chamber allows the miniaturization of the device to the size of a dosimetry badge and avoids the use of power supplies during dose accumulation. The concept of the device, underlying physics and the design of the DIS dosimeter are discussed. The results of preliminary testing of the device are also provided.

  1. Energy-based dosimetry of low-energy, photon-emitting brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Malin, Martha J.

    Model-based dose calculation algorithms (MBDCAs) for low-energy, photon-emitting brachytherapy sources have advanced to the point where the algorithms may be used in clinical practice. Before these algorithms can be used, a methodology must be established to verify the accuracy of the source models used by the algorithms. Additionally, the source strength metric for these algorithms must be established. This work explored the feasibility of verifying the source models used by MBDCAs by measuring the differential photon fluence emitted from the encapsulation of the source. The measured fluence could be compared to that modeled by the algorithm to validate the source model. This work examined how the differential photon fluence varied with position and angle of emission from the source, and the resolution that these measurements would require for dose computations to be accurate to within 1.5%. Both the spatial and angular resolution requirements were determined. The techniques used to determine the resolution required for measurements of the differential photon fluence were applied to determine why dose-rate constants determined using a spectroscopic technique disagreed with those computed using Monte Carlo techniques. The discrepancy between the two techniques had been previously published, but the cause of the discrepancy was not known. This work determined the impact that some of the assumptions used by the spectroscopic technique had on the accuracy of the calculation. The assumption of isotropic emission was found to cause the largest discrepancy in the spectroscopic dose-rate constant. Finally, this work improved the instrumentation used to measure the rate at which energy leaves the encapsulation of a brachytherapy source. This quantity is called emitted power (EP), and is presented as a possible source strength metric for MBDCAs. A calorimeter that measured EP was designed and built. The theoretical framework that the calorimeter relied upon to measure EP

  2. Electronic correlation contributions to structural energies

    NASA Astrophysics Data System (ADS)

    Haydock, Roger

    2015-03-01

    The recursion method is used to calculate electronic excitation spectra including electron-electron interactions within the Hubbard model. The effects of correlation on structural energies are then obtained from these spectra and applied to stacking faults. http://arxiv.org/abs/1405.2288 Supported by the Richmond F. Snyder Fund and Gifts.

  3. TOPICAL REVIEW: Polymer gel dosimetry

    NASA Astrophysics Data System (ADS)

    Baldock, C.; De Deene, Y.; Doran, S.; Ibbott, G.; Jirasek, A.; Lepage, M.; McAuley, K. B.; Oldham, M.; Schreiner, L. J.

    2010-03-01

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented.

  4. Topical Review: Polymer gel dosimetry

    PubMed Central

    Baldock, C; De Deene, Y; Doran, S; Ibbott, G; Jirasek, A; Lepage, M; McAuley, K B; Oldham, M; Schreiner, L J

    2010-01-01

    Polymer gel dosimeters are fabricated from radiation sensitive chemicals which, upon irradiation, polymerize as a function of the absorbed radiation dose. These gel dosimeters, with the capacity to uniquely record the radiation dose distribution in three-dimensions (3D), have specific advantages when compared to one-dimensional dosimeters, such as ion chambers, and two-dimensional dosimeters, such as film. These advantages are particularly significant in dosimetry situations where steep dose gradients exist such as in intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery. Polymer gel dosimeters also have specific advantages for brachytherapy dosimetry. Potential dosimetry applications include those for low-energy x-rays, high-linear energy transfer (LET) and proton therapy, radionuclide and boron capture neutron therapy dosimetries. These 3D dosimeters are radiologically soft-tissue equivalent with properties that may be modified depending on the application. The 3D radiation dose distribution in polymer gel dosimeters may be imaged using magnetic resonance imaging (MRI), optical-computerized tomography (optical-CT), x-ray CT or ultrasound. The fundamental science underpinning polymer gel dosimetry is reviewed along with the various evaluation techniques. Clinical dosimetry applications of polymer gel dosimetry are also presented. PMID:20150687

  5. Observations on personnel dosimetry for radiotherapy personnel operating high-energy LINACs.

    PubMed

    Glasgow, G P; Eichling, J; Yoder, R C

    1986-06-01

    A series of measurements were conducted to determine the cause of a sudden increase in personnel radiation exposures. One objective of the measurements was to determine if the increases were related to changing from film dosimeters exchanged monthly to TLD-100 dosimeters exchanged quarterly. While small increases were observed in the dose equivalents of most employees, the dose equivalents of personnel operating medical electron linear accelerators with energies greater than 20 MV doubled coincidentally with the change in the personnel dosimeter program. The measurements indicated a small thermal neutron radiation component around the accelerators operated by these personnel. This component caused the doses measured with the TLD-100 dosimeters to be overstated. Therefore, the increase in these personnel dose equivalents was not due to changes in work habits or radiation environments. Either film or TLD-700 dosimeters would be suitable for personnel monitoring around high-energy linear accelerators. The final choice would depend on economics and personal preference. PMID:3086255

  6. Observations on personnel dosimetry for radiotherapy personnel operating high-energy LINACs

    SciTech Connect

    Glasgow, G.P.; Eichling, J.; Yoder, R.C.

    1986-06-01

    A series of measurements were conducted to determine the cause of a sudden increase in personnel radiation exposures. One objective of the measurements was to determine if the increases were related to changing from film dosimeters exchanged monthly to TLD-100 dosimeters exchanged quarterly. While small increases were observed in the dose equivalents of most employees, the dose equivalents of personnel operating medical electron linear accelerators with energies greater than 20 MV doubled coincidentally with the change in the personnel dosimeter program. The measurements indicated a small thermal neutron radiation component around the accelerators operated by these personnel. This component caused the doses measured with the TLD-100 dosimeters to be overstated. Therefore, the increase in these personnel dose equivalents was not due to changes in work habits or radiation environments. Either film or TLD-700 dosimeters would be suitable for personnel monitoring around high-energy linear accelerators. The final choice would depend on economics and personal preference.

  7. Results from 2010 Caliban Criticality Dosimetry Intercomparison

    SciTech Connect

    Veinot, K. G.

    2011-10-12

    The external dosimetry program participated in a criticality dosimetry intercomparison conducted at the Caliban facility in Valduc, France in 2010. Representatives from the dosimetry and instrumentation groups were present during testing which included irradiations of whole-body beta/gamma (HBGT) and neutron thermoluminescent dosimeters (TLDs), a fixed nuclear accident dosimeter (FNAD), electronic alarming dosimeters, and a humanoid phantom filled with reference man concentrations of sodium. This report reviews the testing procedures, preparations, irradiations, and presents results of the tests.

  8. SU-E-T-284: Revisiting Reference Dosimetry for the Model S700 Axxent 50 KV{sub p} Electronic Brachytherapy Source

    SciTech Connect

    Hiatt, JR; Rivard, MJ

    2014-06-01

    Purpose: The model S700 Axxent electronic brachytherapy source by Xoft was characterized in 2006 by Rivard et al. The source design was modified in 2006 to include a plastic centering insert at the source tip to more accurately position the anode. The objectives of the current study were to establish an accurate Monte Carlo source model for simulation purposes, to dosimetrically characterize the new source and obtain its TG-43 brachytherapy dosimetry parameters, and to determine dose differences between the source with and without the centering insert. Methods: Design information from dissected sources and vendor-supplied CAD drawings were used to devise the source model for radiation transport simulations of dose distributions in a water phantom. Collision kerma was estimated as a function of radial distance, r, and polar angle, θ, for determination of reference TG-43 dosimetry parameters. Simulations were run for 10{sup 10} histories, resulting in statistical uncertainties on the transverse plane of 0.03% at r=1 cm and 0.08% at r=10 cm. Results: The dose rate distribution the transverse plane did not change beyond 2% between the 2006 model and the current study. While differences exceeding 15% were observed near the source distal tip, these diminished to within 2% for r>1.5 cm. Differences exceeding a factor of two were observed near θ=150° and in contact with the source, but diminished to within 20% at r=10 cm. Conclusions: Changes in source design influenced the overall dose rate and distribution by more than 2% over a third of the available solid angle external from the source. For clinical applications using balloons or applicators with tissue located within 5 cm from the source, dose differences exceeding 2% were observed only for θ>110°. This study carefully examined the current source geometry and presents a modern reference TG-43 dosimetry dataset for the model S700 source.

  9. High energy electron beams characterization using CaSO4:Dy+PTFE phosphors for clinical therapy applications.

    PubMed

    Rivera, T; Espinoza, A; Von, S M; Alvarez, R; Jiménez, Y

    2012-07-01

    In the present work high energy electron beam dosimetry from linear accelerator (LINACs) for clinical applications using dysprosium doped calcium sulfate embedded in polytetrafluorethylene (CaSO4:Dy+PTFE) was studied. The irradiations were carried out using high electron beams (6 to 18 MeV) from a linear accelerator (LINAC) Varian, CLINAC 2300C/D, for clinical practice purpose. The electron irradiations were obtained using the water solid in order to guarantee electronic equilibrium conditions (EEC). Field shaping for electron beams was obtained with electron cones. Glow curve and other thermoluminescent characteristics of CaSO4:Dy+PTFE were conducted under high electrons beams irradiations. The TL response of the pellets showed an intensity peak centered at around 215 °C. TL response of CaSO4:Dy+PTFE as a function of high electron absorbed dose showed a linearity in a wide range. To obtain reproducibility characteristic, a set of pellets were exposed repeatedly for the same electron absorbed dose. The results obtained in this study can suggest the applicability of CaSO4:Dy+PTFE pellets for high electron beam dosimetry, provided fading is correctly accounted for. PMID:22182630

  10. (Biological dosimetry)

    SciTech Connect

    Preston, R.J.

    1990-12-17

    The traveler attended the 1st International Conference on Biological Dosimetry in Madrid, Spain. This conference was organized to provide information to a general audience of biologists, physicists, radiotherapists, industrial hygiene personnel and individuals from related fields on the current ability of cytogenetic analysis to provide estimates of radiation dose in cases of occupational or environmental exposure. There is a growing interest in Spain in biological dosimetry because of the increased use of radiation sources for medical and occupational uses, and with this the anticipated and actual increase in numbers of overexposure. The traveler delivered the introductory lecture on Biological Dosimetry: Mechanistic Concepts'' that was intended to provide a framework by which the more applied lectures could be interpreted in a mechanistic way. A second component of the trip was to provide advice with regard to several recent cases of overexposure that had been or were being assessed by the Radiopathology and Radiotherapy Department of the Hospital General Gregorio Maranon'' in Madrid. The traveler had provided information on several of these, and had analyzed cells from some exposed or purportedly exposed individuals. The members of the biological dosimetry group were referred to individuals at REACTS at Oak Ridge Associated Universities for advice on follow-up treatment.

  11. Radiation dosimetry and spectrometry with superheated emulsions

    NASA Astrophysics Data System (ADS)

    d'Errico, Francesco

    2001-09-01

    Detectors based on emulsions of overexpanded halocarbon droplets in tissue equivalent aqueous gels or soft polymers, known as "superheated drop detectors" or "bubble (damage) detectors", have been used in radiation detection, dosimetry and spectrometry for over two decades. Recent technological advances have led to the introduction of several instruments for individual and area monitoring: passive integrating meters based on the optical or volumetric registration of the bubbles, and active counters detecting bubble nucleations acoustically. These advances in the instrumentation have been matched by the progress made in the production of stable and well-specified emulsions of superheated droplets. A variety of halocarbons are employed in the formulation of the detectors, and this permits a wide range of applications. In particular, halocarbons with a moderate degree of superheat, i.e. a relatively small difference between their operating temperature and boiling point, can be used in neutron dosimetry and spectrometry since they are only nucleated by energetic heavy ions such as those produced by fast neutrons. More recently, halocarbons with an elevated degree of superheat have been utilised to produce emulsions that nucleate with much smaller energy deposition and detect low linear energy transfer radiations, such as photons and electrons. This paper reviews the detector physics of superheated emulsions and their applications in radiation measurements, particularly in neutron dosimetry and spectrometry.

  12. Low-energy x-ray dosimetry studies (7 to 17.5 keV) with synchroton radiation

    SciTech Connect

    Ipe, N.E.; Bellamy, H.; Flood, J.R.

    1995-06-01

    Unique properties of synchrotron radiation (SR), such as its high intensity, brightness, polarization, and broad spectral distribution (extending from x-ray to infra-red wavelengths) make it an attractive light source for numerous experiments. As SR facilities are rapidly being built all over the world, they introduce the need for low-energy x-ray dosemeters because of the potential radiation exposure to experimenters. However, they also provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory are described. Lithium fluoride TLDs (TLD-100) of varying thicknesses (0.015 to 0.08 cm) were exposed free in air to monochromatic x-rays (7 to 17.5 keV). These exposures were monitored with ionization chambers. The response (nC/Gy) was found to increase with increasing TLD thickness and with increasing beam energy. A steeper increase in response with increasing energy was observed with the thicker TLDs. The responses at 7 and 17.5 keV were within a factor of 2.3 and 5.2 for the 0.015 and 0.08 cm-thick TLDs, respectively. The effects of narrow (beam size smaller than the dosemeter) and broad (beam size larger than the dosemeter) beams on the response of the TLDs are also reported.

