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Sample records for dosimeter fxg chemical

  1. Absorbed dose distribution visualization for superficial treatments through the Fricke Xylenol Gel dosimeter (FXG)

    NASA Astrophysics Data System (ADS)

    Alva, M.; Sampaio, F. G. A.; Moreira, M. V.; Petchevist, P. C. D.; de Almeida, A.

    2010-11-01

    Electrons, orthovoltage X-rays and betas are used for superficial treatments. It has been shown that it is practical to measure these three types of radiation using gel dosimetry, which is an accurate dosimetric tool, from which one can infer the absorbed dose. The Fricke Xylenol Gel (FXG) dosimeter has presented adequate results due to its spatial resolution, effective atomic number and density that are near to those of soft tissue. The aim of this work is to compare three types of radiation for skin treatments like orthovoltage (X-rays), brachytherapy (beta rays) and megavoltage (electrons) using the FXG-CCD dosimetric system to determine the calibration curves (CC), beam profiles (BP) and percentage depth dose curves (PDD), evidencing why for clinical applications a specific type of radiation is selected for superficial treatment. From the results obtained we can infer that the FXG-CCD system is adequate for linear, area and volume measurements.

  2. Chemical Dosimeter Tube With Coaxial Sensing Rod

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E.

    1993-01-01

    Improved length-of-stain (LOS) chemical dosimeter indicates total dose of chemical vapor in air. Made with rods and tubes of various diameters to obtain various sensitivities and dynamic ranges. Sensitivity larger and dose range smaller when more room for diffusion in gap between tube and rod. Offers greater resistance to changing of color of exposed dye back to color of unexposed condition, greater sensitivity, and higher degree of repeatability. Developed to measure doses of gaseous HCI, dosimeter modified by use of other dyes to indicate doses of other chemical vapors.

  3. Investigating hydrogel dosimeter decomposition by chemical methods

    NASA Astrophysics Data System (ADS)

    Jordan, Kevin

    2015-01-01

    The chemical oxidative decomposition of leucocrystal violet micelle hydrogel dosimeters was investigated using the reaction of ferrous ions with hydrogen peroxide or sodium bicarbonate with hydrogen peroxide. The second reaction is more effective at dye decomposition in gelatin hydrogels. Additional chemical analysis is required to determine the decomposition products.

  4. SU-E-T-606: Performance of MR-Based 3D FXG Dosimetry for Preclinical Irradiation

    SciTech Connect

    Welch, M; Jaffray, D

    2015-06-15

    Purpose: Technological advances have revolutionized preclinical radiation research to enable precise radiation delivery in preclinical models. Kilovoltage x-rays and complex geometries in preclinical radiation studies challenge conventional dosimetry methods. Previously developed gel-based dosimetry provides a viable means of accommodating complex geometries and accurately reporting dose at kV energies. This paper will describe the development and evaluation of gel-based ferrous xylenol-orange (FXG) dosimetry using a 7T preclinical imaging system. Methods: To confirm water equivalence, Zeff values were calculated for the FXG material, water and ICRU defined soft tissue. Proton T1 relaxivity response in FXG was measured using a preclinical 7T MR and a small animal irradiator for a dose range of 1–22 Gy. FXG was contained in 50 ml centrifuge tubes and irradiated with a 225 kVp x-ray beam at a nominal dose rate of 2.3 Gy/min. Pre and post irradiation maps of the T1 relaxivity were collected using variable TR spin-echo imaging (TE 6.65 ms; TR 500, 750, 1000, 1500, 2000, 3000 and 5000 ms) with 2 mm thick slices, 0.325 mm/pixel, 3 averages and an acquisition time of 26 minutes. A linear fit to the change in relaxation rate (1/T1) for the delivered doses reported the gel sensitivity in units of ms{sup -1}Gy{sup -1}. Irradiation and imaging studies were repeated using three batches of gel over 72 hrs. Results: FXG has a Zeff of 3.8 for the 225 kVp spectrum used; differing from water and ICRU defined soft tissue by 0.5% and 2.5%, respectively. The average sensitivity for the FXG dosimeter was 31.5 ± 0.7 ms{sup -1}Gy{sup -1} (R{sup 2} = 0.9957) with a y-intercept of −29.4 ± 9.0 ms{sup -1}. Conclusion: Preliminary results for the FXG dosimeter properties, sensitivity, and dose linearity at preclinical energies is promising. Future work will explore anatomically relevant tissue inclusions to test MR performance. Student funding provided by The Terry Fox Foundation

  5. Controlling sensitivity and stability of ferrous-xylenol orange-gelatin 3D gel dosimeters by doping with phenanthroline-type ligands and glyoxal

    NASA Astrophysics Data System (ADS)

    Penev, Kalin I.; Mequanint, Kibret

    2013-03-01

    The ferrous-xylenol orange-gelatin (FXG) dosimeter is widely used for three-dimensional ionizing radiation field mapping through optical scanning. Upon irradiation, the ferrous iron (Fe2+) is oxidized to ferric iron (Fe3+), which forms an intensely coloured complex with xylenol orange (XO). XO also acts as a diffusion-limiting additive; however, its presence may cause rapid auto-oxidation of Fe2+ during storage and low stability of the dose response. In this work, phenanthroline-type ligands were added to FXG system in a bid to bind the ferrous iron in a stable complex and minimize the rate of the auto-oxidation, whereas glyoxal was used as a chemical cross-linker, aiming to minimize the ferric iron diffusion. It was found that addition of either 1,10-phenanthroline or 5-nitro-1,10-phenanthroline can improve the auto-oxidation behaviour of the gels. However, the initial background absorbance was slightly increased, and the sensitivity of the dosimeters was decreased. Doping with glyoxal led to a moderate decrease of the diffusion only in those gels that also contained a phenanthroline-type ligand, and did not affect the initial dose response. Glyoxal also afforded an extended period of stable background absorbance level after an initial period of bleaching of the gel. Following re-irradiation, most glyoxal-containing dosimeters showed an excellent linearity of the dose response, albeit at a decreased sensitivity. We recommend further testing of FXG dosimeters, doped with phenanthroline-type ligands and glyoxal as a means for controlling the dose response and improving the long-term storage properties of the gels and the potential for dose fractionation.

  6. Electron Beam Quality Determination Through Fricke Xylenol Gel Dosimeter

    SciTech Connect

    Petchevist, P. C. D.; Moreira, M. V.; Almeida, A. de

    2009-03-10

    According to the IAEA TRS-398 protocol, a parallel plate ionization chamber is recommended to be used in electron dosimetry. The important dosimetric parameters such as R{sub 100} and R{sub 50}, inferred from the percentage depth dose (PDD) curve, allow to obtain the electron beam average energy at the water phantom surface (material equivalent to the soft tissue). In this work, a chemical dosimeter based on the Fe(II) to Fe(III) oxidation was used to obtain the average energies from electrons beams (from nominal energies of 5, 8 and 10 MeV) and related parameters of R{sub 100}, R{sub 50} and z{sub ref}. These energies obtained through the Fricke Xylenol Gel (FXG) were compared to those with a parallel plate ionization chamber, following the cited protocol, which showed no significant differences. From these measurements one can conclude the FXG applicability for R{sub 100}, R{sub 50} and electron beam average energy determination.

  7. Characterization of the chemical stability of irradiated N-isopropylacrylamide gel dosimeter

    NASA Astrophysics Data System (ADS)

    Huang, Y. R.; Hsieh, L. L.; Chang, Y. J.; Wang, T. H.; Hsieh, B. T.

    2013-08-01

    An investigation of the normoxic NIPAM gel dosimeter has been undertaken. The NIPAM gel dosimeter used in the current study was mainly composed of gelatin, NIPAM, N,N‧-methylenebisacrylamide (BIS), and distilled water. This study aims to measure the change in the chemical structure of the NIPAM gel dosimeter after irradiation via the 13C-NMR, 1H-NMR, and Fourier transform Raman (FT-Raman) spectra. The 13C-NMR experimental results show that the C=C bonds of NIPAM and BIS are at 126.74 and 131.62 ppm, respectively. The intensity of the C-C bond of the NIPAM gel dosimeter increases with the absorbed dose, and the dose-intensity curve of the C-C bond is determined by y=0.0506+79.9(1-e0.16x) (R2=0.9997). 1H-NMR and FT-Raman can also effectively determine the positions of the C=C bonds of NIPAM and BIS, and the intensity decreases as the absorbed radiation dose increases. Hence, 13C-NMR, 1H-NMR, and FT-Raman spectrometers can effectively detect the changes in the chemical structure of the polymer gel dosimeter after irradiation and successfully determine the D50 dosage in the NIPAM gel dosimeter.

  8. Application of radiochromic gel detector (FXG) for UVA dose measurements

    NASA Astrophysics Data System (ADS)

    Abukassem, Issam; Bero, Mamdouh A.

    2010-12-01

    Tissue equivalent radiochromic gel material containing ferrous ions, xylenol-orange ion indicator and gelatin as gelling agent (FXG) is known to be sensitive to γ- and X-rays; hence it has been used for ionizing radiation dosimetry. Changes in optical absorbance properties of FXG material over a wide region in the visible spectrum were found to be proportional to the radiation absorbed dose. An earlier study demonstrated the sensitivity of FXG gel detector to ultraviolet radiation and therefore that could give quantitative measure for UV exposure. This study focuses on the detection of UVA radiation (315-400 nm), which forms an important part (˜97%) of the natural solar UV radiation reaching the earth surface. A solar UV simulator device was used to deliver UVA radiation to FXG samples. The beam was optically modified to irradiate gel samples at an exposure level about 58 W/m 2, which is comparable to the summer natural UVA radiation measured outside the laboratory building at midday (˜60 W/m 2). Experimental results were used to generate mathematical second order formulas that give the relationship between UVA dose and optical absorbance changes observed at two wavelengths in the visible region of the spectrum—430 and 560 nm.

  9. The effect of chemical stability on the NIPAM gel dosimeter using 1H-NMR

    NASA Astrophysics Data System (ADS)

    Huang, You-Ruei; Hsieh, Ling-Ling; Chang, Yuan-Jen; Hsieh, Bor-Tsung

    2013-06-01

    Radiation-induced chemical changes in the N-isopropylacrylamide (NIPAM) gels used in three-dimensional dosimeters were investigated using 1H-NMR in this study. The experimental results show that the signal from C=C bonds of NIPAM and N,N'-Methylenediacrylamide (BIS) are 5.5 and 6.3 ppm, respectively. The double bonds from the NIPAM and BIS disappeared with half-dose (D50) were about 10.90 Gy ± 0.76 Gy and 10.09 Gy ± 0.29 Gy, respectively. This observation demonstrates that the polymerization rate of BIS is faster than that of the NIPAM monomer. The 1H-NMR can indicate the chemical structure changes of the polymer gel dosimeter after irradiation and successfully determine the D50 in the NIPAM gel dosimeter.

  10. Timing considerations for preclinical MRgRT: effects of ion diffusion, SNR and imaging times on FXG gel calibration

    NASA Astrophysics Data System (ADS)

    Welch, M.; Foltz, W. D.; Jaffray, D. A.

    2015-01-01

    Sub-millimeter resolution images are required for gel dosimeters to be used in preclinical research, which is challenging for MR probed ferrous xylenol-orange (FXG) dosimeters due to ion diffusion and inadequate SNR. A preclinical 7 T MR, small animal irradiator and FXG dosimeters were used in all experiments. Ion diffusion was analyzed using high resolution (0.2 mm/pixel) T1 MR images collected every 5 minutes, post-irradiation, for an hour. Using Fick's second law, ion diffusion was approximated for the first hour post-irradiation. SNR, T1 map precision and calibration fit were determined for two MR protocols: (1) 10 minute acquisition, 0.35mm/pixel and 3mm slices, (2) 45 minute acquisition, 0. 25 mm/pixel and 2 mm slices. SNR and T1 map precision were calculated using a Monte Carlo simulation. Calibration curves were determined by plotting R1 relaxation rates versus depth dose data, and fitting a linear trend line. Ion diffusion was estimated as 0.003mm2 in the first hour post-irradiation. For protocols (1) and (2) respectively, Monte Carlo simulation predicted T1 precisions of 3% and 5% within individual voxels using experimental SNRs; the corresponding measured T1 precisions were 8% and 12%. The linear trend lines reported slopes of 27 ± 3 Gy*s (R2: 0.80 ± 0.04) and 27 ± 4 Gy*s (R2: 0.90 ± 0.04). Ion diffusion is negligible within the first hour post-irradiation, and an accurate and reproducible calibration can be achieved in a preclinical setting with sub-millimeter resolution.

  11. Study of Fricke gel dosimeter response for different gel quality

    NASA Astrophysics Data System (ADS)

    Cavinato, C. C.; Campos, L. L.

    2010-11-01

    The Fricke xylenol gel (FXG) dosimeter has been studied for application in radiotherapy because it is capable of to measure the spatial distribution of radiation doses. The dosimetry is based on the oxidation of ferrous (Fe2+) to ferric (Fe3+) ions radiation induced, related to the radiation dose. The gel material usually employed is the 300 Bloom gelatin, which is imported and very expensive in Brazil. Aiming to analyze the viability of to use a locally produced and low cost gel material, in this work the spectrophotometric responses of FXG solutions prepared using 270 Bloom gelatin commercially available and 300 Bloom gelatin imported were compared. The absorption spectra of solutions prepared with 5% by weight 270 and 300 Bloom gelatins non-irradiated and irradiated with 60Co gamma radiation in the dose range between 0.5 and 100 Gy were analysed, the dose-response curves were evaluated and the useful dose range was established. The obtained results indicate that the FXG solution prepared with 270 Bloom gelatin presents good performance, similar to that presented by the FXG solution prepared with 300 Bloom gelatin and its use can be recommended owing to the low cost and the availability in local market.

  12. Beta planar source quality assurance with the Fricke xylenol gel dosimeter

    NASA Astrophysics Data System (ADS)

    Alva-Sánchez, Mirko S.; de Oliveira, Lucas N.; Petchevist, Paulo C.; Moreira, Marco V.; de Almeida, Adelaide

    2014-03-01

    Beta therapy is employed in post surgery to treat lesions such as pterygia, keloid and glioblastoma. The beta source most used for these purposes is 90/90Y, whose quality assurance is a challenge, because the detectors currently used for this evaluation do not satisfy the spatial resolution, the effective atomic number and the tissue equivalent conditions. The Fricke xylenol gel (FXG) has been used in several applications in radiotherapy due to its better characteristics. This dosimeter is associated with the Fe(II) to Fe(III) oxidation, post ionizing irradiation, being the final Fe(III) concentration linearly depended on the absorbed dose. The goal of this present work is to show that the FXG, with atomic effective number (Zeff) of 7.75 and high resolution (<1 mm), accomplishes quality assurance for rectangular and square planar 90Sr/90Y sources. In order to demonstrate the quality assurance, calibration curves, percentage depth dose and beam profile from exposed FXG samples were analyzed and from these results, we demonstrate the potential use of the FXG dosimeter for beta source quality control.

  13. Issues involved in the quantitative 3D imaging of proton doses using optical CT and chemical dosimeters.

    PubMed

    Doran, Simon; Gorjiara, Tina; Kacperek, Andrzej; Adamovics, John; Kuncic, Zdenka; Baldock, Clive

    2015-01-21

    Dosimetry of proton beams using 3D imaging of chemical dosimeters is complicated by a variation with proton linear energy transfer (LET) of the dose-response (the so-called 'quenching effect'). Simple theoretical arguments lead to the conclusion that the total absorbed dose from multiple irradiations with different LETs cannot be uniquely determined from post-irradiation imaging measurements on the dosimeter. Thus, a direct inversion of the imaging data is not possible and the proposition is made to use a forward model based on appropriate output from a planning system to predict the 3D response of the dosimeter. In addition to the quenching effect, it is well known that chemical dosimeters have a non-linear response at high doses. To the best of our knowledge it has not yet been determined how this phenomenon is affected by LET. The implications for dosimetry of a number of potential scenarios are examined.Dosimeter response as a function of depth (and hence LET) was measured for four samples of the radiochromic plastic PRESAGE(®), using an optical computed tomography readout and entrance doses of 2.0 Gy, 4.0 Gy, 7.8 Gy and 14.7 Gy, respectively. The dosimeter response was separated into two components, a single-exponential low-LET response and a LET-dependent quenching. For the particular formulation of PRESAGE(®) used, deviations from linearity of the dosimeter response became significant for doses above approximately 16 Gy. In a second experiment, three samples were each irradiated with two separate beams of 4 Gy in various different configurations. On the basis of the previous characterizations, two different models were tested for the calculation of the combined quenching effect from two contributions with different LETs. It was concluded that a linear superposition model with separate calculation of the quenching for each irradiation did not match the measured result where two beams overlapped. A second model, which used the concept of an

  14. Fundamentals of Polymer Gel Dosimeters

    NASA Astrophysics Data System (ADS)

    McAuley, Kim B.

    2006-12-01

    The recent literature on polymer gel dosimetry contains application papers and basic experimental studies involving polymethacrylic-acid-based and polyacrylamide-based gel dosimeters. The basic studies assess the relative merits of these two most commonly used dosimeters, and explore the effects of tetrakis hydroxymethyl phosphonium chloride (THPC) antioxidant on dosimeter performance. Polymer gel dosimeters that contain THPC or other oxygen scavengers are called normoxic dosimeters, because they can be prepared under normal atmospheric conditions, rather than in a glove box that excludes oxygen. In this review, an effort is made to explain some of the underlying chemical phenomena that affect dosimeter performance using THPC, and that lead to differences in behaviour between dosimeters made using the two types of monomer systems. Progress on the development of new more effective and less toxic dosimeters is also reported.

  15. Radiation dosimeters

    DOEpatents

    Hoelsher, James W.; Hegland, Joel E.; Braunlich, Peter F.; Tetzlaff, Wolfgang

    1992-01-01

    Radiation dosimeters and dosimeter badges. The dosimeter badges include first and second parts which are connected to join using a securement to produce a sealed area in which at least one dosimeter is held and protected. The badge parts are separated to expose the dosimeters to a stimulating laser beam used to read dose exposure information therefrom. The badge is constructed to allow automated disassembly and reassembly in a uniquely fitting relationship. An electronic memory is included to provide calibration and identification information used during reading of the dosimeter. Dosimeter mounts which reduce thermal heating requirements are shown. Dosimeter constructions and production methods using thin substrates and phosphor binder-layers applied thereto are also taught.

  16. Wristwatch dosimeter

    DOEpatents

    Wolf, Michael A.; Waechter, David A.; Umbarger, C. John

    1986-01-01

    The disclosure is directed to a wristwatch dosimeter utilizing a CdTe detector, a microprocessor and an audio and/or visual alarm. The dosimeter is entirely housable with a conventional digital watch case having an additional aperture enabling the detector to receive radiation.

  17. Wristwatch dosimeter

    DOEpatents

    Wolf, M.A.; Waechter, D.A.; Umbarger, C.J.

    1986-08-26

    The disclosure is directed to a wristwatch dosimeter utilizing a CdTe detector, a microprocessor and an audio and/or visual alarm. The dosimeter is entirely housable with a conventional digital watch case having an additional aperture enabling the detector to receive radiation. 10 figs.

  18. Dosimetric parameters for small field sizes using Fricke xylenol gel, thermoluminescent and film dosimeters, and an ionization chamber.

    PubMed

    Calcina, Carmen S Guzmán; de Oliveira, Lucas N; de Almeida, Carlos E; de Almeida, Adelaide

    2007-03-01

    Dosimetric measurements in small therapeutic x-ray beam field sizes, such as those used in radiosurgery, that have dimensions comparable to or smaller than the build-up depth, require special care to avoid incorrect interpretation of measurements in regions of high gradients and electronic disequilibrium. These regions occur at the edges of any collimated field, and can extend to the centre of small fields. An inappropriate dosimeter can result in an underestimation, which would lead to an overdose to the patient. We have performed a study of square and circular small field sizes of 6 MV photons using a thermoluminescent dosimeter (TLD), Fricke xylenol gel (FXG) and film dosimeters. PMMA phantoms were employed to measure lateral beam profiles (1 x 1, 3 x 3 and 5 x 5 cm2 for square fields and 1, 2 and 4 cm diameter circular fields), the percentage depth dose, the tissue maximum ratio and the output factor. An ionization chamber (IC) was used for calibration and comparison. Our results demonstrate that high resolution FXG, TLD and film dosimeters agree with each other, and that an ionization chamber, with low lateral resolution, underestimates the absorbed dose. Our results show that, when planning small field radiotherapy, dosimeters with adequate lateral spatial resolution and tissue equivalence are required to provide an accurate basic beam data set to correctly calculate the absorbed dose in regions of electronic disequilibrium.

  19. Citizen's dosimeter

    SciTech Connect

    Klemic, Gladys; Bailey, Paul; Breheny, Cecilia

    2008-09-02

    The present invention relates to a citizen's dosimeter. More specifically, the invention relates to a small, portable, personal dosimetry device designed to be used in the wake of a event involving a Radiological Dispersal Device (RDD), Improvised Nuclear Device (IND), or other event resulting in the contamination of large area with radioactive material or where on site personal dosimetry is required. The card sized dosimeter generally comprises: a lower card layer, the lower card body having an inner and outer side; a upper card layer, the layer card having an inner and outer side; an optically stimulated luminescent material (OSLM), wherein the OSLM is sandwiched between the inner side of the lower card layer and the inner side of the upper card layer during dosimeter radiation recording, a shutter means for exposing at least one side of the OSLM for dosimeter readout; and an energy compensation filter attached to the outer sides of the lower and upper card layers.

  20. Optical properties of a long dynamic range chemical UV dosimeter based on solvent cast polyvinyl chloride (PVC).

    PubMed

    Amar, Abdurazaq; Parisi, Alfio V

    2013-11-01

    The dosimetric properties of the recently introduced UV dosimeter based on 16 μm PVC film have been fully characterised. Drying the thin film in air at 50 °C for at least 28 days was found to be necessary to minimise the temperature effects on the dosimeter response. This research has found that the dosimeter response, previously reported to be mainly to UVB, has no significant dependence on either exposure temperature or dose rate. The dosimeter has negligible dark reaction and responds to the UV radiation with high reproducibility. The dosimeter angular response was found to have a similar pattern as the cosine function but deviates considerably at angles larger than 70°. Dose response curves exhibit monotonically increasing shape and the dosimeter can measure more than 900 SED. This is about 3 weeks of continuous exposure during summer at subtropical sites. Exposures measured by the PVC dosimeter for some anatomical sites exposed to solar radiation for twelve consecutive days were comparable with those concurrently measured by a series of PPO dosimeters and were in line with earlier results reported in similar studies.

  1. RADIATION DOSIMETER

    DOEpatents

    Balkwell, W.R. Jr.; Adams, G.D. Jr.

    1960-05-10

    An improvement was made in the determination of amounts of ionizing radiation, particularly low-energy beta particles of less than 1000 rad total dose by means of fluid-phase dosimeter employing a stabilized-- sensitized ferrous-ferric colorimetric system in a sulphuric acid medium. The improvement in the dosimeter consists of adding to the ferrous-ferric system in concentrations of 10/sub -2/ to 10/sup -4/M an organic compound having one or more carboxylic or equivalent groups, such compounds being capable of chelating or complexing the iron ions in the solution. Suitable sensitizing and stabilizing agents are benzoic, phthalic, salicylic, malonic, lactic, maleic, oxalic, citric, succinic, phenolic tartaric, acetic, and adipic acid, as well as other compounds which are added to the solution alone or in certain combinations. As in conventional fluid-phase dosimeters, the absorbed dosage is correlated with a corresponding change in optical density at particular wavelengths of the solution.

  2. PERSONNEL DOSIMETER

    DOEpatents

    Birkhoff, R.D.; Hubbell, H.H. Jr.; Johnson, R.M.

    1959-02-24

    A personnel dosimeter sensitive to both gamma and beta radiation is described. The dosimeter consists of an electrical conductive cylinder having a wall thickness of substantially 7 milligrams per square centimeter and an electrode disposed axially within the cylinder and insulated therefrom to maintain a potential impressed between the electrode and the cylinder. A cylindrical perforated shield provided with a known percentage of void area is disposed concentrically about the cylinder. The shield is formed of a material which does not contain more than 15 percent of an element higher than atomic weight 13. The dose actually received is at most the gamma dose plus the beta dose indicated by discharge of the dosimeter divided by the known percentage.

  3. Composite material dosimeters

    DOEpatents

    Miller, Steven D.

    1996-01-01

    The present invention is a composite material containing a mix of dosimeter material powder and a polymer powder wherein the polymer is transparent to the photon emission of the dosimeter material powder. By mixing dosimeter material powder with polymer powder, less dosimeter material is needed compared to a monolithic dosimeter material chip. Interrogation is done with excitation by visible light.

  4. Thermoluminescence dosimeter

    DOEpatents

    Zendle, R.

    1983-11-03

    A thermoluminescence dosimeter having a very small rate of decline of sensitivity during subsequent uses after heating is disclosed. The dosimeter includes a detector crystal and a glass enclosure in which the detector crystal is located. The glass enclosure is air tight and is filled with a super dry inert fill gas. The inert fill gas is nonreactive with the detector crystal when the detector crystal is heated to thermoluminescence. The fill gas is selected from the group consisting of air, nitrogen, and argon, suitable admixed with 5 to 25 percent helium. The detector crystal consists essentially of calcium fluoride. The fill gas is preferably contained at a subatmospheric pressure in the glass enclosure.

  5. Thermoluminescence dosimeter

    DOEpatents

    Zendle, Robert

    1985-01-01

    A thermoluminescence dosimeter having a very small rate of decline of sensitivity during subsequent uses after heating is disclosed. The dosimeter includes a detector crystal and a glass enclosure in which the detector crystal is located. The glass enclosure is air tight and is filled with a super dry inert fill gas. The inert fill gas is nonreactive with the detector crystal when the detector crystal is heated to thermoluminescence. The fill gas is selected from the group consisting of air, nitrogen, and argon, suitable admixed with 5 to 25 percent helium. The detector crystal consists essentially of calcium fluoride. The fill gas is preferably contained at a subatmospheric pressure in the glass enclosure.

  6. A Practical Science Investigation for Middle School Students: Designing a Simple Cost Effective Chemical Solar Padiation Dosimeter

    ERIC Educational Resources Information Center

    Downs, Nathan; Larsen, Kim; Parisi, Alfio; Schouten, Peter; Brennan, Chris

    2012-01-01

    A practical exercise for developing a simple cost-effective solar ultraviolet radiation dosimeter is presented for use by middle school science students. Specifically, this exercise investigates a series of experiments utilising the historical blue print reaction, combining ammonium iron citrate and potassium hexacyanoferrate to develop an…

  7. Pocket radiation dosimeter: dosimeter charger assembly

    DOEpatents

    Manning, F.W.

    1982-03-17

    This invention is a novel pocket-type radiation dosimeter comprising an electrometric radiation dosimeter and a charging circuit therefor. The instrument is especially designed to be amenable to mass production, to have a long shelf life, and to be compact, lightweight, and usable by the layman. The dosimeter proper may be of conventional design. The charging circuit includes a shake-type electrostatic generator, a voltage doubler for integrating generator output voltages of one polarity, and a switch operated by an external permanent magnet.

  8. Pocket radiation dosimeter--dosimeter charger assembly

    DOEpatents

    Manning, Frank W.

    1984-01-01

    This invention is a novel pocket-type radiation dosimeter comprising an electrometric radiation dosimeter and a charging circuit therefor. The instrument is especially designed to be amenable to mass production, to have a long shelf life, and to be compact, lightweight, and usable by the layman. The dosimeter proper may be of conventional design. The charging circuit includes a shake-type electrostatic generator, a voltage doubler for integrating generator output voltages of one polarity, and a switch operated by an external permanent magnet.

  9. Dosimeter and method for using the same

    DOEpatents

    Warner, Benjamin P.; Johns, Deidre M.

    2003-06-24

    A very sensitive dosimeter that detects ionizing radiation is described. The dosimeter includes a breakable sealed container. A solution of a reducing agent is inside the container. The dosimeter has an air-tight dosimeter body with a transparent portion and an opaque portion. The transparent portion includes a transparent chamber that holds the breakable container with the reducing agent. The opaque portion includes an opaque chamber that holds an emulsion of silver salt (AgX) selected from silver chloride, silver bromide, silver iodide, and combinations of them. A passageway in the dosimeter provides fluid communication between the transparent chamber and the opaque chamber. The dosimeter may also include a chemical pH indicator in the breakable container that provides a detectable color change to the solution for a pH of about 3-10. The invention also includes a method of detecting ionizing radiation that involves producing the dosimeter, breaking the breakable container, allowing the solution to flow through the passageway and contact the emulsion, detecting any color change in the solution and using the color change to determine a radiation dosage.

  10. RADIATION DOSIMETER AND DOSIMETRIC METHODS

    DOEpatents

    Taplin, G.V.

    1958-10-28

    The determination of ionizing radiation by means of single fluid phase chemical dosimeters of the colorimetric type is presented. A single fluid composition is used consisting of a chlorinated hydrocarbon, an acidimetric dye, a normalizer and water. Suitable chlorinated hydrocarbons are carbon tetrachloride, chloroform, trichloroethylene, trichlorethane, ethylene dichioride and tetracbloroethylene. Suitable acidimetric indicator dyes are phenol red, bromcresol purple, and creosol red. Suitable normallzers are resorcinol, geraniol, meta cresol, alpha -tocopberol, and alpha -naphthol.

  11. Smart Radiological Dosimeter

    SciTech Connect

    Kosslow, William J.; Bandzuch, Gregory S.

    2004-07-20

    A radiation dosimeter providing an indication of the dose of radiation to which the radiation sensor has been exposed. The dosimeter contains features enabling the monitoring and evaluating of radiological risks so that a user can concentrate on the task at hand. The dosimeter provides an audible alarm indication that a predetermined time period has elapsed, an audible alarm indication reminding the user to check the dosimeter indication periodically, an audible alarm indicating that a predetermined accumulated dose has been prematurely reached, and an audible alarm indication prior or to reaching the 3/4 scale point.

  12. Wrist-watch dosimeter

    DOEpatents

    Wolf, M.A.; Waechter, D.A.; Umbarger, C.J.

    1982-04-16

    The disclosure is directed to a wristwatch dosimeter utilizing a CdTe detector, a microprocessor and an audio and/or visual alarm. The dosimeter is entirely housable within a conventional digital watch case having an additional aperture enabling the detector to receive radiation.

  13. ULTRASONIC NEUTRON DOSIMETER

    DOEpatents

    Truell, R.; de Klerk, J.; Levy, P.W.

    1960-02-23

    A neutron dosimeter is described which utilizes ultrasonic waves in the megacycle region for determination of the extent of neutron damage in a borosilicate glass through ultrasonic wave velocity and attenuation measurements before and after damage.

  14. Magnetic field dosimeter development

    SciTech Connect

    Lemon, D.K.; Skorpik, J.R.; Eick, J.L.

    1980-09-01

    In recent years there has been increased concern over potential health hazards related to exposure of personnel to magnetic fields. If exposure standards are to be established, then a means for measuring magnetic field dose must be available. To meet this need, the Department of Energy has funded development of prototype dosimeters at the Battelle Pacific Northwest Laboratory. This manual reviews the principle of operation of the dosimeter and also contains step-by-step instructions for its operation.

  15. Length of stain dosimeter

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E. (Inventor)

    1994-01-01

    Payload customers for the Space Shuttle have recently expressed concerns about the possibility of their payloads at an adjacent pad being contaminated by plume effluents from a shuttle at an active pad as they await launch on an inactive pad. As part of a study to satisfy such concerns a ring of inexpensive dosimeters was deployed around the active pad at the inter-pad distance. However, following a launch, dosimeters cannot be read for several hours after the exposure. As a consequence factors such as different substrates, solvent systems, and possible volatilization of HCl from the badges were studied. This observation led to the length of stain (LOS) dosimeters of this invention. Commercial passive LOS dosimeters are sensitive only to the extent of being capable of sensing 2 ppm to 20 ppm if the exposure is 8 hours. To map and quantitate the HCl generated by Shuttle launches, and in the atmosphere within a radius of 1.5 miles from the active pad, a sensitivity of 2 ppm HCl in the atmospheric gases on an exposure of 5 minutes is required. A passive length of stain dosimeter has been developed having a sensitivity rendering it capable of detecting a gas in a concentration as low as 2 ppm on an exposure of five minutes.

  16. SU-E-T-265: Presage Thin Sheet Dosimeter Characterization

    SciTech Connect

    Dumas, M; Rakowski, J

    2014-06-01

    Purpose: To quantify the sensitivity and stability of the Presage dosimeter in sheet form for different concentrations of chemicals and for a diverse range of clinical photon energies. Methods: Presage polymer dosimeters are formulated to investigate and optimize their sensitivity and stability. The dosimeter is composed of clear polyurethane base, leucomalachite green reporting dye, and bromoform radical initiator in 1mm thick sheets. The chemicals are well mixed together, cast in an aluminum mold, and left to cure at 60 psi for a minimum of 2 days. Dosimeter response will be characterized at multiple energies including Co-60, 6 MV, 15 MV, 50 kVp, and 250 kVp. The dosimeters are read by an Epson 10000 XL scanner at 800 dpi, 2{sup 16} bit depth. Red component images are analyzed with ImageJ. Results: Analysis of optical density verse dose for Co-60 energies indicates that the bromoform containing Presage was able to quantify dose from 0 to 300 Gy, with saturation beyond 300 Gy. Initial results show two regions of linear response, 0–100 Gy and 150–300 Gy. The 150–300 Gy region has a sensitivity of 0.0024 net OD/Gy. Further results on other energies are still in progress. Conclusions: This work shows the potential for use of thin sheets of Presage dosimeter as a dosimeter capable of being analyzed with a flatbed scanner.

  17. Dosimeter for monitoring vapors and aerosols of organic compounds

    DOEpatents

    Vo-Dinh, T.

    1987-07-14

    A dosimeter is provided for collecting and detecting vapors and aerosols of organic compounds. The dosimeter comprises a lightweight, passive device that can be conveniently worn by a person as a badge or placed at a stationary location. The dosimeter includes a sample collector comprising a porous web treated with a chemical for inducing molecular displacement and enhancing phosphorescence. Compounds are collected onto the web by molecular diffusion. The web also serves as the sample medium for detecting the compounds by a room temperature phosphorescence technique. 7 figs.

  18. Dosimeter for monitoring vapors and aerosols of organic compounds

    DOEpatents

    Vo-Dinh, Tuan

    1987-01-01

    A dosimeter is provided for collecting and detecting vapors and aerosols of organic compounds. The dosimeter comprises a lightweight, passive device that can be conveniently worn by a person as a badge or placed at a stationary location. The dosimeter includes a sample collector comprising a porous web treated with a chemical for inducing molecular displacement and enhancing phosphorescence. Compounds are collected onto the web by molecular diffusion. The web also serves as the sample medium for detecting the compounds by a room temperature phosphorescence technique.

  19. A new dosimeter formulation for deformable 3D dose verification

    NASA Astrophysics Data System (ADS)

    Høye, E. M.; Skyt, P. S.; Yates, E. S.; Muren, L. P.; Petersen, J. B. B.; Balling, P.

    2015-01-01

    We present the characteristics of a new silicone-based radiochromic dosimeter containing the leuco-malachite green (LMG) dye. The dose response as well as the dose-rate and photon-energy dependence of the dosimeter were characterized. To optimise the dose response, different concentrations of the chemical components were investigated. The dose response was found to decrease exponentially as a function of time after irradiation. A cylindrical dosimeter was produced and irradiated with a volumetric modulated arc therapy plan; the standard deviation between measured and calculated dose was 5% of the total dose.

  20. Surface-enhanced Raman scattering (SERS) dosimeter and probe

    DOEpatents

    Vo-Dinh, Tuan

    1995-01-01

    A dosimeter and probe for measuring exposure to chemical and biological compounds is disclosed. The dosimeter or probe includes a collector which may be analyzed by surface-enhanced Raman spectroscopy. The collector comprises a surface-enhanced Raman scattering-active material having a coating applied thereto to improve the adsorption properties of the collector. The collector may also be used in automated sequential devises, in probe array devices.

  1. Surface-enhanced Raman scattering (SERS) dosimeter and probe

    DOEpatents

    Vo-Dinh, T.

    1995-03-21

    A dosimeter and probe for measuring exposure to chemical and biological compounds is disclosed. The dosimeter or probe includes a collector which may be analyzed by surface-enhanced Raman spectroscopy. The collector comprises a surface-enhanced Raman scattering-active material having a coating applied thereto to improve the adsorption properties of the collector. The collector may also be used in automated sequential devices, in probe array devices. 10 figures.

  2. [Thermoluminescence Slab Dosimeter].

    PubMed

    Shinsho, Kiyomitsu; Koba, Yusuke; Tamatsu, Satoshi; Sakurai, Noboru; Wakabayashi, Genichiro; Fukuda, Kazusige

    2013-01-01

    In 1953 F. Daniels et al. used the property of thermoluminescence in dosimetry for the first time. Since then, numerous TLD have been developed. 2D TLD was investigated for the first time in 1972 by P Broadhead. However, due to excessive fading, difficulties with handling and the time required for measurements, development stalled. At the current time, the majority of TLD are used in small scale, localized dosimetry with a wide dynamic range and personal dosimeters for exposure management. Urushiyama et. al. have taken advantage of the commoditization of CCD cameras in recent years--making large area, high resolution imaging easier--to introduce and develop a 2D TLD. It is expected that these developments will give rise to a new generation of applications for 2D TL dosimetry. This paper introduces the "TL Slab Dosimeter" developed jointly by Urushiyama et. al. and our team, its measurement system and several typical usage scenarios.

  3. Dose equivalent neutron dosimeter

    DOEpatents

    Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

    1983-01-01

    A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

  4. Dosimeter Badge Detects Hydrazines

    NASA Technical Reports Server (NTRS)

    Young, Rebecca C.; Travis, Joshua C.; Moore, Gerald; Rose-Pehrsson, Susan; Carver, Patricia; Brenner, Karen

    1993-01-01

    Disposable dosimeter badge indicates approximate cumulative exposure to hydrazine or monomethyl hydrazine in air. Indication is change in colors of both paper tapes; one coated with para-N, N-dimethylaminobenzaldehyde. Colors of exposed tapes compared with colors on two preprinted color wheels to obtain estimate of exposure. Badges help minimize risks associated with exposure of personnel to hydrazine or monomethyl hydrazine, or suspected carcinogens. Also used as stationary monitors by taping them on walls or equipment at strategic locations.

  5. Dosimeter Corporation's computer interfacing automatic dosimeter (CID) system

    SciTech Connect

    Bunker, A.S.

    1985-07-01

    This paper reports that the weakest links in most large-scale quartz-fiber direct-reading dosimeter (DRD) programs are the devices used to read the DRD's; that is, the people who are assigned the DRDs and the technicians who log results, rezero dosimeters, and test dosimeters. These reading devices cannot be programmed for consistent interpretation of DRD readings, and they are notoriously slow at performing readings. They also cannot be easily interfaced to computer-based systems. Ideally, these devices should be replaced or supplemented with machines that can offer better precision, speed, and software. Dosimeter Corporation's Computer Interfaced Automatic Dosimetry (CID) system is one such machine.

  6. Hanford personnel dosimeter supporting studies FY-1981

    SciTech Connect

    Not Available

    1982-08-01

    This report examined specific functional components of the routine external personnel dosimeter program at Hanford. Components studied included: dosimeter readout; dosimeter calibration; dosimeter field response; dose calibration algorithm; dosimeter design; and TLD chip acceptance procedures. Additional information is also presented regarding the dosimeter response to light- and medium-filtered x-rays, high energy photons and neutrons. This study was conducted to clarify certain data obtained during the FY-1980 studies.

  7. Ionization chamber dosimeter

    DOEpatents

    Renner, Tim R.; Nyman, Mark A.; Stradtner, Ronald

    1991-01-01

    A method for fabricating an ion chamber dosimeter collecting array of the type utilizing plural discrete elements formed on a uniform collecting surface which includes forming a thin insulating layer over an aperture in a frame having surfaces, forming a predetermined pattern of through holes in the layer, plating both surfaces of the layer and simultaneously tilting and rotating the frame for uniform plate-through of the holes between surfaces. Aligned masking and patterned etching of the surfaces provides interconnects between the through holes and copper leads provided to external circuitry.

  8. PERSONNEL NEUTRON DOSIMETER

    DOEpatents

    Fitzgerald, J.J.; Detwiler, C.G. Jr.

    1960-05-24

    A description is given of a personnel neutron dosimeter capable of indicating the complete spectrum of the neutron dose received as well as the dose for each neutron energy range therein. The device consists of three sets of indium foils supported in an aluminum case. The first set consists of three foils of indium, the second set consists of a similar set of indium foils sandwiched between layers of cadmium, whereas the third set is similar to the second set but is sandwiched between layers of polyethylene. By analysis of all the foils the neutron spectrum and the total dose from neutrons of all energy levels can be ascertained.

  9. Pistol-shaped dosimeter charger

    DOEpatents

    Maples, Robert A.

    1985-01-01

    A pistol-shaped charger assembly clamps a cylindrical radiation dosimeter against one edge thereof. A triggerlike lever on the handgrip of the assembly is manually pivoted to actuate a piezoelectric current generator held in the handgrip and thereby charge the dosimeter.

  10. Pistol-shaped dosimeter charger

    SciTech Connect

    Maples, R.A.

    1985-01-15

    A pistol-shaped charger assembly clamps a cylindrical radiation dosimeter against one edge thereof. A triggerlike lever on the handgrip of the assembly is manually pivoted to actuate a piezoelectric current generator held in the handgrip and thereby charge the dosimeter.

  11. Pistol-shaped dosimeter charger

    DOEpatents

    Maples, R.A.

    A pistol-shaped charger assembly clamps a cylindrical radiation dosimeter against one edge thereof. A triggerlike lever on the handgrip of the assembly is manually pivoted to actuate a piezoelectric current generator held in the handgrip and thereby charge the dosimeter.

  12. A new radiochromic dosimeter film

    NASA Astrophysics Data System (ADS)

    Sidney, L. N.; Lynch, D. C.; Willet, P. S.

    By employing acid-sensitive leuco dyes in a chlorine-containing polymer matrix, a new radiochromic dosimeter film has been developed for gamma, electron beam, and ultraviolet radiation. These dosimeter films undergo a color change from colorless to royal blue, red fuchsia, or black, depending on dye selection, and have been characterized using a visible spectrophotometer over an absorbed dose range of 1 to 100 kGy. The primary features of the film are improved color stability before and after irradiation, whether stored in the dark or under artificial lights, and improved moisture resistance. The effects of absorbed dose, dose rate, and storage conditions on dosimeter performance are discussed. The dosimeter material may be produced as a free film or coated onto a transparent substrate and optionally backed with adhesive. Potential applications for these materials include gamma sterilization indicator films for food and medical products, electron beam dosimeters, and in-line radiation monitors for electron beam and ultraviolet processing.

  13. Personnel electronic neutron dosimeter

    DOEpatents

    Falk, R.B.; Tyree, W.H.

    1982-03-03

    A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

  14. Personnel electronic neutron dosimeter

    DOEpatents

    Falk, Roger B.; Tyree, William H.

    1984-12-18

    A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

  15. Thermoluminescence dosimeter reader

    SciTech Connect

    Miyake, S.; Miura, N.

    1984-10-30

    A thermoluminescence dosimeter reader having a heater for heating a thermoluminescence element, a light measuring circuit for measuring circuit for measuring the intensity of the thermoluminescence emanated from the element when it is heated and a display device for displaying the reading of the dosage of radiation to which the element is exposed according to the intensity of the thermoluminescence is provided with a dosage information inputting means which outputs an electric signal having a value representing a predetermined reference dosage of radiation, a calculating means for calculating a calibration constant which is the ratio between the value of the electric signal and the output value of the light measuring circuit which is the measured value of the dosage of radiation of a reference thermoluminescence element which is exposed to the predetermined reference dosage of radiation, and a memory means for memorizing the calibration constant.

  16. Miniature spectrally selective dosimeter

    NASA Technical Reports Server (NTRS)

    Adams, R. R.; Macconochie, I. O.; Poole, B. D., Jr. (Inventor)

    1980-01-01

    A miniature spectrally selective dosimeter capable of measuring selected bandwidths of radiation exposure on small mobile areas is described. This is achieved by the combination of photovoltaic detectors, electrochemical integrators (E-cells) and filters in a small compact case which can be easily attached in close proximity to and substantially parallel to the surface being measured. In one embodiment two photovoltaic detectors, two E-cells, and three filters are packaged in a small case with attaching means consisting of a safety pin. In another embodiment, two detectors, one E-cell, three filters are packaged in a small case with attaching means consisting of a clip to clip over a side piece of an eye glass frame.

  17. Dose rate dependency of micelle leucodye 3D gel dosimeters

    NASA Astrophysics Data System (ADS)

    Vandecasteele, J.; Ghysel, S.; De Deene, Y.

    2010-11-01

    Recently a novel 3D radiochromic gel dosimeter was introduced which uses micelles to dissolve a leucodye in a gelatin matrix. Experimental results show that this 3D micelle gel dosimeter was found to be dose rate dependent. A maximum difference in optical dose sensitivity of 70% was found for dose rates between 50 cGy min-1 and 400 cGy min-1. A novel composition of 3D radiochromic dosimeter is proposed composed of gelatin, sodium dodecyl sulphate, chloroform, trichloroacetic acid and leucomalachite green. The novel gel dosimeter formulation exhibits comparable radio-physical properties in respect to the composition previously proposed. Nevertheless, the novel formulation was found to be still dose rate dependent. A maximum difference of 33% was found for dose rates between 50 cGy min-1 and 400 cGy min-1. On the basis of these experimental results it is concluded that the leucodye micelle gel dosimeter is still unsatisfactory for clinical radiation therapy dose verifications. Some insights in the physico-chemical mechanisms were obtained and are discussed.

  18. Brachytherapy dosimeter with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Moutinho, L. M.; Castro, I. F. C.; Peralta, L.; Abreu, M. C.; Veloso, J. F. C. A.

    2015-07-01

    In-vivo and in-situ measurement of the radiation dose administered during brachytherapy faces several technical challenges, requiring a very compact, tissue-equivalent, linear and highly sensitive dosimeter, particularly in low-dose rate brachytherapy procedures, which use radioactive seeds with low energy and low dose deposition rate. In this work we present a scintillating optical fiber dosimeter composed of a flexible sensitive probe and a dedicated electronic readout system based on silicon photomultiplier photodetection, capable of operating both in pulse and current modes. The performance of the scintillating fiber optic dosimeter was evaluated in low energy regimes, using an X-ray tube operating at voltages of 40-50 kV and currents below 1 mA, to assess minimum dose response of the scintillating fiber. The dosimeter shows a linear response with dose and is capable of detecting mGy dose variations like an ionization chamber. Besides fulfilling all the requirements for a dosimeter in brachytherapy, the high sensitivity of this device makes it a suitable candidate for application in low-dose rate brachytherapy. According to Peralta and Rego [1], the BCF-10 and BCF-60 scintillating optical fibers used in dosimetry exhibit high variations in their sensitivity for photon beams in the 25-100 kVp energy range. Energy linearity for energies below 50 keV needs to be further investigated, using monochromatic X-ray photons.

  19. Dose-equivalent neutron dosimeter

    DOEpatents

    Griffith, R.V.; Hankins, D.E.; Tomasino, L.; Gomaa, M.A.M.

    1981-01-07

    A neutron dosimeter is disclosed which provides a single measurement indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer contaning conversion material such as /sup 6/Li and /sup 10/B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet.

  20. Spectrophotometry of PRESAGETM polyurethane dosimeters

    NASA Astrophysics Data System (ADS)

    Krstajic, N.; Wai, P.; Adamovics, J.; Doran, S.

    2004-01-01

    Preliminary optical density results on irradiated PRESAGE dosimeter are outlined in this article. PRESAGE is a solid dosimeter, based on a clear polyurethane combined with the leuco-dye leuco-malachite green. The purpose of these measurements was a) to obtain spectra for optimizing the wavelength of a new light source for the equipment and b) to obtain a dose-response relation. 10 PRESAGE cuvettes were given uniform doses from 0.1 to 40 Gy and later read out by spectrophotometer. The instrument used was CAMSPEC M350 Double Beam Spectrophotometer.

  1. Miniature personal UV solar dosimeter

    NASA Technical Reports Server (NTRS)

    Adams, R. R.; Macconochie, I. O.; Poole, B. D., Jr.

    1981-01-01

    Small light-powered meter measures accumulated radiation in ultraviolet or other selected regions. Practical advantages are device's low cost, small size, accuracy, and adaptability to specific wave-band measurements. Medical applications include detection of skin cancer, vitamin D production, and jaundice. Dosimeter also measures sunlight for solar energy designs, agriculture and meteorology, and monitors stability of materials and environmental and occupational lighting.

  2. An angular dependent neutron effective-dose-equivalent dosimeter

    NASA Astrophysics Data System (ADS)

    Veinot, Kenneth Guy

    The effective-dose-equivalent (EDE) is a strong function of angular orientation in a radiation field. Detection systems that attempt to measure the EDE directly would be desirable. Historically, dosimeters have been designed to respond as isotropically as possible in a radiation field. However, since the EDE is strongly dependent upon the incident angle of the radiation, past designs are no longer desirable for personal radiation dosimetry. In addition, the EDE is a function of incident neutron energy. CR-39 foils are commonly used neutron detectors. Neutrons produce tracks in CR-39 (allyl diglycol polycarbonate) detectors over a wide energy range. Through chemical or electrochemical etching, these tracks can be enlarged and counted. From this track count, the fluence of neutrons incident on the CR-39 foils may be inferred. Thermoluminescent dosimeters (TLDs) are another method of neutron detection. Both of these detectors have angular response properties. In the present work, calculations of EDE were compared to calculations and measurements of the angular responses of CR-39 and TLD neutron dosimeters. The measurements used a variety of neutron sources, each with its own characteristic energy spectrum. This research resulted in a neutron personal dosimeter prototype whose angular response properties resembled the angular response of EDE.

  3. Evaluation of a high exposure solar UV dosimeter for underwater use.

    PubMed

    Schouten, Peter W; Parisi, Alfio V; Turnbull, David J

    2007-01-01

    Solar ultraviolet radiation (UV) is known to have a significant effect upon the marine ecosystem. This has been documented by many previous studies using a variety of measurement methods in aquatic environments such as oceans, streams and lakes. Evidence gathered from these investigations has shown that UVB radiation (280-320 nm) can negatively affect numerous aquatic life forms, while UVA radiation (320-400 nm) can both damage and possibly even repair certain types of underwater life. Chemical dosimeters such as polysulphone have been tested to record underwater UV exposures and in turn quantify the relationship between water column depth and dissolved organic carbon levels to the distribution of biologically damaging UV underwater. However, these studies have only been able to intercept UV exposures over relatively short time intervals. This paper reports on the evaluation of a high exposure UV dosimeter for underwater use. The UV dosimeter was fabricated from poly 2,6-dimethyl-1,4-phenylene oxide (PPO) film. This paper presents the dose response, cosine response, exposure additivity and watermarking effect relating to the PPO dosimeter as measured in a controlled underwater environment and will also detail the overnight dark reaction and UVA and visible radiation response of the PPO dosimeter, which can be used for error correction to improve the reliability of the UV data measured by the PPO dosimeters. These results show that this dosimeter has the potential for long-term underwater UV exposure measurements. PMID:17645666

  4. Fast-neutron solid-state dosimeter

    DOEpatents

    Kecker, K.H.; Haywood, F.F.; Perdue, P.T.; Thorngate, J.H.

    1975-07-22

    This patent relates to an improved fast-neutron solid-state dosimeter that does not require separation of materials before it can be read out, that utilizes materials that do not melt or otherwise degrade at about 300$sup 0$C readout temperature, that provides a more efficient dosimeter, and that can be reused. The dosimeters are fabricated by intimately mixing a TL material, such as CaSO$sub 4$:Dy, with a powdered polyphenyl, such as p-sexiphenyl, and hot- pressing the mixture to form pellets, followed by out-gassing in a vacuum furnace at 150$sup 0$C prior to first use dosimeters. (auth)

  5. An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters

    NASA Astrophysics Data System (ADS)

    Babic, Steven; Schreiner, L. John

    2006-09-01

    In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters.

  6. An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters.

    PubMed

    Babic, Steven; Schreiner, L John

    2006-09-01

    In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters. PMID:16912375

  7. Portable neutron spectrometer and dosimeter

    DOEpatents

    Waechter, David A.; Erkkila, Bruce H.; Vasilik, Dennis G.

    1985-01-01

    The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

  8. Portable neutron spectrometer and dosimeter

    DOEpatents

    Waechter, D.A.; Erkkila, B.H.; Vasilik, D.G.

    The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

  9. BETA-GAMMA PERSONNEL DOSIMETER

    DOEpatents

    Davis, D.M.; Gupton, E.D.; Hart, J.C.; Hull, A.P.

    1961-01-17

    A personnel dosimeter is offered which is sensitive to both gamma and soft beta radiations from all directions within a hemisphere. The device is in the shape of a small pill box which is worn on a worker-s wrist. The top and sides of the device are provided with 50 per cent void areas to give 50 per cent response to the beta rays and complete response to the gamma rays. The device is so constructed as to have a response which will approximate the dose received by the basal layer of the human epidermis.

  10. Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography

    PubMed Central

    Shih, Cheng-Ting; Lee, Yao-Ting; Wu, Shin-Hua; Yao, Chun-Hsu; Hsieh, Bor-Tsung

    2016-01-01

    With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation. PMID:26974434

  11. Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography.

    PubMed

    Shih, Tian-Yu; Wu, Jay; Shih, Cheng-Ting; Lee, Yao-Ting; Wu, Shin-Hua; Yao, Chun-Hsu; Hsieh, Bor-Tsung

    2016-01-01

    With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation. PMID:26974434

  12. Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography.

    PubMed

    Shih, Tian-Yu; Wu, Jay; Shih, Cheng-Ting; Lee, Yao-Ting; Wu, Shin-Hua; Yao, Chun-Hsu; Hsieh, Bor-Tsung

    2016-01-01

    With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation.

  13. Eliminating the dose-rate effect in a radiochromic silicone-based 3D dosimeter

    NASA Astrophysics Data System (ADS)

    Høye, E. M.; Balling, P.; Yates, E. S.; Muren, L. P.; Petersen, J. B. B.; Skyt, P. S.

    2015-07-01

    Comprehensive dose verification, such as 3D dosimetry, may be required for safe introduction and use of advanced treatment modalities in radiotherapy. A radiochromic silicone-based 3D dosimetry system has recently been suggested, though its clinical use has so far been limited by a considerable dose-rate dependency of the dose response. In this study we have investigated the dose-rate dependency with respect to the chemical composition of the dosimeter. We found that this dependency was reduced with increasing dye concentration, and the dose response was observed to be identical for dosimeters irradiated with 2 and 6 Gy min-1 at concentrations of 0.26% (w/w) dye and 1% (w/w) dye solvent. Furthermore, for the optimized dosimeter formulation, no dose-rate effect was observed due to the attenuation of the beam fluence with depth. However, the temporal stability of the dose response decreased with dye concentration; the response was reduced by (62  ±  1)% within approximately 20 h upon irradiation, at the optimal chemical composition and storage at room temperature. In conclusion, this study presents a chemical composition for a dose-rate independent silicone dosimeter which has considerably improved the clinical applicability of such dosimeters, but at the cost of a decreased stability.

  14. Comparative study of some new EPR dosimeters

    NASA Astrophysics Data System (ADS)

    Alzimami, K. S.; Maghraby, Ahmed M.; Bradley, D. A.

    2014-02-01

    Investigations have been made of four new radiation dosimetry EPR candidates from the same family of materials: sulfamic acid, sulfanillic acid, homotaurine, and taurine. Mass energy attenuation coefficients, mass stopping power values and the time dependence of the radiation induced radicals are compared. Also investigated are the microwave saturation behavior and the effect of applied modulation amplitude on both peak-to-peak line width (WPP) and peak-to-peak signal height (HPP). The dosimeters are characterized by simple spectra and stable radiation-induced radicals over reasonable durations, especially in taurine dosimeters. Sulfamic acid dosimeters possessed the highest sensitivity followed by taurine and homotaurine and sulfanillic.

  15. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, R.J.

    1985-12-23

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  16. Diffusion properties of a radiochromic hydrogel dosimeter

    NASA Astrophysics Data System (ADS)

    Skyt, P. S.; Kinnari, T. S.; Wahlstedt, I.; Yates, E. S.; Muren, L. P.; Petersen, J. B. B.; Balling, P.

    2013-06-01

    The aim of this study was to investigate the diffusion properties of a radiochromic hydrogel dosimeter based on leuco malachite green dye in a gelatine matrix. One half of each dosimeter was irradiated while the other half was left un-irradiated creating dose gradients over which diffusion could be investigated. Read-out of the optical response was performed with a high-resolution optical scanner. The dosimeters were found to exhibit a low diffusion rate but a high auto-oxidation level leading to a fading of the contrast in the dose response with time.

  17. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, Richard J.

    1987-01-01

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  18. Field calibrations of a long-term UV dosimeter for aquatic UVB exposures.

    PubMed

    Schouten, P W; Parisi, A V; Turnbull, D J

    2008-05-29

    Various methodologies using a wide range of measurement systems have been employed previously in order to determine the amount of UV that could be incident upon various aquatic organisms in a number of different aquatic locales. Broadband meters and spectroradiometers have been employed extensively to take underwater measurements. However, these measurement campaigns are limited by the fact that radiometric equipment requires a human controller, constant power supply and regular calibrations and corrections in order to function properly. Dosimetric measurements have also been made underwater using two distinct types of dosimeter. The first type based on a synthetic chemical, like polysulphone, and the second type based on a biological matter, such as a DNA sample. The studies made using biological dosimeters have displayed very good results, however the time and skill necessary to make these types of dosimeters can outweigh their usefulness. The chemical dosimeters are easier to make and have also provided useable data, but only for short periods of exposure, usually no more than a day. Previous research has shown that Poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) has excellent potential for use as a long-term underwater solar UVB dosimeter. However, there is no documented methodology on how to properly calibrate the PPO dosimeter for water-based measurements and it has yet to be trialled in an outdoors marine environment, either real or simulated. This manuscript shows that calibrations obtained in air can not be transferred to calibrations made in water, calibrations made in one type of water can be employed for another type of water, but only within a certain range of spectral transmission and calibrations made at different depths in the same water type are interchangeable. It was also discovered that changing solar zenith angle had an effect upon calibration data. This research addressed these issues by formulating and developing a calibration methodology

  19. Field calibrations of a long-term UV dosimeter for aquatic UVB exposures.

    PubMed

    Schouten, P W; Parisi, A V; Turnbull, D J

    2008-05-29

    Various methodologies using a wide range of measurement systems have been employed previously in order to determine the amount of UV that could be incident upon various aquatic organisms in a number of different aquatic locales. Broadband meters and spectroradiometers have been employed extensively to take underwater measurements. However, these measurement campaigns are limited by the fact that radiometric equipment requires a human controller, constant power supply and regular calibrations and corrections in order to function properly. Dosimetric measurements have also been made underwater using two distinct types of dosimeter. The first type based on a synthetic chemical, like polysulphone, and the second type based on a biological matter, such as a DNA sample. The studies made using biological dosimeters have displayed very good results, however the time and skill necessary to make these types of dosimeters can outweigh their usefulness. The chemical dosimeters are easier to make and have also provided useable data, but only for short periods of exposure, usually no more than a day. Previous research has shown that Poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) has excellent potential for use as a long-term underwater solar UVB dosimeter. However, there is no documented methodology on how to properly calibrate the PPO dosimeter for water-based measurements and it has yet to be trialled in an outdoors marine environment, either real or simulated. This manuscript shows that calibrations obtained in air can not be transferred to calibrations made in water, calibrations made in one type of water can be employed for another type of water, but only within a certain range of spectral transmission and calibrations made at different depths in the same water type are interchangeable. It was also discovered that changing solar zenith angle had an effect upon calibration data. This research addressed these issues by formulating and developing a calibration methodology

  20. Performance criteria for dosimeter angular response

    SciTech Connect

    Roberson, P.L.; Fox, R. A.; Cummings, F. M.; McDonald, J. C.; Jones, K.L.

    1988-06-01

    This report provides criteria for evaluating the response of personnel dosimeters to radiation at nonperpendicular incidence. The US Department of Energy Laboratory Accreditation Program (DOELAP) ensures that dosimetry systems at DOE facilities meet acceptable standards for precision and accuracy. In the past, these standards were limited to tests for system variability, energy dependence, and level of detection. The proposed criteria will broaden the scope of DOELAP to include the angular response of personnel dosimeters. Because occupational exposures in the workplace are rarely due to radiation from only one direction, dosimeters must accurately assign individual dose equivalent from irradiation at any forward angle of incidence. Including an angular response criterion in DOELAP would improve the quality of personnel monitoring provided that the criterion is developed from appropriate dose quantities. This report provides guidance for assigning individual dose equivalents for radiation fields at nonperpendicular incidence to the dosimeter. 21 refs., 10 figs., 10 tabs.

  1. Polymer gel dosimeter based on itaconic acid.

    PubMed

    Mattea, Facundo; Chacón, David; Vedelago, José; Valente, Mauro; Strumia, Miriam C

    2015-11-01

    A new polymeric dosimeter based on itaconic acid and N, N'-methylenebisacrylamide was studied. The preparation method, compositions of monomer and crosslinking agent and the presence of oxygen in the dosimetric system were analyzed. The resulting materials were irradiated with an X-ray tube at 158cGy/min, 226cGymin and 298cGy/min with doses up to 1000Gy. The dosimeters presented a linear response in the dose range 75-1000Gy, sensitivities of 0.037 1/Gyat 298cGy/min and an increase in the sensitivity with lower dose rates. One of the most relevant outcomes in this study was obtaining different monomer to crosslinker inclusion in the formed gel for the dosimeters where oxygen was purged during the preparation method. This effect has not been reported in other typical dosimeters and could be attributed to the large differences in the reactivity among these species.

  2. The LLNL CR-39 personnel neutron dosimeter

    SciTech Connect

    Hankins, D.E.; Homann, S.; Westermark, J.

    1987-09-29

    We developed a personnel neutron dosimetry system based on the electrochemical etching of CR-39 plastic at elevated temperatures. The doses obtained using this dosimeter system are more accurate than those obtained using other dosimetry systems, especially when varied neutron spectra are encountered. This CR-39 dosimetry system does not have the severe energy dependence that exists with albedo neutron dosimeters or the fading and reading problems encountered with NTA film. 3 refs., 4 figs.

  3. Study of a non-diffusing radiochromic gel dosimeter for 3D radiation dose imaging

    NASA Astrophysics Data System (ADS)

    Marsden, Craig Michael

    2000-12-01

    This thesis investigates the potential of a new radiation gel dosimeter, based on nitro-blue tetrazolium (NBTZ) suspended in a gelatin mold. Unlike all Fricke based gel dosimeters this dosimeter does not suffer from diffusive loss of image stability. Images are obtained by an optical tomography method. Nitro blue tetrazolium is a common biological indicator that when irradiated in an aqueous medium undergoes reduction to a highly colored formazan, which has an absorbance maximum at 525nm. Tetrazolium is water soluble while the formazan product is insoluble. The formazan product sticks to the gelatin matrix and the dose image is maintained for three months. Methods to maximize the sensitivity of the system were evaluated. It was found that a chemical detergent, Triton X-100, in combination with sodium formate, increased the dosimeter sensitivity significantly. An initial G-value of formazan production for a dosimeter composed of 1mM NBTZ, gelatin, and water was on the order of 0.2. The addition of Triton and formate produced a G-value in excess of 5.0. The effects of NBTZ, triton, formate, and gel concentration were all investigated. All the gels provided linear dose vs. absorbance plots for doses from 0 to >100 Gy. It was determined that gel concentration had minimal if any effect on sensitivity. Sensitivity increased slightly with increasing NBTZ concentration. Triton and formate individually and together provided moderate to large increases in dosimeter sensitivity. The dosimeter described in this work can provide stable 3D radiation dose images for all modalities of radiation therapy equipment. Methods to increase sensitivity are developed and discussed.

  4. Fricke xylenol gel characterization using a photoacustic technique

    NASA Astrophysics Data System (ADS)

    Caldeira, A. M. F.; de Almeida, A.; Neto, A. M.; Baesso, M. L.; Bento, A. C.; Silva, M. A.

    2007-11-01

    Fricke chemical dosimetry measurements of the absorbed dose of ionizing radiation depend on the quality and characteristics of the system that reads each dosimeter. The final accuracy is significantly dependent on the technique used for measuring the chemical concentration changes in the dosimeters. We have used a photoacoustic technique to detect the Fricke xylenol gel (FXG) optical absorbance. The FXG, a derivation of the aqueous Fricke dosimeter, is made more sensitive and stable with addition of gelatin (300 Bloom) and xylenol orange. The light intensity transmitted through an FXG sample before and after irradiation was measured with an acoustic detector. The incremental optical absorbance is directly proportional to the ionizing radiation absorbed dose. We present the optical absorbance measurements as a function of absorbed dose and of post-irradiation time. We apply our photoacoustic technique to determine absorbed dose profiles. The results show that the photoacoustic technique applied to FXG provides a new dosimetric system, as good as those already established using spectrophotometric techniques.

  5. Synthetic single crystal diamond dosimeters for Intensity Modulated Radiation Therapy applications

    NASA Astrophysics Data System (ADS)

    Almaviva, S.; Ciancaglioni, I.; Consorti, R.; De Notaristefani, F.; Manfredotti, C.; Marinelli, Marco; Milani, E.; Petrucci, A.; Prestopino, G.; Verona, C.; Verona-Rinati, G.

    2009-09-01

    A synthetic single crystal diamond Schottky diode, in a p-type/intrinsic/metal structure, deposited by Chemical Vapour Deposition (CVD) and operating in photovoltaic regime, with no external bias voltage applied, was tested as a dosimeter for Intensity Modulated Radiation Therapy (IMRT) applications. The device response was compared with dose measurements from two commercial ionization chambers and a 2D diode array in an IMRT prostate cancer treatment plan. The obtained results indicate that CVD synthetic single crystal diamond-based dosimeters can successfully be used for highly conformed radiotherapy and IMRT dosimetry, due to their small size and high sensitivity per unit volume.

  6. PNNL Results from 2009 Silene Criticality Accident Dosimeter Intercomparison Exercise

    SciTech Connect

    Hill, Robin L.; Conrady, Matthew M.

    2010-06-30

    This document reports the results of testing of the Hanford Personnel Nuclear Accident Dosimeter (PNAD) during a criticality accident dosimeter intercomparison exercise at the CEA Valduc Center on October 13, 14, and 15, 2009.

  7. Environmental dosimeter of the thermoluminescent type

    DOEpatents

    Eichner, F.N.; Kocher, L.F.

    1974-01-29

    A dosimeter for accurately monitoring normally low-energy radiation including a thermoluminescent CaF phosphor enclosed within a tantalum capsule is described. The tantalum acts as a filter to weaken the measured dose due to photons having energies below about 0.2 MeV. Tantalum end caps are maintained on the capsule body by a polyolefin sheath formed from heat-contractable tubing. After exposing the dosimeter to environmental radiation, it is placed in a shielded chamber for about 24 h and subsequently annealed at about 80 deg C to release radiation energy accumulated in low-temperature traps. The dosimeter is then disassembled and the phosphors photometrically read at temperatures about 50 deg C to determine the absorbed radiation dose. (Official Gazette)

  8. Solid state neutron dosimeter for space applications

    SciTech Connect

    Nagarkar, V.; Entine, G.; Stoppel, P.; Cirignano, L. ); Swinehart, P. )

    1992-08-01

    One of the most important contributions to the radiation exposure of astronauts engaged in space flight is the significant flux of high energy neutrons arising from both primary and secondary sources of ionizing radiation. Under NASA sponsorship, the authors are developing a solid state neutron sensor capable of being incorporated into a very compact, flight instrument to provide high quality real time measurement of this important radiation flux. The dosimeter uses a special, high neutron sensitivity, PIN diode that is insensitive t the other forms of ionizing radiation. The dosimeter will have the ability to measure and record neutron dose over a range of 50 microgray to tens of milligrays (5 millirads to several rads) over a flight of up to 30 days. the performance characteristics of the PIN diode with a detailed description of the overall dosimeter is presented. in this paper.

  9. Do saccharide doped PAGAT dosimeters increase accuracy?

    NASA Astrophysics Data System (ADS)

    Berndt, B.; Skyt, P. S.; Holloway, L.; Hill, R.; Sankar, A.; De Deene, Y.

    2015-01-01

    To improve the dosimetric accuracy of normoxic polyacrylamide gelatin (PAGAT) gel dosimeters, the addition of saccharides (glucose and sucrose) has been suggested. An increase in R2-response sensitivity upon irradiation will result in smaller uncertainties in the derived dose if all other uncertainties are conserved. However, temperature variations during the magnetic resonance scanning of polymer gels result in one of the highest contributions to dosimetric uncertainties. The purpose of this project was to study the dose sensitivity against the temperature sensitivity. The overall dose uncertainty of PAGAT gel dosimeters with different concentrations of saccharides (0, 10 and 20%) was investigated. For high concentrations of glucose or sucrose, a clear improvement of the dose sensitivity was observed. For doses up to 6 Gy, the overall dose uncertainty was reduced up to 0.3 Gy for all saccharide loaded gels compared to PAGAT gel. Higher concentrations of glucose and sucrose deteriorate the accuracy of PAGAT dosimeters for doses above 9 Gy.

  10. System for use with solid state dosimeter

    DOEpatents

    Miller, S.D.; McDonald, J.C.; Eichner, F.N.; Tomeraasen, P.L.

    1990-09-04

    The present invention constitutes a system for determining the amounts of ionizing radiation to which dosimeters using thermoluminescent materials have been exposed. In accordance with this system, the thermoluminescent materials which comprise the dosimeters are first cooled by contact with a cryogenic substance such as liquefied nitrogen. The thermoluminescent materials are then optically stimulated by exposure to ultraviolet light. Thereafter, the amounts of visible light emitted by the thermoluminescent materials are detected and counted as the materials are allowed to warm up to room temperature. The amounts of luminescence exhibited by the materials are related to radiation exposure and provide a sensitive measure of radiation dosage. It has been discovered that the above procedure is most effective when heavily doped thermoluminescent materials are used and that the procedure allows many useful plastic materials to now be employed in dosimeter constructions. 3 figs.

  11. System for use with solid state dosimeter

    DOEpatents

    Miller, Steven D.; McDonald, Joseph C.; Eichner, Fred N.; Tomeraasen, Paul L.

    1990-01-01

    The present invention constitutes a system for determining the amounts of ionizing radiation to which dosimeters using thermoluminescent materials have been exposed. In accordance with this system, the thermoluminescent materials which comprise the dosimeters are first cooled by contact with a cryogenic substance such as liquified nitrogen. The thermoluminescent materials are then optically stimulated by exposure to ultraviolet light. Thereafter, the amounts of visible light emitted by the thermoluminescent materials are detected and counted as the materials are allowed to warm up to room temperature. The amounts of luminescence exhibited by the materials are related to radiation exposure and provide a sensitive measure of radiation dosage. It has been discovered that the above procedure is most effective when heavily doped thermoluminescent materials are used and that the procedure allows many useful plastic materials to now be employed in dosimeter constructions.