  13. 10 CFR 35.630 - Dosimetry equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Dosimetry equipment. 35.630 Section 35.630 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and Gamma Stereotactic Radiosurgery Units § 35.630 Dosimetry equipment. (a) Except for low dose-rate remote afterloader sources...

  14. The electronic couplings in electron transfer and excitation energy transfer.

    PubMed

    Hsu, Chao-Ping

    2009-04-21

    The transport of charge via electrons and the transport of excitation energy via excitons are two processes of fundamental importance in diverse areas of research. Characterization of electron transfer (ET) and excitation energy transfer (EET) rates are essential for a full understanding of, for instance, biological systems (such as respiration and photosynthesis) and opto-electronic devices (which interconvert electric and light energy). In this Account, we examine one of the parameters, the electronic coupling factor, for which reliable values are critical in determining transfer rates. Although ET and EET are different processes, many strategies for calculating the couplings share common themes. We emphasize the similarities in basic assumptions between the computational methods for the ET and EET couplings, examine the differences, and summarize the properties, advantages, and limits of the different computational methods. The electronic coupling factor is an off-diagonal Hamiltonian matrix element between the initial and final diabatic states in the transport processes. ET coupling is essentially the interaction of the two molecular orbitals (MOs) where the electron occupancy is changed. Singlet excitation energy transfer (SEET), however, contains a Frster dipole-dipole coupling as its most important constituent. Triplet excitation energy transfer (TEET) involves an exchange of two electrons of different spin and energy; thus, it is like an overlap interaction of two pairs of MOs. Strategies for calculating ET and EET couplings can be classified as (1) energy-gap-based approaches, (2) direct calculation of the off-diagonal matrix elements, or (3) use of an additional operator to describe the extent of charge or excitation localization and to calculate the coupling value. Some of the difficulties in calculating the couplings were recently resolved. Methods were developed to remove the nondynamical correlation problem from the highly precise coupled cluster

  15. Applications in Energy, Optics and Electronics.

    ERIC Educational Resources Information Center

    Rosenberg, Robert; And Others

    1980-01-01

    Discusses the applications of thin films in energy, optics and electronics. The use of thin-film technologies for heat mirrors, anti-reflection coatings, interference filters, solar cells, and metal contacts is included. (HM)

  16. Neutron personnel dosimetry

    SciTech Connect

    Griffith, R.V.

    1981-06-16

    The current state-of-the-art in neutron personnel dosimetry is reviewed. Topics covered include dosimetry needs and alternatives, current dosimetry approaches, personnel monitoring devices, calibration strategies, and future developments. (ACR)

  17. Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations.

    PubMed

    Matsui, S; Mori, Y; Nonaka, T; Hattori, T; Kasamatsu, Y; Haraguchi, D; Watanabe, Y; Uchiyama, K; Ishikawa, M

    2016-05-01

    For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management. PMID:27250416

  18. Electron energy-distribution functions in gases

    SciTech Connect

    Pitchford, L.C.

    1981-01-01

    Numerical calculation of the electron energy distribution functions in the regime of drift tube experiments is discussed. The discussion is limited to constant applied fields and values of E/N (ratio of electric field strength to neutral density) low enough that electron growth due to ionization can be neglected. (GHT)

  19. Stability of electron energy in the Fermilab electron cooler

    SciTech Connect

    Shemyakin, A.; Carlson, K.; Prost, L.R.; Saewert, G.; /Fermilab

    2009-02-01

    A powerful electron beam (4.3 MeV, 0.1 A DC) generated by an electrostatic accelerator has been used at Fermilab for three years to cool antiprotons in the Recycler ring. For electron cooling to be effective, the electron energy should not deviate from its optimum value by more than 500V. The main tool for studying the energy stability is the electron beam position in a high-dispersion area. The energy ripple (frequencies above 0.2 Hz) was found to be less than 150 eV rms; the main cause of the ripple is the fluctuations of the chain current. In addition, the energy can drift to up to several keV that is traced to two main sources. One of them is a drift of the charging current, and another is a temperature dependence of generating voltmeter readings. The paper describes the efforts to reach the required level of stability as well as the setup, diagnostics, results of measurements, and operational experience.

  20. Radiation dosimetry.

    PubMed Central

    Cameron, J

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists. PMID:2040250

  1. Cosmic Ray Dosimetry

    NASA Astrophysics Data System (ADS)

    Si Belkhir, F.; Attallah, R.

    2010-10-01

    Radiation levels at aircraft cruising altitudes are twenty times higher than at sea level. Thus, on average, a typical airline pilot receives a larger annual radiation dose than some one working in nuclear industry. The main source of this radiation is from galactic cosmic radiation, high energy particles generated by exploding stars within our own galaxy. In this work we study cosmic rays dosimetry at various aviation altitudes using the PARMA model.

  2. Electronic Devices and Systems. Energy Technology Series.

    ERIC Educational Resources Information Center

    Technical Education Research Centre-Southwest, Waco, TX.

    This course in electronic devices and systems is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

  3. High energy electron positron physics

    SciTech Connect

    Ali, A.; Soding, P.

    1987-01-01

    With the termination of the physics program at PETRA in a year from now, and with the start of TRISTAN and the SLC and later LEP, an era of e/sup +/e/sup -/ physics will come to an end and a new one begins. The field is changing from a field of a few specialists, to becoming one of the mainstream efforts of the high energy community. It seems appropriate at this moment to summarize what has been learned over the past years, in a way more useful to any high energy physicist in particular to newcomers in the e/sup +/e/sup -/ field. This is the purpose of the book. This book should be used as a reference for future workers in the field of e/sup +/e/sup -/ interactions. It includes the most relevant data, parametrizations, theoretical background, and a chapter on detectors. Contents: Foreword; Detectors for High Energy e/sup +/e/sup -/ Physics; Lepton Pair Production and Electroweak Parameters; Hadron Production, Strong and Electroweak Properties; tau Physics; Recent Results on the Charm Sector; Bottom Physics; Lifetime Measurements of tau, Charmed and Beauty Hadrons; UPSILON Spectroscopy; Hadronic Decays of the UPSILON; Quark and Gluon Fragmentation in the e/sup +/e/sup -/ Continuum; Jet Production and QCD; Two Photon Physics; Search for New Particles.

  4. High Energy Electron Detection with ATIC

    NASA Technical Reports Server (NTRS)

    Chang, J.; Schmidt, W. K. H.; Adams, James H., Jr.; Ahn, H.; Ampe, J.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The ATIC (Advanced Thin Ionization Calorimeter) balloon-borne ionization calorimeter is well suited to record and identify high energy cosmic ray electrons. The instrument was exposed to high-energy beams at CERN H2 bean-dine in September of 1999. We have simulated the performance of the instrument, and compare the simulations with actual high energy electron exposures at the CERN accelerator. Simulations and measurements do not compare exactly, in detail, but overall the simulations have predicted actual measured behavior quite well.

  5. Electronic coherence in electronic energy transfer despite fast dephasing

    NASA Astrophysics Data System (ADS)

    Scholes, Gregory

    2009-03-01

    F"orster resonance energy transfer (FRET) is a common and fundamental photophysical process in life and materials sciences. FRET is an interchromophore relaxation process that transmits the electronic excitation from an initially excited donor to a ground state acceptor chromophore (light-absorbing moleule). FRET is used, for example, to harvest light in photosynthesis, measure distances in proteins, and it accelerates the photodegradation of polymers. In recent years attention has turned to the study of FRET in complex assemblies of molecules. While F"orster theory has enabled the efficiency of FRET to be predicted and analyzed in numerous and diverse areas of study, recent work has aimed to discover ways beyond the F"oster mechanism by which electronic energy can be transferred. The talk will compare and contrast theoretical and experimental studies of excitation relaxation in photosynthetic antenna systems with the conjugated polymer poly[2-methoxy,5-(2'-ethyl-hexoxy)-1,4-phenylenevinylene] (MEH-PPV). I will report new work where we have used a new anisotropy experiment to examine coherent energy transfer and a complementary technique using two-dimensional electronic spectroscopy expose the role of coherence transfer in the fastest time dynamics. We find that coherent energy transfer occurs for many tens of femtoseconds, even at room temperature. That leads us to examine the nature and implications of the so-called intermediate coupling regime for EET.

  6. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    SciTech Connect

    Rathbone, Bruce A.

    2011-04-04

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision

  7. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    SciTech Connect

    Rathbone, Bruce A.

    2010-04-01

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision

  8. Bone and mucosal dosimetry in skin radiation therapy: a Monte Carlo study using kilovoltage photon and megavoltage electron beams

    NASA Astrophysics Data System (ADS)

    Chow, James C. L.; Jiang, Runqing

    2012-06-01

    This study examines variations of bone and mucosal doses with variable soft tissue and bone thicknesses, mimicking the oral or nasal cavity in skin radiation therapy. Monte Carlo simulations (EGSnrc-based codes) using the clinical kilovoltage (kVp) photon and megavoltage (MeV) electron beams, and the pencil-beam algorithm (Pinnacle3 treatment planning system) using the MeV electron beams were performed in dose calculations. Phase-space files for the 105 and 220 kVp beams (Gulmay D3225 x-ray machine), and the 4 and 6 MeV electron beams (Varian 21 EX linear accelerator) with a field size of 5 cm diameter were generated using the BEAMnrc code, and verified using measurements. Inhomogeneous phantoms containing uniform water, bone and air layers were irradiated by the kVp photon and MeV electron beams. Relative depth, bone and mucosal doses were calculated for the uniform water and bone layers which were varied in thickness in the ranges of 0.5-2 cm and 0.2-1 cm. A uniform water layer of bolus with thickness equal to the depth of maximum dose (dmax) of the electron beams (0.7 cm for 4 MeV and 1.5 cm for 6 MeV) was added on top of the phantom to ensure that the maximum dose was at the phantom surface. From our Monte Carlo results, the 4 and 6 MeV electron beams were found to produce insignificant bone and mucosal dose (<1%), when the uniform water layer at the phantom surface was thicker than 1.5 cm. When considering the 0.5 cm thin uniform water and bone layers, the 4 MeV electron beam deposited less bone and mucosal dose than the 6 MeV beam. Moreover, it was found that the 105 kVp beam produced more than twice the dose to bone than the 220 kVp beam when the uniform water thickness at the phantom surface was small (0.5 cm). However, the difference in bone dose enhancement between the 105 and 220 kVp beams became smaller when the thicknesses of the uniform water and bone layers in the phantom increased. Dose in the second bone layer interfacing with air was found to be

  9. Fast transit portal dosimetry using density-scaled layer modeling of aSi-based electronic portal imaging device and Monte Carlo method

    SciTech Connect

    Jung, Jae Won; Kim, Jong Oh; Yeo, Inhwan Jason; Cho, Young-Bin; Kim, Sun Mo; DiBiase, Steven

    2012-12-15

    Purpose: Fast and accurate transit portal dosimetry was investigated by developing a density-scaled layer model of electronic portal imaging device (EPID) and applying it to a clinical environment. Methods: The model was developed for fast Monte Carlo dose calculation. The model was validated through comparison with measurements of dose on EPID using first open beams of varying field sizes under a 20-cm-thick flat phantom. After this basic validation, the model was further tested by applying it to transit dosimetry and dose reconstruction that employed our predetermined dose-response-based algorithm developed earlier. The application employed clinical intensity-modulated beams irradiated on a Rando phantom. The clinical beams were obtained through planning on pelvic regions of the Rando phantom simulating prostate and large pelvis intensity modulated radiation therapy. To enhance agreement between calculations and measurements of dose near penumbral regions, convolution conversion of acquired EPID images was alternatively used. In addition, thickness-dependent image-to-dose calibration factors were generated through measurements of image and calculations of dose in EPID through flat phantoms of various thicknesses. The factors were used to convert acquired images in EPID into dose. Results: For open beam measurements, the model showed agreement with measurements in dose difference better than 2% across open fields. For tests with a Rando phantom, the transit dosimetry measurements were compared with forwardly calculated doses in EPID showing gamma pass rates between 90.8% and 98.8% given 4.5 mm distance-to-agreement (DTA) and 3% dose difference (DD) for all individual beams tried in this study. The reconstructed dose in the phantom was compared with forwardly calculated doses showing pass rates between 93.3% and 100% in isocentric perpendicular planes to the beam direction given 3 mm DTA and 3% DD for all beams. On isocentric axial planes, the pass rates varied

  10. Hanford External Dosimetry Program

    SciTech Connect

    Fix, J.J.

    1990-10-01

    This document describes the Hanford External Dosimetry Program as it is administered by Pacific Northwest Laboratory (PNL) in support of the US Department of Energy (DOE) and its Hanford contractors. Program services include administrating the Hanford personnel dosimeter processing program and ensuring that the related dosimeter data accurately reflect occupational dose received by Hanford personnel or visitors. Specific chapters of this report deal with the following subjects: personnel dosimetry organizations at Hanford and the associated DOE and contractor exposure guidelines; types, characteristics, and procurement of personnel dosimeters used at Hanford; personnel dosimeter identification, acceptance testing, accountability, and exchange; dosimeter processing and data recording practices; standard sources, calibration factors, and calibration processes (including algorithms) used for calibrating Hanford personnel dosimeters; system operating parameters required for assurance of dosimeter processing quality control; special dose evaluation methods applied for individuals under abnormal circumstances (i.e., lost results, etc.); and methods for evaluating personnel doses from nuclear accidents. 1 ref., 14 figs., 5 tabs.