  12. Fiber optic dosimeter with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Moutinho, L. M.; Castro, I. F.; Peralta, L.; Abreu, M. C.; Veloso, J. F. C. A.

    2014-08-01

    A small dimension, real-time readout dosimeter is desirable for specific applications in medical physics as for example, dose measurement in prostate brachytherapy. This particular radiotherapy procedure consists in the permanent deposition of low energy, low-dose and low-dose rate small sized radioactive seeds. We developed a scintillating fiber optic based dosimeter suitable for in-vivo, real-time low dose and low dose rate measurements. Due to the low scintillation light produced in the scintillating fiber, a high sensitive and high gain light detector is required. The Silicon Photomultipliers are an interesting option that allowed us to obtain good results in our studies.

  13. Sensitivity and variability of Presage dosimeter formulations in sheet form with application to SBRT and SRS QA

    SciTech Connect

    Dumas, Michael; Rakowski, Joseph T.

    2015-12-15

    Purpose: To measure sensitivity and stability of the Presage dosimeter in sheet form for various chemical concentrations over a range of clinical photon energies and examine its use for stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) QA. Methods: Presage polymer dosimeters were formulated to investigate and optimize their sensitivity and stability. The dosimeter is composed of clear polyurethane base, leucomalachite green (LMG) reporting dye, and bromoform radical initiator in 0.9–1.0 mm thick sheets. The chemicals are mixed together for 2 min, cast in an aluminum mold, and left to cure at 60 psi for a minimum of two days. Dosimeter response was characterized at energies Co-60, 6 MV, 10 MV flattening-filter free, 15 MV, 50 kVp (mean 19.2 keV), and Ir-192. The dosimeters were scanned by a Microtek Scanmaker i800 at 300 dpi, 2{sup 16} bit depth per color channel. Red component images were analyzed with ImageJ and RIT. SBRT QA was done with gamma analysis tolerances of 2% and 2 mm DTA. Results: The sensitivity of the Presage dosimeter increased with increasing concentration of bromoform. Addition of tin catalyst decreased curing time and had negligible effect on sensitivity. LMG concentration should be at least as high as the bromoform, with ideal concentration being 2% wt. Gamma Knife SRS QA measurements of relative output and profile widths were within 2% of manufacturer’s values validated at commissioning, except the 4 mm collimator relative output which was within 3%. The gamma pass rate of Presage with SBRT was 73.7%, compared to 93.1% for EBT2 Gafchromic film. Conclusions: The Presage dosimeter in sheet form was capable of detecting radiation over all tested photon energies and chemical concentrations. The best sensitivity and photostability of the dosimeter were achieved with 2.5% wt. LMG and 8.2% wt. bromoform. Scanner used should not emit any UV radiation as it will expose the dosimeter, as with the Epson 10000 XL scanner

  14. NOTE: Cell-phone interference with pocket dosimeters

    NASA Astrophysics Data System (ADS)

    Djajaputra, David; Nehru, Ramasamy; Bruch, Philip M.; Ayyangar, Komanduri M.; Raman, Natarajan V.; Enke, Charles A.

    2005-05-01

    Accurate reporting of personal dose is required by regulation for hospital personnel that work with radioactive material. Pocket dosimeters are commonly used for monitoring this personal dose. We show that operating a cell phone in the vicinity of a pocket dosimeter can introduce large and erroneous readings of the dosimeter. This note reports a systematic study of this electromagnetic interference. We found that simple practical measures are enough to mitigate this problem, such as increasing the distance between the cell phone and the dosimeter or shielding the dosimeter, while maintaining its sensitivity to ionizing radiation, by placing it inside a common anti-static bag.

  15. Dose-response measurement in gel dosimeter using various imaging modalities

    NASA Astrophysics Data System (ADS)

    Fujibuchi, T.; Kawamura, H.; Yamanashi, K.; Hiroki, A.; Yamashita, S.; Taguchi, M.; Sato, Y.; Mimura, K.; Ushiba, H.; Okihara, T.

    2013-06-01

    Measurement methods that accurately measure radiation dose distribution in a three dimensional manner in order to allow comparisons of treatment plans are needed for quality assurance. One such measurement method involves the use of a polymer gel dosimeter to measure the dose distribution in three dimensions. During irradiation, a polymerization reaction makes new chemical bonds and induces changes of the chemical structure of the gel of the gel dosimeter. In the present study, dose-response measurement of an environment-friendly material used in the gel dosimeter was performed by imaging with computed tomography (CT) and R1, R2, and fluid-attenuated inversion-recovery (FLAIR) magnetic resonance imaging (MRI) under various imaging conditions. Dose-response characteristics in the gel dosimeter used in the experiment were observed at doses of 5-20 Gy administered by X-ray CT and MRI. Although the FLAIR signal was a relative value, the dose-response values with FLAIR were excellent compared to those with R1, R2, and CT. Determination of more appropriate imaging conditions could help expand the dose-response parameters of each measurement method.

  16. Compton effect thermally activated depolarization dosimeter

    DOEpatents

    Moran, Paul R.

    1978-01-01

    A dosimetry technique for high-energy gamma radiation or X-radiation employs the Compton effect in conjunction with radiation-induced thermally activated depolarization phenomena. A dielectric material is disposed between two electrodes which are electrically short circuited to produce a dosimeter which is then exposed to the gamma or X radiation. The gamma or X-radiation impinging on the dosimeter interacts with the dielectric material directly or with the metal composing the electrode to produce Compton electrons which are emitted preferentially in the direction in which the radiation was traveling. A portion of these electrons becomes trapped in the dielectric material, consequently inducing a stable electrical polarization in the dielectric material. Subsequent heating of the exposed dosimeter to the point of onset of ionic conductivity with the electrodes still shorted through an ammeter causes the dielectric material to depolarize, and the depolarization signal so emitted can be measured and is proportional to the dose of radiation received by the dosimeter.

  17. Pen Ink as an Ultraviolet Dosimeter

    ERIC Educational Resources Information Center

    Downs, Nathan; Turner, Joanna; Parisi, Alfio; Spence, Jenny

    2008-01-01

    A technique for using highlighter ink as an ultraviolet dosimeter has been developed for use by secondary school students. The technique requires the students to measure the percentage of colour fading in ink drawn onto strips of paper that have been exposed to sunlight, which can be calibrated to measurements of the ultraviolet irradiance using…

  18. Radio-physical properties of micelle leucodye 3D integrating gel dosimeters

    NASA Astrophysics Data System (ADS)

    Vandecasteele, J.; Ghysel, S.; Baete, S. H.; De Deene, Y.

    2011-02-01

    % was found in optical dose sensitivity when the dose rate varied between 50 and 400 cGy\\,min^{-1}. By pre-irradiating the novel leucomalachite green-type dosimeter to 500 cGy, the apparent difference in dose response between 200 and 400 cGy\\,min^{-1} was eliminated, similar to earlier findings. However, a dose response difference of 38% between 50 and 200 cGy\\,min^{-1} was still measured. On the basis of these experimental results it is concluded that the leucodye micelle gel dosimeter is not yet optimal for dose verifications of high precision radiation therapy treatments. This study, however, indicates that the dose rate dependence has a potential for improvement. Future research is necessary to further minimize the dose rate dependence through extensive chemical analysis and optimization of the gel formulation. Some insights into the physicochemical mechanisms were obtained and are discussed in this paper.

  19. A metal-oxide-semiconductor radiation dosimeter with a thick and defect-rich oxide layer

    NASA Astrophysics Data System (ADS)

    Liu, Hongrui; Yang, Yuhao; Zhang, Jinwen

    2016-04-01

    Enhancing the density of defects in the oxide layer is the main factor in improving the sensitivity of a metal-oxide-semiconductor (MOS) radiation dosimeter. This paper reports a novel MOS dosimeter with a very thick and defect-rich oxide layer fabricated by MEMS technology. The category of defects in SiO2 and their possible effect on the radiation dose sensing was analyzed. Then, we proposed combining deep-reactive-ion etching, thermal oxidation and low pressure chemical vapor deposition to realize an oxide layer containing multiple and large interfaces which can increase defects significantly. The trench-and-beam structure of silicon was considered in detail. The fabrication process was developed for obtaining a thick and compact MEMS-made SiO2. Our devices were irradiated by γ-rays of 60Co at 2 Gy per minute for 2 h and a thermally stimulated current (TSC) method was used to determine the readout of the dosimeters. Results show that there is a peak current of about 450 nA, indicating a total TSC charge of 158 μC and sensitivity of 1.1 μC mm-3·Gy, which is 40 times the sensitivity of previous MOS dosimeters.

  20. Clinical applications of 3-D dosimeters

    NASA Astrophysics Data System (ADS)

    Wuu, Cheng-Shie

    2015-01-01

    Both 3-D gels and radiochromic plastic dosimeters, in conjunction with dose image readout systems (MRI or optical-CT), have been employed to measure 3-D dose distributions in many clinical applications. The 3-D dose maps obtained from these systems can provide a useful tool for clinical dose verification for complex treatment techniques such as IMRT, SRS/SBRT, brachytherapy, and proton beam therapy. These complex treatments present high dose gradient regions in the boundaries between the target and surrounding critical organs. Dose accuracy in these areas can be critical, and may affect treatment outcome. In this review, applications of 3-D gels and PRESAGE dosimeter are reviewed and evaluated in terms of their performance in providing information on clinical dose verification as well as commissioning of various treatment modalities. Future interests and clinical needs on studies of 3-D dosimetry are also discussed.

  1. Exploring the dose response of radiochromic dosimeters

    NASA Astrophysics Data System (ADS)

    Skyt, P. S.; Wahlstedt, I.; Yates, E. S.; Muren, L. P.; Petersen, J. B. B.; Balling, P.

    2013-06-01

    The aim of this study was to explore the dose response of a newly developed radio-chromic hydrogel dosimeter based on leuco malachite green dye in a gelatine matrix. The original dosimeter composition was first investigated in terms of dose response and dose-rate dependence. In addition, the initiating compounds producing chlorine radicals were substituted with compounds producing fluorine radicals, oxygen-centered radicals, carbon-centered radicals and bromine radicals. Also the surfactant was substituted by other compounds of different molecular size and charge. The original composition gave a dose response of 3.5·10-3 Gy-1cm-1 at 6 Gy/min with a dose rate dependence giving a 27 % increase when decreasing the dose rate to 1 Gy/min. None of the substituted initiating components contributed to an increase in dose response while only one surfactant increased the dose response slightly.

  2. Radiological properties of normoxic polymer gel dosimeters

    SciTech Connect

    Venning, A.J.; Nitschke, K.N.; Keall, P.J.; Baldock, C.

    2005-04-01

    The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper; methacrylic acid gelatine gel with ascorbic acid; and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections over the energy range from 10 keV to 20 MeV and by Monte Carlo modeling of depth doses. Normoxic polymer gel dosimeters have a high gelatine and monomer concentration and therefore mass density (kg m{sup -3}) up to 3.8% higher than water. This results in differences between the cross-section ratios of the normoxic polymer gels and water of up to 3% for the attenuation, energy absorption, and collision stopping power coefficient ratios through the Compton dominant energy range. The mass cross-section ratios were within 2% of water except for the mass attenuation and energy absorption coefficients ratios, which showed differences with water of up to 6% for energies less than 100 keV. Monte Carlo modeling was undertaken for the polymer gel dosimeters to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between gel and water were within 1% and the relative percentage differences were within 3.5%. The results show that the MAGAT gel formulation is the most radiological water equivalent of the normoxic polymer gel dosimeters investigated due to its lower mass density measurement compared with MAGAS and MAGIC gels.

  3. Water equivalence of polymer gel dosimeters

    NASA Astrophysics Data System (ADS)

    Sellakumar, P.; James Jebaseelan Samuel, E.; Supe, Sanjay S.

    2007-07-01

    To evaluate the water equivalence and radiation transport properties of polymer gel dosimeters over the wide range of photon and electron energies 14 different types of polymer gels were considered. Their water equivalence was evaluated in terms of effective atomic number ( Zeff), electron density ( ρe), photon mass attenuation coefficient ( μ/ρ), photon mass energy absorption coefficient ( μen/ρ) and total stopping power (S/ρ)tot of electrons using the XCOM and the ESTAR database. The study showed that the effective atomic number of polymer gels were very close ( <1%) to that of water except PAGAT, MAGAT and NIPAM which had the variation of 3%, 2% and 3%, respectively. The value of μ/ρ and μen/ρ for all polymer gels were in close agreement ( <1%) with that of water beyond 80 keV. The value of (S/ρ)tot of electrons in polymer gel dosimeters were within 1% agreement with that of water. From the study we conclude that at lower energy ( <80 keV) the polymer gel dosimeters cannot be considered water equivalent and study has to be carried out before using the polymer gel for clinical application.

  4. Post-Irradiation Study of the Alanine Dosimeter

    PubMed Central

    Desrosiers, Marc F.

    2014-01-01

    Post-irradiation stability of high-dose dosimeters has traditionally been an important measurement influence quantity. Though the exceptional stability of the alanine dosimeter response with time has rendered this factor a non-issue for routine work, the archival quality of the alanine dosimeter has not been characterized. Here the alanine pellet dosimeter response is measured up to seven years post-irradiation for a range of absorbed doses. This long-term study is accompanied by an examination of the environmental influence quantities (e.g., ambient light) on the relatively short-term (3–4 month) stability of both pellet and film commercial dosimeters. Both dosimeter types demonstrated exceptional stability in the short term and proved to be relatively insensitive to common influence quantities. The long-term data revealed a complex dose-dependent response trend. PMID:26601033

  5. Methacholine bronchial challenge using a dosimeter with controlled tidal breathing.

    PubMed Central

    Nieminen, M M; Lahdensuo, A; Kellomaeki, L; Karvonen, J; Muittari, A

    1988-01-01

    A new inhalation synchronised dosimeter triggered by low inspiratory flow rates has been assessed. The methacholine challenge test using dosimeter nebulisation with controlled tidal breathing was compared with continuous nebulisation using De Vilbiss No 40 nebulisers with deep inhalations in 11 asthmatic subjects. Within subject PD20 FEV1 values were lower with the dosimeter method than with the continuous nebulisation method (geometric means 158 and 588 micrograms). The repeatability of the dosimeter method with controlled tidal breathing was studied in 11 asthmatic subjects, and the 95% range for a single measurement was +/- 0.72 doubling doses of methacholine. The dosimeter method has greater efficacy because aerosol is delivered during the first part of an inhalation, minimising loss of aerosol outside the respiratory tract. The dosimeter technique combined with controlled tidal breathing appears to be a useful method for carrying out standardised non-specific bronchoprovocation tests. Images PMID:3065974

  6. Comparison of the fiber optic dosimeter and semiconductor dosimeter for use in diagnostic radiology

    NASA Astrophysics Data System (ADS)

    Yoo, W. J.; Shin, S. H.; Sim, H. I.; Hong, S.; Kim, S. G.; Jang, J. S.; Kim, J. S.; Jeon, H. S.; Kwon, G. W.; Jang, K. W.; Cho, S.; Lee, B.

    2014-05-01

    A fiber-optic dosimeter (FOD) was fabricated using a plstic scintillating fiber, a plastic optical fiber, and a multi-pixel photon counter to measure entrance surface dose (ESD) in diagnostic radiology. Under changing tube current and irradition time of the digital radiography (DR) system, we measured the scintillating light and the ESD simultaneously. As experiemtnal results, the total counts of the FOD were changed in a manner similar to the ESDs of the semiconductor dosimeter (SCD). In conclusion, we demonstrated that the proposed FOD minimally affected the diagnostic information of DR image while the SCD caused serious image artifacts.

  7. Passive electronic dosimeters based on direct ion storage

    SciTech Connect

    Kahilainen, J.

    1995-12-31

    Using non-volatile semiconductor memories as dosimeters in radiation protection is made possible by the application of the so-called DIS (Direct Ion Storage) method, where the charge collected from a small volume of gas is directly stored in a non-volatile memory cell. This allows the construction of small and simple electronic passive dosimeters with features not available in conventional passive Film or TLD dosimeters. The basic design principles and properties of DIS dosimeters are presented and the application potential for the measurement of various categories of ionizing radiation is discussed.

  8. GAMMA AND X-RAY DOSIMETER AND DOSIMETRIC METHOD

    DOEpatents

    Taplin, G.V.; Douglas, C.H.; Sigoloff, S.C.

    1958-08-19

    An improvement in colorimetric gamma and x-ray dosimeter systems and a self-contained. hand carried dostmeter of the afore-mentioned type ts described. A novel point of the invention ltes in the addition of specific quantities of certain normalizing agents to the two phase chlorinated hydro-carbon-aqueous dyc colortmetric dosimeter to eliminate the after reaction and thereby extend the utility of such systein. The structure of the two phase colorimetric dosimeter tubes and the carrying case for the tubes of the portable dosimeter are unique features.

  9. Development of an Automated Reader for Analysis and Storage of Personnel Dosimeter Badge Data

    NASA Technical Reports Server (NTRS)

    Meneghelli, B. J.; Hodge, T. R.; Robinson, L. J.; Lueck, D. E.

    1997-01-01

    The collection and archiving of data from personnel dosimeters has become increasingly important in light of the lowered Threshold Limit Values (TLV) for HydraZine (HZ), MonoMethylHydrazine (MMH), and Unsymmetrical DiMethylHydrazine (UDMH). The American Conference of Government Industrial Hygienists (ACGIH) lowered the TLV from 100 parts per billion (ppb) to IO ppb and has caused increased concern over long term exposures of personnel to trace levels of these hypergols and other potentially harmful chemicals. An automated system of reading the exposure levels of personnel dosimeters and storing exposure data for subsequent evaluation has been developed. The reading of personnel dosimeter badges for exposure to potentially harmful vapor concentrations of hydrazines or other chemicals is performed visually by comparing the color developed by the badge with a calibrated color comparator. The result obtained using visual comparisons of the developed badge color with the comparator may vary widely from user to user. The automated badge reader takes the variability out of the dosimeter reading by accurately comparing the reflectance obtained from a colored spot on the badge with a reading on the same spot prior to any exposure to chemical vapors. The observed difference between the reflectance values is used as part of a calculation of the dose value for the badge based on a stored calibration curve. The badge reader also stores bar-code data unique to each badge, as well as bar-code information on the user, as part of the permanent badge record. The start and stop exposure times for each badge are recorded and can be used as part of the calculated concentration, in ppm, for each badge logged during a recording period. The badge reader is equipped with a number of badge holders, each of which is unique to a specific type of personnel dosimeter badge. This gives the reader maximum flexibility to allow for the reading of several different types of badges. Test results of

  10. Evaluation of all dose components in the LVR-15 reactor epithermal neutron beam using Fricke gel dosimeter layers.

    PubMed

    Bartesaghi, G; Burian, J; Gambarini, G; Marek, M; Negri, A; Viererbl, L

    2009-07-01

    Fricke gel dosimeters in the form of layers are suitable to reconstruct bidimensional distributions of the absorbed dose; in accordance with their chemical composition and applying suitably developed algorithms, they can provide dose images of the different radiation components in a BNCT field. After the description of the applied method, this work presents the results obtained at the epithermal column of the BNCT facility at the NRI in Rez (CZ). The measured dose distributions are shown in comparison with data taken by means of other dosimeters thermoluminescence dosimeters (TLDs) and with calculations carried out with the Monte Carlo code MCNP5. The agreement with the results obtained by means of the different techniques is satisfying.

  11. Angular dependence of a simple accident dosimeter

    SciTech Connect

    Devine, R. T.; Romero, L. L.; Olsher, R. H.

    2004-01-01

    A simple dosimeter made of a sulfur tablet, bare and cadmium covered indium foils and a cadmium covered copper foil has been modeled using MCNP5. Studies of the model without phantom or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high energy component. The threshold cross sections for the detectors on a phantom were calculated. The resulting doses assigned agree well with exposures made to three critical assemblies. In this study the angular dependence on a phantom is studied and compared with measurements taken on the GODIVA reactor. The dosimeter positions on the phantom are facing the source, on the back and the side. In previous papers the modeling of a simple dosimeter made of a sulfur tablet, bare and cadmium covered indium foils and a cadmium covered copper foil has been modeled using MCNP5. The conclusion made was that most of the neutron dose from criticality assemblies results from the high energy neutron fluences determined by the sulfur and indium detectors. The results using doses measured from the GODIVA, SHEBA, and bare and lead shielded SILENE reactors confirmed this. The angular dependence of an accident dosemeter is of interest in evaluating the exposure of personnel. To investigate this effect accident dosemeters were placed on a phantom and exposed to the GODIVA reactor at phantom orientations of 0{sup o}, 45{sup o}, 90{sup o}, 135{sup o}, and 180{sup o} to the assembly center line.

  12. A sensitive neutron dosimeter using superheated liquid.

    PubMed

    Das, M; Roy, B; Chatterjee, B K; Roy, S C

    2000-01-01

    The present work relates to a sensitive neutron dosimeter, a device for monitoring neutron dose in some accelerator and reactor sites. This device is capable of measuring a neutron dose as small as 0.1 microSv using superheated liquid as a sensitive liquid. The nucleation was measured by the volumetric method developed in our laboratory. The dose response of superheated drops of four liquids having boiling points of 8.92, -29.79, -40.75 and -45.6 degrees C, irradiated by a 3 Ci Am-Be neutron source has also been presented in this article.

  13. Quantitative evaluation of polymer gel dosimeters by broadband ultrasound attenuation

    NASA Astrophysics Data System (ADS)

    Khoei, S.; Trapp, J. V.; Langton, C. M.

    2013-06-01

    Ultrasound has been examined previously as an alternative readout method for irradiated polymer gel dosimeters, with authors reporting varying dose response to ultrasound transmission measurements. In this current work we extend previous work to measure the broadband ultrasound attenuation (BUA) response of irradiated PAGAT gel dosimeters, using a novel ultrasound computed tomography system.

  14. Preliminary investigation and application of a novel deformable PRESAGE® dosimeter

    PubMed Central

    Juang, T; Newton, J; Das, S; Adamovics, J; Oldham, M

    2013-01-01

    Deformable 3D dosimeters have potential applications in validating deformable dose mapping algorithms. This study evaluates a novel deformable PRESAGE® dosimeter and its application toward validating the deformable algorithm employed by VelocityAI. The deformable PRESAGE® dosimeter exhibited a linear dose response with a sensitivity of 0.0032 ΔOD/(Gy/cm). Comparison of an experimental dosimeter irradiated with an MLC pencilbeam checkerboard pattern under lateral compression up to 27% to a non-deformed control dosimeter irradiated with the same pattern verified dose tracking under deformation. CTs of the experimental dosimeter prior to and during compression were exported into VelocityAI and used to map an Eclipse dose distribution calculated on the compressed dosimeter to its original shape. A comparison between the VelocityAI dose distribution and the distribution from the dosimeter showed field displacements up to 7.3 mm and up to a 175% difference in field dimensions. These results highlight the need for validating deformable dose mapping algorithms to ensure patient safety and quality of care. PMID:24454522

  15. Evaluation of a Colorimetric Personal Dosimeter for Nitrogen Oxide.

    ERIC Educational Resources Information Center

    Diamond, Philip

    A personal colorimetric dosimeter for nitrogen dioxide was developed. Tests were performed to determine the response of these strips to various concentrations of NO2. The dosimeter strips were satisfactory for approximate determinations of total exposure (concentration + time) of nitrogen dioxide. The total exposure was calculated in terms of time…

  16. The development of a passive dosimeter for airborne aniline vapors.

    PubMed

    Campbell, J E; Konzen, R B

    1980-03-01

    A passive diffusion dosimeter has been suggested as an economical and accurate means of sampling airborne concentrations of gases and vapors in the working environment. The dosimeter utilizes molecular diffusion through a tube of known geometry to obtain a quantitative determination of airborne concentrations of the contaminant of interest. A passive sampling dosimeter was designed to measure concentrations of aniline vapor in air. Diffusion tubes of 1.5, 3.0, and 4.5 cm lengths were tested under controlled conditions of relative humidity, air temperature, and vapor concentrations. The results indicate that the use of a passive diffusion dosimeter for determining time-weighted average concentrations of aniline is feasible. It was shown that a 1 cm diameter 3.0 cm length diffusion tube gave the most consistent results. It is suggested that further investigations be conducted in the development of passive diffusion dosimeters for other gaseous contaminants.

  17. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    DOEpatents

    Braunlich, Peter F.; Tetzlaff, Wolfgang

    1989-01-01

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phoshphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate.

  18. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    DOEpatents

    Braunlich, P.F.; Tetzlaff, W.

    1989-04-25

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs.

  19. A scintillating fiber dosimeter for radiotherapy

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Conti, V.; Bolognini, D.; Grigioni, S.; Mascagna, V.; Prest, M.; Scazzi, S.; Mozzanica, A.; Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A.; Giannini, G.; Vallazza, E.

    2007-10-01

    Radiotherapy, together with chemotherapy and surgery, is one of the main methods applied in the fight against cancer; in order to increase the chances of a successful radiotherapy treatment the dose delivery to the tumor and the surrounding normal tissues has to be computed with high accuracy. Traditional dosimeters are accurate but single channel (ionization chambers and diodes) or non real-time (radiographic films) devices. At present there is no device water equivalent that can perform real-time and bidimensional measurements of a dose distribution. This article describes the development of a real-time dosimeter based on scintillating fibers for photon and electron beams; the fibers are made of polystyrene, that is water equivalent and thus tissue equivalent, allowing a direct dose calculation. Three prototypes (single and multichannel) have been assembled, consisting in small scintillators coupled to white fibers that carry the light to photomultiplier tubes. In this article the prototypes and the readout electronics are described, together with the results of the measurements with electron and photon beams with energy up to 20 MeV (produced by linear accelerators Varian Clinac 1800 and 2100CD).

  20. Fricke gel dosimeter with improved sensitivity for low-dose-level measurements.

    PubMed

    Valente, Mauro; Molina, Wladimir; Carrizales Silva, Lila; Figueroa, Rodolfo; Malano, Francisco; Pérez, Pedro; Santibañez, Mauricio; Vedelago, José

    2016-01-01

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue-equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity. Properties of standard Fricke gel dosimeter for high-dose levels are used as a starting point, and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low-dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose-dependency, showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain an adequate dosimeter response for low-dose levels. A suitable composition from among those studied is selected as a good candidate for low-dose-level radiation dosimetry consisting of a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, Xylenol orange, and tridistilled water. Dosimeter samples are prepared in standard vials for in-phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated using typical X-ray tubes for radiology and calibrated Farmer-type ionization chamber is used as reference to measure dose rates inside phantoms at vial locations. Once sensitive material composition is optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels

  1. Limitations of using dosimeters in impulse noise environments.

    PubMed

    Kardous, Chucri A; Willson, Robert D

    2004-07-01

    The National Institute for Occupational Safety and Health (NIOSH) investigated the capabilities of noise dosimeters to measure personal exposure to impulse noise. The two leading types of commercially available dosimeters were evaluated in terms of their ability to measure and integrate impulses generated from gunfire during live-fire exercises at a law enforcement indoor firing range. Sound measurements were conducted throughout the firing range using dosimeters, sound level meters, and a measurement configuration that consisted of a quarter-inch microphone and a digital audiotape recorder to capture the impulse waveforms. Personal dosimetry was conducted on eight shooters, an observer, and the range master. Peak levels from gunfire reached 163 decibels (dB), exceeding the nominal input limit of the dosimeters. The dosimeters "clipped" the impulses by acting as if the gunfire had a maximum level of 146 dB. In other cases, however, peak levels (e.g., 108 dB) were below the dosimeter input limits, but the dosimeters still showed a peak level of 146 dB. Although NIOSH recommends that sound levels from 80 to 140 dB (A-weighted) be integrated in the calculation of dose and the time-weighted average, our present data suggest this criterion may be inadequate. These results showed that some instruments are incapable of providing accurate measures of impulse sounds because of their electroacoustic limitations.

  2. Light scattering in optical CT scanning of Presage dosimeters

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Adamovics, J.; Cheeseborough, J. C.; Chao, K. S.; Wuu, C. S.

    2010-11-01

    The intensity of the scattered light from the Presage dosimeters was measured using a Thorlabs PM100D optical power meter (Thorlabs Inc, Newton, NJ) with an optical sensor of 1 mm diameter sensitive area. Five Presage dosimeters were made as cylinders of 15.2 cm, 10 cm, 4 cm diameters and irradiated with 6 MV photons using a Varian Clinac 2100EX. Each dosimeter was put into the scanning tank of an OCTOPUS" optical CT scanner (MGS Research Inc, Madison, CT) filled with a refractive index matching liquid. A laser diode was positioned at one side of the water tank to generate a stationary laser beam of 0.8 mm width. On the other side of the tank, an in-house manufactured positioning system was used to move the optical sensor in the direction perpendicular to the outgoing laser beam from the dosimeters at an increment of 1 mm. The amount of scattered photons was found to be more than 1% of the primary light signal within 2 mm from the laser beam but decreases sharply with increasing off-axis distance. The intensity of the scattered light increases with increasing light attenuations and/or absorptions in the dosimeters. The scattered light at the same off-axis distance was weaker for dosimeters of larger diameters and for larger detector-to-dosimeter distances. Methods for minimizing the effect of the light scattering in different types of optical CT scanners are discussed.

  3. Radiation Measured during ISS-Expedition 13 with Different Dosimeters

    NASA Technical Reports Server (NTRS)

    Zhou, D.; Semones, E.; Gaza, R.; Johnson, S.; Zapp, N.; Lee, K.; George, T.

    2008-01-01

    Radiation in low Earth orbit (LEO) is mainly composed of Galactic Cosmic Rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). The biological impact of space radiation to astronauts depends strongly on the particles linear energy transfer (LET) and is dominated by high LET radiation. It is important to measure the LET spectrum for the space radiation field and to investigate the influence of radiation on astronauts. At present, the preferred active dosimeters sensitive to all LET are the tissue equivalent proportional counter (TEPC) and silicon detectors in various configurations; the preferred passive dosimeters are thermoluminescence dosimeters (TLDs) and optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET as well as CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET. The TEPC, CR-39 PNTDs, TLDs and OSLDs were used to investigate the radiation exposure for the ISS mission Expedition 13 (ISS-12S) in LEO. LET spectra and radiation quantities (fluence, absorbed dose, dose equivalent and quality factor) were measured for the space mission with different dosimeters. This paper introduces the operational principles for the dosimeters, describes the method to combine the results measured by TLDs/OSLDs and CR-39 PNTDs, and presents the LET spectra and the radiation quantities measured. Keywords: space radiation; cosmic rays; active and passive dosimeters; LET spectra

  4. A search for novel thermoluminescent radiation dosimeter media.

    PubMed

    Al-Hinai, Khalid H; Benkara Mohd, Nadjima; Rozullyah Zulkepely, Nurul; Md Nor, Roslan; Mohd Amin, Yusoff; Bradley, D A

    2013-12-01

    We describe two example pilot efforts to help define new thermoluminescent dosimeter media. The first concerns ZnS:Mn nanophosphors, prepared by chemical precipitation using zinc and sodium sulfate, doped with manganese sulfate at concentrations varying from 1 to 3mol. The second concerns chemical vapor deposited diamond, produced as a thin film or as amorphous carbon on a single-crystal silicon substrate, each deposited under the same conditions, use being made of the hot filament-chemical vapor deposition (HFCVD) technique. The gas concentrations used were 1% CH4 in 99% H2 and 25% CH4 in 75% H2. Characterization of formations used FESEM, XRD and EDX. The nanophosphors consisted of particles of sizes in the range 85-150nm, the thermoluminescence (TL)-based radiation detection medium giving rise to a single peaked glow curve of maximum yield at a temperature of 250°C at a heating rate of 5°C/s. The TL response increased linearly with radiation dose, ZnS doped to 2mol of Mn being found the most sensitive. Regarding chemical vapor deposited (CVD) carbon, inappreciable TL was found for the resultant ball-like amorphous carbon films, graphite, and the silicon substrate, whereas CVD diamond films showed a promising degree of linearity with dose. For both the ZnS and diamond samples, TL signal fading was appreciable, being some 40% per day for ZnS and>50% per day for CVD films even under storage in the dark at room temperature, making it apparent that there is need to adjust parameters such as the size of nanoparticles.

  5. Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters.

    PubMed

    Mattea, Facundo; Romero, Marcelo R; Vedelago, José; Quiroga, Andrés; Valente, Mauro; Strumia, Miriam C

    2015-06-01

    Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution in diagnostic and therapeutic medical applications. But, even in systems where the 3D structure is usually maintained for long periods of time after irradiation, it is still not possible to eliminate the diffusion of the different species in the regions of dose gradients within the gel. As a consequence, information of the dose loses quality over time. In the pursuit of a solution and to improve the understanding of this phenomenon a novel system based on itaconic acid and N-N'-methylene-bisacrylamide (BIS) is hereby proposed. Effects of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species was studied. In this study, one of the carboxylic groups of the itaconic acid molecule was modified with aniline to obtain molecules with similar reactivity but different molecular sizes. Then, dosimeters based on these modified species and on the original ITA molecules were irradiated in an X-ray tomography apparatus at different doses up to 173Gy. Afterwards, the resulting dosimeters were characterized by Raman spectroscopy and optical absorbance in order to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the post irradiation diffusion.

  6. p-MOSFET total dose dosimeter

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G. (Inventor); Blaes, Brent R. (Inventor)

    1994-01-01

    A p-MOSFET total dose dosimeter where the gate voltage is proportional to the incident radiation dose. It is configured in an n-WELL of a p-BODY substrate. It is operated in the saturation region which is ensured by connecting the gate to the drain. The n-well is connected to zero bias. Current flow from source to drain, rather than from peripheral leakage, is ensured by configuring the device as an edgeless MOSFET where the source completely surrounds the drain. The drain junction is the only junction not connected to zero bias. The MOSFET is connected as part of the feedback loop of an operational amplifier. The operational amplifier holds the drain current fixed at a level which minimizes temperature dependence and also fixes the drain voltage. The sensitivity to radiation is made maximum by operating the MOSFET in the OFF state during radiation soak.

  7. Characterization of a nuclear accident dosimeter

    SciTech Connect

    Burrows, R.A.

    1995-12-01

    The 23rd nuclear accident dosimetry intercomparison was held during the week of June 12--16, 1995 at Los Alamos National Laboratory. This report presents the results of this event, referred to as NAD 23, as related to the performance of Sandia National Laboratories (SNL) personal nuclear accident dosimeter (PNAD). Two separate critical assemblies, SHEBA and Godiva, were used to generate seven separate neutron spectra for use in dose comparisons. SNL`s PNAD measured absorbed doses that were within +16 to +26% of the reference doses. In addition, a preliminary investigation was undertaken to determine the feasibility of using the data obtained from an irradiated PNAD to correct for body orientation. This portion of the experiment was performed with a TRIGA reactor at the Nuclear Science Center at Texas A and M University.

  8. A miniature MOSFET radiation dosimeter probe.

    PubMed

    Gladstone, D J; Lu, X Q; Humm, J L; Bowman, H F; Chin, L M

    1994-11-01

    Prototype miniature dosimeter probes have been designed, built, and characterized employing a small, radiation sensitive metal oxide semiconductor field effect transistor (MOSFET) chip to measure, in vivo, the total accumulated dose and dose rate as a function of time after internal administration of long range beta particle radiolabeled antibodies and in external high energy photon and electron beams. The MOSFET detector is mounted on a long narrow alumina substrate to facilitate electrical connection. The MOSFET, alumina substrate, and lead wires are inserted into a 16 gauge flexineedle, which, in turn, may be inserted into tissue. The radiation dosimeter probe has overall dimensions of 1.6 mm diam and 3.5 cm length. The MOSFET probe signals are read, stored, and analyzed using an automated data collection and analysis system. Initially, we have characterized the probe's response to long range beta particle emission from 90Y sources in solution and to high energy photon and electron beams from linear accelerators. Since the prototype has a finite substrate thickness, the angular dependence has been studied using beta particle emission from a 90Sr source. Temperature dependence and signal drift have been characterized and may be corrected for. Measurements made in spherical volumes containing 90Y with diameters less than the maximum electron range, to simulate anticipated geometries in animal models, agree well with Berger point kernel and EGS4 Monte Carlo calculations. The results from the prototype probes lead to design requirements for detection of shorter range beta particles used in radioimmunotherapy and lower photon energies used in brachytherapy. PMID:7891632

  9. Method and apparatus for reading free falling dosimeter punchcodes

    DOEpatents

    Langsted, J.M.