  11. Prostate PDT dosimetry

    PubMed Central

    Zhu, Timothy C.; Finlay, Jarod C.

    2015-01-01

    Summary We provide a review of the current state of dosimetry in prostate photodynamic therapy (PDT). PDT of the human prostate has been performed with a number of different photosensitizers and with a variety of dosimetry schemes. The simplest clinical light dose prescription is to quantify the total light energy emitted per length (J/cm) of cylindrical diffusing fibers (CDF) for patients treated with a defined photosensitizer injection per body weight. However, this approach does not take into account the light scattering by tissue and usually underestimates the local light fluence rate, and consequently the fluence. Techniques have been developed to characterize tissue optical properties and light fluence rates in vivo using interstitial measurements during prostate PDT. Optical methods have been developed to characterize tissue absorption and scattering spectra, which in turn provide information about tissue oxygenation and drug concentration. Fluorescence techniques can be used to quantify drug concentrations and photobleaching rates of photosensitizers. PMID:25046988

  12. Electron energy loss spectroscopy of disilane

    SciTech Connect

    Dillon, M.A.; Spence, D.; Boesten, L.; Tanaka, H.

    1988-04-01

    Electron energy loss spectra of disilane have been recorded over an excitation energy range of 20 eV employing electrons of 20 and 200 eV incident energy for scattering angles of 0/sup 0/--90/sup 0/. Every transition detected except one appears at an energy consistent with the first observed members of Rydberg series converging to one of four possible ion states. The first two observed transitions belong to (2a/sub 1//sub g/)/sup 2/..-->../sup 1//sup ,//sup 3/(2a/sub 1//sub g/,4s) dipole forbidden channels appearing at excitation energies of )similarreverse arrowto)6.3 and 7.05 eV for the triplet and singlet, respectively. Evidence is presented for the identification of additional forbidden transitions as well as possible low-lying valence transition

  13. 10 CFR 835.1304 - Nuclear accident dosimetry.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b)...

  14. 10 CFR 835.1304 - Nuclear accident dosimetry.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304... Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material to... nuclear accident is possible, shall provide nuclear accident dosimetry for those individuals. (b)...

  15. Image simulation for electron energy loss spectroscopy

    SciTech Connect

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations. Finally, the affect of the channelling of the electron probe within the sample is also discussed.

  16. Image simulation for electron energy loss spectroscopy

    DOE PAGESBeta

    Oxley, Mark P.; Pennycook, Stephen J.

    2007-10-22

    In this paper, aberration correction of the probe forming optics of the scanning transmission electron microscope has allowed the probe-forming aperture to be increased in size, resulting in probes of the order of 1 Å in diameter. The next generation of correctors promise even smaller probes. Improved spectrometer optics also offers the possibility of larger electron energy loss spectrometry detectors. The localization of images based on core-loss electron energy loss spectroscopy is examined as function of both probe-forming aperture and detector size. The effective ionization is nonlocal in nature, and two common local approximations are compared to full nonlocal calculations.more » Finally, the affect of the channelling of the electron probe within the sample is also discussed.« less

  17. Performance of two commercial electron beam algorithms over regions close to the lung-mediastinum interface, against Monte Carlo simulation and point dosimetry in virtual and anthropomorphic phantoms.

    PubMed

    Ojala, J; Hyödynmaa, S; Barańczyk, R; Góra, E; Waligórski, M P R

    2014-03-01

    Electron radiotherapy is applied to treat the chest wall close to the mediastinum. The performance of the GGPB and eMC algorithms implemented in the Varian Eclipse treatment planning system (TPS) was studied in this region for 9 and 16 MeV beams, against Monte Carlo (MC) simulations, point dosimetry in a water phantom and dose distributions calculated in virtual phantoms. For the 16 MeV beam, the accuracy of these algorithms was also compared over the lung-mediastinum interface region of an anthropomorphic phantom, against MC calculations and thermoluminescence dosimetry (TLD). In the phantom with a lung-equivalent slab the results were generally congruent, the eMC results for the 9 MeV beam slightly overestimating the lung dose, and the GGPB results for the 16 MeV beam underestimating the lung dose. Over the lung-mediastinum interface, for 9 and 16 MeV beams, the GGPB code underestimated the lung dose and overestimated the dose in water close to the lung, compared to the congruent eMC and MC results. In the anthropomorphic phantom, results of TLD measurements and MC and eMC calculations agreed, while the GGPB code underestimated the lung dose. Good agreement between TLD measurements and MC calculations attests to the accuracy of "full" MC simulations as a reference for benchmarking TPS codes. Application of the GGPB code in chest wall radiotherapy may result in significant underestimation of the lung dose and overestimation of dose to the mediastinum, affecting plan optimization over volumes close to the lung-mediastinum interface, such as the lung or heart. PMID:23702438

  18. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  19. Total π-electron and HOMO energy

    NASA Astrophysics Data System (ADS)

    Gutman, Ivan; Radenković, Slavko; Ðorđević, Slađana; Milovanović, Igor Ž.; Milovanović, Emina I.

    2016-04-01

    A relation is obtained between the total π-electron energy Eπ and the HOMO energy EHOMO, valid within the HMO approximation. This seems to be the very first relation between Eπ and EHOMO ever established. It enables a much more accurate assessment of Eπ of alternant conjugated hydrocarbons than that based on McClelland's formula and on other (n, m)-type approximate expressions.

  20. Applications for Energy Recovering Free Electron Lasers

    SciTech Connect

    George Neil

    2007-08-01

    The availability of high-power, high-brilliance sources of tunable photons from energy-recovered Free Electron Lasers is opening up whole new fields of application of accelerators in industry. This talk will review some of the ideas that are already being put into production, and some of the newer ideas that are still under development.

  1. Electron energy flux in the solar wind.

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Sugiura, M.

    1971-01-01

    Description of studies of electrons between 10 eV and 9.9 keV in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy-flux density to exceed the heat flow due to thermal electrons. In one such event, the observations are shown to be consistent with the solar-electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary-field line, a comparatively large energy flux along the field toward the sun is observed, but the heat flow remains outwardly directed during this time interval. In either situation the heat flow is found to be consistent with measurements made on Vela satellites by a different method. These values, less than .01 ergs/sq cm/sec, are sufficiently low to require modifications to the Spitzer-Harm conductivity formula for use in solar-wind theories.

  2. Electron energy deposition in carbon monoxide gas

    NASA Technical Reports Server (NTRS)

    Liu, Weihong; Victor, G. A.

    1994-01-01

    A comprehensive set of electron impact cross sections for carbon monoxide molecules is presented on the basis of the most recent experimental measurements and theoretical calculations. The processes by which energetic electrons lose energy in CO gas are analyzed with these input cross sections. The efficiencies are computed of vibrational and electronic excitation, dissociation, ionization, and heating for CO gas with fractional ionization ranging from 0% to 10%. The calculated mean energy per ion pair for neutral CO gas is 32.3 eV, which is in excellent agreement with the experimental value of 32.2 eV. It increases to 35.6 eV at a fractional ionization of 1%, typical of supernovae ejecta.

  3. Measurement of the electron energy and energy spread at the electron storage ring BESSY I.

    PubMed

    Klein, R; Mayer, T; Kuske, P; Thornagel, R; Ulm, G

    1998-05-01

    Knowledge of the electron energy with a small uncertainty is necessary for the Physikalisch-Technische Bundesanstalt (PTB) to operate the electron storage ring BESSY I, and the future BESSY II, as a primary radiation source standard of calculable synchrotron radiation. At BESSY I the electron energy can now be measured either by the long-established method of resonant spin depolarization or by the newly set up method of Compton backscattering (CBS) of laser photons (CO(2) laser, lambda = 10.6 micro m). Results obtained at different electron energies by these two independent methods are presented. They agree within a relative uncertainty of better than 10(-4). The advantages and disadvantages of these two complementary techniques are described and applications of CBS for the measurement of other storage-ring parameters, e.g. the electron energy spread, are given. PMID:15263521

  4. SU-E-T-308: Systematic Characterization of the Energy Response of Different LiF TLD Crystals for Dosimetry Applications

    SciTech Connect

    Pena, E; Caprile, P; Sanchez-Nieto, B

    2014-06-01

    Purpose: The thermoluminiscense dosimeters (TLDs) are widely used in personal and clinical dosimetry due to its small size, good sensitivity and tissue equivalence, among other advantages. This study presents the characterization of Lithium Fluoride based TLDs, in terms of their absorbed dose response to successive irradiation cycles in a broad range of beam energies, measured under reference conditions. Methods: Four types of Harshaw TLD chips were used: TLD-100, TLD-600 TLD-700 and 100-H. They were irradiated with 10 photon beams of different energy spectrums, from 28 kVp to 18MV (in 30 consecutive cycles for 6 and 18 MV). Results: It was found that the response of the dosimetric system was stabilized (less than ±3%) after 10 cycles for TLD-600 and TLD-700. In the case of TLD-100 and TLD-100H this dependence was not observed. A decreased response to increasing beam energy in terms of absorbed dose to water was observed, as expected, except for TLD-100H which showed the opposite behavior. The less energy dependent detector was the TLD-100H exhibiting a maximum deviation of 12%. The highest variation observed was 33% for TLD-100. The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy. Conclusion: The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy.

  5. Inspection applications with higher electron beam energies

    NASA Astrophysics Data System (ADS)

    Norman, D. R.; Jones, J. L.; Yoon, W. Y.; Haskell, K. J.; Sterbentz, J. W.; Zabriskie, J. M.; Hunt, A. W.; Harmon, F.; Kinlaw, M. T.

    2005-12-01

    The Idaho National Laboratory has developed prototype shielded nuclear material detection systems based on pulsed photonuclear assessment (PPA) techniques for the inspection of cargo containers. During this work, increased nuclear material detection capabilities have been demonstrated at higher electron beam energies than those allowed by federal regulations for cargo inspection. This paper gives a general overview of a nuclear material detection system, the PPA technique and discusses the benefits of using these higher energies. This paper also includes a summary of the numerical and test results from LINAC operations up to 24 MeV and discusses some of the federal energy limitations associated with cargo inspection.

  6. Dosimetry and fast neutron energies characterization of photoneutrons produced in some medical linear accelerators

    NASA Astrophysics Data System (ADS)

    Khaled, N. E.; Attalla, E. M.; Ammar, H.; Khalil, W.

    2011-12-01

    This work focusses on the estimation of induced photoneutrons energy, fluence, and strength using nuclear track detector (NTD) (CR-39). Photoneutron energy was estimated for three different linear accelerators, LINACs as an example for the commonly used accelerators. For high-energy linear accelerators, neutrons are produced as a consequence of photonuclear reactions in the target nuclei, accelerator head, field-flattening filters and beam collimators, and other irradiated objects. NTD (CR-39) is used to evaluate energy and fluence of the fast neutron. Track length is used to estimate fast photoneutrons energy for linear accelerators (Elekta 10 MV, Elekta 15 MV, and Varian 15 MV). Results show that the estimated neutron energies for the three chosen examples of LINACs reveals neutron energies in the range of 1-2 MeV for 10 and 15 MV X-ray beams. The fluence of neutrons at the isocenter (Φtotal) is found to be (4×106 n cm2 Gy-1) for Elekta machine 10 MV. The neutron source strengths Q are calculated. It was found to be 0.2×1012 n Gy-1 X-ray at the isocenter. This work represents simple, low cost, and accurate methods of measuring fast neutrons dose and energies.