    1992-12-22

    A punchcode reader is provided for reading data encoded in a punchcode hole array on a dosimeter. The dosimeter falls through a passage in the reader containing photosensor detectors disposed along the passage which provide output signals to a microprocessor. The signals are processed to determine the orientation of the dosimeter in the reader, the location and state of punchcode holes in a two row array thereby decoding the encoded data. Multiple rate of fall calculations are made, and if appropriate matching of the punchcode array is not obtained in three tries, an error signal is output to the operator. The punchcode reader also provides for storage of data from multiple dosimeters passed through the reader, and for the output of decoded data to an external display or a computer for further processing. 8 figs.

  10. Method and apparatus for reading free falling dosimeter punchcodes

    DOEpatents

    Langsted, James M.

    1992-12-22

    A punchcode reader is provided for reading data encoded in a punchcode hole array on a dosimeter. The dosimeter falls through a passage in the reader containing photosensor detectors disposed along the passage which provide output signals to a microprocessor. The signals are processed to determine the orientation of the dosimeter in the reader, the location and state of punchcode holes in a two row array thereby decoding the encoded data. Multiple rate of fall calculations are made, and if appropriate matching of the punchcode array is not obtained in three tries, an error signal is outputted to the operator. The punchcode reader also provides for storage of data from multiple dosimeters passed through the reader, and for the output of decoded data to an external display or a computer for further processing.

  11. [Fabrication of annealing equipment for optically stimulated luminescence (OSL) dosimeter].

    PubMed

    Nakagawa, Kohei; Hayashi, Hiroaki; Okino, Hiroki; Takegami, Kazuki; Okazaki, Tohru; Kobayashi, Ikuo

    2014-10-01

    The optically stimulated luminescence (OSL) dosimeter is a useful detector for measuring absorbed doses of X-rays. A small-type OSL dosimeter, "nanoDot", has recently been developed by Landauer, Inc., who also manufacture "microStar" reading equipment. However, additional annealing equipment is needed if the nanoDot OSL dosimeter is used repeatedly. The aim of this study was to fabricate suitable annealing equipment using commonly available products. Our device positions four fluorescent light tubes in a close configuration. The heat from the fluorescent light tubes is dissipated using fans. Experiments using diagnostic X-ray equipment were carried out to evaluate the capability of our annealing equipment. The results indicated that our equipment can fully anneal the nanoDot OSL dosimeter with annealing times of approximately 20 hours. PMID:25327423

  12. Fast neutron detection with Al 2O 3 thermoluminescence dosimeter

    NASA Astrophysics Data System (ADS)

    Ranogajec-Komor, Maria; Osvay, Margit; Dvornik, Igor; Biró, Tamàs

    1983-07-01

    The technique of thermoluminescent (TL) dosimeter activation can be used to detect any radiation making TL dosimeters radioactive. In the experiment discussed in this paper Al2O3:Mg, Y TL dosimeters were irradiated by cyclotron neutrons with 5±1 MeV mean energy and by accompanying gamma rays. The gamma and the fast neutron component can be separately measured by the same dosimeter. Because of low neutron sensitivity of Al2O3 the gamma dose can be determined by the first TL reading while the 27Al(n, α)24 Na reaction provides the possibility of fast neutron detection by the subsequent reading of thermoluminescence induced in the TL material by the decay of 24Na.

  13. Antioxidant effect of green tea on polymer gel dosimeter

    NASA Astrophysics Data System (ADS)

    Samuel, E. J. J.; Sathiyaraj, P.; Deena, T.; Kumar, D. S.

    2015-01-01

    Extract from Green Tea (GTE) acts as an antioxidant in acrylamide based polymer gel dosimeter. In this work, PAGAT gel was used for investigation of antioxidant effect of GTE.PAGAT was called PAGTEG (Polyacrylamide green tea extract gel dosimeter) after adding GTE. Free radicals in water cause pre polymerization of polymer gel before irradiation. Polyphenols from GTE are highly effective to absorb the free radicals in water. THPC is used as an antioxidant in polymer gel dosimeter but here we were replaced it by GTE and investigated its effect by spectrophotometer. GTE added PAGAT samples response was lower compared to THPC added sample. To increase the sensitivity of the PAGTEG, sugar was added. This study confirmed that THPC was a good antioxidant for polymer gel dosimeter. However, GTE also can be used as an antioxidant in polymer gel if use less quantity (GTE) and add sugar as sensitivity enhancer.

  14. Methods and means of checking thermoluminescent and radiophotoluminescent dosimeters

    SciTech Connect

    Fominykh, V.I.; Oborin, A.V.; Sebekin, A.P.; Uryaev, I.A.

    1987-06-01

    The authors discuss methods of checking thermoluminescent and radiophotoluminescent dosimeters which are used often in monitoring radiation safety in various areas including nuclear power stations. When the dosimeters are checked in the fields of standard beta-ray sources, it is recommended that the standard absorbed-dose or equivalent-dose measures for beta radiation should be sources of /sup 90/Sr + /sup 90/Y, /sup 204/Tl, and /sup 147/Pm. Various safety guidelines are discussed.

  15. Response of the Hanford Combination Neutron Dosimeter in plutonium environments

    SciTech Connect

    Endres, A.W.; Brackenbush, L.W.; Baumgartner, W.V.

    1996-02-01

    This report documents response characteristics and the development of dose algorithms for the Hanford Combination Neutron Dosimeter (HCNO) implemented on January 1, 1995. The HCND was accredited under the U.S. Department of Energy (DOE) Laboratory Accreditation Program (DOELAP) during 1994. The HCND employs two neutron dose components consisting of (1) an albedo thermoluminescent dosimeter (TLD), and (2) a track-etch dosimeter (TED). Response characteristics of these two dosimeter components were measured under the low-scatter conditions of the Hanford 318 Building Calibration Laboratory, and under the high-scatter conditions in the workplace at the Plutonium Finishing Plant (PFP). The majority of personnel neutron dose at Hanford (currently and historically) occurs at the PFP. National Institute of Standards and Technology (NIST) traceable sources were used to characterize dosimeter response in the laboratory. At the PFP, neutron spectra and dose-measuring instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters, were used to determine the neutron dose under several configurations from three different plutonium sources: (1) plutonium tetrafluoride, (2) plutonium metal, and (3) plutonium oxide. In addition, measurements were performed at many selected work locations. The HCNDs were included in all measurements. Comparison of dosimeter- and instrument-measured dose equivalents provided the data necessary to develop HCND dose algorithms and to assess the accuracy of estimated neutron dose under actual work conditions.

  16. Radiation measured with passive dosimeters in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Zhou, D.; Semones, E.; Gaza, R.; Weyland, M.

    begin center Radiation Measured with Passive Dosimeters in Low Earth Orbit end center begin center D Zhou 1 2 E Semones 1 R Gaza 1 2 M Weyland 1 end center begin center 1 Johnson Space Center - NASA 2101 Nasa Road 1 Houston 77058 USA end center begin center 2 Universities Space Research Association 2101 Nasa Parkway Houston 77058 USA end center begin center Abstract end center The linear energy transfer LET of particles in low Earth orbit LEO is extended from sim 0 1 to sim 1000 keV mu m water The best passive dosimeters for the radiation measurement are thermoluminescence dosimeters TLDs or optically stimulated luminescence dosimeters OSLDs for low LET and CR-39 plastic nuclear track detectors PNTDs for high LET Radiation quantities fluence absorbed dose dose equivalent and quality factor were measured with the passive dosimeters composed of TLDs OSLDs and CR-39 PNTDs for STS-114 mission This paper introduces the operation principles for TLDs OSLDs and CR-39 PNTDs describes the method to combine the results measured by TLDs OSLDs and CR-39 PNTDs and presents the results measured by different dosimeters for different LET band and that combined for all LET

  17. Mayak Film Dosimeter Response Studies, Part I: Measurements

    SciTech Connect

    Vasilenko, E. K.; Knyazev, V.; Gorelov, Mikhail; Smetanin, Mikhail; Scherpelz, Robert I.; Fix, John J.

    2007-09-01

    The Mayak Worker Dosimetry study is a joint Russian/US project to evaluate doses received by workers at the Mayak Production Association facilities from 1948-1972. A key investigation in this project is the characterization of responses of the three types of film dosimeters used to monitor workers during this time period. Experimental irradiations of the dosimeters were performed in the radiation calibration laboratories at the National Research Center for Environment and Health (GSF) in Munich, Germany. The irradiations used photon sources from X-ray beams with ten different energy distributions and with 60Co and 137Cs isotopic gamma sources. Irradiations were performed with the dosimeters on phantoms and free-in-air. The dosimeters and phantoms were also positioned at varying angles to the radiation beam. The result of the experiments was a thorough characterization of the dosimeter response as a function of photon energy and as a function of angle for energy and angular ranges that cover the conditions encountered in the Mayak workplaces. The characterization data were then available for use in developing correction factors which could be applied to worker dosimeter readings to provide a more accurate assessment of worker dose and estimates of doses to organs.

  18. Applicability of the polysulphone horizontal calibration to differently inclined dosimeters.

    PubMed

    Casale, Giuseppe R; Siani, Anna Maria; Diémoz, Henri; Kimlin, Michael G; Colosimo, Alfredo

    2012-01-01

    Polysulphone (PS) dosimetry has been a widely used technique for more than 30 years to quantify the erythemally effective UV dose received by anatomic sites (personal exposure). The calibration of PS dosimeters is an important issue as their spectral response is different from the erythemal action spectrum. It is performed exposing a set of PS dosimeters on a horizontal plane and measuring the UV doses received by dosimeters using calibrated spectroradiometers or radiometers. In this study, data collected during PS field campaigns (from 2004 to 2006), using horizontal and differently inclined dosimeters, were analyzed to provide some considerations on the transfer of the horizontal calibration to differently inclined dosimeters, as anatomic sites usually are. The role of sky conditions, of the angle of incidence between the sun and the normal to the slope, and of the type of surrounding surface on the calibration were investigated. It was concluded that PS horizontal calibrations apply to differently inclined dosimeters for incidence angles up to approximately 70° and for surfaces excluding ones with high albedo. Caution should be used in the application of horizontal calibrations for cases of high-incidence angle and/or high albedo surfaces.

  19. Potential High Resolution Dosimeters For MRT

    NASA Astrophysics Data System (ADS)

    Bräuer-Krisch, E.; Rosenfeld, A.; Lerch, M.; Petasecca, M.; Akselrod, M.; Sykora, J.; Bartz, J.; Ptaszkiewicz, M.; Olko, P.; Berg, A.; Wieland, M.; Doran, S.; Brochard, T.; Kamlowski, A.; Cellere, G.; Paccagnella, A.; Siegbahn, E. A.; Prezado, Y.; Martinez-Rovira, I.; Bravin, A.; Dusseau, L.; Berkvens, P.

    2010-07-01

    resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic® films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al2O3:C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1×1 cm5 field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared with Monte Carlo calculations.

  20. Potential High Resolution Dosimeters For MRT

    SciTech Connect

    Braeuer-Krisch, E.; Brochard, T.; Prezado, Y.; Bravin, A.; Berkvens, P.; Rosenfeld, A.; Lerch, M.; Petasecca, M.; Akselrod, M.; Sykora, J.; Bartz, J.; Ptaszkiewicz, M.; Olko, P.; Berg, A.; Wieland, M.; Doran, S.; Kamlowski, A.; Cellere, G.

    2010-07-23

    /s, micron resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic registered films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al{sub 2}O{sub 3}:C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1x1 cm{sup 5} field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared with Monte Carlo calculations.

  1. Real time chemical exposure and risk monitor

    DOEpatents

    Thrall, Karla D.; Kenny, Donald V.; Endres, George W. R.; Sisk, Daniel R.

    1997-01-01

    The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose.

  2. PDT Dose Dosimeter for Pleural Photodynamic Therapy

    PubMed Central

    Kim, Michele M.; Darafsheh, Arash; Ahmad, Mahmoud; Finlay, Jarod C.; Zhu, Timothy C.

    2016-01-01

    PDT dose is the product of the photosensitizer concentration and the light fluence in the target tissue. For improved dosimetry during plural photodynamic therapy (PDT), a PDT dose dosimeter was developed to measure both the light fluence and the photosensitizer concentration simultaneously in the same treatment location. Light fluence and spectral data were rigorously compared to other methods of measurement (e.g. photodiode, multi-fiber spectroscopy contact probe) to assess the accuracy of the measurements as well as their uncertainty. Photosensitizer concentration was obtained by measuring the fluorescence of the sensitizer excited by the treatment light. Fluence rate based on the intensity of the laser spectrum was compared to the data obtained by direct measurement of fluence rate by a fiber-coupled photodiode. Phantom studies were done to obtain an optical property correction for the fluorescence signal. Measurements were performed in patients treated Photofrin for different locations in the pleural cavity. Multiple sites were measured to investigate the heterogeneity of the cavity and to provide cross-validation via relative dosimetry. This novel method will allow for accurate real-time determination of delivered PDT dose and improved PDT dosimetry. PMID:27053825

  3. PDT dose dosimeter for pleural photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Kim, Michele M.; Darafsheh, Arash; Ahmad, Mahmoud; Finlay, Jarod C.; Zhu, Timothy C.

    2016-03-01

    PDT dose is the product of the photosensitizer concentration and the light fluence in the target tissue. For improved dosimetry during plural photodynamic therapy (PDT), a PDT dose dosimeter was developed to measure both the light fluence and the photosensitizer concentration simultaneously in the same treatment location. Light fluence and spectral data were rigorously compared to other methods of measurement (e.g. photodiode, multi-fiber spectroscopy contact probe) to assess the accuracy of the measurements as well as their uncertainty. Photosensitizer concentration was obtained by measuring the fluorescence of the sensitizer excited by the treatment light. Fluence rate based on the intensity of the laser spectrum was compared to the data obtained by direct measurement of fluence rate by a fiber-coupled photodiode. Phantom studies were done to obtain an optical property correction for the fluorescence signal. Measurements were performed in patients treated Photofrin for different locations in the pleural cavity. Multiple sites were measured to investigate the heterogeneity of the cavity and to provide cross-validation via relative dosimetry. This novel method will allow for accurate real-time determination of delivered PDT dose and improved PDT dosimetry.

  4. Mixed-radiation discrimination using thermoluminescent dosimeters

    NASA Astrophysics Data System (ADS)

    Skopec, Marlene

    This work has developed, analyzed, and tested methods to discriminate among different types of radiation exposures using the glow curves of thermoluminescent dosimeters (TLDs). Thermoluminescent materials, Harshaw LiF:Mg,Ti (TLD-100) and CaF2:Tm (TLD-300), were exposed to pure proton, pure photon (x-ray and gamma), and mixed fields to examine and use differences in the thermoluminescent (TL) glow curve shapes for the purpose of radiation type discrimination. The effect of radiation type exposure order on thermoluminescent glow curve shape and the principle of superposition of glow curves were evaluated. Using computerized glow curve deconvolution (CGCD), no significant differences in glow curve shape or magnitude were found. Results demonstrated that the superposition of pure field glow curves is a valid method of simulating mixed field glow curves (i.e., the principle of superposition holds). Two robust and novel techniques for radiation type discrimination were developed: vector representation (VR) and principal component analysis (PCA). In VR, vectors were constructed from glow curve points and classified based on the vector inner product with a unit vector and vector magnitude. In PCA, variations in the glow curves due to radiation type are classified according to one principal component. The two methods were tested for accuracy using leave-one-out validation (LOOV) with classification based on the Mahalanobis distance. Overall, both techniques performed equally well, with over 92% accurate three category classification using the high temperature peak of TLD-100 and nearly 100% correct classification in TLD-300.

  5. Solid state neutron dosimeter for space applications

    NASA Technical Reports Server (NTRS)

    Entine, Gerald; Nagargar, Vivek; Sharif, Daud

    1990-01-01

    Personnel engaged in space flight are exposed to significant flux of high energy neutrons arising from both primary and secondary sources of ionizing radiation. Presently, there exist no compact neutron sensor capable of being integrated in a flight instrument to provide real time measurement of this radiation flux. A proposal was made to construct such an instrument using special PIN silicon diode which has the property of being insensitive to the other forms of ionizing radiation. Studies were performed to determine the design and construction of a better reading system to allow the PIN diode to be read with high precision. The physics of the device was studied, especially with respect to those factors which affect the sensitivity and reproducibility of the neutron response. This information was then used to develop methods to achieve high sensitivity at low neutron doses. The feasibility was shown of enhancing the PIN diode sensitivity to make possible the measurement of the low doses of neutrons encountered in space flights. The new PIN diode will make possible the development of a very compact, accurate, personal neutron dosimeter.

  6. Description and evaluation of the Hanford personnel dosimeter program from 1944 through 1989. [Contain Glossary

    SciTech Connect

    Wilson, R.H.; Fix, J.J.; Baumgartner, W.V.; Nichols, L.L.

    1990-09-01

    This report describes the evolution of personnel dosimeter technology at Hanford since the inception of Hanford operations in 1944. Each of the personnel dosimeter systems used by people working or visiting Hanford is described. In addition, the procedures used to calibrate and calculate dose for each of the dosimeter systems are described. The accuracy of the recorded dose, primarily whole body deep dose, for the different dosimeter systems is evaluated. The evaluation is based on an extensive review of historical literature, as well as a 1989 intercomparison study of all film dosimeters and performance testing of the thermoluminescent dosimeter, also conducted during 1989. 73 refs., 40 figs., 41 tabs.

  7. Angular dependence of mammographic dosimeters in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Bradley, Lena R.; Carton, Ann-Katherine; Maidment, Andrew D. A.

    2010-04-01

    Digital Breast Tomosynthesis (DBT) is an emerging imaging modality that combines tomography with conventional digital mammography. In developing DBT dosimetry, a direct application of mammographic dosimetry has appeal. However, DBT introduces rotation of the x-ray tube relative to the dosimeter, thus raising questions about the angular dependence of mammographic dosimeters. To measure this dependence, two ionization chambers, two solid-stated detectors, and one photodiode were rotated relative to an incident Mo/Mo x-ray beam. In this isocentric DBT simulation, the signal of each dosimeter was studied over an angular range of 180° for tube voltages of 26 to 34 kV. One ionization chamber was then modeled numerically to study the response to various monoenergetic beams. The results show that all dosimeters underestimate dose to varying degrees; solid-state detectors show the greatest angular dependence while ionization chambers show the least. Correction factors were computed from the data for isocentric DBT images using projection angles up to +/-25° these factors ranged from 1.0014 to 1.1380. The magnitude of the angular dependence generally decreased with increasing energy, as shown with both the measured and modeled data. As a result, the error arising in measuring DBT dose with a mammographic dosimeter varies significantly; it cannot always be disregarded. The use of correction factors may be possible but is largely impractical, as they are specific to the dosimeter, x-ray beam, and DBT geometry. Instead, an angle-independent dosimeter may be more suitable for DBT.

  8. PNNL Results from 2010 CALIBAN Criticality Accident Dosimeter Intercomparison Exercise

    SciTech Connect

    Hill, Robin L.; Conrady, Matthew M.

    2011-10-28

    This document reports the results of the Hanford personnel nuclear accident dosimeter (PNAD) and fixed nuclear accident dosimeter (FNAD) during a criticality accident dosimeter intercomparison exercise at the CEA Valduc Center on September 20-23, 2010. Pacific Northwest National Laboratory (PNNL) participated in a criticality accident dosimeter intercomparison exercise at the Commissariat a Energie Atomique (CEA) Valduc Center near Dijon, France on September 20-23, 2010. The intercomparison exercise was funded by the U.S. Department of Energy, Nuclear Criticality Safety Program, with Lawrence Livermore National Laboratory as the lead Laboratory. PNNL was one of six invited DOE Laboratory participants. The other participating Laboratories were: Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Savannah River Site (SRS), the Y-12 National Security Complex at Oak Ridge, and Sandia National Laboratory (SNL). The goals of PNNL's participation in the intercomparison exercise were to test and validate the procedures and algorithm currently used for the Hanford personnel nuclear accident dosimeters (PNADs) on the metallic reactor, CALIBAN, to test exposures to PNADs from the side and from behind a phantom, and to test PNADs that were taken from a historical batch of Hanford PNADs that had varying degrees of degradation of the bare indium foil. Similar testing of the PNADs was done on the Valduc SILENE test reactor in 2009 (Hill and Conrady, 2010). The CALIBAN results are reported here.

  9. Effect of bloom strength on radiochromic gel dosimeters

    NASA Astrophysics Data System (ADS)

    Ebenezer Suman Babu, S.; Ravindran, B. Paul

    2015-01-01

    The Fricke gel dosimeter has been the widely used dosimeter among the gel dosimeters because of its dose response characteristics and easy preparation. The ferrous to ferric conversion that happens in this gel dosimeter on irradiation, corresponds to the absorbed dose of radiation. Gel dosimetry in India is not moving forward because of the import restrictions on the commercially available high bloom strength gelatin (imported 300 bloom). The feasibility of using Fricke gel dosimeter prepared with the locally available gelatin of 240 bloom and 200 bloom were compared with the 300 bloom gelatin taken as standard. The gel samples were prepared with 5% gelatin by weight and irradiated with 60Co gamma radiation for a dose range from 0-3 Gy used clinically. The optical absorption of gel samples were analyzed using spectrophotometer at 585 nm and dose response curves were generated. The results indicate that Fricke gels prepared with 240 bloom have linear dose response and comparable with those prepared with 300 bloom but the use of gels prepared with 200 bloom was found to be limited because of its poor optical transmittance.

  10. A real-time pulsed photon dosimeter

    NASA Astrophysics Data System (ADS)

    Brown, David; Olsher, Richard H.; Eisen, Yosef; Rodriguez, Joseph F.

    1996-02-01

    Radiation sources producing short pulses of photon radiation are now widespread. Such sources include electron and proton linear accelerators, betatrons, synchrotrons, and field-emission impulse generators. It is often desirable to measure leakage and skyshine radiation from such sources in real time, on a single-pulse basis as low as 8.7 nGy (1 μR) per pulse. This paper describes the design and performance of a prototype, real-time, pulsed photon dosimeter (PPD) capable of single-pulse dose measurements over the range from 3.5 nGy to 3.5 μGy (0.4 to 400 μR). The PPD may also be operated in a multiple-pulse mode that integrates the dose from a train of radiation pulses over a 3-s period. A pulse repetition rate of up to 300 Hz is accommodated. The design is eminently suitable for packaging as a lightweight, portable, survey meter. The PPD uses a CdWO 4 scintillator optically coupled to a photodiode to generate a charge at the diode output. A pulse amplifier converts the charge to a voltage pulse. A digitizer circuit generates a burst of logic pulses whose number is proportional to the peak value of the voltage pulse. The digitizer output is recorded by a pulse counter and suitably displayed. A prototype PPD was built for testing and evaluation purposes. The performance of the PPD was evaluated with a variety of pulsed photon sources. The dynamic range, energy response, and response to multiple pulses were characterized. The experimental data confirm the viability of the PPD for pulsed photon dosimetry.

  11. Monitoring of environmental UV radiation by biological dosimeters.

    PubMed

    Ronto, G; Berces, A; Grof, P; Fekete, A; Kerekgyarto, T; Gaspar, S; Stick, C

    2000-01-01

    As a consequence of the stratospheric ozone layer depletion biological systems can be damaged due to increased UV-B radiation. The aim of biological dosimetry is to establish a quantitative basis for the risk assessment of the biosphere. DNA is the most important target molecule of biological systems having special sensitivity against short wavelength components of the environmental radiation. Biological dosimeters are usually simple organisms, or components of them, modeling the cellular DNA. Phage T7 and polycrystalline uracil biological dosimeters have been developed and used in our laboratory for monitoring the environmental radiation in different radiation conditions (from the polar to equatorial regions). Comparisons with Robertson-Berger (RB) meter data, as well as with model calculation data weighted by the corresponding spectral sensitivities of the dosimeters are presented. Suggestion is given how to determine the trend of the increase in the biological risk due to ozone depletion.

  12. Development and evaluation of polycrystalline cadmium telluride dosimeters for accurate quality assurance in radiation therapy

    NASA Astrophysics Data System (ADS)

    Oh, K.; Han, M.; Kim, K.; Heo, Y.; Moon, C.; Park, S.; Nam, S.

    2016-02-01

    For quality assurance in radiation therapy, several types of dosimeters are used such as ionization chambers, radiographic films, thermo-luminescent dosimeter (TLD), and semiconductor dosimeters. Among them, semiconductor dosimeters are particularly useful for in vivo dosimeters or high dose gradient area such as the penumbra region because they are more sensitive and smaller in size compared to typical dosimeters. In this study, we developed and evaluated Cadmium Telluride (CdTe) dosimeters, one of the most promising semiconductor dosimeters due to their high quantum efficiency and charge collection efficiency. Such CdTe dosimeters include single crystal form and polycrystalline form depending upon the fabrication process. Both types of CdTe dosimeters are commercially available, but only the polycrystalline form is suitable for radiation dosimeters, since it is less affected by volumetric effect and energy dependence. To develop and evaluate polycrystalline CdTe dosimeters, polycrystalline CdTe films were prepared by thermal evaporation. After that, CdTeO3 layer, thin oxide layer, was deposited on top of the CdTe film by RF sputtering to improve charge carrier transport properties and to reduce leakage current. Also, the CdTeO3 layer which acts as a passivation layer help the dosimeter to reduce their sensitivity changes with repeated use due to radiation damage. Finally, the top and bottom electrodes, In/Ti and Pt, were used to have Schottky contact. Subsequently, the electrical properties under high energy photon beams from linear accelerator (LINAC), such as response coincidence, dose linearity, dose rate dependence, reproducibility, and percentage depth dose, were measured to evaluate polycrystalline CdTe dosimeters. In addition, we compared the experimental data of the dosimeter fabricated in this study with those of the silicon diode dosimeter and Thimble ionization chamber which widely used in routine dosimetry system and dose measurements for radiation

  13. Angular dependence of the nanoDot OSL dosimeter

    SciTech Connect

    Kerns, James R.; Kry, Stephen F.; Sahoo, Narayan; Followill, David S.; Ibbott, Geoffrey S.

    2011-07-15

    Purpose: Optically stimulated luminescent detectors (OSLDs) are quickly gaining popularity as passive dosimeters, with applications in medicine for linac output calibration verification, brachytherapy source verification, treatment plan quality assurance, and clinical dose measurements. With such wide applications, these dosimeters must be characterized for numerous factors affecting their response. The most abundant commercial OSLD is the InLight/OSL system from Landauer, Inc. The purpose of this study was to examine the angular dependence of the nanoDot dosimeter, which is part of the InLight system. Methods: Relative dosimeter response data were taken at several angles in 6 and 18 MV photon beams, as well as a clinical proton beam. These measurements were done within a phantom at a depth beyond the build-up region. To verify the observed angular dependence, additional measurements were conducted as well as Monte Carlo simulations in MCNPX. Results: When irradiated with the incident photon beams parallel to the plane of the dosimeter, the nanoDot response was 4% lower at 6 MV and 3% lower at 18 MV than the response when irradiated with the incident beam normal to the plane of the dosimeter. Monte Carlo simulations at 6 MV showed similar results to the experimental values. Examination of the results in Monte Carlo suggests the cause as partial volume irradiation. In a clinical proton beam, no angular dependence was found. Conclusions: A nontrivial angular response of this OSLD was observed in photon beams. This factor may need to be accounted for when evaluating doses from photon beams incident from a variety of directions.

  14. Implanted Dosimeters Identify Radiation Overdoses During IMRT for Prostate Cancer

    SciTech Connect

    Den, Robert B.; Nowak, Kamila; Buzurovic, Ivan; Cao Junsheng; Harrison, Amy S.; Lawrence, Yaacov R.; Dicker, Adam P.; Showalter, Timothy N.

    2012-07-01

    Purpose: Image-guided dose-escalated radiotherapy is the standard of care for the treatment of prostate cancer. Although many published methods are available that account for prostate motion during delivery, evidence demonstrating that the planned dose is actually delivered on a daily basis is lacking. We report our initial clinical experience using implantable dosimeters to quantify and adjust the dose received during intensity-modulated radiotherapy (IMRT). Methods and Materials: A total of 20 patients undergoing IMRT with cone-beam computed tomography (CT) image guidance for prostate cancer had the dose verification system with radiopaque metal-oxide-semiconductor field effect transistor dosimeters implanted before treatment planning. All patients underwent planning with CT simulation in the supine position with custom immobilization, and the implanted dosimeters were located in the IMRT plans. The predicted dose for each dosimeter was defined and compared with the wireless readings before and after each treatment session. Investigations by physicians and medical physicists were initiated for two or more discrepancies >6% for any five consecutive fractions or for any discrepancy {>=}10%. Results: Using implanted in vivo dosimeters, dose measurements consistently >6% greater than the predicted values were observed during treatment for 3 of 20 prostate cancer patients who received IMRT with daily image guidance. A review of the daily cone-beam CT images revealed acceptable alignment of the prostate target volumes and implanted dosimeters but identified significant anatomic changes within the treated region. Repeat CT simulation and RT planning was performed, with resolution of the dose discrepancies in all 3 cases with the adoption of a new IMRT plan. Conclusions: Our report illustrates the potential effect of implanted in vivo dosimetry for prostate IMRT and emphasizes the importance of careful planning and delivery with attention to systematic shifts or anatomic

  15. Angular dependence of the nanoDot OSL dosimeter

    PubMed Central

    Kerns, James R.; Kry, Stephen F.; Sahoo, Narayan; Followill, David S.; Ibbott, Geoffrey S.

    2011-01-01

    Purpose: Optically stimulated luminescent detectors (OSLDs) are quickly gaining popularity as passive dosimeters, with applications in medicine for linac output calibration verification, brachytherapy source verification, treatment plan quality assurance, and clinical dose measurements. With such wide applications, these dosimeters must be characterized for numerous factors affecting their response. The most abundant commercial OSLD is the InLight∕OSL system from Landauer, Inc. The purpose of this study was to examine the angular dependence of the nanoDot dosimeter, which is part of the InLight system.Methods: Relative dosimeter response data were taken at several angles in 6 and 18 MV photon beams, as well as a clinical proton beam. These measurements were done within a phantom at a depth beyond the build-up region. To verify the observed angular dependence, additional measurements were conducted as well as Monte Carlo simulations in MCNPX.Results: When irradiated with the incident photon beams parallel to the plane of the dosimeter, the nanoDot response was 4% lower at 6 MV and 3% lower at 18 MV than the response when irradiated with the incident beam normal to the plane of the dosimeter. Monte Carlo simulations at 6 MV showed similar results to the experimental values. Examination of the results in Monte Carlo suggests the cause as partial volume irradiation. In a clinical proton beam, no angular dependence was found.Conclusions: A nontrivial angular response of this OSLD was observed in photon beams. This factor may need to be accounted for when evaluating doses from photon beams incident from a variety of directions. PMID:21858992

  16. Monte Carlo simulation experiments on box-type radon dosimeter

    NASA Astrophysics Data System (ADS)

    Jamil, Khalid; Kamran, Muhammad; Illahi, Ahsan; Manzoor, Shahid

    2014-11-01

    Epidemiological studies show that inhalation of radon gas (222Rn) may be carcinogenic especially to mine workers, people living in closed indoor energy conserved environments and underground dwellers. It is, therefore, of paramount importance to measure the 222Rn concentrations (Bq/m3) in indoors environments. For this purpose, box-type passive radon dosimeters employing ion track detector like CR-39 are widely used. Fraction of the number of radon alphas emitted in the volume of the box type dosimeter resulting in latent track formation on CR-39 is the latent track registration efficiency. Latent track registration efficiency is ultimately required to evaluate the radon concentration which consequently determines the effective dose and the radiological hazards. In this research, Monte Carlo simulation experiments were carried out to study the alpha latent track registration efficiency for box type radon dosimeter as a function of dosimeter's dimensions and range of alpha particles in air. Two different self developed Monte Carlo simulation techniques were employed namely: (a) Surface ratio (SURA) method and (b) Ray hitting (RAHI) method. Monte Carlo simulation experiments revealed that there are two types of efficiencies i.e. intrinsic efficiency (ηint) and alpha hit efficiency (ηhit). The ηint depends upon only on the dimensions of the dosimeter and ηhit depends both upon dimensions of the dosimeter and range of the alpha particles. The total latent track registration efficiency is the product of both intrinsic and hit efficiencies. It has been concluded that if diagonal length of box type dosimeter is kept smaller than the range of alpha particle then hit efficiency is achieved as 100%. Nevertheless the intrinsic efficiency keeps playing its role. The Monte Carlo simulation experimental results have been found helpful to understand the intricate track registration mechanisms in the box type dosimeter. This paper explains that how radon concentration from the

  17. Strategy for finding new materials for ESR dosimeters

    PubMed

    Ikeya; Hassan; Sasaoka; Kinoshita; Takaki; Yamanaka

    2000-05-01

    The right strategy for finding a new ESR dosimetric material sensitive to radiation is to follow the orthodox procedures used in the development of thermoluminescence dosimeters (TLD) and phosphorescence studies. Modern procedures used in materials sciences, such as computer calculation of molecular orbitals (MO), should be employed to estimate the ESR and optical properties of prospective materials. Radiation effects in lithium and magnesium sulfates and metal salts of organic acids, such as lithium and magnesium lactates, have been investigated in search for tissue-equivalent dosimeter with a large G value.

  18. Measurement of a PAGAT gel dosimeter by ultrasound computed tomography

    NASA Astrophysics Data System (ADS)

    Khoei, S.; Trapp, J. V.; Langton, C. M.

    2013-06-01

    In this work we used a 3D quantitative CT ultrasound imaging system to characterise polymer gel dosimeters. The system comprised of two identical 5 MHz 128 element phased-array ultrasound transducers co-axially aligned and submerged in water as a coupling agent. Rotational and translational movement of the gel dosimeter sample between the transducers were performed using a robotic arm. Ultrasound signals were generated and received using an Olympus Omniscan unit. Dose sensitivity of attenuation and time of flight ultrasonic parameters were assessed using this system.

  19. Influencing Factors on Reproducibility and Stability of MRI NIPAM Polymer Gel Dosimeter

    PubMed Central

    Pak, Farideh; Farajollahi, Alireza; Movafaghi, Ali; Naseri, Alireza

    2013-01-01

    Introduction: At present, the polymer gel dosimeter is considered to be the best possible dosimeter for measuring 3-dimesional radiation dose distribution in radiotherapy. These gels are normally toxic; therefore, manufacturing, handling and discarding them require special attention. In order to find less toxic recipe, N-isopropyle acrylamide polymer gel (NIPAM) was introduced. In this study, the reproducibility and stability of NIPAM polymer gel dose response together with some influencing factors related to MR imaging were studied. Methods: The NIPAM gel was prepared according to a method, described by senden et al in 2006. The gels were irradiated approximately 2 h after manufacturing and MR images of the gel were made 24 h after irradiation. The effects of different batches, post-irradiation time and the MRI room temperature on reproducibility and stability of polymer gel dose response were explored by analyzing the NMR response (R2) of the gel. Results:: In a fixed temperature, the response of the gel was found to be stable 24 h after irradiation. The results showed that the dose response of the NIPAM polymer gel is highly reproducible in the same and different batches of chemical. No inhomogeneity was observed for magnetic fields in the specified position of measurements and 5°C fluctuation was recorded for MRI room temperature. Conclusion: Fluctuation in MRI room temperature necessitates that stringent attention to be paid to controlling the gel temperature at the time of imaging. The new formulation of polymer gel ensures stability of the gels’ spatial resolution and makes it a suitable dosimeter for distant or remote measurements. PMID:24455479

  20. The use of LiF (TLD-100) as an out-of-field dosimeter.

    PubMed

    Kry, Stephen F; Price, Michael; Followill, David; Mourtada, Firas; Salehpour, Mohammad

    2007-09-24

    The commonly used thermoluminescent dosimeter TLD-100 (Harshaw Chemical Company, Solon, OH) responds not only to photons and electrons, but also to neutrons that are produced during high-energy therapies. As a result, TLD-100 measurements outside of the treatment field are suspect when high-energy radiation is used. Although alternatives such as TLD-700 do not respond to neutrons, specialty dosimeters of this kind are expensive and are not routinely used in most clinics. In the current study, we examined the accuracy of TLD-100 in measuring the out-of-field photon dose as a function of treatment energy. To determine the accuracy of TLD-100 as compared with TLD-700, TLD-100 was irradiated outside of the treatment field by medical accelerators operated at 6, 10, 15, and 18 MV. In an effort to eliminate the response of TLD-100 to neutrons, TLD capsules were encased in varying thicknesses of cadmium foil (0.25 - 0.75 mm) before being irradiated at 18 MV. The out-of-field TLD-100 was found to be accurate at 6 MV and 10 MV, but to be substantially over-responsive at 15 MV and 18 MV (by up to 1063% relative to TLD-700). By wrapping the TLD-100 in up to 0.75 mm of cadmium, it was possible to drastically reduce (down to 39% on average) the over-response of the TLD-100; however, total removal of the over-responsiveness was not possible. Although TLD-100 is well suited for measuring out-of-field dose at energies as high as 10 MV, at higher energies (15 MV or greater), this dosimeter over-responds substantially and should not be used. Although encasing the TLD in cadmium minimized over-response to a degree, the reduction was not sufficient to make TLD-100 viable for measuring out-of-field dose at high treatment energies.

  1. Influence of preparation and calibration method of PAGAT dosimeter on TSE MR readout results

    NASA Astrophysics Data System (ADS)

    Vávrů, K.; Dvořák, P.; Tintěra, J.; Spěváček, V.

    2013-06-01

    In this study PAGAT dosimeter evaluation by TSE sequence was tested. PAGAT dosimeter preparation procedure was modified to increase the dosimeter sensitivity. Because THPC reacts with gelatin, adding THPC to monomer solution prior to dissolved gelatine helps exploit THPC as an antioxidant. Turbo spin echo sequence enables to evaluate gel dosimeter with 3D equidistant resolution in a reasonable scanning time. Glass walls of the phantom cause problems both by computing inaccuracies and MR imaging artefacts. The inner dosimeter volume is not affected by these inaccuracies and should be used for radiotherapy plan verification.

  2. Deconnable self-reading pocket dosimeter containment with self-contained light

    DOEpatents

    Stevens, Robyn L.; Arnold, Greg N.; McBride, Ryan G.

    1996-01-01

    A container for a self-reading pocket dosimeter includes a transparent tube for receiving the self-reading pocket dosimeter, a light source mounted at one end of the transparent tube, and an eyepiece mounted on an opposite end of the transparent tube for viewing a read-out of the self-reading pocket dosimeter. The container may further include an activation device for selectively supplying power to the light source. The container both protects the dosimeter from being contaminated and provides a light source for viewing the dosimeter.

  3. Deconnable self-reading pocket dosimeter containment with self-contained light

    SciTech Connect

    Stevens, R.L.; Arnold, G.N.; McBride, R.G.

    1995-12-31

    A container for a self-reading pocket dosimeter includes a transparent tube for receiving the self-reading pocket dosimeter, a light source mounted at one end of the transparent tube, and an eyepiece mounted on an opposite end of the transparent tube for viewing a read-out of the self-reading pocket dosimeter. The container may further include an activation device for selectively supplying power to the light source. The container both protects the dosimeter from being contaminated and provides a light source for viewing the dosimeter.

  4. The European Light Dosimeter Network: four years of measurements.

    PubMed

    Lebert, Michael; Schuster, Martin; Häder, Donat Peter

    2002-02-01

    The European Light Dosimeter Network (ELDONET) has now been functional for more than four years. The network is based on dosimeters which measure radiation in three biologically relevant wavelength bands (UV-B, 280-315 nm; UV-A, 315-400 nm; and Photosynthetic Active Radiation, PAR, 400-700 nm). The ELDONET network is currently based on 33 stations with 40 instruments. The distribution of the instruments all over Europe allows measurement of the latitudinal and longitudinal light climate distribution. In addition, several instruments are active in South America, New Zealand, India, Africa and Japan. With some exceptions, the measured yearly doses depend on the latitude. While the maximal daily doses are almost comparable from station to station, seasonal changes and the different maximal solar zenith angles account for the differences in total yearly doses. Ratioing between UV-B and PAR allows the detection of subtle changes in the local light climate, due, for example, to mini-ozone holes encountered in northern Europe during spring. Comparison of satellite ozone data with terrestrial ELDONET measurements revealed an overall weak correlation between these data sets. However, local weather conditions, solar zenith angle and latitude as well as reflectivity (i.e. clouds and aerosol; satellite data) show a much stronger correlation to the doses received. The close relationship between the spectral sensitivity of the UV-B sensor used in the ELDONET dosimeter and the CIE erythemal action spectrum allows determination of the erythemal dose on the basis of the dosimeter readings.

  5. Characterization of a reusable PRESAGE® 3D dosimeter

    NASA Astrophysics Data System (ADS)

    Juang, T.; Adamovics, J.; Oldham, M.

    2015-01-01

    This study investigates a reusable PRESAGE® 3D dosimeter (Presage-RU), which would improve cost-effectiveness and facilitate wider implementation of comprehensive, high resolution 3D dosimetry. Small (1x1x4.5 cm) and large (8 cm diameter, 4.5 cm length) sample dosimeters were irradiated multiple times to characterize dose response (i.e. radiation-induced change in optical density (ΔOD)), optical clearing rate, and dose distribution stability. Presage- RU exhibited an initial dose response sensitivity of 0.0119 ΔOD/(cm-Gy), a reduction in response with subsequent irradiations, and a small, permanent ΔOD (~1-6% of initial signal) following each irradiation. Dosimeters optically cleared at an exponential rate (average T1/2 = 24.8±3.6 h), and were effectively cleared after ~5-8 days. 3D gamma analysis (3%/3mm, 10% dose threshold) of a 4-field box plan applied to the large dosimeter showed good agreement following initial irradiation (96.6% passing), but a reduction in passing rate (89.1% passing) with subsequent irradiation. Further study is warranted to fully assess and quantify the performance of Presage-RU for repeat irradiations.

  6. Improvements in opti-chromic dosimeters for radiation processing

    NASA Astrophysics Data System (ADS)

    Humpherys, K. C.; Kantz, A. D.

    "Opti-Chromic" dosimeters consisting of radiachromic dye in flourinated polymer tubing have been introduced as a dosimetry system in the range from 10 1 to 5 × 10 4 Gy. Batches of "Opti-Chromic" dosimeters have been produced to evaluate performance under large scale industrial conditions. A systematic study was undertaken to determine the effect of various dosimeter parameters on radiation sensitivity, shelf life, and response characteristics at the higher absorbed doses. These parameters were (A) Type of flourinated polymer tubing; (B) Organic solvent used to activate the radiachromic dye; (C) Concentration of radiachromic dye; (D) Additives to provide proper viscosity, color stability, and high-dose response. Prototype batches were produced and experimental dosimeters exposed to a range of absorbed doses and the response measured as a function of shelf life and dose. The results of the study are presented, and an improved formulation recommended for application to Food Processing. Other formulations may be of value in specific requirements of sensitivity or temperature.

  7. Reevaluation of the employment of Fick's law for diffusion dosimeters.

    PubMed

    Cross, John H

    2003-04-15

    This paper reconsiders the means of applying Fick's first law to passive diffusion dosimeters. The performance of the organic vapor monitor (OVM), a commercially available dosimeter, is modeled in terms of gradients, which are generated by evaporating a compound from the dosimeter. The fluxes induced by the gradients are determined gravimetrically. The ratio of a flux and a gradient is reported as a Fick's law proportionality constant, the sampling rate. The sampling rate for the gradient across the OVM is calculated from a harmonic average of the sampling rates of two other gradients. The OVM sampling rates for nine compounds determined by the new methodology agree well with published values. Further analysis of the other two gradients provides a value for an apparent reduction in sampling rate in the absence of airflow across the dosimeter (a boundary-layer effect). Procedures are also described to validate measured air concentrations by determining the sampling rates before and after exposure and by correcting for the boundary-layer effect. Sampling rates were found to be stable during 2-4-day exposures in a variety of conditions. In contrast, the boundary-layer effect caused the measured air concentrations to be substantially lower than the estimated true air concentrations.

  8. Hanford Personnel Dosimeter supporting studies FY-1980. [Lead abstract

    SciTech Connect

    Endres, G.W.R.; Cummings, F.M.; Aldrich, J.M.; Thorson, M.R.; Kathren, R.L.

    1981-02-01

    Separate abstracts were prepared for the 10 sections of this report which describe fundamental characteristics of the Hanford multipurpose personnel dosimeter (HMPD). Abstracts were not prepared for Appendix A and Appendix B which deal with calculated standard deviations for 100 mrem mixed field exposures and detailed calculations of standard deviations, respectively. (KRM)

  9. Thin thermoluminescent dosimeter and method of making same

    DOEpatents

    Simons, Gale G.; DeBey, Timothy M.

    1987-01-01

    An improved thermoluminescent ionizing radiation dosimeter of solid, extremely thin construction for more accurate low energy beta dosimetry is provided, along with a method of fabricating the dosimeter. In preferred forms, the dosimeter is a composite including a backing support (which may be tissue equivalent) and a self-sustaining body of solid thermoluminescent material such as LiF having a thickness of less than about 0.25 millimeters and a volume of at least about 0.0125 mm.sup.3. In preferred fabrication procedures, an initially thick (e.g., 0.89 millimeters) TLD body is wet sanded using 600 grit or less sandpaper to a thickness of less than about 0.25 millimeters, followed by adhesively attaching the sanded body to an appropriate backing. The sanding procedure permits routine production of extremely thin (about 0.05 millimeters) TLD bodies, and moreover serves to significantly reduce non-radiation-induced thermoluminescence. The composite dosimeters are rugged in use and can be subjected to annealing temperatures for increased accuracy.

  10. Two methods for examining angular response of personnel dosimeters

    SciTech Connect

    Plato, P.; Leib, R.; Miklos, J.

    1988-06-01

    The American National Standard ANSI N13.11-1983 is used to test the accuracy (bias plus precision) of dosimetry processors as part of the dosimetry accreditation program of the National Voluntary Laboratory Accreditation Program (NVLAP). Section 3.8 of the ANSI N13.11-1983 standard requires that a study of the angular response of a dosimeter be carried out once, although no pass/fail criterion is given for angular response. The NVLAP accreditation program excluded Section 3.8, and thus no angular response data have been generated in an organized fashion. The objective of this project is to examine the feasibility of two alternative methods to test the angular response of personnel dosimeters. The first alternative involves static irradiations with the dosimeters at fixed angles to a radiation source. The second alternative involves dynamic irradiations with the dosimeters mounted on a rotating phantom. A Panasonic UD-802 personnel dosimetry system** was used to generate data to examine both alternatives. The results lead to two major conclusions. Firstly, Section 3.8 of the ANSI N13.11-1983 standard should be amended to require a pass/fail test for angular response. Secondly, a comparison between angular response data generated with a fixed or a rotating phantom shows that the rotating phantom is the more cost-effective method.

  11. Portable battery-free charger for radiation dosimeters

    DOEpatents

    Manning, Frank W.

    1984-01-01

    This invention is a novel portable charger for dosimeters of the electrometer type. The charger does not require batteries or piezoelectric crystals and is of rugged construction. In a preferred embodiment, the charge includes a housing which carries means for mounting a dosimeter to be charged. The housing also includes contact means for impressing a charging voltage across the mounted dosimeter. Also, the housing carries a trigger for operating a charging system mounted in the housing. The charging system includes a magnetic loop including a permanent magnet for establishing a magnetic field through the loop. A segment of the loop is coupled to the trigger for movement thereby to positions opening and closing the loop. A coil inductively coupled with the loop generates coil-generated voltage pulses when the trigger is operated to open and close the loop. The charging system includes an electrical circuit for impressing voltage pulses from the coil across a capacitor for integrating the pulses and applying the resulting integrated voltage across the above-mentioned contact means for charging the dosimeter.

  12. NOTE: Detection of radiation effects in polymer gel dosimeters using 129Xe NMR

    NASA Astrophysics Data System (ADS)

    Joers, J. M.; Fong, P. M.; Gore, J. C.

    2006-01-01

    Polymer gel dosimeters consist of monomers, with or without cross-linking agents, dispersed in a gel. Upon exposure to ionizing radiation, polymerization proceeds within the gel matrix, thereby changing several measurable physical properties that can then be related quantitatively to absorbed dose. Several previous studies have examined how various nuclear magnetic resonance (NMR) properties, such as the relaxation rates of water protons, change with dose, and magnetic resonance imaging (MRI) has been used successfully to measure three-dimensional dose distributions in irradiated polymer gels. Here we report our first observations of the manner in which the chemical shift of xenon gas (129Xe) dissolved in a gel changes with absorbed dose, and we introduce the potential use of high resolution xenon NMR spectra for understanding better the dose response of gels. 129Xe possesses a large chemical shift range and xenon spectra are sensitive to subtle changes in the physical and chemical environments in which the gas is dissolved. For doses ranging from 0 Gy to 40 Gy we found that the mean chemical shift of 129Xe was linearly related to dose, and that the gel dosimeter could be described in terms of a two-component model undergoing fast exchange. We found no evidence of radiation damage to the gelatin matrix at doses between 0 Gy and 40 Gy. At 40 Gy, the fast-exchange model begins to break down, and distinct gelatin and poly(methacrylate) resonances are observed at higher doses. High resolution NMR measurements of xenon provide a novel method for probing radiation dose effects in irradiated polymer gels.

  13. Development of a DNA-dosimeter system for monitoring the effects of solar-ultraviolet radiation.

    PubMed

    Schuch, André Passaglia; da Silva Galhardo, Rodrigo; de Lima-Bessa, Keronninn Moreno; Schuch, Nelson Jorge; Menck, Carlos Frederico Martins

    2009-01-01

    Solar radiation sustains and affects all life forms on Earth. In recent years, the increase in environmental levels of solar-UV radiation due to depletion of the stratospheric ozone layer, as a result of anthropogenic emission of destructive chemicals, has highlighted serious issues of social concern. This becomes still more dramatic in tropical and subtropical regions, where the intensity of solar radiation is higher. To better understand the impact of the harmful effects of solar-UV radiation on the DNA molecule, we developed a reliable biological monitoring system based on the exposure of plasmid DNA to artificial UV lamps and sunlight. The determination and quantification of different types of UV photoproducts were performed through the use of specific DNA repair enzymes and antibodies. As expected, a significant number of CPDs and 6-4PPs was observed when the DNA-dosimeter system was exposed to increasing doses of UVB radiation. Moreover, CPDs could also be clearly detected in plasmid DNA when this system was exposed to either UVA or directly to sunlight. Interestingly, although less abundant, 6-4PPs and oxidative DNA damage were also generated after exposure to both UVA and sunlight. These results confirm the genotoxic potential of sunlight, reveal that UVA may also produce CPDs and 6-4PPs directly in naked DNA and demonstrate the applicability of a DNA-dosimeter system for monitoring the biological effects of solar-UV radiation.

  14. LET effects following neutron irradiation of lithium formate EPR dosimeters.

    PubMed

    Malinen, Eirik; Waldeland, Einar; Hole, Eli Olaug; Sagstuen, Einar

    2006-03-13

    Lithium formate electron paramagnetic resonance (EPR) dosimeters were irradiated using 60Co gamma-rays or fast neutrons to doses ranging from 5 to 20 Gy and investigated by EPR spectroscopy. Using a polynomial fitting procedure in order to accurately analyze peak-to-peak line widths of first derivative EPR spectra, dosimeters irradiated with neutrons had on average 4.4+/-0.9% broader EPR resonance lines than gamma-irradiated dosimeters. The increase in line width was slightly asymmetrical. Computer simulated first derivative polycrystalline EPR spectra of a *CO2- radical gave very good reconstructions of experimental spectra of irradiated dosimeters. The spectrum simulations could then be used as a tool to investigate the line broadening observed following neutron irradiation. It was shown that an increase in the simulated Lorentzian line width could explain both the observed line broadening and the asymmetrical effect. The ratio of the peak-to-peak amplitude of first derivative EPR spectra obtained at two different microwave powers (20 and 0.5 mW) was 7.8+/-1.2% higher for dosimeters irradiated with neutrons. The dependence of the spectrum amplitude on the microwave power was extensively investigated by fitting observations to an analytical non-linear model incorporating, among others, the spin-lattice (T1) and spin-spin (T2) relaxation times as fitting parameters. Neutron irradiation resulted in a reduction in T(2) in comparison with gamma-irradiation, while a smaller difference in T1 was found. The effects observed indicate increased local radical density following irradiation using high linear energy transfer (LET) neutrons as compared to low LET gamma-irradiation. A fingerprint of the LET may thus be found either by an analysis of the line width or of the dependence of the spectrum amplitude on the microwave power. Lithium formate is therefore a promising material for EPR dosimetry of high LET radiation.

  15. VALIDATION OF HANFORD PERSONNEL AND EXTREMITY DOSIMETERS IN PLUTONIUM ENVIRONMENTS

    SciTech Connect

    Scherpelz, Robert I.; Fix, John J.; Rathbone, Bruce A.

    2000-02-10

    A study was performed in the Plutonium Finishing Plant to assess the performance of Hanford personnel neutron dosimetry. The study was assessed whole body dosimetry and extremity dosimetry performance. For both parts of the study, the TEPC was used as the principle instrument for characterizing workplace neutron fields. In the whole body study, 12.7-cm-diameter TEPCs were used in ten different locations in the facility. TLD and TED personnel dosimeters were exposed on a water-filled phantom to enable a comparison of TEPC and dosimeter response. In the extremity study, 1.27-cm-diameter TEPCs were exposed inside the fingers of a gloveboxe glove. Extremity dosimeters were wrapped around the TEPCs. The glove was then exposed to six different cans of plutonium, simulating the exposure that a worker's fingers would receive in a glovebox. The comparison of TEPC-measured neutron dose equivalent to TLD-measured gamma dose equivalent provided neutron-to-gamma ratios that can be used to estimate the neutron dose equivalent received by a worker's finger based on the gamma readings of an extremity dosimeter. The study also utilized a Snoopy and detectors based on bubble technology for assessing neutron exposures, providing a comparison of the effectiveness of these instruments for workplace monitoring. The study concludes that the TLD component of the HCND performs adequately overall, with a positive bias of 30%, but exhibits excessive variability in individual results due to instabilities in the algorithm. The TED response was less variable but only 20% of the TEPC reference dose on average because of the low neutron energies involved. The neutron response of the HSD was more variable than the TLD component of the HCND and biased high by a factor of 8 overall due to its calibration to unmoderated 252Cf. The study recommends further work to correct instabilities in the HCND algorithm and to explore the potential shown by the bubble-based dosimeters.

  16. Section 9.1 new dosimeters. New dosimetry systems

    NASA Astrophysics Data System (ADS)

    McLaughlin, William L.

    During the past two years there have been significant advances in several forms of radiation measurement systems for radiation processing, covering dose ranges of 1-10 6 Gy. Calorimeters as reference standards for both ionizing photon and electron fields have become well-established. In addition to the older ceric-cerous dosimetry solution analyzed potentiometrically, new liquid-phase dosimeters include those analyzed by spectrophotometry, e.g., improved forms of acidic aqueous solutions of K-Ag dichromate and organic radiochromic dye solutions. It has recently been demonstrated that by using certain refined sugars, e.g., D-(-) ribose, optical rotation response in aqueous solutions can be enhanced for dosimetry at doses > 10 4 Gy. There has been expanded development, use, and formulation (rods, tablets, and thin films) of the amino acid, alanine, as a solid-phase dosimeter analyzed by either ESR spectrometry or by glutamine or alanine spectrophotometry of complexes with ferric ion in the presence of a sulfonphthalein dye (xylenol orange). New commercial types of radiochromic plastic dosimeters, e.g., GafChromic TM, Riso B3 TM, GAMMACHROME YR TM, Radix TM, and Gammex TM, have been introduced and applied in practice. Improvements and broader use of optical waveguide dosimeters, e.g., Opti-Chromic TM, have also been reported, especially in food irradiation applications. Several novel dyed plastic dosimeters are available in large quantities and they lose color due to irradiation. An example is a dyed cellulosic thin film (ATC type DY-42 TM) which can be measured spectrophotometrically or densitometrically up to doses as high as 10 6 Gy.

  17. a Thermally Desorbable Miniature Passive Dosimeter for Organic Vapors

    NASA Astrophysics Data System (ADS)

    Gonzalez, Jesus Antonio

    A thermally desorbable miniature passive dosimeter (MPD) for organic vapors has been developed in conformity with theoretical and practical aspects of passive dosimeter design. The device was optimized for low sample loadings resulting from short-term and/or low concentration level exposure. This was accomplished by the use of thermal desorption rather than solvent elution, which provided the GC method with significantly higher sensitivity. Laboratory evaluation of this device for factors critical to the performance of passive dosimeters using benzene as the test vapor included: desorption efficiency (97.2%), capacity (1400 ppm-min), sensitivity (7ng/sample or 0.06 ppmv for 15 minutes sampling) accuracy and precision, concentration level, environmental conditions (i.e., air face velocity, relative humidity) and sample stability during short (15 minutes) and long periods of time (15 days). This device has demonstrated that its overall accuracy meets NIOSH and OSHA requirements for a sampling and analytical method for the exposure concentration range of 0.1 to 50 ppm (v/v) and 15 minutes exposures. It was demonstrated that the MPD operates in accordance with theoretically predicted performance and should be adequate for short-term and/or low concentration exposure monitoring of organic vapors in the workplace. In addition a dynamic vapor exposure evaluation system for passive dosimeters have been validated using benzene as the test vapor. The system is capable of generating well defined short-square wave concentration profiles suitable for the evaluation of passive dosimeters for ceiling exposure monitoring.

  18. A proposed four-element neutron-photon-beta thermoluminescence dosimeter.

    PubMed

    Liu, J C; Sims, C S; Ahmed, A B

    1992-09-01

    It is common practice for a worker exposed to a mixed field with neutrons to wear both a photon-beta dosimeter and a neutron dosimeter. In this study, a thermoluminescence dosimeter has been designed and is proposed for use in mixed fields. The maximum applicable ranges of the mixed field can have photons with unknown energy from 20 keV to 2 MeV, betas with unknown energy from 147Pm to 90Sr-Y, and neutrons of known energy from thermal to 15 MeV. This proposed dosimeter (a combination of Harshaw beta-gamma thermoluminescence dosimeter and albedo neutron thermoluminescence dosimeter) has an advantage of using a minimum number of thermoluminescence dosimeter elements (therefore, making it less costly) to measure the dose equivalents in a mixed field of neutron, photon, and beta radiation. The basic dosimeter design consists of four thermoluminescence elements of TLD-600 and TLD-700 with different filtrations. Using the high-temperature peak methodology for TLD-600 and a filtration algorithm, the neutron, photon, and beta dose equivalents in a mixed field can be determined. The design, detection principle, and three dosimetric algorithms for three versions of the basic design of the four-element dosimeter are presented and discussed. The work that is required for the proposed dosimeter to be usable when it is made is also presented. PMID:1644568

  19. Characterization of high-sensitivity metal oxide semiconductor field effect transistor dosimeters system and LiF:Mg,Cu,P thermoluminescence dosimeters for use in diagnostic radiology.

    PubMed

    Dong, S L; Chu, T C; Lan, G Y; Wu, T H; Lin, Y C; Lee, J S

    2002-12-01

    Monitoring radiation exposure during diagnostic radiographic procedures has recently become an area of interest. In recent years, the LiF:Mg,Cu,P thermoluminescence dosimeter (TLD-100H) and the highly sensitive metal oxide semiconductor field effect transistor (MOSFET) dosimeter were introduced as good candidates for entrance skin dose measurements in diagnostic radiology. In the present study, the TLD-100H and the MOSFET dosimeters were evaluated for sensitivity, linearity, energy, angular dependence, and post-exposure response. Our results indicate that the TLD-100H dosimeter has excellent linearity within diagnostic energy ranges and its sensitivity variations were under 3% at tube potentials from 40Vp to 125kVp. Good linearity was also observed with the MOSFET dosimeter, but in low-dose regions the values are less reliable and were found to be a function of the tube potentials. Both dosimeters also presented predictable angular dependence in this study. Our findings suggest that the TLD-100H dosimeter is more appropriate for low-dose diagnostic procedures such as chest and skull projections. The MOSFET dosimeter system is valuable for entrance skin dose measurement with lumbar spine projections and certain fluoroscopic procedures.

  20. Characterization of high-sensitivity metal oxide semiconductor field effect transistor dosimeters system and LiF:Mg,Cu,P thermoluminescence dosimeters for use in diagnostic radiology.

    PubMed

    Dong, S L; Chu, T C; Lan, G Y; Wu, T H; Lin, Y C; Lee, J S

    2002-12-01

    Monitoring radiation exposure during diagnostic radiographic procedures has recently become an area of interest. In recent years, the LiF:Mg,Cu,P thermoluminescence dosimeter (TLD-100H) and the highly sensitive metal oxide semiconductor field effect transistor (MOSFET) dosimeter were introduced as good candidates for entrance skin dose measurements in diagnostic radiology. In the present study, the TLD-100H and the MOSFET dosimeters were evaluated for sensitivity, linearity, energy, angular dependence, and post-exposure response. Our results indicate that the TLD-100H dosimeter has excellent linearity within diagnostic energy ranges and its sensitivity variations were under 3% at tube potentials from 40Vp to 125kVp. Good linearity was also observed with the MOSFET dosimeter, but in low-dose regions the values are less reliable and were found to be a function of the tube potentials. Both dosimeters also presented predictable angular dependence in this study. Our findings suggest that the TLD-100H dosimeter is more appropriate for low-dose diagnostic procedures such as chest and skull projections. The MOSFET dosimeter system is valuable for entrance skin dose measurement with lumbar spine projections and certain fluoroscopic procedures. PMID:12406633

  1. [Measurement of the Dose Rate Using Dosimeters in Interventional Radiology and Its Difficulty].

    PubMed

    Yoshida, Hidenori; Takahashi, Chiharu; Narita, Nobuhiro; Mizusawa, Yasuhiko; Sekiya, Masaru; Ohkubo, Masaki

    2016-01-01

    In equipment used for interventional radiology (IVR), automatic exposure control (AEC) is incorporated to obtain the X-ray output suitable for the treatment of targeted lesions. For the AEC, users select a region as the signal sensing region (measuring field, MF) in the flat panel detector; MFs with various sizes and shapes were pre-defined and prepared in the system. The aim of this study was to examine the change of measured dose rate with the selection of MFs, the type of dosimeters (the ionization chamber dosimeter and the semiconductor dosimeter), and the dosimeter placement relative to the direction of X-ray tube (from cathode to anode). The IVR equipment was Allura Xper FD20/10 (Philips Medical Systems), and six kinds of built-in MFs were used. It was found that dose rate measured by the ionization chamber dosimeter showed a variation of -2 mGy/min with the MFs and the ionization chamber dosimeter placement. The dose rate measured by the semiconductor dosimeter showed more variation than the ionization chamber dosimeter. The change of dose rate with the dosimeter placement would be caused by the MF overlapping the dosimeter which would affect the AEC (the X-ray output). Also, the change of dose rate with the dosimeter placement was considered to be related to the heel effect of the X-ray beam. When performing dose rate measurements, we should notice that the selection of MFs, the type of dosimeters, and the dosimeter placement would affect the measured values. PMID:26796935

  2. Strontium sulfate as an EPR dosimeter for radiation technology application

    NASA Astrophysics Data System (ADS)

    Rushdi, M. A. H.; Abdel-Fattah, A. A.; Sherif, M. M.; Soliman, Y. S.; Mansour, A.

    2015-01-01

    The dosimetric characteristics of γ-radiation induced defects in strontium sulfate rod dosimeter are investigated using electron paramagnetic resonance (EPR) technique focusing on the low dose range of 1-100 Gy. Significant EPR signals of spectroscopic splitting factor (g) 2.01075, 2.04225, 2.03166, 2.00774 and 1.9219086 are observed in the rod upon γ-irradiation. The intensity of the signals increases linearly with increasing absorbed doses up to 100 Gy. The EPR response of irradiated dosimeter exhibits good stability over three months of storage. In addition, the response during irradiation is independent on both relative humidity (from 0% to 65%) and temperature (from 10 °C to 35 °C). The prepared rods are nearly water equivalent in the range of 0.4-5 MeV and the overall uncertainty (2σ) of dose monitoring is approximately 4.26%.

  3. A genipin-gelatin gel dosimeter for radiation processing

    NASA Astrophysics Data System (ADS)

    Davies, J. B.; Bosi, S. G.; Baldock, C.

    2012-08-01

    Genipin, a fruit extract from Gardenia jasminoides Ellis, forms cross-links in solutions of gelatin, to form a blue hydrogel that bleaches quantitatively upon irradiation and the colour change can be measured with a spectrophotometer. With the addition of sulphuric acid this dosimeter is sufficiently sensitive for quality assurance of radiotherapy level dosimetry. Without sulphuric acid the gel has a reduced sensitivity and responds linearly with dose between 100 and 1000 Gy, making it potentially useful as a dosimeter for radiation processing applications such as the phytosanitary irradiation treatment of food. We investigated the dose response characteristics of this new formulation and found that the darker gels are more sensitive to dose and have a reduced uncertainty.

  4. 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.

  5. Laser CT evaluation on normoxic PAGAT gel dosimeter

    NASA Astrophysics Data System (ADS)

    Kumar, D. S.; Samuel, E. J. J.; Watanabe, Y.

    2013-06-01

    Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to describe the initial evaluation of a newly fabricated laser CT scanner for 3D gel dosimetry which works using the first generation principle. A normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When a laser passes through the gel phantom, absorption and scattering of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor. The scanner motion is controlled by a computer program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software.

  6. An optical dosimeter for monitoring heavy metal ions in water

    NASA Astrophysics Data System (ADS)

    Mignani, Anna G.; Regan, Fiona; Leamy, D.; Mencaglia, A. A.; Ciaccheri, L.

    2005-05-01

    This work presents an optochemical dosimeter for determining and discriminating nickel, copper, and cobalt ions in water that can be used as an early warning system for water pollution. An inexpensive fiber optic spectrophotometer monitors the sensor's spectral behavior under exposure to water solutions of heavy metal ions in the 1-10 mg/l concentration range. The Principal Component Analysis (PCA) method quantitatively determines the heavy metals and discriminates their type and combination.

  7. Low-cost commercial glass beads as dosimeters in radiotherapy

    NASA Astrophysics Data System (ADS)

    Jafari, S. M.; Bradley, D. A.; Gouldstone, C. A.; Sharpe, P. H. G.; Alalawi, A.; Jordan, T. J.; Clark, C. H.; Nisbet, A.; Spyrou, N. M.

    2014-04-01

    Recent developments in advanced radiotherapy techniques using small field photon beams, require small detectors to determine the delivered dose in steep dose gradient fields. Commercially available glass jewellery beads exhibit thermoluminescent properties and have the potential to be used as dosimeters in radiotherapy due to their small size (<5 mm), low cost, reusability and inert nature. This study investigated the dosimetric characteristics of glass beads. The beads were irradiated by 6 MV photons using a medical linear-accelerator and 60Co gamma rays over doses ranging from 1 to 2500 cGy. A thermoluminescence (TL) system and an electron paramagnetic resonance (EPR) system were employed for read out. Both the TL and EPR studies demonstrated a radiation-induced signal, the sensitivity of which varied with bead colour. White coloured beads proved to be the most sensitive for both systems. The smallest and therefore least sensitive bead sizes allowed measurement of doses of 1 cGy using the TL system while that for the EPR system was approximately 1000 cGy. The fading rate was found to be 10% 30 days after irradiation with both readout systems. The dose response is linear with measured dose over the dose range 1 to 2500 cGy, with an R2 correlation coefficient of greater than 0.999. The batch-to-batch reproducibility of a set of dosimeters after a single irradiation was found to be 3% (1 SD). The reproducibility of individual dosimeters was found to be 1.7%. No measurable angular dependence was found (results agreed within 1%). Dose rate response was found to agree within 1% for dose rates of 100 to 600 cGy/min. These results demonstrate the potential use of glass beads as TL dosimeters over the dose range commonly applied in radiotherapy.

  8. Characterization and application of two kinds of ESR dosimeters

    NASA Astrophysics Data System (ADS)

    Marchioni, Eric; Pabst, Jean-Yves; Kuntz, Florent

    2002-09-01

    Many previous papers described the use of low-concentration alanine pellets, powder or films for industrial high-dose application, but very few authors presented applications of such dosimeters to the low-dose range used for wastewater, flowers or radiotherapy treatment. The present paper describes the large-scale manufacturing process of high-concentration alanine pellets used for radiotherapy dose control in some French hospitals. The fading process due to sunlight exposure has been evaluated by means of direct UV light irradiation. The major disadvantage of alanine is its strong solubility in water (the pellets are completely dissolved when immersed for 10 min in pure water). The use of barium sulphate, not soluble in water, made it possible to carry out dosimetric measurements even when the dosimeter is completely immersed in water or stored after irradiation in high humidity levels. The paper presents manufacturing process of barium sulphate pellets, their dosimetric characteristics and one application of this dosimeter for the control of the absorbed doses during wastewater treatments.

  9. Response of ionization chamber based pocket dosimeter to beta radiation.

    PubMed

    Kumar, Munish; Gupta, Anil; Pradhan, S M; Bakshi, A K; Chougaonkar, M P; Babu, D A R

    2013-12-01

    Quantitative estimate of the response of ionization chamber based pocket dosimeters (DRDs) to various beta sources was performed. It has been established that the ionization chamber based pocket dosimeters do not respond to beta particles having energy (Emax)<1 MeV and same was verified using (147)Pm, (85)Kr and (204)Tl beta sources. However, for beta particles having energy >1 MeV, the DRDs exhibit measureable response and the values are ~8%, ~14% and ~27% per mSv for natural uranium, (90)Sr/(90)Y and (106)Ru/(106)Rh beta sources respectively. As the energy of the beta particles increases, the response also increases. The response of DRDs to beta particles having energy>1 MeV arises due to the fact that the thickness of the chamber walls is less than the maximum range of beta particles. This may also be one of the reasons for disparity between doses measured with passive/legal dosimeters (TLDs) and DRDs in those situations in which radiation workers are exposed to mixed field of gamma photons and beta particles especially at uranium processing plants, nuclear (power and research) reactors, waste management facilities and fuel reprocessing plants etc. The paper provides the reason (technical) for disparity between the doses recorded by TLDs and DRDs in mixed field of photons and beta particles.