  7. Clinical implementation and rapid commissioning of an EPID based in-vivo dosimetry system.

    PubMed

    Hanson, Ian M; Hansen, Vibeke N; Olaciregui-Ruiz, Igor; van Herk, Marcel

    2014-10-01

    Using an Electronic Portal Imaging Device (EPID) to perform in-vivo dosimetry is one of the most effective and efficient methods of verifying the safe delivery of complex radiotherapy treatments. Previous work has detailed the development of an EPID based in-vivo dosimetry system that was subsequently used to replace pre-treatment dose verification of IMRT and VMAT plans. Here we show that this system can be readily implemented on a commercial megavoltage imaging platform without modification to EPID hardware and without impacting standard imaging procedures. The accuracy and practicality of the EPID in-vivo dosimetry system was confirmed through a comparison with traditional TLD in-vivo measurements performed on five prostate patients.The commissioning time required for the EPID in-vivo dosimetry system was initially prohibitive at approximately 10 h per linac. Here we present a method of calculating linac specific EPID dosimetry correction factors that allow a single energy specific commissioning model to be applied to EPID data from multiple linacs. Using this method reduced the required per linac commissioning time to approximately 30 min.The validity of this commissioning method has been tested by analysing in-vivo dosimetry results of 1220 patients acquired on seven linacs over a period of 5 years. The average deviation between EPID based isocentre dose and expected isocentre dose for these patients was (-0.7  ±  3.2)%.EPID based in-vivo dosimetry is now the primary in-vivo dosimetry tool used at our centre and has replaced nearly all pre-treatment dose verification of IMRT treatments. PMID:25211121

  8. Clinical implementation and rapid commissioning of an EPID based in-vivo dosimetry system

    NASA Astrophysics Data System (ADS)

    Hanson, Ian M.; Hansen, Vibeke N.; Olaciregui-Ruiz, Igor; van Herk, Marcel

    2014-10-01

    Using an Electronic Portal Imaging Device (EPID) to perform in-vivo dosimetry is one of the most effective and efficient methods of verifying the safe delivery of complex radiotherapy treatments. Previous work has detailed the development of an EPID based in-vivo dosimetry system that was subsequently used to replace pre-treatment dose verification of IMRT and VMAT plans. Here we show that this system can be readily implemented on a commercial megavoltage imaging platform without modification to EPID hardware and without impacting standard imaging procedures. The accuracy and practicality of the EPID in-vivo dosimetry system was confirmed through a comparison with traditional TLD in-vivo measurements performed on five prostate patients. The commissioning time required for the EPID in-vivo dosimetry system was initially prohibitive at approximately 10 h per linac. Here we present a method of calculating linac specific EPID dosimetry correction factors that allow a single energy specific commissioning model to be applied to EPID data from multiple linacs. Using this method reduced the required per linac commissioning time to approximately 30 min. The validity of this commissioning method has been tested by analysing in-vivo dosimetry results of 1220 patients acquired on seven linacs over a period of 5 years. The average deviation between EPID based isocentre dose and expected isocentre dose for these patients was (-0.7  ±  3.2)%. EPID based in-vivo dosimetry is now the primary in-vivo dosimetry tool used at our centre and has replaced nearly all pre-treatment dose verification of IMRT treatments.

  9. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. C. A.; Silva, D. G. M.; Bettega, M. H. F.; da Costa, R. F.; Lima, M. A. P.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2012-11-01

    In order to understand and optimize processes occurring during the ignition of plasma and its consequences in post-discharge for an internal combustion engine, especially considering the spark plug, we have produced in this work some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules in the energy range from 60 to 500 eV are reported, using the linear transmission method based on the Beer-Lambert law to first approximation. Aditionally to that, measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering were also discussed, for impact energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. The measurements were obtained using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons.

  10. History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

    NASA Astrophysics Data System (ADS)

    Williamson, Jeffrey F.

    2006-09-01

    This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

  11. High Energy Electron Detectors on Sphinx

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Porte, A.; Zucchini, F.; Calamy, H.; Auriel, G.; Coleman, P. L.; Bayol, F.; Lalle, B.; Krishnan, M.; Wilson, K.

    2008-11-01

    Z-pinch plasma radiation sources are used to dose test objects with K-shell (˜1-4keV) x-rays. The implosion physics can produce high energy electrons (> 50keV), which could distort interpretation of the soft x-ray effects. We describe the design and implementation of a diagnostic suite to characterize the electron environment of Al wire and Ar gas puff z-pinches on Sphinx. The design used ITS calculations to model detector response to both soft x-rays and electrons and help set upper bounds to the spurious electron flux. Strategies to discriminate between the known soft x-ray emission and the suspected electron flux will be discussed. H.Calamy et al, ``Use of microsecond current prepulse for dramatic improvements of wire array Z-pinch implosion,'' Phys Plasmas 15, 012701 (2008) J.A.Halbleib et al, ``ITS: the integrated TIGER series of electron/photon transport codes-Version 3.0,'' IEEE Trans on Nuclear Sci, 39, 1025 (1992)

  12. Energy response of CaSO4:Dy teflon TLD disk dosimeters to photons and electrons.

    PubMed

    Sharada, K S

    1983-01-01

    The photon energy response of CaSO4:Dy teflon disk dosimeters used widely in radiation dosimetry is computed using the energy absorption coefficient values for calcium, sulfur, oxygen, and carbon taken from J. H. Hubbell's tables. For fluorine, the energy absorption coefficients were obtained from the values given by F. H. Attix for CaF2 and Ca. The energy response of the radiation-monitoring disk for the range of 10 keV to 10 MeV, relative to air, is computed and plotted. The response is maximum between 20 and 30 keV and then gradually falls to a constant at 200 keV to 10 MeV. This computed response for different energies is compared with the experimental TL response of the dosimeter. The electron energy response of these TLD disks is computed using the stopping-power values for the different component elements. The electron stopping power for sulfur and calcium from 10 keV to 10 MeV is computed using the Bethe-Bloch formula. Those for oxygen and carbon are taken from the tables given by M. J. Berger and S. M. Seltzer. For fluorine, the values are computed from those for Li and LiF given in the same tables. This calculated response is compared with the experimental beta response of the TL dosimeter. PMID:6823508

  13. Production and dosimetry of simultaneous therapeutic photons and electrons beam by linear accelerator: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Khledi, Navid; Arbabi, Azim; Sardari, Dariush; Mohammadi, Mohammad; Ameri, Ahmad

    2015-02-01

    Depending on the location and depth of tumor, the electron or photon beams might be used for treatment. Electron beam have some advantages over photon beam for treatment of shallow tumors to spare the normal tissues beyond of the tumor. In the other hand, the photon beam are used for deep targets treatment. Both of these beams have some limitations, for example the dependency of penumbra with depth, and the lack of lateral equilibrium for small electron beam fields. In first, we simulated the conventional head configuration of Varian 2300 for 16 MeV electron, and the results approved by benchmarking the Percent Depth Dose (PDD) and profile of the simulation and measurement. In the next step, a perforated Lead (Pb) sheet with 1mm thickness placed at the top of the applicator holder tray. This layer producing bremsstrahlung x-ray and a part of the electrons passing through the holes, in result, we have a simultaneous mixed electron and photon beam. For making the irradiation field uniform, a layer of steel placed after the Pb layer. The simulation was performed for 10×10, and 4×4 cm2 field size. This study was showed the advantages of mixing the electron and photon beam by reduction of pure electron's penumbra dependency with the depth, especially for small fields, also decreasing of dramatic changes of PDD curve with irradiation field size.

  14. Production and dosimetry of simultaneous therapeutic photons and electrons beam by linear accelerator: A Monte Carlo study

    SciTech Connect

    Khledi, Navid; Sardari, Dariush; Arbabi, Azim; Ameri, Ahmad; Mohammadi, Mohammad

    2015-02-24

    Depending on the location and depth of tumor, the electron or photon beams might be used for treatment. Electron beam have some advantages over photon beam for treatment of shallow tumors to spare the normal tissues beyond of the tumor. In the other hand, the photon beam are used for deep targets treatment. Both of these beams have some limitations, for example the dependency of penumbra with depth, and the lack of lateral equilibrium for small electron beam fields. In first, we simulated the conventional head configuration of Varian 2300 for 16 MeV electron, and the results approved by benchmarking the Percent Depth Dose (PDD) and profile of the simulation and measurement. In the next step, a perforated Lead (Pb) sheet with 1mm thickness placed at the top of the applicator holder tray. This layer producing bremsstrahlung x-ray and a part of the electrons passing through the holes, in result, we have a simultaneous mixed electron and photon beam. For making the irradiation field uniform, a layer of steel placed after the Pb layer. The simulation was performed for 10×10, and 4×4 cm2 field size. This study was showed the advantages of mixing the electron and photon beam by reduction of pure electron's penumbra dependency with the depth, especially for small fields, also decreasing of dramatic changes of PDD curve with irradiation field size.

  15. Dosimetry tools and techniques for IMRT

    SciTech Connect

    Low, Daniel A.; Moran, Jean M.; Dempsey, James F.; Dong Lei; Oldham, Mark

    2011-03-15

    Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA) radiation dose distributions. This report provides a comprehensive overview of how dosimeters, phantoms, and dose distribution analysis techniques should be used to support the commissioning and quality assurance requirements of an IMRT program. The proper applications of each dosimeter are described along with the limitations of each system. Point detectors, arrays, film, and electronic portal imagers are discussed with respect to their proper use, along with potential applications of 3D dosimetry. Regardless of the IMRT technique utilized, some situations require the use of multiple detectors for the acquisition of accurate commissioning data. The overall goal of this task group report is to provide a document that aids the physicist in the proper selection and use of the dosimetry tools available for IMRT QA and to provide a resource for physicists that describes dosimetry measurement techniques for purposes of IMRT commissioning and measurement-based characterization or verification of IMRT treatment plans. This report is not intended to provide a comprehensive review of commissioning and QA procedures for IMRT. Instead, this report focuses on the aspects of metrology, particularly the practical aspects of measurements that are unique to IMRT. The metrology of IMRT concerns the application of measurement instruments and their suitability, calibration, and quality control of measurements. Each of the dosimetry measurement tools has limitations that need to be considered when incorporating them into a commissioning process or a comprehensive QA program. For example, routine quality assurance procedures require the use of robust field dosimetry systems. These often exhibit limitations with respect to spatial resolution or energy response and need to themselves be commissioned against more established dosimeters. A chain of

  16. Dosimetry tools and techniques for IMRT.

    PubMed

    Low, Daniel A; Moran, Jean M; Dempsey, James F; Dong, Lei; Oldham, Mark

    2011-03-01

    Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA) radiation dose distributions. This report provides a comprehensive overview of how dosimeters, phantoms, and dose distribution analysis techniques should be used to support the commissioning and quality assurance requirements of an IMRT program. The proper applications of each dosimeter are described along with the limitations of each system. Point detectors, arrays, film, and electronic portal imagers are discussed with respect to their proper use, along with potential applications of 3D dosimetry. Regardless of the IMRT technique utilized, some situations require the use of multiple detectors for the acquisition of accurate commissioning data. The overall goal of this task group report is to provide a document that aids the physicist in the proper selection and use of the dosimetry tools available for IMRT QA and to provide a resource for physicists that describes dosimetry measurement techniques for purposes of IMRT commissioning and measurement-based characterization or verification of IMRT treatment plans. This report is not intended to provide a comprehensive review of commissioning and QA procedures for IMRT. Instead, this report focuses on the aspects of metrology, particularly the practical aspects of measurements that are unique to IMRT. The metrology of IMRT concerns the application of measurement instruments and their suitability, calibration, and quality control of measurements. Each of the dosimetry measurement tools has limitations that need to be considered when incorporating them into a commissioning process or a comprehensive QA program. For example, routine quality assurance procedures require the use of robust field dosimetry systems. These often exhibit limitations with respect to spatial resolution or energy response and need to themselves be commissioned against more established dosimeters. A chain of

  17. Prediction of electron energies in metal oxides.

    PubMed

    Walsh, Aron; Butler, Keith T

    2014-02-18

    The ability to predict energy levels in metal oxides is paramount to developinguseful materials, such as in the development of water photolysis catalysts and efficient photovoltaic cells. The binding energy of electrons in materials encompasses a wealth of information concerning their physicochemistry. The energies control the optical and electrical properties, dictating for which kinds of chemistry and physics a particular material is useful. Scientists have developed theories and models for electron energies in a variety of chemical systems over the past century. However, the prediction of quantitative energy levels in new materials remains a major challenge. This issue is of particular importance in metal oxide research, where novel chemistries have opened the possibility of a wide range of tailored systems with applications in important fields including light-emitting diodes, energy efficient glasses, and solar cells. In this Account, we discuss the application of atomistic modeling techniques, covering the spectrum from classical to quantum descriptions, to explore the alignment of electron energies between materials. We present a number of paradigmatic examples, including a series of oxides (ZnO, In2O3, and Cu2O). Such calculations allow the determination of a "band alignment diagram" between different materials and can facilitate the prediction of the optimal chemical composition of an oxide for use in a given application. Throughout this Account, we consider direct computational solutions in the context of heuristic models, which are used to relate the fundamental theory to experimental observations. We review a number of techniques that have been commonly applied in the study of electron energies in solids. These models have arisen from different answers to the same basic question, coming from solid-state chemistry and physics perspectives. We highlight common factors, as well as providing a critical appraisal of the strengths and weaknesses of each

  18. Nuclear accident dosimetry intercomparison studies.

    PubMed

    Sims, C S

    1989-09-01

    Twenty-two nuclear accident dosimetry intercomparison studies utilizing the fast-pulse Health Physics Research Reactor at the Oak Ridge National Laboratory have been conducted since 1965. These studies have provided a total of 62 different organizations a forum for discussion of criticality accident dosimetry, an opportunity to test their neutron and gamma-ray dosimetry systems under a variety of simulated criticality accident conditions, and the experience of comparing results with reference dose values as well as with the measured results obtained by others making measurements under identical conditions. Sixty-nine nuclear accidents (27 with unmoderated neutron energy spectra and 42 with eight different shielded spectra) have been simulated in the studies. Neutron doses were in the 0.2-8.5 Gy range and gamma doses in the 0.1-2.0 Gy range. A total of 2,289 dose measurements (1,311 neutron, 978 gamma) were made during the intercomparisons. The primary methods of neutron dosimetry were activation foils, thermoluminescent dosimeters, and blood sodium activation. The main methods of gamma dose measurement were thermoluminescent dosimeters, radiophotoluminescent glass, and film. About 68% of the neutron measurements met the accuracy guidelines (+/- 25%) and about 52% of the gamma measurements met the accuracy criterion (+/- 20%) for accident dosimetry. PMID:2777549

  19. Heavy-ion dosimetry

    SciTech Connect

    Schimmerling, W.

    1980-03-01

    This lecture deals with some of the more important physical characteristics of relativistic heavy ions and their measurement, with beam delivery and beam monitoring, and with conventional radiation dosimetry as used in the operation of the BEVALAC biomedical facility for high energy heavy ions (Lyman and Howard, 1977; BEVALAC, 1977). Even so, many fundamental aspects of the interaction of relativistic heavy ions with matter, including important atomic physics and radiation chemical considerations, are not discussed beyond the reminder that such additional understanding is required before an adequte perspective of the problem can be attained.

  20. Fast neutron dosimetry

    SciTech Connect

    DeLuca, P.M. Jr.; Pearson, D.W.

    1992-01-01

    This progress report concentrates on two major areas of dosimetry research: measurement of fast neutron kerma factors for several elements for monochromatic and white spectrum neutron fields and determination of the response of thermoluminescent phosphors to various ultra-soft X-ray energies and beta-rays. Dr. Zhixin Zhou from the Shanghai Institute of Radiation Medicine, People's Republic of China brought with him special expertise in the fabrication and use of ultra-thin TLD materials. Such materials are not available in the USA. The rather unique properties of these materials were investigated during this grant period.

  1. High-energy neutron dosimetry at the Clinton P. Anderson Meson Physics Facility

    SciTech Connect

    Mallett, M.W.; Vasilik, D.G.; Littlejohn, G.J.; Cortez, J.R.

    1990-01-01

    Neutron energy spectrum measurements performed at the Clinton P. Anderson Meson Physics Facility indicated potential areas for high energy neutron exposure to personnel. The low sensitivity of the Los Alamos thermoluminescent dosimeter (TLD) to high energy neutrons warranted issuing a NTA dosimeter in addition to the TLD badge to employees entering these areas. The dosimeter consists of a plastic holder surrounding NTA film that has been desiccated and sealed in a dry nitrogen environment. A study of the fading of latent images in NTA film demonstrated the success of this packaging method to control the phenomenon. The Los Alamos NTA dosimeter is characterized and the fading study discussed. 10 refs., 4 figs., 2 tabs.

  2. Fluctuations in energy loss and their implications for dosimetry and radiobiology

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Steigerwalt, J. E.

    1972-01-01

    Serious consideration of the physics of energy deposition indicates that a fundamental change in the interpretation of absorbed dose is required at least for considerations of effects in biological systems. In addition, theoretical approaches to radiobiology and microdosimetry seem to require statistical considerations incorporating frequency distributions of the magnitude of the event sizes within the volume of interest.

  3. Energy Transformation in Molecular Electronic Systems

    SciTech Connect

    Kasha, Michael

    1999-05-17

    This laboratory has developed many new ideas and methods in the electronic spectroscopy of molecules. This report covers the contract period 1993-1995. A number of the projects were completed in 1996, and those papers are included in the report. The DOE contract was terminated at the end of 1995 owing to a reorganizational change eliminating nationally the projects under the Office of Health and Environmental Research, U. S. Department of Energy.

  4. Development of a pMOSFET sensor with a Gd converter for low energy neutron dosimetry.

    PubMed

    Lee, N H; Kim, S H; Youk, G U; Park, I J; Kim, Y M

    2004-01-01

    A pMOSFET having a 10 microm thick Gadolinium (Gd) layer has been invented as a slow neutron sensor. When slow neutrons are incident to the Gd layer, conversion electrons, which generate electron-hole pairs in the SiO2 layer of the pMOSFET, are generated by a neutron capture process. The holes are easily trapped in the oxide and act as positive-charge centres in the oxide. Due to the induced charges, the threshold turn-on voltage of the pMOSFET is changed. The developed sensors were tested at a neutron beam port of the HANARO research reactor and a 60Co irradiation facility to investigate slow neutron response and gamma ray contamination, respectively. The resultant voltage change was proportional to the accumulated neutron dose and it was very sensitive to slow neutrons. Moreover, ionising radiation contamination was negligible. It can also be used in a mixed radiation field by subtracting the voltage change of a pMOSFET without Gd from that of the Gd-pMOSFET. PMID:15353659

  5. Photon dosimetry using plastic scintillators in pulsed radiation fields

    SciTech Connect

    David L. Chichester; Brandon W. Blackburn; James T. Johnson; Scott W. Watson

    2007-04-01

    Simulations and experiments have been carried out to explore using a plastic scintillator as a dosimetry probe in the vicinity of a pulsed bremsstrahlung source in the range 4 to 20 MeV. Taking advantage of the tissue-equivalent properties of this detector in conjunction with the use of a fast digital signal processor near real-time dosimetry was shown to be possible. The importance of accounting for a broad energy electron beam in bremsstrahlung production, and photon scattering and build-up, in correctly interpreting dosimetry results at long stand-off distances is highlighted by comparing real world experiments with ideal geometry simulations. Close agreement was found between absorbed energy calculations based upon spectroscopic techniques and calculations based upon signal integration, showing a ratio between 10 MeV absorbed dose to 12 MeV absorbed dose of 0.66 at a distance of 91.4 m from the accelerator. This is compared with an idealized model simulation with a monoenergetic electron beam and without scattering, where the ratio was 0.46.

  6. EPR/PTFE dosimetry for test reactor environments

    SciTech Connect

    Vehar, D.W.; Griffin, P.J.; Quirk, T.J.

    2011-07-01

    The use of Electron Paramagnetic Resonance (EPR) spectroscopy with materials such as alanine is well established as a technique for measurement of ionizing radiation absorbed dose in photon and electron fields such as Co-60, high-energy bremsstrahlung and electron-beam fields [1]. In fact, EPR/Alanine dosimetry has become a routine transfer standard for national standards bodies such as NIST and NPL. In 1992 the Radiation Metrology Laboratory (RML) at Sandia National Laboratories implemented EPR/Alanine capabilities for use in routine and calibration activities at its Co-60 and pulsed-power facilities. At that time it also investigated the usefulness of the system for measurement of absorbed dose in the mixed neutron/photon environments of reactors such as the Sandia Pulsed Reactor and the Annular Core Research Reactor used for hardness testing of electronics. The RML concluded that the neutron response of alanine was a sufficiently high fraction of the overall dosimeter response that the resulting uncertainties in the photon dose would be unacceptably large for silicon-device testing. However, it also suggested that non-hydrogenous materials such as polytetrafluoroethylene (PTFE) would exhibit smaller neutron response and might be useful in mixed environments. Preliminary research with PTFE in photon environments indicated considerable promise, but further development was not pursued at that time. Because of renewed interest in absorbed dose measurements that could better define the individual contributions of photon and neutron components to the overall dose delivered to a test object, the RML has re-initiated the development of an EPR/PTFE dosimetry system. This effort consists of three stages: 1) Identification of PTFE materials that may be suitable for dosimetry applications. It was speculated that the inconsistency of EPR signatures in the earlier samples may have been due to variability in PTFE manufacturing processes. 2) Characterization of dosimetry in

  7. Influence of trace elements in human tissue in low-energy photon brachytherapy dosimetry

    NASA Astrophysics Data System (ADS)

    White, Shane A.; Landry, Guillaume; van Gils, Francis; Verhaegen, Frank; Reniers, Brigitte

    2012-06-01

    The aim of this paper is to determine the dosimetric impact of trace elements in human tissues for low-energy photon sources used in brachytherapy. Monte Carlo dose calculations were used to investigate the dosimetric effect of trace elements present in normal or cancerous human tissues. The effect of individual traces (atomic number Z = 11-30) was studied in soft tissue irradiated by low-energy brachytherapy sources. Three other tissue types (prostate, adipose and mammary gland) were also simulated with varying trace concentrations to quantify the contribution of each trace to the dose distribution. The dose differences between cancerous and healthy prostate tissues were calculated in single- and multi-source geometries. The presence of traces in a tissue produces a difference in the dose distribution that is dependent on Z and the concentration of the trace. Low-Z traces (Na) have a negligible effect (<0.3%) in all tissues, while higher Z (K) had a larger effect (>3%). There is a potentially significant difference in the dose distribution between cancerous and healthy prostate tissues (4%) and even larger if compared to the trace-free composition (15%) in both single- and multi-sourced geometries. Trace elements have a non-negligible (up to 8% in prostate D90) effect on the dose in tissues irradiated with low-energy photon sources. This study underlines the need for further investigation into accurate determination of the trace composition of tissues associated with low-energy brachytherapy. Alternatively, trace elements could be incorporated as a source of uncertainty in dose calculations. This work was part of an invited presentation at the ‘International Workshop on Recent Advances in Monte Carlo Techniques for Radiation Therapy’, held in Montreal, June 8-10, 2011.

  8. Electron beam effective source surface distances for a high energy linear accelerator.

    PubMed

    Sharma, S C; Johnson, M W

    1991-06-01

    The design of the Varian Clinac 1800 linear accelerator electron applicator system does not allow clearance for all head and neck patients to be treated at the standard calibration distance of 100 cm. Discrepancies have been found between dose calculations using the inverse square law for extended distances and their measured data. A 4 X 4 cm2 applicator at an energy of 9 MeV, for example, had dose differences of 13 and 23% at distances of 105 and 110 cm SSD. Because of these discrepancies, effective source surface distances (SSDeff) were determined for all the standard electron energies and applicators of a Clinac 1800. These effective source surface distances ranged from 41.6 cm to 92.6 cm for the 4 X 4 cm2 cone/6 MeV electron beam through the 25 X 25 cm2 cone/20 MeV electron beam. A summary of these distances and an analysis of the clinical use of both a best fit SSDeff and a common SSDeff for patient dosimetry calculations is presented. PMID:1907830

  9. Collisions between low-energy electrons and small polyatomic targets of biological relevance

    NASA Astrophysics Data System (ADS)

    Hargreaves, Leigh

    2016-05-01

    Over the last decade, cross section measurements and calculations for DNA prototype molecules have received significant attention from the collisions community, due to the potential applications of this data in modelling electron transport through biological matter with a view to improving radiation dosimetry. Such data are additionally interesting from a fundamental aspect, as small carbon-based molecules are ideal targets for considering effects including target conformation, long-range dynamical interactions and coupling effects between the various degrees of freedom on the scattering properties of the target. At the California State University Fullerton, we have made a series of measurements of the elastic, vibrationally inelastic and electronically inelastic cross sections for a variety of small polyatomic targets, including water and the basic alcohols, ethylene, toluene and several fluorinated alkanes. These processes are important in a range of applications, primarily for modelling electron transport and thermalization, and energy deposition to a biological media. The data were obtained using a high resolution electron energy-loss spectrometer, operating in a crossed beam configuration with a moveable aperture gas source. The gas source design facilitates both an expedient and highly accurate method of removing background signal, and removes uncertainties from the data due to uncertainties in the beam profile. We have also performed scattering calculations employing the Schwinger Multichannel method, in collaboration with the California institute of technology, to compare with our measurements. In this talk, I will present an overview of our recent data and future research plans.

  10. Emerging technological bases for retrospective dosimetry.

    PubMed

    Straume, T; Anspaugh, L R; Haskell, E H; Lucas, J N; Marchetti, A A; Likhtarev, I A; Chumak, V V; Romanyukha, A A; Khrouch, V T; Gavrilin YuI; Minenko, V F

    1997-01-01

    In this article we discuss examples of challenging problems in retrospective dosimetry and describe some promising solutions. The ability to make measurements by accelerator mass spectrometry and luminescence techniques promises to provide improved dosimetry for regions of Belarus, Ukraine and Russian Federation contaminated by radionuclides from the Chernobyl accident. In addition, it may soon be possible to resolve the large neutron discrepancy in the dosimetry system for Hiroshima through novel measurement techniques that can be used to reconstruct the fast-neutron fluence emitted by the bomb some 51 years ago. Important advances in molecular cytogenetics and electron paramagnetic resonance measurements have produced biodosimeters that show potential in retrospective dosimetry. The most promising of these are the frequency of reciprocal translocations measured in chromosomes of blood lymphocytes using fluorescence in situ hybridization and the electron paramagnetic resonance signal in tooth enamel. PMID:9368303

  11. DOSEXPRT: A bioassay dosimetry code for Martin Marietta Energy Systems, Inc.

    SciTech Connect

    Ward, R.C.; Eckerman, K.F.

    1992-04-01

    The bioassay code DOSEXPRT was developed for Martin Marietta Energy Systems, Inc., to provide compliance with Department of Energy (DOE) Order 5480, Chapter 11. DOSEXPRT computes the intake of a radionuclide in any year (considering both acute and chronic intakes) from in vivo measurements of the retained activity and/or measurements of the activity in excreta. The committed effective and organ doses for the intake are computed as well as the effective and organ doses expected to be received in each calendar year out to 50 years beyond the year of intake. The bioassay records used as input for DOSEXPRT are extracted from the Martin Marietta Energy Systems Occupational Health Information System (OHIS). DOSEXPRT implements a set of algorithms with parameters governing the translocation, retention, and excretion of the nuclide contained in data files specific to the nuclide. These files also contain dose-per-unit-intake coefficients used to compute the committed dose equivalent for the intakes in the year. Annual organ and effective doses are computed using additional dose-rate files that contain data on the dose rate at various times following a unit intake. If measurements are presented for more than one assay for a given nuclide, DOSEXPRT estimates the intake by applying weights assigned in the nuclide file for each assay. DOSEXPRT is accessed off the OHIS MENU No. 4 and designed to be run as a batch processor, but can also be run interactively for testing purposes.