  10. Real-time dosimeter targeted to nuclear applications

    NASA Astrophysics Data System (ADS)

    Correia, Alexandre; Rosa, Carla C.; Santos, Pedro M. P.; Falcão, António N.; Lorentz, Katharina

    2014-08-01

    An intrinsic fiber optic dosimeter (FOD) targeted to nuclear applications is presented. The proposed real-time dosimeter provides dose information based on the historic record over time of the effects of ionizing radiation on single- and multimode pure silica fibers, and also on PMMA plastic fibers. The effect of 60Co gamma irradiation on optical links based on silica and plastic fibers were assessed, considering thermal environment effects over a wide range of variation of the operating parameters. Cerenkov radiation and radiation-induced absorption effects were in focus. The corresponding distortion and spectral transmission degradation were evaluated over wide range of the operating parameters. Radiation induced attenuation (RIA) has shown a spectral band dependent behaviour up to 840 Gy dose levels. The performance of different fibers was assessed against the performance of non-irradiated fibers. From the measurements of dose rate and total dose imparted by ionizing radiation in the fibers we verified that fibers with radiation resistance issues showed wavelength-dependent radiation sensitivity increasing with dose rate. Upon evaluation of correlations between the total dose, the induced loss at various dose rates and different wavelengths, it was concluded that intrinsic fiber dosimeters can be used for dose rates in the range 4 - 28 Gy/min., typical of severe radiation environments.

  11. Response of Panasonic dosimeters to submersion exposure by 133Xe.

    PubMed

    Hoffman, J M; Catchen, G L

    1990-01-01

    The dose response to 133Xe radiation of several types of Panasonic 800 series thermoluminescent dosimeters (TLD) were evaluated. The dosimeters were exposed by submersion in 133Xe gas. The relative sensitivities of the lithium borate and the calcium sulfate phosphors were determined for several configurations. The TLDs were exposed in the holders (as the devices came from the vendor) with various shields covering the elements, and they were exposed with the TLDs removed from the holders. Some dosimeters were exposed, both in holders and out of holders (TL insert only configuration), both in plastic bags and free in air. For the in-holder configuration, the responses of the heavily shielded (greater than 170 mg cm-2) elements were used to obtain the photon dose-rate component, and the responses of the lightly shielded (less than 13 mg cm-2) element were used to obtain the beta component. Similarly, for the insert-only configurations, the observed over-response of the calcium sulfate phosphors to low-energy photons could be used to separate the beta dose rate component. By using the calculated beta doses, correction factors were determined for the apparent under-responses of the elements to beta radiation. The results of both methods are consistent. These results also suggest that the beta component could be used in environmental monitoring as a more sensitive means to determine 133Xe activities in clouds and to separate some of the effects of submersion exposure from those of distant exposure.

  12. A new 2 methylalanine-PVC ESR dosimeter.

    PubMed

    Rossi, Bruno T; Chen, Felipe; Baffa, Oswaldo

    2005-02-01

    The use of polyvinyl chloride (PVC) as a binder to 2-methylalanine (2MA) dosimeters was investigated. It was recently shown by Olsson et al. (Radiat. Res. 157 (2002) 113), that 2MA is approximately 70% more sensitive than L-alanine which makes this substance a good candidate to replace alanine in ESR dosimetry. PVC is a low yield material for free radical production by ionizing radiation and a good binding material easily processed and widely available. PVC can be prepared at room temperature and mixed up to 50% in weight with 2MA to produce a pellet stable in mass and physical dimensions, in large quantities and with low background signal. Pure PVC pellet irradiated at 50 Gy gave weaker ESR signals compared to 2MA at the region of spectral interest. Spectrometer settings such as microwave power, and modulation amplitude were optimized for the measurements. This dosimeter production scheme allows the addition of Mn2+ ions for an internal reference signal, leading to a self-calibrated dosimeter (J. Radional. Nucl. Chem. 240 (1999) 215).

  13. Third intercomparison of DOE High-Energy Neutron Personnel Dosimeters

    SciTech Connect

    McDonald, J.C.; Akabani, G.; Loesch, R.M.

    1995-12-31

    An intercomparison of the dose equivalent response of personal dosimeters in use at U.S. Department of Energy (DOE) accelerator facilities was performed at the European Laboratory for Particle Physics (CERN). This is the third such intercomparison sponsored by the DOE. The two previous intercomparisons were performed in a U.S. laboratory using a source of high-energy neutrons. This intercomparison was performed at two positions relative to the main beam line at CERN. The neutron-energy spectra present at these two locations were measured by CERN personnel using Bonner sphere spectrometer systems. In addition, the dose equivalents at these two positions were also measured by CERN personnel using a tissue equivalent proportional counter system. The DOE dosimeters were mailed to CERN and returned after irradiation for readout. The results of this intercomparison are relatively consistent with the two previous intercomparisons performed in the U.S. The relative dose equivalent responses of neutron dosimeter types, such as albedo, nuclear emulsion and track-etch plastics, were found to have variations relative to the mean value responses of up to a factor of three.

  14. Method for preparing dosimeter for measuring skin dose

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1982-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with neutron-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  15. Dosimeter for measuring skin dose and more deeply penetrating radiation

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1981-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with netruon-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  16. Optimizing the sensitivity and radiological properties of the PRESAGE® dosimeter using metal compounds

    NASA Astrophysics Data System (ADS)

    Alqathami, Mamdooh; Blencowe, Anton; Qiao, Greg; Adamovics, John; Geso, Moshi

    2012-11-01

    The aim of this study is to investigate the radiation-modifying effects of incorporating commercially available bismuth-, tin- and zinc-based compounds in the composition of the PRESAGE® dosimeter, and the feasibility of employing such compounds for radiation dose enhancement. Furthermore, we demonstrate that metal compounds can be included in the formulation to yield water-equivalent PRESAGE® dosimeters with enhanced dose response. Various concentrations of the metal compounds were added to a newly developed PRESAGE® formulation and the resulting dosimeters were irradiated with 100 kV and 6 MV photon beams. A comparison between sensitivity and radiological properties of the PRESAGE® dosimeters with and without the addition of metal compounds was carried out. Optical density changes of the dosimeters before and after irradiation were measured using a spectrophotometer. In general, when metal compounds were incorporated in the composition of the PRESAGE® dosimeter, the sensitivity of the dosimeters to radiation dose increased depending on the type and concentration of the metal compound, with the bismuth compound showing the highest dose enhancement factor. In addition, these metal compounds were also shown to improve the retention of the post-response absorption value of the PRESAGE® dosimeter over a period of 2 weeks. Thus, incorporating 1-3 mM (ca. 0.2 wt%) of any of the three investigated metal compounds in the composition of the PRESAGE® dosimeter is found to be an efficient way to enhance the sensitivity of the dosimeter to radiation dose and stabilize its post-response for longer times. Furthermore, the addition of small amounts of the metal compounds also accelerates the polymerization of the PRESAGE® dosimeter precursors, significantly reducing the fabrication time. Finally, a novel water-equivalent PRESAGE® dosimeter formula optimized with metal compounds is proposed for clinical use in both kilovoltage and megavoltage radiotherapy dosimetry.

  17. The Assessment of Effective Dose Equivalent Using Personnel Dosimeters

    NASA Astrophysics Data System (ADS)

    Xu, Xie

    From January 1994, U.S. nuclear plants must develop a technically rigorous approach for determining the effective dose equivalent for their work forces. This dissertation explains concepts associated with effective dose equivalent and describes how to assess effective dose equivalent by using conventional personnel dosimetry measurements. A Monte Carlo computer code, MCNP, was used to calculate photon transport through a model of the human body. Published mathematical phantoms of the human adult male and female were used to simulate irradiation from a variety of external radiation sources in order to calculate organ and tissue doses, as well as effective dose equivalent using weighting factors from ICRP Publication 26. The radiation sources considered were broad parallel photon beams incident on the body from 91 different angles and isotropic point sources located at 234 different locations in contact with or near the body. Monoenergetic photons of 0.08, 0.3, and 1.0 MeV were considered for both sources. Personnel dosimeters were simulated on the surface of the body and exposed to with the same sources. From these data, the influence of dosimeter position on dosimeter response was investigated. Different algorithms for assessing effective dose equivalent from personnel dosimeter responses were proposed and evaluated. The results indicate that the current single-badge approach is satisfactory for most common exposure situations encountered in nuclear plants, but additional conversion factors may be used when more accurate results become desirable. For uncommon exposures involving source situated at the back of the body or source located overhead, the current approach of using multi-badges and assigning the highest dose is overly conservative and unnecessarily expensive. For these uncommon exposures, a new algorithm, based on two dosimeters, one on the front of the body and another one on the back of the body, has been shown to yield conservative assessment of

  18. Investigation of radiological properties and water equivalency of PRESAGE dosimeters

    SciTech Connect

    Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Adamovics, John; Bosi, Stephen; Kim, Jung-Ha; Baldock, Clive

    2011-04-15

    Purpose: PRESAGE is a dosimeter made of polyurethane, which is suitable for 3D dosimetry in modern radiation treatment techniques. Since an ideal dosimeter is radiologically water equivalent, the authors investigated water equivalency and the radiological properties of three different PRESAGE formulations that differ primarily in their elemental compositions. Two of the formulations are new and have lower halogen content than the original formulation. Methods: The radiological water equivalence was assessed by comparing the densities, interaction probabilities, and radiation dosimetry properties of the three different PRESAGE formulations to the corresponding values for water. The relative depth doses were calculated using Monte Carlo methods for 50, 100, 200, and 350 kVp and 6 MV x-ray beams. Results: The mass densities of the three PRESAGE formulations varied from 5.3% higher than that of water to as much as 10% higher than that of water for the original formulation. The probability of photoelectric absorption in the three different PRESAGE formulations varied from 2.2 times greater than that of water for the new formulations to 3.5 times greater than that of water for the original formulation. The mass attenuation coefficient for the three formulations is 12%-50% higher than the value for water. These differences occur over an energy range (10-100 keV) in which the photoelectric effect is the dominant interaction. The collision mass stopping powers of the relatively lower halogen-containing PRESAGE formulations also exhibit marginally better water equivalency than the original higher halogen-containing PRESAGE formulation. Furthermore, the depth dose curves for the lower halogen-containing PRESAGE formulations are slightly closer to that of water for a 6 MV beam. In the kilovoltage energy range, the depth dose curves for the lower halogen-containing PRESAGE formulations are in better agreement with water than the original PRESAGE formulation. Conclusions: Based

  19. Scintillation dosimeter arrays using air core light guides: simulation and experiment.

    PubMed

    Naseri, Pourandokht; Suchowerska, Natalka; McKenzie, David R

    2010-06-21

    The performance of a scintillation dosimeter that uses a silvered air core light guide is examined by Monte Carlo (MC) simulations and by experiment to determine its suitability for array dosimetry in external beam radiotherapy. The air core light guide avoids the generation of the Cerenkov background that is produced in a conventional optical fibre. MC simulations using a 6 MV photon beam showed that silver thicknesses of less than 1 microm compensated for the effects of the other material components, to give the dosimeter water equivalence within 0.5%. A second dosimeter located adjacent to the primary dosimeter in any direction affected the dose measurement by less than 1.5%, when the centre-to-centre spacing was 1.3 mm or greater. When the dosimeter array is located perpendicular to the beam central axis, with a spacing of 2.5 mm, the calculated deviation from the dose deposited in water was less than 2%. When the dosimeter array is located parallel to the beam central axis with a spacing of 10 mm, the calculated dose readings deviated from water by less than 2.5%. The simulation results were confirmed with experiment for two neighbouring dosimeters and a small densely packed array. No proximity effects were measured within the experimental error of +/-1.5%. These results confirm the dosimetric accuracy of the air core dosimeter design without the need for correction factors. The dosimeter has excellent potential for use in arrays.

  20. Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

    NASA Astrophysics Data System (ADS)

    Gorjiara, Tina; Hill, Robin; Bosi, Stephen; Kuncic, Zdenka; Baldock, Clive

    2013-10-01

    Two new formulations of N-isopropylacrylamide (NIPAM) based three dimensional (3D) gel dosimeters have recently been developed with improved sensitivity to x-ray CT readout, one without any co-solvent and the other one with isopropanol co-solvent. The water equivalence of the NIPAM gel dosimeters was investigated using different methods to calculate their radiological properties including: density, electron density, number of electrons per grams, effective atomic number, photon interaction probabilities, mass attenuation and energy absorption coefficients, electron collisional, radiative and total mass stopping powers and electron mass scattering power. Monte Carlo modelling was also used to compare the dose response of these gel dosimeters with water for kilovoltage and megavoltage x-ray beams and for megavoltage electron beams. We found that the density and electron density of the co-solvent free gel dosimeter are more water equivalent with less than a 2.6% difference compared to a 5.7% difference for the isopropanol gel dosimeter. Both the co-solvent free and isopropanol solvent gel dosimeters have lower effective atomic numbers than water, differing by 2.2% and 6.5%, respectively. As a result, their photoelectric absorption interaction probabilities are up to 6% and 19% different from water, respectively. Compton scattering and pair production interaction probabilities of NIPAM gel with isopropanol differ by up to 10% from water while for the co-solvent free gel, the differences are 3%. Mass attenuation and energy absorption coefficients of the co-solvent free gel dosimeter and the isopropanol gel dosimeter are up to 7% and 19% lower than water, respectively. Collisional and total mass stopping powers of both gel dosimeters differ by less than 2% from those of water. The dose response of the co-solvent free gel dosimeter is water equivalent (with <1% discrepancy) for dosimetry of x-rays with energies <100 keV while the discrepancy increases (up to 5%) for the

  1. Real time chemical exposure and risk monitor

    DOEpatents

    Thrall, K.D.; Kenny, D.V.; Endres, G.W.R.; Sisk, D.R.

    1997-07-08

    The apparatus of the present invention is a combination of a breath interface and an external exposure dosimeter interface to a chemical analysis device, all controlled by an electronic processor for quantitatively analyzing chemical analysis data from both the breath interface and the external exposure dosimeter for determining internal tissue dose. The method of the present invention is a combination of steps of measuring an external dose, measuring breath content, then analyzing the external dose and breath content and determining internal tissue dose. 7 figs.

  2. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  3. Lower limits of detection for thermal luminescent dosimeters

    SciTech Connect

    Spacher, P.J. ); Mis, F.J.; Klueber, M.R. )

    1990-08-01

    This paper reports that Groups of Panasonic UD-802 thermoluminescent dosimeters (TLDs) were irradiated to successively increasing doses of Cesium-137 gamma radiation (0.662 MeV gamma rays) and then processed using a Panasonic UD-710 automatic TLD reader. The results were subjected to statistical tests to determine the critical level, the level of detection, and the less-than level. The critical level is equivalent to 1.7 mrad, the lower limit of detection is equivalent to 5 mrad and the less-than level has a high range value of 7.5 mrad.

  4. Analysis of anomalous data produced by Harshaw Model 8801 thermoluminescent dosimeter cards

    SciTech Connect

    Sonder, E.; Ahmed, A.B.

    1993-05-01

    A large number of dosimeters that have produced abnormal data during field assignment have been stored, reirradiated, and studied. Results are summarized and comparisons are made with normal dosimeters. Summarized here are anomalous glow curve shapes, distributions of anomalies in the residual luminescent responses, and historical and repeat-irradiation behavior of abnormal dosimeters. The results indicate that by far the most frequent abnormal data involve elevated readings from Chip 3, accompanied by excess luminescence at temperatures higher than that of the normal radiation produced band. There is no sharp division between normal and abnormal dosimeters (dosimeters yielding excess luminescence at high temperature). Rather, dosimeters exhibit a continuum of behavior from very good (little high temperature luminescence) to clearly abnormal behavior. The excess luminescence emitted at high temperature in abnormal dosimeters is not proportional to absorbed dose; it has a radiation-independent average value that depends on the dosimeter but varies erratically above and below that average for consecutive anneals. At relatively high radiation exposures (>100 mR), the amount of excess high temperature luminescence becomes unimportant and abnormal data are rare.

  5. Comparative study of three types of civil defense high-range pocket dosimeters

    SciTech Connect

    Siskel, R.L.; Sims, C.S.; Swaja, R.

    1987-01-01

    Civil defense shelters are stocked with high-range (0- to 200-R) CDV-742 pocket dosimeters. These dosimeters are intended for use by people that must leave the shelter when the environmental radiation level is either high or unknown. A total of 67 CDV-742 dosimeters were obtained and studied during the summer of 1986 at Oak Ridge National Lab. Health Physics Research Reactor (HPRR). Three different types of dosimeters (27 Bendix, 20 Landsverk-Gold, and 20 Landsverk-Yellow) in various combinations were exposed to 14 separate pulse operations of the HPRR. It can be concluded that the CDV-742 type dosimeters were not suitable for use in a neutron or mixed radiation field unless the spectra is known and correction factors determined in this study are properly applied. Further study is needed to determine the accuracy of these dosimeters in a pure gamma field and to determine their precision at the extreme ends of the dosimeter range. Furthermore, because of their failure rates, shelter occupants should consider exposure data from the Bendix and Landsverk-Yellow dosimeters to be highly unreliable unless sufficient evidence exists to support the exposure readings.

  6. Longevity Tests of High-Sensitivity BD-PND Bubble Dosimeters

    SciTech Connect

    Radev, R; Carlberg, E

    2002-07-09

    Medium- and very-high-sensitivity neutron bubble dosimeters (BD-PNDs) made by Bubble Technology Industries (BTI) were used to study the life span of such dosimeters in a standard setup with a {sup 252}Cf source. Although data on the longevity of bubble dosimeters with low and medium sensitivity exist, such data for dosimeters with high and very high sensitivity are not readily available. The manufacturer guarantees optimum dosimeter performance for 3 months after receipt. However, it is important to know the change in the dosimeters' characteristics with time, especially after the first 3 months. The long-term performance of four sets of very high sensitivity and one set of medium-sensitivity bubble dosimeters was examined for periods of up to 13 months. During that time, the detectors were exposed and reset more than 20 times. Although departures from initial detection sensitivity were observed in several cases, the detectors indicated a significantly longer life span than stated in the manufacturer's warranty. In addition, the change in the number of bubbles and in evaluated neutron dose as a function of the time from the end of exposure until the dosimeters were read was investigated.

  7. Adaptation of a Pocket PC for Use as a Wearable Voice Dosimeter

    ERIC Educational Resources Information Center

    Popolo, Peter S.; Svec, Jan G.; Titze, Ingo R.

    2005-01-01

    This article deals with the adaptation of a commercially available Pocket PC for use as a voice dosimeter, a wearable device that measures the vocal dose of teachers or other individuals on the job, at home, and elsewhere during the course of an entire day. An engineering approach for designing a voice dosimeter is described, and design data are…

  8. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry.

    PubMed

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-11-17

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter.

  9. Dosimeter for the measurement of UV exposures related to melanoma induction.

    PubMed

    Turnbull, David J; Parisi, Alfio V

    2010-07-01

    This paper reports on the development of a dosimeter for the measurement of biologically effective UV exposures related to melanoma induction. The melanoma (UVMel) dosimeter is based on the combination of polysulfone and nalidixic acid. This research found that the combination of these photosensitive chromophores reacts to UV wavelengths from 290 to 390 nm. It was found that a large change in optical absorbance occurred at 345 nm when the dosimeter was employed to quantify the solar UV waveband. Preliminary results indicate that this UVMel dosimeter can measure exposures of more than 189 kJ m(-2) of biologically effective weighted solar UV radiation with an inter-dosimeter variability of no more than +/-5%. PMID:20551501

  10. An analysis of an implantable dosimeter system for external beam therapy

    PubMed Central

    Black, Robert D.; Scarantino, Charles W.; Mann, Gregory G.; Anscher, Mitchell S.; Ornitz, Robert D.; Nelms, Benjamin E.

    2006-01-01

    Background and purpose To review the data from an implantable radiation dosimetry system used in a clinical setting and examine correlations between dosimeter readings and potential causative error sources. Material and methods MOSFET-based, encapsulated dosimeters were evaluated in a phantom (in vitro) and in a study with 18 patients. The dosimeters were placed in the gross tumor volume or in collateral normal tissue. Predicted dose values were established by imaging the dosimeters in the planning CT’s. Results The in vitro study confirmed that bounding cumulative errors due to setup, planning, and machine output within a +/−5% level is achievable. In patients, it was found that deviations from the targeted dose often exceeded the 5% level. Conclusions The use of an implantable dosimeter system could provide an effective empirical check on the dose delivered at depth. Such a tool may have value for institutional QA as well as for therapy delivered to individual patients. PMID:16111599

  11. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry

    PubMed Central

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-01-01

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter. PMID:26593917

  12. 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.

  13. New radiochromic gel for 3D dosimetry based on Turnbull blue: basic properties.

    PubMed

    Solc, Jaroslav; Spevácek, Václav

    2009-09-01

    The recently developed new radiochromic gel dosimeter based on Turnbull blue dye formed by irradiation (the TBG dosimeter) does not exhibit dose pattern degradation due to diffusion effects as observed in the Fricke-gel dosimeter with xylenol orange incorporated into the gel matrix (the FXG dosimeter). The TBG dosimeter can be easily prepared and its optical properties enable evaluation of the gel's response using the cone-beam optical computed tomography technique. The preparation procedure is described in the paper along with the basic characteristics of the gel, including dose response, dose sensitivity, ageing under different storage conditions, diffusion rates of Turnbull blue and gel density. The measurement of diffusion is described in more detail. The same method was applied to the FXG dosimeter for direct comparison. It was found that the diffusion coefficient of the TBG dosimeter stored at 24 degrees C is less than 4 x 10(-3) mm(2) h(-1) (1sigma confidence level), compared to the value of 7.3 x 10(-1) mm(2) h(-1) (1sigma) of the FXG dosimeter measured at the same temperature. Although the TBG dosimeter is less sensitive than the FXG dosimeter, its diffusion coefficient is practically negligible and, therefore, it offers large potential as a three-dimensional dosimeter for applications encompassing sharp dose gradients such as high-dose-rate brachytherapy. PMID:19652291

  14. Alcohol solutions of triphenyl-tetrazolium chloride as high-dose radiochromic dosimeters

    NASA Astrophysics Data System (ADS)

    Kovács, A.; Wojnárovits, L.; El-assy, N. B.; Afeefy, H. Y.; Al-Sheikhly, M.; Walker, M. L.; McLaughlin, W. L.

    1995-09-01

    The radiolytic reduction of colorless tetrazolium salts in aqueous solution to the highly colored formazan dye is a well-known acid-forming radiation chemical reaction. Radiochromic thin films and three-dimensional hydrocolloid gels have been used for imaging and mapping absorbed dose distributions. The high solubility of 2,3,5-triphenyl-tetrazolium chloride (TTC) in alcohols provides a useful liquid dosimeter (45 mM TTC in aerated ethanol) and shows a linear response of absorbance increase (λmax = 480 nm) with dose over the range 1-16 kGy. The linear molar absorption coefficient (ɛm) for the formazan at the absorption peak is 1.5 × 103 m2 mol-1, and the radiation chemical yield for the above solution is G (formazan) = 0.014 μmol J-1. The irradiation temperature coefficient is about 0.8 percent per degree Celsius rise in temperature over the temperature range 0-30 °C but is much larger between 30° and 60 °C. The unirradiated and irradiated solutions are stable over at least five days storage at normal laboratory temperature in the dark, but when stored in daylight at elevated temperature, the unirradiated solution in sealed amber glass ampoules undergoes slow photolytic dye formation, and the irradiated solution experiences initial fading and subsequent reversal (photochromism) when exposed to direct sunlight.

  15. Is a quasi-3D dosimeter better than a 2D dosimeter for Tomotherapy delivery quality assurance?

    NASA Astrophysics Data System (ADS)

    Xing, Aitang; Deshpande, Shrikant; Arumugam, Sankar; George, Armia; Holloway, Lois; Vial, Philip; Goozee, Gary

    2015-01-01

    Delivery quality assurance (DQA) has been performed for each Tomotherapy patient either using ArcCHECK or MatriXX Evolution in our clinic since 2012. ArcCHECK is a quasi-3D dosimeter whereas MatriXX is a 2D detector. A review of DQA results was performed for all patients in the last three years, a total of 221 DQA plans. These DQA plans came from 215 patients with a variety of treatment sites including head-neck, pelvis, and chest wall. The acceptable Gamma pass rate in our clinic is over 95% using 3mm and 3% of maximum planned dose with 10% dose threshold. The mean value and standard deviation of Gamma pass rates were 98.2% ± 1.98(1SD) for MatriXX and 98.5%±1.88 (1SD) for ArcCHECK. A paired t-test was also performed for the groups of patients whose DQA was performed with both the ArcCHECK and MatriXX. No statistical dependence was found in terms of the Gamma pass rate for ArcCHECK and MatriXX. The considered 3D and 2D dosimeters have achieved similar results in performing routine patient-specific DQA for patients treated on a TomoTherapy unit.

  16. Development and characterization of a three-dimensional radiochromic film stack dosimeter for megavoltage photon beam dosimetry

    SciTech Connect

    McCaw, Travis J. Micka, John A.; DeWerd, Larry A.

    2014-05-15

    Purpose: Three-dimensional (3D) dosimeters are particularly useful for verifying the commissioning of treatment planning and delivery systems, especially with the ever-increasing implementation of complex and conformal radiotherapy techniques such as volumetric modulated arc therapy. However, currently available 3D dosimeters require extensive experience to prepare and analyze, and are subject to large measurement uncertainties. This work aims to provide a more readily implementable 3D dosimeter with the development and characterization of a radiochromic film stack dosimeter for megavoltage photon beam dosimetry. Methods: A film stack dosimeter was developed using Gafchromic{sup ®} EBT2 films. The dosimeter consists of 22 films separated by 1 mm-thick spacers. A Virtual Water™ phantom was created that maintains the radial film alignment within a maximum uncertainty of 0.3 mm. The film stack dosimeter was characterized using simulations and measurements of 6 MV fields. The absorbed-dose energy dependence and orientation dependence of the film stack dosimeter were investigated using Monte Carlo simulations. The water equivalence of the dosimeter was determined by comparing percentage-depth-dose (PDD) profiles measured with the film stack dosimeter and simulated using Monte Carlo methods. Film stack dosimeter measurements were verified with thermoluminescent dosimeter (TLD) microcube measurements. The film stack dosimeter was also used to verify the delivery of an intensity-modulated radiation therapy (IMRT) procedure. Results: The absorbed-dose energy response of EBT2 film differs less than 1.5% between the calibration and film stack dosimeter geometries for a 6 MV spectrum. Over a series of beam angles ranging from normal incidence to parallel incidence, the overall variation in the response of the film stack dosimeter is within a range of 2.5%. Relative to the response to a normally incident beam, the film stack dosimeter exhibits a 1% under-response when the

  17. Characterization of the nanoDot OSLD dosimeter in CT

    SciTech Connect

    Scarboro, Sarah B.; Cody, Dianna; Followill, David; Court, Laurence; Stingo, Francesco C.; Kry, Stephen F.; Alvarez, Paola; Zhang, Di; McNitt-Gray, Michael

    2015-04-15

    Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due

  18. Characterization of the nanoDot OSLD dosimeter in CT

    PubMed Central

    Scarboro, Sarah B.; Cody, Dianna; Alvarez, Paola; Followill, David; Court, Laurence; Stingo, Francesco C.; Zhang, Di; Kry, Stephen F.

    2015-01-01

    Purpose: The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring air kerma. The purpose of this work was to characterize the OSLD nanoDot for CT dosimetry, quantifying necessary correction factors, and evaluating the uncertainty of these factors. Methods: A characterization of the Landauer OSL nanoDot (Landauer, Inc., Greenwood, IL) was conducted using both measurements and theoretical approaches in a CT environment. The effects of signal depletion, signal fading, dose linearity, and angular dependence were characterized through direct measurement for CT energies (80–140 kV) and delivered doses ranging from ∼5 to >1000 mGy. Energy dependence as a function of scan parameters was evaluated using two independent approaches: direct measurement and a theoretical approach based on Burlin cavity theory and Monte Carlo simulated spectra. This beam-quality dependence was evaluated for a range of CT scanning parameters. Results: Correction factors for the dosimeter response in terms of signal fading, dose linearity, and angular dependence were found to be small for most measurement conditions (<3%). The relative uncertainty was determined for each factor and reported at the two-sigma level. Differences in irradiation geometry (rotational versus static) resulted in a difference in dosimeter signal of 3% on average. Beam quality varied with scan parameters and necessitated the largest correction factor, ranging from 0.80 to 1.15 relative to a calibration performed in air using a 120 kV beam. Good agreement was found between the theoretical and measurement approaches. Conclusions: Correction factors for the measurement of air kerma were generally small for CT dosimetry, although angular effects, and particularly effects due

  19. Monte Carlo-based energy response studies of diode dosimeters in radiotherapy photon beams.

    PubMed

    Arun, C; Palani Selvam, T; Dinkar, Verma; Munshi, Prabhat; Kalra, Manjit Singh

    2013-01-01

    This study presents Monte Carlo-calculated absolute and normalized (relative to a (60)Co beam) sensitivity values of silicon diode dosimeters for a variety of commercially available silicon diode dosimeters for radiotherapy photon beams in the energy range of (60)Co-24 MV. These values were obtained at 5 cm depth along the central axis of a water-equivalent phantom of 10 cm × 10 cm field size. The Monte Carlo calculations were based on the EGSnrc code system. The diode dosimeters considered in the calculations have different buildup materials such as aluminum, brass, copper, and stainless steel + epoxy. The calculated normalized sensitivity values of the diode dosimeters were then compared to previously published measured values for photon beams at (60)Co-20 MV. The comparison showed reasonable agreement for some diode dosimeters and deviations of 5-17 % (17 % for the 3.4 mm brass buildup case for a 10 MV beam) for some diode dosimeters. Larger deviations of the measurements reflect that these models of the diode dosimeter were too simple. The effect of wall materials on the absorbed dose to the diode was studied and the results are presented. Spencer-Attix and Bragg-Gray stopping power ratios (SPRs) of water-to-diode were calculated at 5 cm depth in water. The Bragg-Gray SPRs of water-to-diode compare well with Spencer-Attix SPRs for ∆ = 100 keV and above at all beam qualities.

  20. The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere

    SciTech Connect

    Yang, Zhen; Chen, Bo Zhuo, Weihai; Fan, Dunhuang; Zhang, Yu; Zhao, Chao

    2015-12-15

    For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of {sup 137}Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmic rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account.

  1. The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere.

    PubMed

    Yang, Zhen; Chen, Bo; Zhuo, Weihai; Fan, Dunhuang; Zhao, Chao; Zhang, Yu

    2015-12-01

    For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of (137)Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmic rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account.

  2. The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere.

    PubMed

    Yang, Zhen; Chen, Bo; Zhuo, Weihai; Fan, Dunhuang; Zhao, Chao; Zhang, Yu

    2015-12-01

    For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of (137)Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmic rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account. PMID:26724019

  3. Monte Carlo simulation of single and two-dosimeter approaches in a steam generator channel head.

    PubMed

    Kim, C H; Reece, W D

    2002-08-01

    In a steam generator channel head, it was not unusual to see radiation workers wearing as many as twelve dosimeters over the surface of the body to avoid a possible underestimation of effective dose equivalent (H(E)) or effective dose (E). This study shows that only one or two dosimeters can be used to estimate H(E) and E without a significant underestimation. MCNP and a point-kernel approach were used to model various exposure situations in a steam generator channel head. The single-dosimeter approach (on the chest) was found to underestimate H(E) and E significantly for a few exposure situations, i.e., when the major portion of radiation source is located in the backside of a radiation worker. In this case, the photons from the source pass through the body and are attenuated before reaching the dosimeter on the chest. To assure that a single dosimeter provides a good estimate of worker dose, these few exposure situations cannot dominate a worker's exposure. On the other hand, the two-dosimeter approach (on the chest and back) predicts H(E) and E very well, hardly ever underestimating these quantities by more than 4% considering all worker positions and contamination situations in a steam generator channel head. This study shows that two dosimeters are adequate for an accurate estimation of H(E) and E in a steam generator channel head. PMID:12132712

  4. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    SciTech Connect

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford's mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  5. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    SciTech Connect

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford`s mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  6. Dental enamel as an in vivo radiation dosimeter

    SciTech Connect

    Pass, B.; Aldrich, J.E.

    1985-05-01

    The determination of the radiation exposure history of the population has become increasingly important in the study of the effects of low-level radiation. The present work was started to try to obtain an in vivo dosimeter that could give an indication of radiation exposure. Dental enamel is the only living tissue which retains indefinitely its radiation history, and electron spin resonance measurements have shown that the radiation signal can be resolved down to about 10 cGy. Measurements on samples from the general population give radiation exposure estimates that are reasonable, and one measurement on a patient who had radiotherapy to the mouth area showed a good correlation with tumor dose.We believe that this is an important new indicator of radiation dose and taken together with exposure histories should provide important data for epidemiological studies as well as accidental exposures.

  7. [AOR characterization and zoning: a dosimeter for blue light].

    PubMed

    Dario, R; Uva, J; Di Lecce, V; Quarto, A

    2011-01-01

    The paper presents the results obtained thanks to an innovative experimental device for the assessment of artificial optical radiation (AOR) exposure in workplace. This . device was developed by 'Politecnico di Bari-DIASS'. The wearable personal dosimeter has three sensors: one is used for measuring head position/movement, therefore there is a color light sensor to determine the AOR and finally there is a video camera to localize sources. Our system is connected to a netbook via USB cable that allows one to obtain the real and extimated value of worker's exposure, also with "augmented reality". The aim of this paper is realizing work place safety zoning for the classifacation of not only specific dangerous areas through the analysis of overlapping information from the device. PMID:23393888

  8. Review of four novel dosimeters developed for use in radiotherapy

    NASA Astrophysics Data System (ADS)

    Metcalfe, P.; Quinn, A.; Loo, K.; Lerch, M.; Petasecca, M.; Wong, J.; Hardcastle, N.; Carolan, M.; McNamara, J.; Cutajar, D.; Fuduli, I.; Espinoza, A.; Porumb, C.; Rosenfeld, A.

    2013-06-01

    Centre for Medical Radiation Physics (CMRP) is a research strength at the University of Wollongong, the main research theme of this centre is to develop prototype novel radiation dosimeters. Multiple detector systems have been developed by Prof Rosenfelds' group for various radiation detector applications. This paper focuses on four current detector systems being developed and studied at CMRP. Two silicon array detectors include the magic plate and dose magnifying glass (DMG), the primary focus of these two detectors is high spatial and temporal resolution dosimetry in intensity modulated radiation therapy (IMRT) beams. The third detector discussed is the MOSkinTM which is a high spatial resolution detector based on MOSFET technology, its primary role is in vivo dosimetry. The fourth detector system discussed is BrachyView, this is a high resolution dose viewing system based on Medipix detector technology.

  9. [AOR characterization and zoning: a dosimeter for blue light].

    PubMed

    Dario, R; Uva, J; Di Lecce, V; Quarto, A

    2011-01-01

    The paper presents the results obtained thanks to an innovative experimental device for the assessment of artificial optical radiation (AOR) exposure in workplace. This . device was developed by 'Politecnico di Bari-DIASS'. The wearable personal dosimeter has three sensors: one is used for measuring head position/movement, therefore there is a color light sensor to determine the AOR and finally there is a video camera to localize sources. Our system is connected to a netbook via USB cable that allows one to obtain the real and extimated value of worker's exposure, also with "augmented reality". The aim of this paper is realizing work place safety zoning for the classifacation of not only specific dangerous areas through the analysis of overlapping information from the device.

  10. Applicability of the Sunna dosimeter for food irradiation control

    NASA Astrophysics Data System (ADS)

    Kovács, A.; Baranyai, M.; Wojnárovits, L.; Miller, S.; Murphy, M.; McLaughlin, W. L.; Slezsák, I.; Kovács, A. I.

    2002-03-01

    The quick development concerning the commercial application of food irradiation in the USA recently resulted in growing marketing of irradiated red meat as well as irradiated fresh and dried fruits. These gamma and electron irradiation technologies require specific dosimetry systems for process control. The new version of the Sunna dosimeter has been characterized in gamma, electron and bremsstrahlung radiation fields by measuring the optically stimulated luminescence (osl) at 530 nm both below and above 1 kGy, i.e. for disinfestation and for meat irradiation purposes. No humidity and no significant dose rate effect on the green osl signal was observed. The temperature coefficient was determined from 0°C up to about 40°C and to stabilize the osl signal after irradiation a heat treatment method was introduced. Based on these investigations the Sunna 'gamma' film is a suitable candidate for dose control below and above 1 kGy for food irradiation technologies.