  12. DOSEXPRT: A bioassay dosimetry code for Martin Marietta Energy Systems, Inc

    SciTech Connect

    Ward, R.C.; Eckerman, K.F.

    1992-04-01

    The bioassay code DOSEXPRT was developed for Martin Marietta Energy Systems, Inc., to provide compliance with Department of Energy (DOE) Order 5480, Chapter 11. DOSEXPRT computes the intake of a radionuclide in any year (considering both acute and chronic intakes) from in vivo measurements of the retained activity and/or measurements of the activity in excreta. The committed effective and organ doses for the intake are computed as well as the effective and organ doses expected to be received in each calendar year out to 50 years beyond the year of intake. The bioassay records used as input for DOSEXPRT are extracted from the Martin Marietta Energy Systems Occupational Health Information System (OHIS). DOSEXPRT implements a set of algorithms with parameters governing the translocation, retention, and excretion of the nuclide contained in data files specific to the nuclide. These files also contain dose-per-unit-intake coefficients used to compute the committed dose equivalent for the intakes in the year. Annual organ and effective doses are computed using additional dose-rate files that contain data on the dose rate at various times following a unit intake. If measurements are presented for more than one assay for a given nuclide, DOSEXPRT estimates the intake by applying weights assigned in the nuclide file for each assay. DOSEXPRT is accessed off the OHIS MENU No. 4 and designed to be run as a batch processor, but can also be run interactively for testing purposes.

  13. Personnel neutron dosimetry

    SciTech Connect

    Hankins, D.

    1982-04-01

    This edited transcript of a presentation on personnel neutron discusses the accuracy of present dosimetry practices, requirements, calibration, dosemeter types, quality factors, operational problems, and dosimetry for a criticality accident. 32 figs. (ACR)

  14. Effect of tissue inhomogeneity on dose distribution of point sources of low-energy electrons.

    PubMed

    Kwok, C S; Bialobzyski, P J; Yu, S K; Prestwich, W V

    1990-01-01

    Perturbation in dose distributions of point sources of low-energy electrons at planar interfaces of cortical bone (CB) and red marrow (RM) was investigated experimentally and by Monte Carlo codes EGS and the TIGER series. Ultrathin LiF thermoluminescent dosimeters were used to measure the dose distributions of point sources of 204Tl and 147Pm in RM. When the point sources were at 12 mg/cm2 from a planar interface of CB and RM equivalent plastics, dose enhancement ratios in RM averaged over the region 0-12 mg/cm2 from the interface were measured to be 1.08 +/- 0.03 (SE) and 1.03 +/- 0.03 (SE) for 204Tl and 147Pm, respectively. The Monte Carlo codes predicted 1.05 +/- 0.02 and 1.01 +/- 0.02 for the two nuclides, respectively. However, EGS gave consistently 3% higher dose in the dose scoring region than the TIGER series when point sources of monoenergetic electrons up to 0.75 MeV energy were considered in the homogeneous RM situation or in the CB and RM heterogeneous situation. By means of the TIGER series, it was demonstrated that aluminum, which is normally assumed to be equivalent to CB in radiation dosimetry, leads to an overestimation of backscattering of low-energy electrons in soft tissue at a CB-soft-tissue interface by as much as a factor of 2. PMID:2233564

  15. EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications

    NASA Astrophysics Data System (ADS)

    Ceccolini, E.; Rocchi, F.; Mostacci, D.; Sumini, M.; Tartari, A.; Mariotti, F.

    2012-09-01

    The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 μm brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

  16. EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications

    SciTech Connect

    Ceccolini, E.; Mostacci, D.; Sumini, M.; Rocchi, F.; Tartari, A.; Mariotti, F.

    2012-09-01

    The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 {mu}m brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

  17. Electronic energy transfer: Localized operator partitioning of electronic energy in composite quantum systems

    NASA Astrophysics Data System (ADS)

    Khan, Yaser; Brumer, Paul

    2012-11-01

    A Hamiltonian based approach using spatially localized projection operators is introduced to give precise meaning to the chemically intuitive idea of the electronic energy on a quantum subsystem. This definition facilitates the study of electronic energy transfer in arbitrarily coupled quantum systems. In particular, the decomposition scheme can be applied to molecular components that are strongly interacting (with significant orbital overlap) as well as to isolated fragments. The result defines a consistent electronic energy at all internuclear distances, including the case of separated fragments, and reduces to the well-known Förster and Dexter results in their respective limits. Numerical calculations of coherent energy and charge transfer dynamics in simple model systems are presented and the effect of collisionally induced decoherence is examined.

  18. Fundamentals of high energy electron beam generation

    NASA Astrophysics Data System (ADS)

    Turman, B. N.; Mazarakis, M. G.; Neau, E. L.

    High energy electron beam accelerator technology has been developed over the past three decades in response to military and energy-related requirements for weapons simulators, directed-energy weapons, and inertially-confined fusion. These applications required high instantaneous power, large beam energy, high accelerated particle energy, and high current. These accelerators are generally referred to as 'pulsed power' devices, and are typified by accelerating potential of millions of volts (MV), beam current in thousands of amperes (KA), pulse duration of tens to hundreds of nanoseconds, kilojoules of beam energy, and instantaneous power of gigawatts to teffawatts (10(exp 9) to 10(exp 12) watts). Much of the early development work was directed toward single pulse machines, but recent work has extended these pulsed power devices to continuously repetitive applications. These relativistic beams penetrate deeply into materials, with stopping range on the order of a centimeter. Such high instantaneous power deposited in depth offers possibilities for new material fabrication and processing capabilities that can only now be explored. Fundamental techniques of pulse compression, high voltage requirements, beam generation and transport under space-charge-dominated conditions will be discussed in this paper.

  19. Dosimetry for Neutrons from 0.25 to 15 MeV by the Measurement of Linear Energy Transfer Distributions for Secondary Charged Particles in CR-39 Plastic

    NASA Astrophysics Data System (ADS)

    Tawara, Hiroko; Eda, Kazuyoshi; Sanami, Toshiya; Sasaki, Shinichi; Takahashi, Kazutoshi; Sonkawade, Rajendra; Nagamatsu, Aiko; Kitajo, Keiichi; Kumagai, Hidenori; Doke, Tadayoshi

    2008-03-01

    In the radiation fields of high energy accelerator facilities, high-altitude aircraft and space flights, high-energy neutron dosimetry of ˜20 MeV or more is a significant issue for radiological protection. We studied the feasibility of experimental measurements of linear energy transfer (LET) distributions for secondary charged particles induced by fast neutrons using CR-39 plastic nuclear track detectors. In order to investigate a method of analyzing the CR-39 detectors that is appropriate for fast neutron dosimetry, two-layer CR-39 stacks were exposed to monochromatic neutrons (0.25, 0.55, 5, and 15 MeV) at the Fast Neutron Laboratory of Tohoku University in Japan. We also conducted Monte Carlo calculations to estimate the detection efficiency of the CR-39 detector for recoil protons. The CR-39 detectors treated by single-step chemical etching were used to obtain LET distributions for LET > 10 keV/µm-water. The results indicated that measurements of short-range particles are very important for obtaining the correct LET distributions. Using the measured LET distributions, we calculated neutron sensitivities, absorbed doses and dose equivalents based on the ICRP 60 Q-L relation and averaged quality factors. The dose equivalents were compared with the neutron fluence-to-dose equivalent conversion factors given by ICRP 74 and the averaged quality factors were compared with weighting factors given by ICRP 60 and ICRP 92.

  20. Methods and computer readable medium for improved radiotherapy dosimetry planning

    DOEpatents

    Wessol, Daniel E.; Frandsen, Michael W.; Wheeler, Floyd J.; Nigg, David W.

    2005-11-15

    Methods and computer readable media are disclosed for ultimately developing a dosimetry plan for a treatment volume irradiated during radiation therapy with a radiation source concentrated internally within a patient or incident from an external beam. The dosimetry plan is available in near "real-time" because of the novel geometric model construction of the treatment volume which in turn allows for rapid calculations to be performed for simulated movements of particles along particle tracks therethrough. The particles are exemplary representations of alpha, beta or gamma emissions emanating from an internal radiation source during various radiotherapies, such as brachytherapy or targeted radionuclide therapy, or they are exemplary representations of high-energy photons, electrons, protons or other ionizing particles incident on the treatment volume from an external source. In a preferred embodiment, a medical image of a treatment volume irradiated during radiotherapy having a plurality of pixels of information is obtained.

  1. Electron energy distribution in a dusty plasma: analytical approach.

    PubMed

    Denysenko, I B; Kersten, H; Azarenkov, N A

    2015-09-01

    Analytical expressions describing the electron energy distribution function (EEDF) in a dusty plasma are obtained from the homogeneous Boltzmann equation for electrons. The expressions are derived neglecting electron-electron collisions, as well as transformation of high-energy electrons into low-energy electrons at inelastic electron-atom collisions. At large electron energies, the quasiclassical approach for calculation of the EEDF is applied. For the moderate energies, we account for inelastic electron-atom collisions in the dust-free case and both inelastic electron-atom and electron-dust collisions in the dusty plasma case. Using these analytical expressions and the balance equation for dust charging, the electron energy distribution function, the effective electron temperature, the dust charge, and the dust surface potential are obtained for different dust radii and densities, as well as for different electron densities and radio-frequency (rf) field amplitudes and frequencies. The dusty plasma parameters are compared with those calculated numerically by a finite-difference method taking into account electron-electron collisions and the transformation of high-energy electrons at inelastic electron-neutral collisions. It is shown that the analytical expressions can be used for calculation of the EEDF and dusty plasma parameters at typical experimental conditions, in particular, in the positive column of a direct-current glow discharge and in the case of an rf plasma maintained by an electric field with frequency f=13.56MHz. PMID:26465570

  2. Propagation of low energy solar electrons

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.; Mcfadden, J. P.; Lin, R. P.

    1981-01-01

    Two events are reported in which 2-10 keV electrons of solar energy have undergone significant adiabatic mirroring and pitch angle scattering in large scale magnetic structures in the interplanetary medium within a distance of about 0.5 AU from the earth. Electrons of 3 keV, typical of the energies measured, have a speed of about one-tenth of the speed of light, so that their travel time from the sun at 0 deg pitch angle would be about 100 minutes. Their cyclotron radius is about 20 km for a pitch angle of 30 deg, and a field of magnitude of 5 nT, and the cyclotron period is about 7.1 milliseconds. The electrons are scattered by spatial variations in the interplanetary magnetic field. When the spatial variations are convected past a stationary spacecraft by a 500 km/sec solar wind, they are seen as temporal fluctuations at a frequency of about 3 Hz.

  3. Transient electron energy distribution in supported Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Merschdorf, M.; Kennerknecht, C.; Willig, K.; Pfeiffer, W.

    2002-11-01

    The electron relaxation in Ag nanoparticles supported on graphite is investigated by time-resolved multiphoton photoemission spectroscopy. The photoemission spectra map the transient electron energy distribution in the nanoparticles and reveal the internal thermalization and cooling of the electron gas. The excess energy stored in the electron gas is calculated using the free-electron model. In contrast to the behaviour of isolated nanoparticles the energy loss rate from the electron gas increases with the pump fluence. This indicates that the electron gas equilibration in Ag nanoparticles on graphite is modified by excited electron transport.

  4. Electron energy loss spectroscopy in advanced materials

    SciTech Connect

    Zaluzec, N.J.

    1991-01-01

    The combination of a Transmission Electron Microscope (TEM) with an electron energy loss spectrometer (EELS) yields a powerful tool for the microcharacterization of materials. However, the application of this technique to advanced materials problems can only be fully appreciated when the information obtained using EELS is related to that obtained from other analytical spectroscopies. In this chapter, we briefly discuss the relative performance of X-ray, Auger and Photoelectron Spectroscopies with EELS pointing out the limitations and merits of each. This comparison is followed by examples of the application of EELS to investigations involving high {Tc} superconductors, artificial metallic superlattices, amorphous magnetic materials and the characterization of metallic hydride phases. 14 refs., 22 figs.

  5. Composite Transport Coefficient for Electron Thermal Energy

    NASA Astrophysics Data System (ADS)

    Coppi, B.; Daughton, W.