  11. Calibration results obtained with Liulin-4 type dosimeters.

    PubMed

    Dachev, Ts; Tomov, B; Matviichuk, Yu; Dimitrov, Pl; Lemaire, J; Gregoire, Gh; Cyamukungu, M; Schmitz, H; Fujitaka, K; Uchihori, Y; Kitamura, H; Reitz, G; Beaujean, R; Petrov, V; Shurshakov, V; Benghin, V; Spurny, F

    2002-01-01

    The Mobile Radiation Exposure Control System's (Liulin-4 type) main purpose is to monitor simultaneously the doses and fluxes at 4 independent places. It can also be used for personnel dosimetry. The system consists of 4 battery-operated 256-channel dosimeters-spectrometers. We describe results obtained during the calibrations of the spectrometers at the Cyclotron facilities of the University of Louvain, Belgium and of the National Institute of Radiological Sciences-STA, Chiba, Japan with protons of energies up to 70 MeV. The angular sensitivities of the devices are studied and compared with Monte-Carlo predictions. We also present the results obtained at the HIMAC accelerator with 500 MeV/u Fe ions and at the CERN high energy radiation reference fields. Records made during airplane flights are shown and compared with the predictions of the CARI-6 model.

  12. A Radiation Dosimeter Concept for the Lunar Surface Environment

    NASA Technical Reports Server (NTRS)

    Adams, James H.; Christl, Mark J.; Watts, John; Kuznetsov, Eugeny N.; Parnell, Thomas A.; Pendleton, Geoff N.

    2007-01-01

    A novel silicon detector configuration for radiation dose measurements in an environment where solar energetic particles are of most concern is described. The dosimeter would also measure the dose from galactic cosmic rays. In the lunar environment a large range in particle flux and ionization density must be measured and converted to dose equivalent. This could be accomplished with a thick (e.g. 2mm) silicon detector segmented into cubic volume elements "voxels" followed by a second, thin monolithic silicon detector. The electronics needed to implement this detector concept include analog signal processors (ASIC) and a field programmable gate array (FPGA) for data accumulation and conversion to linear energy transfer (LET) spectra and to dose-equivalent (Sievert). Currently available commercial ASIC's and FPGA's are suitable for implementing the analog and digital systems.

  13. Sugar as an emergency populace dosimeter for radiation accidents

    SciTech Connect

    Nakajima, T.

    1988-12-01

    Ordinary sugar can be used as an emergency dosimeter for any person exposed to a nuclear or radiation accident. The number of free radicals in sugar created by radiation does not decrease at room temperature for two months after irradiation and is not changed by thermal treatment for about 18 h at even 55 degrees C. A 600 mg granulated sugar sample can detect about 0.05 Gy (5 rad) as the minimum detectable absorbed dose using electron spin resonance equipment. If sugar is present at the time of a radiation or nuclear accident, the absorbed dose can be evaluated from the sugar and will be useful for both the medical treatment and health effects of the exposed persons.

  14. Preliminary dosimetry investigation of Tc-99m diagnostic radionuclide by NIPAM gel dosimeter

    NASA Astrophysics Data System (ADS)

    Huang, You-Ruei; Chang, Yuan-Jen; Hsieh, Ling-Ling; Yu, Bi-Wei; Chu, Chien-Hau; Hsieh, Bor-Tsung

    2013-06-01

    The N-isopropylacrylamide (NIPAM) gel dosimeter was investigated as a suitable material for measuring absorbed doses from radionuclide sources. In this study, NIPAM gel dosimeter was used to evaluate the dose distributions of the Tc-99m radionuclide in NIPAM gel. The accumulated radioactivity range of the Tc-99m NIPAM gel is from approximately 0 MBq to 13.6 MBq (about 0.37 mCi). The NIPAM gel dosimeter with high stability and high-dose linear and non-energy dependent properties can provide various radiopharmaceutical activity intensities in the conduct of dose assessment in nuclear medicine, thereby producing the most promising dose verification tools.

  15. Laboratory facilities and recommendations for the characterization of biological ultraviolet dosimeters.

    PubMed

    Bolsée, D; Webb, A R; Gillotay, D; Dörschel, B; Knuschke, P; Krins, A; Terenetskaya, I

    2000-06-01

    A laboratory facility for characterizing biological dosimeters for the measurement of UV radiation has been built and tested. The facility is based on a solar simulator, stabilized by photofeedback, and monitored by a spectroradiometer, with a versatile filter arrangement. This enables the following characteristics of the dosimeters to be ascertained: spectral response, linearity, and reciprocity; angular acceptance and response; calibration in simulated sunlight. The system has been tested on a variety of dosimeters and has the potential to be used with other radiometers, subject currently to the size of their active surface. PMID:18345205

  16. Measurement of a 200 MeV proton beam using a polyurethane dosimeter

    NASA Astrophysics Data System (ADS)

    Heard, Malcolm; Adamovics, John; Ibbott, Geoffrey

    2006-12-01

    PRESAGETM (Heuris Pharma LLC, Skillman, NJ) is a three-dimensional polyurethane dosimeter containing a leuco dye that generates a color change when irradiated. The dosimeter is solid and does not require a container to maintain its shape. The dosimeter is transparent before irradiation and the maximum absorbance of the leuco dye occurs at 633 nm which is compatible with the OCT-OPUSTM laser CT scanner (MGS Research, Inc., Madison, CT). The purpose of this study was to investigate the response of PRESAGETM to proton beam radiotherapy.

  17. Thermal drift reduction with multiple bias current for MOSFET dosimeters.

    PubMed

    Carvajal, M A; Martínez-Olmos, A; Morales, D P; Lopez-Villanueva, J A; Lallena, A M; Palma, A J

    2011-06-21

    New thermal compensation methods suitable for p-channel MOSFET (pMOS) dosimeters with the usual dose readout procedure based on a constant drain current are presented. Measuring the source-drain voltage shifts for two or three different drain currents and knowing the value of the zero-temperature coefficient drain current, I(ZTC), the thermal drift of source-drain or threshold voltages can be significantly reduced. Analytical expressions for the thermal compensation have been theoretically deduced on the basis of a linear dependence on temperature of the parameters involved. The proposed thermal modelling has been experimentally proven. These methods have been applied to a group of ten commercial pMOS transistors (3N163). The thermal coefficients of the source-drain voltage and the threshold voltage were reduced from -3.0 mV  °C(-1), in the worst case, down to -70 µV  °C(-1). This means a thermal drift of -2.4 mGy  °C(-1) for the dosimeter. When analysing the thermal drifts of all the studied transistors, in the temperature range from 19 to 36 °C, uncertainty was obtained in the threshold voltage due to a thermal drift of ±9 mGy (2 SD), a commonly acceptable value in most radiotherapy treatments. The procedures described herein provide thermal drift reduction comparable to that of other technological or numerical strategies, but can be used in a very simple and low-cost dosimetry sensor. PMID:21606552

  18. Thermal drift reduction with multiple bias current for MOSFET dosimeters

    NASA Astrophysics Data System (ADS)

    Carvajal, M. A.; Martínez-Olmos, A.; Morales, D. P.; Lopez-Villanueva, J. A.; Lallena, A. M.; Palma, A. J.

    2011-06-01

    New thermal compensation methods suitable for p-channel MOSFET (pMOS) dosimeters with the usual dose readout procedure based on a constant drain current are presented. Measuring the source-drain voltage shifts for two or three different drain currents and knowing the value of the zero-temperature coefficient drain current, IZTC, the thermal drift of source-drain or threshold voltages can be significantly reduced. Analytical expressions for the thermal compensation have been theoretically deduced on the basis of a linear dependence on temperature of the parameters involved. The proposed thermal modelling has been experimentally proven. These methods have been applied to a group of ten commercial pMOS transistors (3N163). The thermal coefficients of the source-drain voltage and the threshold voltage were reduced from -3.0 mV °C-1, in the worst case, down to -70 µV °C-1. This means a thermal drift of -2.4 mGy °C-1 for the dosimeter. When analysing the thermal drifts of all the studied transistors, in the temperature range from 19 to 36 °C, uncertainty was obtained in the threshold voltage due to a thermal drift of ±9mGy (2 SD), a commonly acceptable value in most radiotherapy treatments. The procedures described herein provide thermal drift reduction comparable to that of other technological or numerical strategies, but can be used in a very simple and low-cost dosimetry sensor.

  19. Calibration factors for the SNOOPY NP-100 neutron dosimeter

    NASA Astrophysics Data System (ADS)

    Moscu, D. F.; McNeill, F. E.; Chase, J.

    2007-10-01

    Within CANDU nuclear power facilities, only a small fraction of workers are exposed to neutron radiation. For these individuals, roughly 4.5% of the total radiation equivalent dose is the result of exposure to neutrons. When this figure is considered across all workers receiving external exposure of any kind, only 0.25% of the total radiation equivalent dose is the result of exposure to neutrons. At many facilities, the NP-100 neutron dosimeter, manufactured by Canberra Industries Incorporated, is employed in both direct and indirect dosimetry methods. Also known as "SNOOPY", these detectors undergo calibration, which results in a calibration factor relating the neutron count rate to the ambient dose equivalent rate, using a standard Am-Be neutron source. Using measurements presented in a technical note, readings from the dosimeter for six different neutron fields in six source-detector orientations were used, to determine a calibration factor for each of these sources. The calibration factor depends on the neutron energy spectrum and the radiation weighting factor to link neutron fluence to equivalent dose. Although the neutron energy spectra measured in the CANDU workplace are quite different than that of the Am-Be calibration source, the calibration factor remains constant - within acceptable limits - regardless of the neutron source used in the calibration; for the specified calibration orientation and current radiation weighting factors. However, changing the value of the radiation weighting factors would result in changes to the calibration factor. In the event of changes to the radiation weighting factors, it will be necessary to assess whether a change to the calibration process or resulting calibration factor is warranted.

  20. Development of a novel UV indicator and dosimeter film.

    PubMed

    Mills, Andrew; Lee, Soo-Keun; Sheridan, Martin

    2005-07-01

    A novel UV indicator is described, comprising nanocrystalline particles of titania dispersed in a film of a polymer, hydroxyl ethyl cellulose (HEC), containing: a mild reducing agent, triethanolamine (TEOA) and a redox indicator, methylene blue (MB). The UV indicator film is blue-coloured in the absence of UV light and loses colour upon exposure to UV light, attaining within a few min a steady-state degree of bleaching that can provide a measure of the irradiance of the incident light. The original blue colour of the film returns once the source of UV light is removed. The spectral characteristics of a typical UV indicator film, and its components, are discussed and the UV-absorbing action of the titania particles highlighted. From the measured %bleaching undergone by a typical UV indicator as a function of light irradiance the indicator appears fully bleached, within 7 min, by a UV irradiance of 3 mW cm(-2) or greater. The mechanism by which the UV indicator works is described. The reversible nature of the UV indicator is removed by covering a typical UV indicator with a thin, largely oxygen impermeable, polymer film, such as the regenerated cellulose found in Sellotape. The product is a UV dosimeter, the response of which is related to the intensity and duration of the incident UV light, as well as the amount of titania in the film. A typical UV dosimeter film is fully bleached by 250 mJ cm(-2) of UV light. The possible use of these novel indicators to measure UV exposure levels, irradiance and dose, is discussed.

  1. Biological UV dosimeters in simulated space irradiation conditions

    NASA Astrophysics Data System (ADS)

    Rontó, G.; Bérces, A.; Fekete, A.; Kovács, G.; Lammer, H.

    For the measurement of the harmful biological effect of solar UV radiation bacteriophage T7 and polycrystalline uracil dosimeters were used. For terrestrial dosimetric purposes bacteriophage T7 has been applied in solution, while uracil in the form of thin layers. For space irradiation dosimetry the uracil, phage T7-DNA and bacteriophage T7 thin layer samples were prepared in vacuum tightly closed sandwich forms covered either by calciumfluoride or quartz windows. The experimental conditions tested correspond to the conditions planned in the EXPOSE facility: the samples were surrounded by nitrogen atmosphere at various humidities, their vacuum stability was tested in the vacuum chamber of the Institute of Space Research,, Graz. All kinds of the thin film samples have been stored in an atmosphere containing Nitrogen and Hidrogen, in quality control no change in the structure of them has been found. To attenuate the high extraterrestrial irradiance neutral filters of 0.5 and 1.0 optical densities have been tested. Irradiation of the samples has been performed with various UV sources: solar simulator, low pressure Mercury lamp, Deuterium lamp. Dose-effect functions have been determined using for the evaluation spectrophotometry in the characteristic UV range, HPLC of photoproducts, PCR of two different primer sequences of phage T7-DNA. Photoproduct formation kinetics was followed by the saturation level of uracil thin layer. Attenuation ability of the neutral filters was controlled with low pressure Mercury lamp by the exposure necessary for saturation of uracil dosimeters. A three and tenfold increase in the exposure was found respectively, while the influence of spectral composition of the irradiation source was tested using Deuterium lamp supplied with Ca F2 and quartz filters respectively. A doubling of the irradiance was necessary for the saturation of uracil with quartz filter.

  2. Characterization of metal oxide semiconductor field effect transistor dosimeters for application in clinical mammography.

    PubMed

    Benevides, Luis A; Hintenlang, David E

    2006-02-01

    Five high-sensitivity metal oxide semiconductor field effect transistor dosimeters in the TN-502 and 1002 series (Thomson Nielsen Electronics Ltd., 25B, Northside Road, Ottawa, ON K2H8S1, Canada) were evaluated for use in the mammography x-ray energy range (22-50 kVp) as a tool to assist in the documentation of patient specific average glandular dose. The dosimeters were interfaced with the Patient Dose Verification System, model No. TN-RD 15, which consisted of a dosimeter reader and up to four dual bias power supplies. Two different dual bias power supplies were evaluated in this study, model No. TN-RD 22 in high-sensitivity mode and a very-high sensitivity prototype. Each bias supply accommodates up to five dosimeters for 20 dosimeters per system. Sensitivity of detectors, defined as the mV/C kg(-1), was measured free in air with the bubble side of the dosimeter facing the x-ray field with a constant exposure. All dosimeter models' angular response showed a marked decrease in response when oriented between 120 degrees and 150 degrees and between at 190 degrees and 220 degrees relative to the incident beam. Sensitivity was evaluated for Mo/Mo, Mo/Rh, and Rh/Rh target-filter combinations. The individual dosimeter model sensitiVity was 4.45 x 10(4) mV/C kg(-1) (11.47 mV R(-1)) for TN-502RDS(micro); 5.93 x 10(4) mV per C kg(-1) (15.31 mV R(-1)) for TN-1002RD; 6.06 x 10(4) mV/C kg(-1) (15.63 mV R(-1)) for TN-1002RDI; 9.49 x 10(4) mV per C kg(-1) (24.49 mV R(-1)) for TN-1002RDM (micro); and 11.20 x 10(4) mV/C kg(-1) (28.82 mV R(-1)) for TN-1002RDS (micro). The energy response is presented and is observed to vary with dosimeter model, generally increasing with tube potential through the mammography energy range. An intercomparison of the high-sensitivity mode of TN-RD-22 was made to the very-high sensitivity bias power supply using a Mo/Mo target-filter. The very-high sensitivity-bias power supply increased dosimeter response by 1.45 +/- 0.04 for dosimeter models TN

  3. NASA Crew Personal Active Dosimeters (CPADs): Leveraging Novel Terrestrial Personal Radiation Monitoring Capabilities for Space Exploration

    NASA Technical Reports Server (NTRS)

    Leitgab, Martin; Semones, Edward; Lee, Kerry

    2016-01-01

    The NASA Space Radiation Analysis Group (SRAG) is developing novel Crew Personal Active Dosimeters (CAPDs) for upcoming crewed space exploration missions and beyond. To reduce the resource footprint of the project a COTS dosimeter base is used for the development of CPADs. This base was identified from evaluations of existing COTS personal dosimeters against the concept of operations of future crewed missions and tests against detection requirements for radiation characteristic of the space environment. CPADs exploit operations efficiencies from novel features for space flight personal dosimeters such as real-time dose feedback, and autonomous measuring and data transmission capabilities. Preliminary CPAD design, results of radiation testing and aspects of operational integration will be presented.

  4. Measurements of entrance surface dose using a fiber-optic dosimeter in diagnostic radiology

    NASA Astrophysics Data System (ADS)

    Yoo, Wook Jae; Seo, Jeong Ki; Shin, Sang Hun; Han, Ki-Tek; Jeon, Dayeong; Jang, Kyoung Won; Sim, Hyeok In; Lee, Bongsoo; Park, Jang-Yeon

    2013-03-01

    In this study, a fiber-optic dosimeter (FOD) was developed to measure entrance surface dose (ESD) in diagnostic radiology. We measured the scintillating lights in order to obtain ESDs, which changed with the various exposure parameters of a digital radiography (DR) system, such as tube potential, current-time product, focus-surface distance (FSD), and field size, using the fabricated FOD system. From the experimental results, the output light signals of the FOD were similar to the ESDs of the conventional semiconductor dosimeter. In conclusion, we characterized the measured ESDs as functions of exposure parameters by using two different types of dosimeters and demonstrated that the proposed FOD using a plastic scintillating fiber and a plastic optical fiber (POF) makes it possible to measure ESDs in the energy range of diagnostic radiology. From the results of this study, it is anticipated that the FOD will be a useful dosimeter in low-energy photon applications including diagnostic radiology.

  5. Novel composition of polymer gel dosimeters based on N-(Hydroxymethyl)acrylamide for radiation therapy

    NASA Astrophysics Data System (ADS)

    Basfar, Ahmed A.; Moftah, Belal; Rabaeh, Khalid A.; Almousa, Akram A.

    2015-07-01

    A new composition of polymer gel dosimeters is developed based on radiation induced polymerization of N-(Hydroxymethyl)acrylamide (NHMA) for radiotherapy treatment planning. The dosimeters were irradiated by 10 MV photon beam of a medical linear accelerator at a constant dose rate of 600 cGy/min with doses up to 20 Gy. The polymerization occurs and increases with increasing absorbed dose. The dose response of polymer gel dosimeters was studied using nuclear magnetic imaging (NMR) for relaxation rate (R2) of water proton. Dose rate, energy of radiation and the stability of the polymerization after irradiation were investigated. No appreciable effects of these parameters on the performance of the novel gel dosimeters were observed.

  6. Indoor light on thermoluminescence of CVD diamond film used as a high-energy photon dosimeter.

    PubMed

    Liu, Chi-Chang; Chu, Tieh-Chi; Lin, Sung-Yen; Lin, Jao-Perng

    2003-01-01

    The effect of light on polycrystalline diamond film that was produced by chemical vapor deposition and is used as a thermoluminescent dosimeter should be considered, although some researchers have indicated that such an effect was theoretically unlikely to happen. A 15 min exposure to a normal desk light bulb induces significant thermoluminescence (TL) comparable to a 0.5 Gy exposure to high-energy photons. This light-induced TL will be saturated within 2 h. The saturated TL intensity depends on the frequency of the light and the blue light dominates. The TL peak area at a temperature of 605 K is insensitive to light but is sensitive to high-energy photons. Another peak at about 410 K is caused by light only, because the TL from the ionization radiation at the same location is bleached. The effect of light could be easily distinguished by a numerical or an experimental method. Lamps with a green lampshade or pure red lights are suggested for use as indoor light sources. To reduce the effect of light, pre-heating treatment before readout is also suggested.

  7. Flexydos3D: A new deformable anthropomorphic 3D dosimeter readout with optical CT scanning

    NASA Astrophysics Data System (ADS)

    De Deene, Yves; Hill, Robin; Skyt, Peter S.; Booth, Jeremy

    2015-01-01

    A new deformable polydimethylsiloxane (PDMS) based dosimeter is proposed that can be cast in an anthropomorphic shape and that can be used for 3D radiation dosimetry of deformable targets. The new material has additional favorable characteristics as it is tissue equivalent for high-energy photons, easy to make and is non-toxic. In combination with dual wavelength optical scanning, it is a powerful dosimeter for dose verification of image gated or organ tracked radiotherapy with moving and deforming targets.

  8. Water and tissue equivalency of some gel dosimeters for photon energy absorption.

    PubMed

    Un, Adem

    2013-12-01

    The mass energy absorption coefficients,, effective atomic numbers for photon energy absorption, ZPEAeff, and effective electron numbers for photon-energy absorption, NPEAeff, is calculated for 14 polymer gel dosimeter, five gel dosimeter, soft tissue and water, in the energy range from 1 keV to 20 MeV. The ZPEAeff(Gel)/ZPEAeff(Tissue) and NPEAeff(Gel)/NPEAeff (Tissue) are used to evaluate the tissue equivalency.

  9. Impact of the Fukushima nuclear accident on background radiation doses measured by control dosimeters in Japan.

    PubMed

    Romanyukha, Alexander; King, David L; Kennemur, Lisa K

    2012-05-01

    After the 9.0 magnitude earthquake and subsequent massive tsunami on 11 March 2011 in Japan, several reactors at the Fukushima Daiichi Nuclear Power Plant suffered severe damage. There was immediate participation of U.S. Navy vessels and other United States Department of Defense (DoD) teams that were already in the area at the time of the disaster or arrived shortly thereafter. The correct determination of occupational dose equivalent requires estimation of the background dose component measured by control dosimeters, which is subsequently subtracted from the total dose equivalent measured by personal dosimeters. The purpose of the control dosimeters is to determine the amount of radiation dose equivalent that has accumulated on the dosimeter from background or other non-occupational sources while they are in transit or being stored. Given the release of radioactive material and potential exposure to radiation from the Fukushima Daiichi Nuclear Power Plant and the process by which the U.S. Navy calculates occupational exposure to ionizing radiation, analysis of pre- and post-event control dosimeters is warranted. Several hundred historical dose records from the Naval Dosimetry Center (NDC) database were analyzed and compared with the post-accident dose equivalent data of control dosimeters. As result, it was shown that the dose contribution of the radiation and released radiological materials from the Fukushima nuclear accident to background radiation doses is less than 0.375 μSv d for shallow and deep photon dose equivalent. There is no measurable effect on neutron background exposure. The latter has at least two important conclusions. First, the NDC can use doses measured by control dosimeters at issuing sites in Japan for determination of personnel dose equivalents; second, the dose data from control dosimeters prior to and after the Fukushima accident may be used to assist in dose reconstruction of non-radiological (non-badged) personnel at these locations.

  10. Performance of KCl:Eu2+ storage phosphor dosimeters for low dose measurements

    PubMed Central

    Li, H. Harold; Hansel, Rachael; Knutson, Nels; Yang, Deshan

    2013-01-01

    Recent research has demonstrated that europium doped potassium chloride (KCl:Eu2+) storage phosphor material has the potential to become the physical foundation of a novel and reusable dosimetry system using either film-like devices or devices similar to thermoluminescent dosimeter (TLD) chips. The purposes of this work are to quantify the performance of KCl:Eu2+ prototype dosimeters for low dose measurements and to demonstrate how it can be incorporated into clinical application for in vivo peripheral dose measurements. Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The dosimeters were read using a laboratory photostimulated luminescence detection system. KCl:Eu2+ prototype storage phosphor dosimeter was capable of measuring a dose-to-water as low as 0.01 cGy from a 6 MV photon beam with a signal-to-noise ratio greater than 6. A pre-readout thermal annealing procedure enabled the dosimeter to be read within an hour post irradiation. After receiving large accumulated doses (~10 kGy), the dosimeters retained linear response in the low dose region with only a 20 percent loss of sensitivity comparing to a fresh sample (zero Gy history). The energy-dependence encountered during low dose peripheral measurements could be accounted for via a single point outside-field calibration per each beam quality. With further development the KCl:Eu2+− based dosimeter could become a versatile and durable dosimetry tool with large dynamic range (sub-cGy to 100 Gy). PMID:23735856

  11. Dosimeter incorporating radiophotoluminescent detectors for thermal neutrons and γ-rays in n-γ fields

    NASA Astrophysics Data System (ADS)

    Salem, Y. O.; Nachab, A.; Roy, C.; Nourreddine, A.

    2016-10-01

    We have developed a dosimeter associating different neutron converters with two radiophotoluminescent detectors to measure thermal neutrons and γ-rays in a mixed n-γ field. Tests show that the H∗(10) and Hp(10) responses to thermal neutrons and γ-rays are linear with detection limits lower than 0.4 mSv. The angular dependence of the dosimeter response is satisfactory and the influence of a phantom on the results is examined.

  12. Mycosis Fungoides electron beam absorbed dose distribution using Fricke xylenol gel dosimetry

    NASA Astrophysics Data System (ADS)

    da Silveira, Michely C.; Sampaio, Francisco G. A.; Petchevist, Paulo C. D.; de Oliveira, André L.; Almeida, Adelaide de

    2011-12-01

    Radiotherapy uses ionizing radiation to destroy tumor cells. The absorbed dose control in the target volume is realized through radiation sensors, such as Fricke dosimeters and radiochromic film, which permit to realize bi-dimensional evaluations at once and because of that, they will be used in this study as well. Among the several types of cancer suitable for ionizing radiation treatment, the Mycosis Fungoides, a lymphoma that spreads on the skin surface and depth, requires for its treatment total body irradiation by high-energy electrons. In this work the Fricke xylenol gel (FXG) was used in order to obtain information about the absorbed dose distribution induced by the electron interactions with the irradiated tissues and to control this type of treatment. FXG can be considered as an alternative dosimeter, since up to now only films have been used. FXG sample cuvettes, simulating two selected tomos (cranium and abdomen) of the Rando anthropomorphic phantom, were positioned along with radiochromic films for comparison. The phantom was subjected to Stanford total body irradiation using 6 MeV electrons. Tomographic images were acquired for both dosimeters and evaluated through horizontal and vertical profiles along the tomographic centers. These profiles were obtained through a Matlab routine developed for this purpose. From the obtained results, one could infer that, for a superficial and internal patient irradiation, the FXG dosimeter showed an absorbed dose distribution similar to the one of the film. These results can validate the FXG dosimeter as an alternative dosimeter for the Mycosis Fungoides treatment planning.

  13. N-isopropylacrylamide gel dosimeter to evaluate clinical photon beam characteristics.

    PubMed

    Chiu, Chung-Yu; Tsang, Yuk-Wah; Hsieh, Bor-Tsung

    2014-08-01

    The introduction of beam intensity control concept in current radiotherapy techniques has increased treatment planning complexity. Thus, small-field dose measurement has become increasingly vital. Polymer gel dosimetry method is widely studied. It is the only dose measurement tool that provides 3D dose distribution. This study aims to use an N-isopropylacrylamide (NIPAM) gel dosimeter to conduct beam performance measurements of percentage depth dose (PDD), beam flatness, and symmetry for photon beams with field sizes of 3×3 and 4×4 cm(2). Computed tomography scans were used to readout the gel dosimeters. In the PDD measurement, the NIPAM gel dosimeter and Gafchromic™ EBT3 radiochromic film displayed high consistency in the region deeper than the build-up region. The gel dosimeter dose profile had 3% lower flatness and symmetry measurement at 5 cm depth for different fields compared with that of the Gafchromic™ EBT3 film. During gamma evaluation under 3%/3 mm dose difference/distance-to-agreement standard, the pass rates of the polymer gel dosimeter to the TPS and EBT3 film were both higher than 96%. Given that the gel is tissue equivalent, it did not exhibit the energy dependence problems of radiochromic films. Therefore, the practical use of NIPAM polymer gel dosimeters is enhanced in clinical dose verification. PMID:24836904

  14. Characterization of a water-equivalent fiber-optic coupled dosimeter for use in diagnostic radiology

    SciTech Connect

    Hyer, Daniel E.; Fisher, Ryan F.; Hintenlang, David E.

    2009-05-15

    This work reports on the characterization of a new fiber-optic coupled (FOC) dosimeter for use in the diagnostic radiology energy range. The FOC dosimeter was constructed by coupling a small cylindrical plastic scintillator, 500 {mu}m in diameter and 2 mm in length, to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube (PMT). A serial port interface on the PMT permits real-time monitoring of light output from the dosimeter via a custom computer program. The FOC dosimeter offered excellent sensitivity and reproducibility, allowing doses as low as 0.16 mGy to be measured with a coefficient of variation of only 3.64%. Dose linearity was also excellent with a correlation coefficient of 1.000 over exposures ranging from 0.16 to 57.29 mGy. The FOC dosimeter exhibited little angular dependence from axial irradiation, varying by less than 5% over an entire revolution. A positive energy dependence was observed and measurements performed within a scatter medium yielded a 10% variation in sensitivity as beam quality changed due to hardening and scatter across a 16 cm depth range. The current dosimetry system features an array of five PMTs to allow multiple FOC dosimeters to be monitored simultaneously. Overall, the system allows for rapid and accurate dose measurements relevant to a range of diagnostic imaging applications.

  15. The thermoluminescence study of epoxy based LiF:Mg,Cu,P dosimeters

    NASA Astrophysics Data System (ADS)

    Rahangdale, S. R.; Wankhede, S. P.; Kadam, Sonal; Dhabekar, Bhushan. S.; Palikundwar, U. A.; Moharil, S. V.

    2016-05-01

    The LiF:Mg,Cu,P phosphor is the most investigated phosphor in radiation dosimetry. Results on thermoluminescence of the epoxy based LiF:Mg,Cu,P dosimeters irradiated with gamma radiations are presented and compared with results of LiF:Mg,Cu,P powder. The glow curve structure of both LiF powder and dosimeter are same and only difference is found in the glow curve peak temperature. The LiF dosimeters were made from the 5012A and 5012B epoxy. The dosimeters had a mass of about 18 mg, 5.0 mm diameter and 0.5 mm thickness. The sensitivity variation of the dosimeters for exposure to 60Co gamma rays at different angles of incidence of the radiation is found to be within 4%. Its minimum detectable dose is about 3020 µGy. The epoxy based dosimeters withstand different environment and it can be used with general TL reader without need of any special design due to its small size and plane surface.

  16. First dose-map measured with a polycrystalline diamond 2D dosimeter under an intensity modulated radiotherapy beam

    NASA Astrophysics Data System (ADS)

    Scaringella, M.; Zani, M.; Baldi, A.; Bucciolini, M.; Pace, E.; de Sio, A.; Talamonti, C.; Bruzzi, M.

    2015-10-01

    A prototype of bidimensional dosimeter made on a 2.5×2.5 cm2 active area polycrystalline Chemical Vapour Deposited (pCVD) diamond film, equipped with a matrix of 12×12 contacts connected to the read-out electronics, has been used to evaluate a map of dose under Intensity Modulated Radiation Therapy (IMRT) fields for a possible application in pre-treatment verifications of cancer treatments. Tests have been performed under a 6-10 MVRX beams with IMRT fields for prostate and breast cancer. Measurements have been taken by measuring the 144 pixels in different positions, obtained by shifting the device along the x/y axes to span a total map of 14.4×10 cm2. Results show that absorbed doses measured by our pCVD diamond device are consistent with those calculated by the Treatment Planning System (TPS).

  17. Characterization of a new radiochromic three-dimensional dosimeter

    PubMed Central

    Guo, P. Y.; Adamovics, J. A.; Oldham, M.

    2006-01-01

    The development of intensity-modulated radiotherapy (IMRT) has created a clear need for a dosimeter that can accurately and conveniently measure dose distributions in three dimensions to assure treatment quality. PRESAGE™ is a new three dimensional (3D) dosimetry material consisting of an optically clear polyurethane matrix, containing a leuco dye that exhibits a radiochromic response when exposed to ionizing radiation. A number of potential advantages accrue over other gel dosimeters, including insensitivity to oxygen, radiation induced light absorption contrast rather than scattering contrast, and a solid texture amenable to machining to a variety of shapes and sizes without the requirement of an external container. In this paper, we introduce an efficient method to investigate the basic properties of a 3D dosimetry material that exhibits an optical dose response. The method is applied here to study the key aspects of the optical dose response of PRESAGE™: linearity, dose rate dependency, reproducibility, stability, spectral changes in absorption, and temperature effects. PRESAGE™ was prepared in 1×1×4.5 cm3 optical cuvettes for convenience and was irradiated by both photon and electron beams to different doses, dose rates, and energies. Longer PRESAGE™ columns (2 ×2×13 cm3) were formed without an external container, for measurements of photon and high energy electron depth-dose curves. A linear optical scanning technique was used to detect the depth distribution of radiation induced optical density (OD) change along the PRESAGE™ columns and cuvettes. Measured depth-OD curves were compared with percent depth dose (PDD). Results indicate that PRESAGE™ has a linear optical response to radiation dose (with a root mean square error of ∼1%), little dependency on dose rate (∼2%), high intrabatch reproducibility (<2%), and can be stable (∼2%) during 2 hours to 2 days post irradiation. Accurate PRESAGE™ dosimetry requires temperature control

  18. An investigation of a PRESAGE® in vivo dosimeter for brachytherapy

    NASA Astrophysics Data System (ADS)

    Vidovic, A. K.; Juang, T.; Meltsner, S.; Adamovics, J.; Chino, J.; Steffey, B.; Craciunescu, O.; Oldham, M.

    2014-07-01

    Determining accurate in vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm × 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® in vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with a commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0-15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy ṡ cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (˜1 mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in vivo dose verification

  19. Validation of an "Intelligent Mouthguard" Single Event Head Impact Dosimeter.

    PubMed

    Bartsch, Adam; Samorezov, Sergey; Benzel, Edward; Miele, Vincent; Brett, Daniel

    2014-11-01

    Dating to Colonel John Paul Stapp MD in 1975, scientists have desired to measure live human head impacts with accuracy and precision. But no instrument exists to accurately and precisely quantify single head impact events. Our goal is to develop a practical single event head impact dosimeter known as "Intelligent Mouthguard" and quantify its performance on the benchtop, in vitro and in vivo. In the Intelligent Mouthguard hardware, limited gyroscope bandwidth requires an algorithm-based correction as a function of impact duration. After we apply gyroscope correction algorithm, Intelligent Mouthguard results at time of CG linear acceleration peak correlate to the Reference Hybrid III within our tested range of pulse durations and impact acceleration profiles in American football and Boxing in vitro tests: American football, IMG=1.00REF-1.1g, R2=0.99; maximum time of peak XYZ component imprecision 3.6g and 370 rad/s2; maximum time of peak azimuth and elevation imprecision 4.8° and 2.9°; maximum average XYZ component temporal imprecision 3.3g and 390 rad/s2. Boxing, IMG=1.00REF-0.9 g, R2=0.99, R2=0.98; maximum time of peak XYZ component imprecision 3.9 g and 390 rad/s2, maximum time of peak azimuth and elevation imprecision 2.9° and 2.1°; average XYZ component temporal imprecision 4.0 g and 440 rad/s2. In vivo Intelligent Mouthguard true positive head impacts from American football players and amateur boxers have temporal characteristics (first harmonic frequency from 35 Hz to 79 Hz) within our tested benchtop (first harmonic frequency<180 Hz) and in vitro (first harmonic frequency<100 Hz) ranges. Our conclusions apply only to situations where the rigid body assumption is valid, sensor-skull coupling is maintained and the ranges of tested parameters and harmonics fall within the boundaries of harmonics validated in vitro. For these situations, Intelligent Mouthguard qualifies as a single event dosimeter in American football and Boxing.

  20. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect.

    PubMed

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-03-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter.

  1. Development of a fiber-optic dosimeter based on modified direct measurement for real-time dosimetry during radiation diagnosis

    NASA Astrophysics Data System (ADS)

    Yoo, W. J.; Shin, S. H.; Jeon, D.; Han, K.-T.; Hong, S.; Kim, S. G.; Cho, S.; Lee, B.