    1996-11-01

    A series of experiments by the Alcator C-Mod machine over a range of heating conditions (ohmic to strongly r.f. heated) has led to the construction of a composite transport coefficient for the electron thermal energy. This is represented by the difference of two terms: one corresponding to an outflow of thermal energy and the other one corresponding to an inflow. There are theoretical arguments(B. Coppi and F. Pegoraro, Phys. Fluids B) 3 p. 2582 (1991) in support of a composite transport coefficient involving the elements of a transport matrix with an inflow term related for instance to the features of the current density profile relative to those of the electron temperature. In deriving the transport coefficient D_e^th that has been used to simulate the Alcator C-Mod plasmas, we have assumed that the driving factor of the underlying modes is the plasma pressure gradient. Thus D_e^th ∝ D_e^o [β_p* - C] where β_p* = (8π p* / B_p^2), p* ≡ -r(dp/dr) is evaluated at the point of maximum pressure gradient, C ≈ 3/16 is a positive numerical coefficient and D_e^o ∝ I_p/(nT)^5/6 is basically the Coppi-Mazzucato-Gruber diffusion coefficient introduced earlier to reproduce the results of experiments with ohmic heating. Supported in part by the U.S. Department of Energy

  6. Comparison of CREME (Cosmic Ray Effects on Microelectronics) model LET (Linear Energy Transfer) spaceflight dosimetry data

    NASA Astrophysics Data System (ADS)

    Letaw, John R.; Adams, James H., Jr.

    1986-07-01

    The galactic cosmic radiation (GCR) component of space radiation is the dominant cause of single event phenomena in microelectronic circuits when Earth's magnetic shielding is low. Spaceflights outside the magnetosphere and in high inclination orbits are examples of such circumstances. In high inclination orbits, low energy (high LET) particles are transmitted through the field only at extreme latitudes, but can dominate the orbit-averaged dose. GCR is an important part of the radiation dose to astronauts under the same conditions. As a test of the CREME environmental model and particle transport codes used to estimate single event upsets, we have compiled existing measurements of HZE doses where GCR is expected to be important: Apollo 16 and 17, Skylab, Apollo Soyuz Test Project, and Kosmos 782. The LET spectra, due to direct ionization from GCR, for each of these missions has been estimated. The resulting comparisons with data validate the CREME model predictions of high LET galactic cosmic ray fluxes to within a factor of two. Some systematic differences between the model and data are identified.

  7. 10 CFR 835.1304 - Nuclear accident dosimetry.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Emergency Exposure Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material...

  8. 10 CFR 835.1304 - Nuclear accident dosimetry.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Emergency Exposure Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material...

  9. 10 CFR 835.1304 - Nuclear accident dosimetry.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Nuclear accident dosimetry. 835.1304 Section 835.1304 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Emergency Exposure Situations § 835.1304 Nuclear accident dosimetry. (a) Installations possessing sufficient quantities of fissile material...

  10. A small-scale anatomical dosimetry model of the liver

    NASA Astrophysics Data System (ADS)

    Stenvall, Anna; Larsson, Erik; Strand, Sven-Erik; Jönsson, Bo-Anders

    2014-07-01

    Radionuclide therapy is a growing and promising approach for treating and prolonging the lives of patients with cancer. For therapies where high activities are administered, the liver can become a dose-limiting organ; often with a complex, non-uniform activity distribution and resulting non-uniform absorbed-dose distribution. This paper therefore presents a small-scale dosimetry model for various source-target combinations within the human liver microarchitecture. Using Monte Carlo simulations, Medical Internal Radiation Dose formalism-compatible specific absorbed fractions were calculated for monoenergetic electrons; photons; alpha particles; and 125I, 90Y, 211At, 99mTc, 111In, 177Lu, 131I and 18F. S values and the ratio of local absorbed dose to the whole-organ average absorbed dose was calculated, enabling a transformation of dosimetry calculations from macro- to microstructure level. For heterogeneous activity distributions, for example uptake in Kupffer cells of radionuclides emitting low-energy electrons (125I) or high-LET alpha particles (211At) the target absorbed dose for the part of the space of Disse, closest to the source, was more than eight- and five-fold the average absorbed dose to the liver, respectively. With the increasing interest in radionuclide therapy of the liver, the presented model is an applicable tool for small-scale liver dosimetry in order to study detailed dose-effect relationships in the liver.

  11. Photon and electron collimator effects on electron output and abutting segments in energy modulated electron therapy

    SciTech Connect

    Olofsson, Lennart; Karlsson, Magnus G.; Karlsson, Mikael

    2005-10-15

    In energy modulated electron therapy a large fraction of the segments will be arranged as abutting segments where inhomogeneities in segment matching regions must be kept as small as possible. Furthermore, the output variation between different segments should be minimized and must in all cases be well predicted. For electron therapy with add-on collimators, both the electron MLC (eMLC) and the photon MLC (xMLC) contribute to these effects when an xMLC tracking technique is utilized to reduce the x-ray induced leakage. Two add-on electron collimator geometries have been analyzed using Monte Carlo simulations: One isocentric eMLC geometry with an isocentric clearance of 35 cm and air or helium in the treatment head, and one conventional proximity geometry with a clearance of 5 cm and air in the treatment head. The electron fluence output for 22.5 MeV electrons is not significantly affected by the xMLC if the shielding margins are larger than 2-3 cm. For small field sizes and 9.6 MeV electrons, the isocentric design with helium in the treatment head or shielding margins larger than 3 cm is needed to avoid a reduced electron output. Dose inhomogeneity in the matching region of electron segments is, in general, small when collimator positions are adjusted to account for divergence in the field. The effect of xMLC tracking on the electron output can be made negligible while still obtaining a substantially reduced x-ray leakage contribution. Collimator scattering effects do not interfere significantly when abutting beam techniques are properly applied.

  12. Electron-energy losses in hemispherical targets

    SciTech Connect

    Aizpurua, J.; Rivacoba, A.; Apell, S.P.

    1996-07-01

    In the framework of classical dielectric theory, the hemispherical geometry is studied. Calculations on surface modes are carried out for isolated Drude-like hemispheres. The convergence of the results with respect to the number of coupled terms in the expressions of the potential is discussed. The electron-energy-loss probability is studied for Al and Ag particles involving this geometry. The surface modes and hence the energy-loss probability are given by coupled expressions, the physical meaning of which is the coupling among multipolar terms, because of the particular geometry. The results obtained here present a good quantitative agreement with experiments in the case of clear surfaces (Ag) and provide a qualitative understanding for the experiments in Al, in terms of the position and impact parameter of the beam. This allows us to set the validity of the dielectric theory for cases that seemed to question it. {copyright} {ital 1996 The American Physical Society.}

  13. Low-energy electron collisions with biomolecules

    NASA Astrophysics Data System (ADS)

    Winstead, Carl; McKoy, Vincent

    2012-11-01

    We report recent progress in applying the Schwinger multichannel computational method to the interactions of slow electrons with biomolecules. Calculations on constituents of DNA, including nucleobases, phosphate esters, and models of the backbone sugar, have provided insight into the nature of the low-energy shape resonances, and thereby into possible sites and mechanisms for electron attachment that may lead to strand-breaking. At the same time, more approximate calculations on larger assemblies such as nucleosides and deoxyadenosine monophosphate indicate how the resonance properties of the subunits will or will not persist in DNA itself. We are pursuing a similar strategy for another major class of biomolecules, the proteins, by beginning with fixed-nuclei studies of the constituent amino acids; here we present preliminary results for the simplest amino acid, glycine. We also describe efforts directed at an improved understanding electron collisions with alcohols, which, in addition to basic scientific interest, may prove useful in the modeling of ignition and combustion within biofuel-powered engines.

  14. Low-energy electron collisions with thiophene

    NASA Astrophysics Data System (ADS)

    da Costa, R. F.; Varella, M. T. do N.; Lima, M. A. P.; Bettega, M. H. F.

    2013-05-01

    We report on elastic integral, momentum transfer, and differential cross sections for collisions of low-energy electrons with thiophene molecules. The scattering calculations presented here used the Schwinger multichannel method and were carried out in the static-exchange and static-exchange plus polarization approximations for energies ranging from 0.5 eV to 6 eV. We found shape resonances related to the formation of two long-lived π* anion states. These resonant structures are centered at the energies of 1.00 eV (2.85 eV) and 2.82 eV (5.00 eV) in the static-exchange plus polarization (static-exchange) approximation and belong to the B1 and A2 symmetries of the C2v point group, respectively. Our results also suggest the existence of a σ* shape resonance in the B2 symmetry with a strong d-wave character, located at around 2.78 eV (5.50 eV) as obtained in the static-exchange plus polarization (static-exchange) calculation. It is worth to mention that the results obtained at the static-exchange plus polarization level of approximation for the two π* resonances are in good agreement with the electron transmission spectroscopy results of 1.15 eV and 2.63 eV measured by Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004), 10.1021/jp048759a]. The existence of the σ* shape resonance is in agreement with the observations of Dezarnaud-Dandiney et al. [J. Phys. B 31, L497 (1998), 10.1088/0953-4075/31/11/004] based on the electron transmission spectra of dimethyl(poly)sulphides. A comparison among the resonances of thiophene with those of pyrrole and furan is also performed and, altogether, the resonance spectra obtained for these molecules point out that electron attachment to π* molecular orbitals is a general feature displayed by these five-membered heterocyclic compounds.

  15. Cross sections required for FMIT dosimetry

    SciTech Connect

    Gold, R.; McElroy, W.N.; Lippincott, E.P.; Mann, F.M.; Oberg, D.L.; Roberts, J.H.; Ruddy, F.H.

    1980-05-02

    The Fusion Materials Irradiation Test (FMIT) facility, currently under construction, is designed to produce a high flux of high energy neutrons for irradiation effects experiments on fusion reactor materials. Characterization of the flux-fluence-spectrum in this rapidly varying neutron field requires adaptation and extension of currently available dosimetry techniques. This characterization will be carried out by a combination of active, passive, and calculational dosimetry. The goal is to provide the experimenter with accurate neutron flux-fluence-spectra at all positions in the test cell. Plans have been completed for a number of experimental dosimetry stations and provision for these facilities has been incorporated into the FMIT design. Overall needs of the FMIT irradiation damage program delineate goal accuracies for dosimetry that, in turn, create new requirements for high energy neutron cross section data. Recommendations based on these needs have been derived for required cross section data and accuracies.

  16. A survey of physical dosimetry to date and in the near future: Part 1. Review of standards and regulatory issues.

    PubMed

    Cassata, James R

    2002-02-01

    This article summarizes the status of the relevant standards and current regulatory issues for use of physical dosimetry devices for the occupational worker in the United States. Included is a summary of relevant standards from the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), the American National Standards Institute (ANSI), the United States Nuclear Regulatory Commission NUREG-Series, the National Voluntary Laboratory Accreditation Program (NVLAP), the Department of Energy Laboratory Accreditation Program (DOELAP), and the U.S. Military Specifications and Standards (MIL-STD). Proposed changes to ANSI N13.11-1993, "American National Standard for Dosimetry-Personnel Dosimetry Performance Criteria for Testing," are listed. The strategic changes that the United States Nuclear Regulatory Commission (NRC) is making in rulemaking activities related to dosimetry and standards are given. The status of Measurement Program Description (MPD) C.18, "Implementation of Electronic Dosimetry for Primary Dosimetry," from the Council on Ionizing Radiation Measurements and Standards (CIRMS) is given. PMID:11873507

  17. Shashlik calorimeter response to high energy electrons

    NASA Astrophysics Data System (ADS)

    Dobrzynski, L.

    1994-04-01

    We report the results coming from an extensive study of a Shashlik calorimeter prototype for CMS. Nine (47 × 47 mm 2) towers were exposed to a high energy electron beam at CERN SPS and read out by silicon photodiodes followed by low noise preamplifiers. The main results are the measurements of: -|the energy resolution: {σ}/{E}(%)= {(8.4±0.1)}/{E}⊕ {(0.37±0.03)}/{E}⊕(0.8±0.2) ; -|the shower resolution: σ x,y(mm)= {9.1±0.3 stat±0.7 syst}/{E}⊕ {27±1.4 stat±2.1 syst}/{E}. -|We also give the angular resolution of the direction of an electron shower. It is estimated by using one point from a preshower detector located at 3 X0 and the second point on a barycenter in the calorimeter mosaic. The result is encouraging being in agreement with a resolution of σ θ( mrad) = {70}/{√E}, which gives for an electron of 50 GeV an angular resolution of 10 mrad. -|The uniformity of the calorimeter response is found to be better than ± 1%. -|The mean light yield measured in Shashlik towers equipped with Y7 WLS fibres from Kuraray and aluminized at the front side of the tower is of the order of 12300 γ/ GeV assuming a quantum efficiency of 62.5% for the Si photodiode.

  18. Fundamentals of Radiation Dosimetry

    NASA Astrophysics Data System (ADS)

    Bos, Adrie J. J.

    2011-05-01

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  19. Fundamentals of Radiation Dosimetry

    SciTech Connect

    Bos, Adrie J. J.

    2011-05-05

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  20. Health physics research reactor reference dosimetry

    SciTech Connect

    Sims, C.S.; Ragan, G.E.

    1987-06-01

    Reference neutron dosimetry is developed for the Health Physics Research Reactor (HPRR) in the new operational configuration directly above its storage pit. This operational change was physically made early in CY 1985. The new reference dosimetry considered in this document is referred to as the 1986 HPRR reference dosimetry and it replaces any and all HPRR reference documents or papers issued prior to 1986. Reference dosimetry is developed for the unshielded HPRR as well as for the reactor with each of five different shield types and configurations. The reference dosimetry is presented in terms of three different dose and six different dose equivalent reporting conventions. These reporting conventions cover most of those in current use by dosimetrists worldwide. In addition to the reference neutron dosimetry, this document contains other useful dosimetry-related data for the HPRR in its new configuration. These data include dose-distance measurements and calculations, gamma dose measurements, neutron-to-gamma ratios, ''9-to-3 inch'' ratios, threshold detector unit measurements, 56-group neutron energy spectra, sulfur fluence measurements, and details concerning HPRR shields. 26 refs., 11 figs., 31 tabs.

  1. Characterization of calibration curves and energy dependence GafChromic{sup TM} XR-QA2 model based radiochromic film dosimetry system

    SciTech Connect

    Tomic, Nada Quintero, Chrystian; Aldelaijan, Saad; Bekerat, Hamed; Liang, LiHeng; DeBlois, François; Devic, Slobodan; Whiting, Bruce R.; Seuntjens, Jan

    2014-06-15

    Purpose: The authors investigated the energy response of XR-QA2 GafChromic{sup TM} film over a broad energy range used in diagnostic radiology examinations. The authors also made an assessment of the most suitable functions for both reference and relative dose measurements. Methods: Pieces of XR-QA2 film were irradiated to nine different values of air kerma in air, following reference calibration of a number of beam qualities ranging in HVLs from 0.16 to 8.25 mm Al, which corresponds to effective energy range from 12.7 keV to 56.3 keV. For each beam quality, the authors tested three functional forms (rational, linear exponential, and power) to assess the most suitable function by fitting the delivered air kerma in air as a function of film response in terms of reflectance change. The authors also introduced and tested a new parameterχ = netΔR·e{sup m} {sup netΔR} that linearizes the inherently nonlinear response of the film. Results: The authors have found that in the energy range investigated, the response of the XR-QA2 based radiochromic film dosimetry system ranges from 0.222 to 0.420 in terms of netΔR at K{sub air}{sup air} = 8 cGy. For beam qualities commonly used in CT scanners (4.03–8.25 mm Al), the variation in film response (netΔR at K{sub air}{sup air} = 8 cGy) amounts to ± 5%, while variation in K{sub air}{sup air} amounts to ± 14%. Conclusions: Results of our investigation revealed that the use of XR-QA2 GafChromic{sup TM} film is accompanied by a rather pronounced energy dependent response for beam qualities used for x-ray based diagnostic imaging purposes. The authors also found that the most appropriate function for the reference radiochromic film dosimetry would be the power function, while for the relative dosimetry one may use the exponential response function that can be easily linearized.

  2. Ionization By Impact Electrons in Solids: Electron Mean Free Path Fitted Over A Wide Energy Range

    SciTech Connect

    Ziaja, B; London, R A; Hajdu, J

    2005-06-09

    We propose a simple formula for fitting the electron mean free paths in solids both at high and at low electron energies. The free-electron-gas approximation used for predicting electron mean free paths is no longer valid at low energies (E < 50 eV), as the band structure effects become significant at those energies. Therefore we include the results of the band structure calculations in our fit. Finally, we apply the fit to 9 elements and 2 compounds.

  3. SU-E-T-335: Transit Dosimetry for Verification of Dose Delivery Using Electronic Portal Imaging Device (EPID)

    SciTech Connect

    Baek, T; Chung, E; Lee, S; Yoon, M

    2014-06-01

    Purpose: To evaluate the effectiveness of transit dose, measured with an electronic portal imaging device (EPID), in verifying actual dose delivery to patients. Methods: Plans of 5 patients with lung cancer, who received IMRT treatment, were examined using homogeneous solid water phantom and inhomogeneous anthropomorphic phantom. To simulate error in patient positioning, the anthropomorphic phantom was displaced from 5 mm to 10 mm in the inferior to superior (IS), superior to inferior (SI), left to right (LR), and right to left (RL) directions. The transit dose distribution was measured with EPID and was compared to the planed dose using gamma index. Results: Although the average passing rate based on gamma index (GI) with a 3% dose and a 3 mm distance-to-dose agreement tolerance limit was 94.34 % for the transit dose with homogeneous phantom, it was reduced to 84.63 % for the transit dose with inhomogeneous anthropomorphic phantom. The Result also shows that the setup error of 5mm (10mm) in IS, SI, LR and SI direction can Result in the decrease in values of GI passing rates by 1.3% (3.0%), 2.2% (4.3%), 5.9% (10.9%), and 8.9% (16.3%), respectively. Conclusion: Our feasibility study suggests that the transit dose-based quality assurance may provide information regarding accuracy of dose delivery as well as patient positioning.

  4. The radiation dosimetry of intrathecally administered radionuclides

    SciTech Connect

    Stabin, M.G.; Evans, J.F.

    1999-01-01

    The radiation dose to the spine, spinal cord, marrow, and other organs of the body from intrathecal administration of several radiopharmaceuticals was studied. Anatomic models were developed for the spine, spinal cerebrospinal fluid (CSF), spinal cord, spinal skeleton, cranial skeleton, and cranial CSF. A kinetic model for the transport of CSF was used to determine residence times in the CSF; material leaving the CSF was thereafter assumed to enter the bloodstream and follow the kinetics of the radiopharmaceutical as if intravenously administered. The radiation transport codes MCNP and ALGAMP were used to model the electron and photon transport and energy deposition. The dosimetry of Tc-99m DTPA and HSA, In-111 DTPA, I-131 HSA, and Yb-169 DTPA was studied. Radiation dose profiles for the spinal cord and marrow in the spine were developed and average doses to all other organs were estimated, including dose distributions within the bone and marrow.

  5. Path forward for dosimetry cross sections

    SciTech Connect

    Griffin, P.J.; Peters, C.D.

    2011-07-01

    In the 1980's the dosimetry community embraced the need for a high fidelity quantification of uncertainty in nuclear data used for dosimetry applications. This led to the adoption of energy-dependent covariance matrices as the accepted manner of quantifying the uncertainty data. The trend for the dosimetry community to require high fidelity treatment of uncertainty estimates has continued to the current time where requirements on nuclear data are codified in standards such as ASTM E 1018. This paper surveys the current state of the dosimetry cross sections and investigates the quality of the current dosimetry cross section evaluations by examining calculated-to-experimental ratios in neutron benchmark fields. In recent years more nuclear-related technical areas are placing an emphasis on uncertainty quantification. With the availability of model-based cross sections and covariance matrices produced by nuclear data codes, some nuclear-related communities are considering the role these covariance matrices should play. While funding within the dosimetry community for cross section evaluations has been very meager, other areas, such as the solar-related astrophysics community and the US Nuclear Criticality Safety Program, have been supporting research in the area of neutron cross sections. The Cross Section Evaluation Working Group (CSEWG) is responsible for the creation and maintenance of the ENDF/B library which has been the mainstay for the reactor dosimetry community. Given the new trends in cross section evaluations, this paper explores the path forward for the US nuclear reactor dosimetry community and its use of the ENDF/B cross-sections. The major concern is maintenance of the sufficiency and accuracy of the uncertainty estimate when used for dosimetry applications. The two major areas of deficiency in the proposed ENDF/B approach are: 1) the use of unrelated covariance matrices in ENDF/B evaluations and 2) the lack of 'due consideration' of experimental data

  6. Controlling electron energy distributions for plasma technologies

    NASA Astrophysics Data System (ADS)

    Kushner, Mark

    2009-10-01

    The basic function of low temperature plasmas in society benefiting technologies is to channel power into specific modes of atoms and molecules to excite desired states or produce specified radicals. This functionality ultimately depends on the ability to craft an electron energy distribution (EED) to match cross sections. Given electric fields, frequencies, gas mixtures and pressures, predicting EEDs and excitation rates can in large part be reliably done. The inverse problem, specifying the conditions that produce a given EED, is less well understood. Early strategies to craft EEDs include adjusting gas mixtures, such as the rare gas-Hg mixtures in fluorescent lamps, and externally sustained discharges, such as electron-beam sustained plasmas for molecular lasers. More recent strategies include spiker-sustainer circuitry which produces desired EEDs in non-self-sustained plasmas; and adjusting frequency in capacitively coupled plasmas. In this talk, past strategies for customizing EEDs in low pressure plasmas will be reviewed and prospects for improved control of plasma kinetics will be discussed using results from 2-dimensional computer models.

  7. Application of a new dosimetry formalism to volumetric modulated arc therapy (VMAT)

    NASA Astrophysics Data System (ADS)

    Rosser, Karen E.; Bedford, James L.

    2009-12-01

    Volumetric modulated arc therapy (VMAT) offers a challenge to classical dosimetry protocols as the beams are dynamic in orientation and aperture shape and may include small apertures. The aim of this paper is to apply a formalism to VMAT beams that has recently been published by the International Atomic Energy Agency (IAEA) working party to improve the dosimetry for small and non-standard fields. We investigated three possible fields and assessed their suitability as plan class specific reference (pcsr) fields. The factors in the new dosimetry formalism were investigated: the conversion of dose to water from the conventional reference field to the pcsr and then from the pcsr to a treatment plan, using a PTW semiflex chamber, two Farmer chambers and an electron diode. Finally, the dose was compared for Alanine, the new formalism and calculated using Pinnacle3 (Philips Radiation Oncology Systems) for two typical clinical VMAT beams. Correction factors between the reference field and the pcsr determined with Alanine range from 0.1% to 2.3% for the three pcsr fields. Dose to water measured using the calibrated ionization chambers is less than 2% different to the dose calculated by Pinnacle3. VMAT planning and delivery procedures have been successfully implemented and a new dosimetry protocol has been investigated for this new technique. Calibration factors for pcsr fields are found to be up to 2.3% different when using the new formalism, compared to using a standard dosimetry protocol. Using the calibration factors determined in the pcsr fields, the ionization chambers and electron diode agree to within 1% with Alanine dosimetry for two clinical VMAT plans. Good agreements between calculations and measurements are found for these two plans when the new formalism is used.

  8. Readout electronics for the Dark Energy Camera

    NASA Astrophysics Data System (ADS)

    Castilla, Javier; Ballester, Otger; Cardiel, Laia; Chappa, Steve; de Vicente, Juan; Holm, Scott; Huffman, David; Kozlovsky, Mark; Martinez, Gustavo; Olsen, Jamieson; Shaw, Theresa; Stuermer, Walter

    2010-07-01

    The goal of the Dark Energy Survey (DES) is to measure the dark energy equation of state parameter with four complementary techniques: galaxy cluster counts, weak lensing, angular power spectrum and type Ia supernovae. DES will survey a 5000 sq. degrees area of the sky in five filter bands using a new 3 deg2 mosaic camera (DECam) mounted at the prime focus of the Blanco 4-meter telescope at the Cerro-Tololo International Observatory (CTIO). DECam is a ~520 megapixel optical CCD camera that consists of 62 2k x 4k science sensors plus 4 2k x 2k sensors for guiding. The CCDs, developed at the Lawrence Berkeley National Laboratory (LBNL) and packaged and tested at Fermilab, have been selected to obtain images efficiently at long wavelengths. A front-end electronics system has been developed specifically to perform the CCD readout. The system is based in Monsoon, an open source image acquisition system designed by the National Optical Astronomy Observatory (NOAO). The electronics consists mainly of three types of modules: Control, Acquisition and Clock boards. The system provides a total of 132 video channels, 396 bias levels and around 1000 clock channels in order to readout the full mosaic at 250 kpixel/s speed with 10 e- noise performance. System configuration and data acquisition is done by means of six 0.8 Gbps optical links. The production of the whole system is currently underway. The contribution will focus on the testing, calibration and general performance of the full system in a realistic environment.

  9. Sterilization of foods with low-energy electrons (``soft-electrons'')

    NASA Astrophysics Data System (ADS)

    Hayashi, Toru; Takahashi, Yoko; Todoriki, Setsuko

    1998-06-01

    Electrons with an energy of 300 keV or lower were defined as "Soft-electrons", which showed several advantages over conventional irradiation with gamma-rays or high-energy electrons in decontamination of grains and spices. Energies of electrons necessary to reduce microbial loads to levels lower than 10 CFU/g were 60 keV for brown rice, 75 keV for wheat, 100 keV for white pepper, coriander and basil, 130 keV for buckwheat, 160 keV for rough rice, and 210 keV for black pepper. Electrons with such energies did not significantly influence the quality.

  10. Electron energy distribution function by using probe method in electron cyclotron resonance multicharged ion source

    SciTech Connect

    Kumakura, Sho Kurisu, Yosuke; Kimura, Daiju; Yano, Keisuke; Imai, Youta; Sato, Fuminobu; Kato, Yushi; Iida, Toshiyuki

    2014-02-15

    We are constructing a tandem type electron cyclotron resonance (ECR) ion source (ECRIS). High-energy electrons in ECRIS plasma affect electron energy distribution and generate multicharged ion. In this study, we measure electron energy distribution function (EEDF) of low energy region (≦100 eV) in ECRIS plasma at extremely low pressures (10{sup −3}–10{sup −5} Pa) by using cylindrical Langmuir probe. From the result, it is found that the EEDF correlates with the electron density and the temperature from the conventional probe analysis. In addition, we confirm that the tail of EEDF spreads to high energy region as the pressure rises and that there are electrons with high energy in ECR multicharged ion source plasma. The effective temperature estimated from the experimentally obtained EEDF is larger than the electron temperature obtained from the conventional method.