    2013-09-01

    For applying modified direct measurement, we developed a fiber-optic dosimeter (FOD) with two dosimeter probes to infer the entrance surface dose (ESD) at the center of an x-ray beam field without the obstruction of radiation imaging. The dosimeter probe of the FOD was fabricated by coupling a plastic scintillating fiber to a plastic optical fiber. Under varying exposure parameters, we measured the scintillating light signals using two dosimeter probes, which were placed at the center and the edge of the beam field, respectively, and compared the results with the absorbed doses obtained using a conventional semiconductor dosimeter. Various correlations between the two dosimeter probes according to the exposure parameters were obtained for measuring ESD using a new modified direct measurement approach during a medical imaging task.

  2. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect

    PubMed Central

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-01-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter. PMID:25618136

  3. Investigations of interference between electromagnetic transponders and wireless MOSFET dosimeters: A phantom study

    PubMed Central

    Su, Zhong; Zhang, Lisha; Ramakrishnan, V.; Hagan, Michael; Anscher, Mitchell

    2011-01-01

    Purpose: To evaluate both the Calypso Systems’ (Calypso Medical Technologies, Inc., Seattle, WA) localization accuracy in the presence of wireless metal–oxide–semiconductor field-effect transistor (MOSFET) dosimeters of dose verification system (DVS, Sicel Technologies, Inc., Morrisville, NC) and the dosimeters’ reading accuracy in the presence of wireless electromagnetic transponders inside a phantom.Methods: A custom-made, solid-water phantom was fabricated with space for transponders and dosimeters. Two inserts were machined with positioning grooves precisely matching the dimensions of the transponders and dosimeters and were arranged in orthogonal and parallel orientations, respectively. To test the transponder localization accuracy with∕without presence of dosimeters (hypothesis 1), multivariate analyses were performed on transponder-derived localization data with and without dosimeters at each preset distance to detect statistically significant localization differences between the control and test sets. To test dosimeter dose-reading accuracy with∕without presence of transponders (hypothesis 2), an approach of alternating the transponder presence in seven identical fraction dose (100 cGy) deliveries and measurements was implemented. Two-way analysis of variance was performed to examine statistically significant dose-reading differences between the two groups and the different fractions. A relative-dose analysis method was also used to evaluate transponder impact on dose-reading accuracy after dose-fading effect was removed by a second-order polynomial fit.Results: Multivariate analysis indicated that hypothesis 1 was false; there was a statistically significant difference between the localization data from the control and test sets. However, the upper and lower bounds of the 95% confidence intervals of the localized positional differences between the control and test sets were less than 0.1 mm, which was significantly smaller than the minimum

  4. Feasibility Study of Glass Dosimeter for In Vivo Measurement: Dosimetric Characterization and Clinical Application in Proton Beams

    SciTech Connect

    Rah, Jeong-Eun; Oh, Do Hoon; Kim, Jong Won; Kim, Dae-Hyun; Suh, Tae-Suk; Ji, Young Hoon; Shin, Dongho; Lee, Se Byeong; Kim, Dae Yong; Park, Sung Yong

    2012-10-01

    Purpose: To evaluate the suitability of the GD-301 glass dosimeter for in vivo dose verification in proton therapy. Methods and Materials: The glass dosimeter was analyzed for its dosimetrics characteristic in proton beam. Dosimeters were calibrated in a water phantom using a stairlike holder specially designed for this study. To determine the accuracy of the glass dosimeter in proton dose measurements, we compared the glass dosimeter and thermoluminescent dosimeter (TLD) dose measurements using a cylindrical phantom. We investigated the feasibility of the glass dosimeter for the measurement of dose distributions near the superficial region for proton therapy plans with a varying separation between the target volume and the surface of 6 patients. Results and Discussion: Uniformity was within 1.5%. The dose-response has good linearity. Dose-rate, fading, and energy dependence were found to be within 3%. The beam profile measured using the glass dosimeter was in good agreement with the profile obtained from the ionization chamber. Depth-dose distributions in nonmodulated and modulated proton beams obtained with the glass dosimeter were estimated to be within 3%, which was lower than those with the ionization chamber. In the phantom study, the difference of isocenter dose between the delivery dose calculated by the treatment planning system and that measured by the glass dosimeter was within 5%. With in vivo dosimetry, the calculated surface doses overestimated measurements by 4%-16% using glass dosimeter and TLD. Conclusion: It is recommended that bolus be added for these clinical cases. We also believe that the glass dosimeter has considerable potential for use with in vivo patient proton dosimetry.

  5. A small active dosimeter for applications in space

    NASA Astrophysics Data System (ADS)

    Ritter, Birgit; Maršálek, Karel; Berger, Thomas; Burmeister, Sönke; Reitz, Günther; Heber, Bernd

    2014-06-01

    The radiation field in low Earth orbits (LEO) differs significantly from the radiation environment on Earth's surface. Exposures are by far higher and pose an additional health risk for astronauts. Continuous monitoring is therefore a necessary task in the frame of radiation protection measures. A small battery-driven active dosimeter telescope based on silicon detectors meeting the requirements for LEO applications has been developed. The instrument, the Mobile Dosimetric Telescope (MDT), is designed to measure the absorbed dose rate and the linear energy transfer (LET) spectra. From the latter the mean quality factor of the radiation field can be derived and hence an estimate of the dose equivalent as a measure of the exposure. The calibration of the device is done using radioactive isotopes and heavy ions. Fragmentation products of heavy ions are used to show the ability of the MDT to reliably detect energy depositions from high energetic nuclei. Radiation measurements inside aircraft during long distance flights, serving as field tests of the instrument, prove the good performance of the instrument.

  6. Dose measurements in intraoral radiography using thermoluminescent dosimeters

    NASA Astrophysics Data System (ADS)

    Azorín, C.; Azorín, J.; Aguirre, F.; Rivera, T.

    2015-01-01

    The use of X-ray in medicine demands to expose the patient and the professional to the lowest radiation doses available in agreement with ALARA philosophy. The reference level for intraoral dental radiography is 7 mGy and, in Mexico, a number of examinations of this type are performed annually. It is considered that approximately 25% of all the X-rays examinations carried out in our country correspond to intraoral radiographies. In other hand, most of the intraoral X-ray equipment correspond to conventional radiological systems using film, which are developed as much manual as automatically. In this work the results of determining the doses received by the patients in intraoral radiological examinations made with different radiological systems using LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters are presented. In some conventional radiological systems using film, when films are developed manual or automatically, incident kerma up to 10.61 ± 0.74 mGv were determined. These values exceed that reference level suggested by the IAEA and in the Mexican standards for intraoral examinations.

  7. Automated gamma spectrometry and data analysis on radiometric neutron dosimeters

    SciTech Connect

    Matsumoto, W.Y.

    1983-01-01

    An automated gamma-ray spectrometry system was designed and implemented by the Westinghouse Hanford Company at the Hanford Engineering Development Laboratory (HEDL) to analyze radiometric neutron dosimeters. Unattended, automatic, 24 hour/day, 7 day/week operation with online data analysis and mainframe-computer compatible magnetic tape output are system features. The system was used to analyze most of the 4000-plus radiometric monitors (RM's) from extensive reactor characterization tests during startup and initial operation of th Fast Flux Test Facility (FFTF). The FFTF, operated by HEDL for the Department of Energy, incorporates a 400 MW(th) sodium-cooled fast reactor. Aumomated system hardware consists of a high purity germanium detector, a computerized multichannel analyzer data acquisition system (Nuclear Data, Inc. Model 6620) with two dual 2.5 Mbyte magnetic disk drives plus two 10.5 inch reel magnetic tape units for mass storage of programs/data and an automated Sample Changer-Positioner (ASC-P) run with a programmable controller. The ASC-P has a 200 sample capacity and 12 calibrated counting (analysis) positions ranging from 6 inches (15 cm) to more than 20 feet (6.1 m) from the detector. The system software was programmed in Fortran at HEDL, except for the Nuclear Data, Inc. Peak Search and Analysis Program and Disk Operating System (MIDAS+).

  8. Thermoluminescent dosimeters for low dose X-ray measurements.

    PubMed

    Fernández, S Del Sol; García-Salcedo, R; Sánchez-Guzmán, D; Ramírez-Rodríguez, G; Gaona, E; de León-Alfaro, M A; Rivera-Montalvo, T

    2016-01-01

    The response of TLD-100, CaSO4:Dy and LiF:Mg,Cu,P for a range of X-ray low dose was measured. For calibration, the TLDs were arranged at the center of the X-ray field. The dose output of the X-ray machine was determined using an ACCU-Gold. All dosimeters were exposed at the available air kerma values of 14.69 mGy within a field 10×10 cm(2) at 80 cm of SSD. Results of LiF:Mg,Cu,P X-ray irradiated showed 4.8 times higher sensitivity than TLD-100. Meanwhile, TL response of CaSO4:Dy exposed at the same dose was 5.6 time higher than TLD-100. Experimental results show for low dose X-ray measurements a better linearity for LiF:Mg,Cu,P compared with that of TLD-100. CaSO4:Dy showed a linearity from 0.1 to 60 mGy.

  9. Thermoluminescent dosimeters for low dose X-ray measurements.

    PubMed

    Fernández, S Del Sol; García-Salcedo, R; Sánchez-Guzmán, D; Ramírez-Rodríguez, G; Gaona, E; de León-Alfaro, M A; Rivera-Montalvo, T

    2016-01-01

    The response of TLD-100, CaSO4:Dy and LiF:Mg,Cu,P for a range of X-ray low dose was measured. For calibration, the TLDs were arranged at the center of the X-ray field. The dose output of the X-ray machine was determined using an ACCU-Gold. All dosimeters were exposed at the available air kerma values of 14.69 mGy within a field 10×10 cm(2) at 80 cm of SSD. Results of LiF:Mg,Cu,P X-ray irradiated showed 4.8 times higher sensitivity than TLD-100. Meanwhile, TL response of CaSO4:Dy exposed at the same dose was 5.6 time higher than TLD-100. Experimental results show for low dose X-ray measurements a better linearity for LiF:Mg,Cu,P compared with that of TLD-100. CaSO4:Dy showed a linearity from 0.1 to 60 mGy. PMID:26609683

  10. Polymer gel dosimeters with reduced toxicity: a preliminary investigation of the NMR and optical dose response using different monomers

    NASA Astrophysics Data System (ADS)

    Senden, R. J.; DeJean, P.; McAuley, K. B.; Schreiner, L. J.

    2006-07-01

    In this work, three new polymer gel dosimeter recipes were investigated that may be more suitable for widespread applications than polyacrylamide gel dosimeters, since the extremely toxic acrylamide has been replaced with the less harmful monomers N-isopropylacrylamide (NIPAM), diacetone acrylamide and N-vinylformamide. The new gel dosimeters studied contained gelatin (5 wt%), monomer (3 wt%), N,N'-methylene-bis-acrylamide crosslinker (3 wt%) and tetrakis (hydroxymethyl) phosphonium chloride antioxidant (10 mM). The NMR response (R2) of the dosimeters was analysed for conditions of varying dose, dose rate, time post-irradiation, and temperature during irradiation and scanning. It was shown that the dose-response behaviour of the NIPAM/Bis gel dosimeter is comparable to that of normoxic polyacrylamide gel (PAGAT) in terms of high dose-sensitivity and low dependence on dose rate and irradiation temperature, within the ranges considered. The dose-response (R2) of NIPAM/Bis appears to be linear over a greater dose range than the PAGAT gel dosimeter. The effects of time post-irradiation (temporal instability) and temperature during NMR scanning on the R2 response were more significant for NIPAM/Bis dosimeters. Diacetone acrylamide and N-vinylformamide gel dosimeters possessed considerably lower dose-sensitivities. The optical dose-response, measured in terms of the attenuation coefficient for each polymer gel dosimeter, showed potential for the use of optical imaging techniques in future studies.

  11. Polymer gel dosimeters with reduced toxicity: a preliminary investigation of the NMR and optical dose-response using different monomers.

    PubMed

    Senden, R J; De Jean, P; McAuley, K B; Schreiner, L J

    2006-07-21

    In this work, three new polymer gel dosimeter recipes were investigated that may be more suitable for widespread applications than polyacrylamide gel dosimeters, since the extremely toxic acrylamide has been replaced with the less harmful monomers N-isopropylacrylamide (NIPAM), diacetone acrylamide and N-vinylformamide. The new gel dosimeters studied contained gelatin (5 wt%), monomer (3 wt%), N,N'-methylene-bis-acrylamide crosslinker (3 wt%) and tetrakis (hydroxymethyl) phosphonium chloride antioxidant (10 mM). The NMR response (R2) of the dosimeters was analysed for conditions of varying dose, dose rate, time post-irradiation, and temperature during irradiation and scanning. It was shown that the dose-response behaviour of the NIPAM/Bis gel dosimeter is comparable to that of normoxic polyacrylamide gel (PAGAT) in terms of high dose-sensitivity and low dependence on dose rate and irradiation temperature, within the ranges considered. The dose-response (R2) of NIPAM/Bis appears to be linear over a greater dose range than the PAGAT gel dosimeter. The effects of time post-irradiation (temporal instability) and temperature during NMR scanning on the R2 response were more significant for NIPAM/Bis dosimeters. Diacetone acrylamide and N-vinylformamide gel dosimeters possessed considerably lower dose-sensitivities. The optical dose-response, measured in terms of the attenuation coefficient for each polymer gel dosimeter, showed potential for the use of optical imaging techniques in future studies. PMID:16825731

  12. SU-E-T-368: Effect of a Strong Magnetic Field On Select Radiation Dosimeters

    SciTech Connect

    Mathis, M; Wen, Z; Tailor, R; Sawakuchi, G; Flint, D; Beddar, S; Ibbott, G

    2014-06-01

    Purpose: To determine the effect of a strong magnetic field on TLD-100, OSLD (Al{sub 2}O{sub 2}:C), and PRESAGE dosimetry devices. This study will help to determine which types of dosimeters can be used for quality assurance and in-vivo dosimetry measurements in a magnetic resonance imaginglinear accelerator (MRI-linac) system. Methods: The dosimeters were separated into two categories which were either exposed or not exposed to a strong magnetic field. In each category a set of dosimeters was irradiated with 0, 2, or 6 Gy. To expose the dosimeters to a magnetic field the samples in that category were place in a Bruker small animal magnetic resonance scanner at a field strength slightly greater than 2.5 T for at least 1 hour preirradiation and at least 1 hour post-irradiation. Irradiations were performed with a 6 MV x-ray beam from a Varian TrueBeam linac with 10×10 cm{sup 2} field at a 600 MU/min dose rate. The samples that received no radiation dose were used as control detectors. Results: The readouts of the dosimeters which were not exposed to a strong magnetic field were compared with the measurements of the dosimetry devices which were exposed to a magnetic field. No significant differences (less than 2% difference) in the performance of TLD, OSLD, or PRESAGE dosimeters due to exposure to a strong magnetic field were observed. Conclusion: Exposure to a strong magnetic field before and after irradiation does not appear to change the dosimetric properties of TLD, OSLD, or PRESAGE which indicates that these dosimeters have potential for use in quality assurance and in-vivo dosimetry in a MRI-linac. We plan to further test the effect of magnetic fields on these devices by irradiating them in the presence of a magnetic fields similar to those produced by a MRI-linac system. Elekta-MD Anderson Cancer Center Research Agreement.

  13. Early development and characterization of a DNA-based radiation dosimeter

    NASA Astrophysics Data System (ADS)

    Avarmaa, Kirsten A.

    It is the priority of first responders to minimize damage to persons and infrastructure in the case of a nuclear emergency due to an accident or deliberate terrorist attack -- if this emergency includes a radioactive hazard, first responders require a simple-to-use, accurate and complete dosimeter for radiation protection purposes in order to minimize the health risk to these individuals and the general population at large. This work consists of the early evaluation of the design and performance of a biologically relevant dosimeter which uses DNA material that can respond to the radiation of any particle type. The construct consists of fluorescently tagged strands of DNA. The signalling components of this dosimeter are also investigated for their sensitivity to radiation damage and light exposure. The dual-labelled dosimeter that is evaluated in this work gave a measurable response to gamma radiation at dose levels of 10 Gy for the given detector design and experimental setup. Further testing outside of this work confirmed this finding and indicated a working range of 100 mGy to 10 Gy using a custom-built fluorimeter as part of a larger CRTI initiative. Characterization of the chromatic components of the dosimeter showed that photobleaching is not expected to have an effect on dosimeter performance, but that radiation can damage the non-DNA signalling components at higher dose levels, although this damage is minimal at lower doses over the expected operating ranges. This work therefore describes the early steps in the quantification of the behaviour of the DNA dosimeter as a potential biologically-based device to measure radiation dose.

  14. Dual calibrated dosimeter for simultaneous measurements of erythemal and vitamin D effective solar ultraviolet radiation.

    PubMed

    Wainwright, L; Parisi, A V; Downs, N

    2016-04-01

    A miniaturized ultraviolet radiation (UV) dosimeter based on polyphenylene oxide (PPO) has been dual calibrated for both erythemal and vitamin D effective exposures (UVB 280 - 320 nm) over extended periods up to five days. Optimal human health requires a balanced amount of UVB exposure as both too much and too little have different but serious potential health consequences. Dosimetry is an established method of measuring specific UV exposures to an object or subject. PPO dosimeters have previously been used to measure the erythemally effective UV exposure. An extension of this use is to dual calibrate the miniaturized dosimeter which will also enable measurement of vitamin D effective exposures. By calibration to the erythemal and vitamin D effective action spectra, PPO dosimeters were able to record both types of biologically effective exposure as both are active within the UVB waveband. Dose response tests were conducted in each season by exposure to solar UV with the corresponding dual calibrations made for each season. The calibration provided an R(2) of 0.95-0.99 for erythemal UV and an R(2) of 0.99 for vitamin D effective UV. The successful outcome of this testing has established that PPO is suitable for use as a long term, dual calibrated dosimeter provided the film is seasonally calibrated. This enables one dosimeter to provide two sets of exposure results. The combination of dual calibration and the long term exposure potential of PPO makes the PPO dosimeter more versatile and increases the scope of UV field research on erythemal UV and vitamin D effective UV in the future. PMID:26878218

  15. The characterization of a commercial MOSFET dosimeter system for use in diagnostic x ray.

    PubMed

    Bower, M W; Hintenlang, D E

    1998-08-01

    A commercial patient dose verification system utilizing non-invasive metal oxide semiconductor field effect transistor (MOSFET) dosimeters originally designed for radiotherapy applications has been evaluated for use at diagnostic energy levels. The system features multiple dosimeters that may be used to monitor entrance or exit skin dose and intracavity doses in phantoms in real time. We have characterized both the standard MOSFET dosimeter designed for radiotherapy dose verification and a newly developed "high sensitivity" MOSFET dosimeter designed for lower dose measurements. The sensitivity, linearity, angular response, post-exposure response, and physical characteristics were evaluated. The average sensitivity (free in air, including backscatter) of the radiotherapy MOSFET dosimeters ranged from 3.55 x 10(4) mV per C kg(-1) (9.2 mV R(-1)) to 4.87 x 10(4) mV per C kg(-1) (12.6 mV R(-1)) depending on the energy of the x-ray field. The sensitivity of the "high sensitivity" MOSFET dosimeters ranged from 1.15 x 10(5) mV per C kg(-1) (29.7 mV R(-1)) to 1.38 x 10(5) mV per C kg(-1) (35.7 mV R(-1)) depending on the energy of the x-ray field. The high sensitivity dosimeters demonstrated excellent linearity at high energies (90 and 120 kVp) and acceptable linearity at lower energies (60 kVp). The angular response was significant for free-in-air exposures, as illustrated by the sensitivity differences between the two sides of the dosimeter, but was excellent for measurements within a tissue equivalent cylinder. The post-exposure drift response is a complicated but reproducible function of time. Real-time monitoring requires little if any corrections for the post-exposure drift response. The MOSFET dosimeter system brings some unique capabilities to diagnostic radiology dosimetry including small size, real-time capabilities, nondestructive measurement, good linearity, and a predictable angular response. PMID:9685076

  16. Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors

    SciTech Connect

    Karsch, L.; Beyreuther, E.; Burris-Mog, T.; Kraft, S.; Richter, C.; Zeil, K.; Pawelke, J.

    2012-05-15

    Purpose: The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10{sup 11} Gy/s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. Methods: The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the number of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. Results: The dosimeters are dose rate independent up to 410{sup 9} Gy/s within 2% (OSL and TLD) and up to 1510{sup 9} Gy/s within 5% (EBT films). The diamond detectors show strong dose rate dependence. Conclusions: TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.

  17. Photofission Analysis for Fissile Dosimeters Dedicated to Reactor Pressure Vessel Surveillance

    NASA Astrophysics Data System (ADS)

    Bourganel, Stéphane; Faucher, Margaux; Thiollay, Nicolas

    2016-02-01

    Fissile dosimeters are commonly used in reactor pressure vessel surveillance programs. In this paper, the photofission contribution is analyzed for in-vessel 237Np and 238U fissile dosimeters in French PWR. The aim is to reassess this contribution using recent tools (the TRIPOLI-4 Monte Carlo code) and latest nuclear data (JEFF3.1.1 and ENDF/B-VII nuclear libraries). To be as exhaustive as possible, this study is carried out for different configurations of fissile dosimeters, irradiated inside different kinds of PWR: 900 MWe, 1300 MWe, and 1450 MWe. Calculation of photofission rate in dosimeters does not present a major problem using the TRIPOLI-4® Monte Carlo code and the coupled neutron-photon simulation mode. However, preliminary studies were necessary to identify the origin of photons responsible of photofissions in dosimeters in relation to the photofission threshold reaction (around 5 MeV). It appears that the main contribution of high enough energy photons generating photofissions is the neutron inelastic scattering in stainless steel reactor structures. By contrast, 137Cs activity calculation is not an easy task since photofission yield data are known with high uncertainty.

  18. FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties

    NASA Astrophysics Data System (ADS)

    De Deene, Y.; Skyt, P. S.; Hil, R.; Booth, J. T.

    2015-02-01

    Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software. A new three dimensional anthropomorphically shaped flexible dosimeter, further called ‘FlexyDos3D’, has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision. The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence. The first authors Y De Deene and P S Skyt made an equivalent contribution to the experimental work presented in this paper.

  19. Undoped and doped poly(tetraphenylbenzidine) as sensitive material for an impedimetric nitrogen dioxide gas dosimeter

    SciTech Connect

    Marr, I.; Moos, R.; Neumann, K.; Thelakkat, M.

    2014-09-29

    This article presents a nitrogen dioxide (NO{sub 2}) detecting gas dosimeter based on poly(tetraphenylbenzidine) poly(TPD) as nitrogen oxide (NO{sub x}) sensitive layer. Gas dosimeters are suitable devices to determine reliably low levels of analytes over a long period of time. During NO{sub x} exposure, the analyte molecules are accumulated irreversibly in the sensing layer of the dosimeter enhancing the conductivity of the hole conducting poly(TPD), which can be measured by impedance spectroscopy. Due to their possibility for low cost production by simple printing techniques and very good physical, photochemical, and electrochemical properties, poly(TPD)s are suitable for application in gas dosimeters operated at room temperature. We studied the effect of doping with a Co(III)-complex in combination with a conducting salt on the dosimeter behavior. Compared to the undoped material, a strong influence of the doping can be observed: the conductivity of the sensing material increases significantly, the noise of the signal decreases and an unwanted recovery of the sensor signal can be prevented, leading to a NO{sub x} detection limit <10 ppm.

  20. Characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam

    NASA Astrophysics Data System (ADS)

    Bong, Jihye; Shin, Dongho; Kwon, Soo-Il

    2014-01-01

    The characteristics of a normoxic polymethacrylic acid gel dosimeter for a 72-MeV proton beam were evaluated. A polymer gel dosimeter was synthesized using gelatin, methacrylic acid, hydroquinone, tetrakis(hydroxymethyl) phosphonium chloride, and highly purified distilled water. The dosimeter was manufactured by placement in a polyethylene (PE) container. Irradiated dosimeters were analyzed to determine the transverse relaxation time (T2) using a 1.5-T MRI. A calibration curve was obtained as a function of the absorbed dose. A Bragg curve made by irradiating the gel with mono-energy was compared with the results for a parallel plate ionization chamber. The spread-out Bragg peak (SOBP) range and distal dose fall-off (DDF) were comparatively analyzed by comparing the irradiated gel with a spread-out Bragg peak against with the ion chamber. Lastly, the gel's usefulness as a dosimeter for therapeutic radiation quality assurance was evaluated by obtaining its practical field size, flatness, and symmetry, through comparison of the profiles of the gel and ion chamber.

  1. Applicability of the polyphenylene oxide film dosimeter to high UV exposures in aquatic environments.

    PubMed

    Schouten, P W; Parisi, A V; Turnbull, D J

    2009-09-01

    Previous research has proven that the Poly (2,6-dimethyl-1, 4-phenylene oxide) (PPO) dosimeter is capable of receiving both in-air and underwater UV exposures that are significantly greater than those of the more commonly used polysulphone dosimeter, within a range of accuracy close to what would be expected of dosimetric measurements made in-air provided that the necessary calibrations are completed correctly by factoring in different atmospheric column ozone levels, SZA ranges, varying water turbidity and DOM levels. However, there is yet to be an investigation detailing the performance of the PPO dosimeter and its ability to measure UV in an actual field environment over an extended period of time. This research aims to bridge this gap in the knowledge by presenting a measurement campaign carried out in two real world aquatic environments and a simulated sea water environment using a batch of PPO dosimeters set at different depths and aligned to a range of different angles and geographical directions by means of attachment to a custom built dosimeter submersible float (DSF) unit over the space of a year at a sub-tropical location. Results obtained from this measurement campaign were used to compute a K(d) value for the sea water in each particular season. These K(d) values where found to be in close agreement to standalone K(d) values derived from results taken using a standard calibrated spectrometer in the same sea water. PMID:19596202

  2. Undoped and doped poly(tetraphenylbenzidine) as sensitive material for an impedimetric nitrogen dioxide gas dosimeter

    NASA Astrophysics Data System (ADS)

    Marr, I.; Neumann, K.; Thelakkat, M.; Moos, R.

    2014-09-01

    This article presents a nitrogen dioxide (NO2) detecting gas dosimeter based on poly(tetraphenylbenzidine) poly(TPD) as nitrogen oxide (NOx) sensitive layer. Gas dosimeters are suitable devices to determine reliably low levels of analytes over a long period of time. During NOx exposure, the analyte molecules are accumulated irreversibly in the sensing layer of the dosimeter enhancing the conductivity of the hole conducting poly(TPD), which can be measured by impedance spectroscopy. Due to their possibility for low cost production by simple printing techniques and very good physical, photochemical, and electrochemical properties, poly(TPD)s are suitable for application in gas dosimeters operated at room temperature. We studied the effect of doping with a Co(III)-complex in combination with a conducting salt on the dosimeter behavior. Compared to the undoped material, a strong influence of the doping can be observed: the conductivity of the sensing material increases significantly, the noise of the signal decreases and an unwanted recovery of the sensor signal can be prevented, leading to a NOx detection limit <10 ppm.

  3. SU-D-213-07: Initial Characterization of a Gel Patch Dosimeter for in Vivo Dosimetry

    SciTech Connect

    Matrosic, C; Culberson, W; Rosen, B; Madsen, E; Frank, G; Bednarz, B

    2015-06-15

    Purpose: In vivo dosimetry, despite being the most direct method for monitoring the dose delivered during radiation therapy and being recommended by several national and international organizations (AAPM, ICRU, NACP), is underutilized in the clinic due to issues associated with dose sensitivity, feasibility, and cost. Given the increasing complexity of radiation therapy modern treatments, there is a compelling need for a robust, affordable in vivo dosimetry option. In this work we present the initial characterization of a novel gel patch in vivo dosimeter. Methods: DEFGEL (6%T) was used to make 1-cm thick small cylindrical patch dosimeters. The optical density of each dosimeter was read before and after irradiation by an in-house laser densitometer. The dosimeters were irradiated using a Varian Clinac EX linac. Three separate batches of gel patches were used to create dose response curves and evaluate repeatability. The development time of the dosimeter was also evaluated. Results: The dose response of the dosimeter was found to be linear from a range of approximately 1-Gy to 20-Gy, which is a larger window of linearity compared to other in vivo dosimeters. At doses below 1-Gy, the cumulative uncertainties were on the order of the measured data. When compared, the three batches demonstrated repeatability from 1-Gy to approximately 13-Gy, with some variation at higher doses. For doses of >8-Gy, the dosimeter reached full optical density after 4-hours, whereas low doses developed within an hour. Conclusion: Initial results indicate that the gel patch dosimeter is a reliable and simple way to measure a large range of doses, including high doses such as those delivered during hypofractionated treatments (e.g. SBRT or MR-guided radiotherapy). The simple fabrication method for the dosimeter and the use of a laser densitometer would allow for the dosimeter to used and read in-house, cheaply and easily.

  4. Temperature response of a number of plastic dosimeters for radiation processing

    NASA Astrophysics Data System (ADS)

    Sohrabpour, M.; Kazemi, A. A.; Mousavi, H.; Solati, K.

    1993-10-01

    Various plastic dosemeters are employed for dosimetry control of radiation processing within gamma and electron irradiation facilities. The temperature response of a dosimeter is important when the dose to such a dosimeter is accumulated under varying irradiation temperatures. Such measurements would be significant for proper assessment of the dose for better process control, as well as, performance evaluation of dosimetry systems. In this work we have developed a high current peltier junction temperature controller system for our Gammacell-220. This system has been designed to regulate the operating temperature of the irradiation chamber in the range of 0 to 80 C this system has been applied to measure the temperature response of the red perspex, a local clear PMMA, Gammex, Gammachrome, and Gafchromic dosimeters. The curves of relative performance or variation of the induced optical densities of the above dosemeters versus the irradiation temperature at fixed dose values are obtained.

  5. The study of N-isopropylacrylamide gel dosimeter doped iodinated contrast agents

    NASA Astrophysics Data System (ADS)

    Chang, Y. J.; Hsieh, L. L.; Liu, M. H.; Liu, J. S.; Hsieh, B. T.

    2013-06-01

    Low toxicity of N-isopropylacrylamide (NIPAM) dosimeter was doped with clinical iodinated contrast medium agents(Iobitridol (Xenetix® 350) and organically bound iodine (Conray® 60) as radiation sensitizers; The suitable gel dosimeter preparation formula in this research was 5 w/w% gelatin, 5 w/w% N-isopropylacrylamide, 3 w/w% N,N-methylene-bis-acrylamide, and 5 mM Tetrakis phosphonium chloride. The spiral CT was irradiator, and 120 kVp was the operating tube voltage. The maximum radiation dose was 0.6 Gy, and optical CT was the gel measurement device used. The results showed SERs with the addition of radiosensitizers were 10.70 (Xenetix® 350) and 9.67 (Conray® 60), respectively. Thus, the polymerized gel dosimeter could be used in the efficacy evaluation of low-energy and low-radiation dose.

  6. Improving the Success Rate of Delivering Annual Occupational Dosimetry Reports to Persons Issued Temporary External Dosimeters

    SciTech Connect

    Mallett, Michael Wesley

    2014-09-09

    Workers who are not routinely monitored for occupational radiation exposure at LANL may be issued temporary dosimeters in the field. Per 10CFR835 and DOE O 231.1A, the Laboratory's radiation protection program is responsible for reporting these results to the worker at the end of the year. To do so, the identity of the worker and their mailing address must be recorded by the delegated person at the time the dosimeter is issued. Historically, this data has not been consistently captured. A new online application was developed to record the issue of temporary dosimeters. The process flow of the application was structured such that: 1) the worker must be uniquely identified in the Lab's HR database, and 2) the mailing address of record is verified live time via a commercial web service, for the transaction to be completed. A COPQ savings (Type B1) of $96K/year is demonstrated for the new application.

  7. Real-time monitoring and diagnosis of scintillation dosimeters using an ultraviolet light emitting diode

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Lambert, J.; McKenzie, D. R.; Suchowerska, N.

    2008-05-01

    Plastic scintillator fibre optic dosimeters (FODs) have advantages for both brachytherapy and external beam radiotherapy applications. Convenient real-time monitoring and diagnosis of such dosimeters are desirable because of changes in the optical circuit that may arise in use. In this paper, we propose and demonstrate a real-time method using ultraviolet light emitting diodes (LED) to stimulate the scintillator and to diagnose failures of FODs. Key aspects of the LED FOD dosimetry design are investigated, enabling the design of a stable and accurate real-time monitoring dosimetry system. We demonstrate experimentally that the real-time monitoring FOD system is convenient to be used to monitor FOD dosimeters and to diagnose their failures resulted from different mechanisms.

  8. Response of aqueous dichromate and nanoclay dichromate gel dosimeters to carbon ion irradiation

    NASA Astrophysics Data System (ADS)

    Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Fukasaku, K.; Furuta, T.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2013-06-01

    We have recently reported the significant reduction of radiation product diffusion by the incorporation of clay nanoparticles into dichromate gel (DCG) dosimeters. In this work, we investigate the influence of the nanoclay addition and gelation on the MRI R1 (1/T1) image response of the dichromate dosimeter to the therapeutic carbon ion beam (12C6+ 290 MeV/u). The MRI R1 distribution in the aqueous dichromate solution well reproduces physical dose-depth distribution with a high linear-energy-transfer (LET) efficiency. The nanoclay DCG dosimeters, on the other hand, exhibit composition-dependent LET efficiency degradation, while a sharp Bragg peak can still be detected. These results indicate that the nanocomposite gel addition may induce change in the radiation-induced reaction mechanism.

  9. Feasibility of PET/CT 3-D dosimetry for proton-activated PRESAGE® dosimeters

    NASA Astrophysics Data System (ADS)

    Carroll, M.; Ibbott, G.; Adamovics, J.

    2015-01-01

    A feasibility study is considered using PRESAGE® dosimeters as a direct dosimetry comparison tool to correlate proton activation to dose in a clinical beam. Proton activation measured by PET/CT has been studied as a future tool method for in vivo dosimetry. PRESAGE® is a 3D offline dosimeter that has a material composition giving it a longer activation decay time than similar dosimeters allowing easier measurements. In this study, the PRESAGE® positron emissions were measured by PET and directly compared to dose measurements made by optical-CT to make spatial comparisons of dose and proton activation. Profiles along the central axis of the beam found a shift in the distal-80% resulting in the proton activation profile being 1 cm shallower than the dose profile. Cross beam profiles demonstrated little discrepancy between long (3 hour) and short (30 minute) PET scan times.

  10. Thermal neutron response of the Li 2B 4O 7:Cu TL dosimeter

    NASA Astrophysics Data System (ADS)

    Gauld, I. C.; Harvey, J. W.; Kennett, T. J.; Prestwich, W. V.

    1986-10-01

    A measurement of the thermal neutron response of the Li 2B 4O 7:Cu TLD has been conducted. The results obtained using the Panasonic UD-806 dosimeter and UD-854A holder yield a free-in-air response of 3.3±0.1 R 60Co equivalent per mSv of thermal neutrons. A thermal neutron response of over 7 R 60Co equivalent per mSv was observed when the dosimeter was irradiated on water phantoms. The high sensitivity may result in a substantial overestimate of the gamma dose equivalent if the TLD is used in a mixed neutron and gamma environment of unknown ratio. Measurements of the Li 2B 4O 7:Cu glow curve, TL saturation curve and the thermal neutron response dependence of the dosimeter filtration thickness are also presented.

  11. Method for correcting for isotope burn-in effects in fission neutron dosimeters

    DOEpatents

    Gold, Raymond; McElroy, William N.

    1988-01-01

    A method is described for correcting for effect of isotope burn-in in fission neutron dosimeters. Two quantities are measured in order to quantify the "burn-in" contribution, namely P.sub.Z',A', the amount of (Z', A') isotope that is burned-in, and F.sub.Z', A', the fissions per unit volume produced in the (Z', A') isotope. To measure P.sub.Z', A', two solid state track recorder fission deposits are prepared from the very same material that comprises the fission neutron dosimeter, and the mass and mass density are measured. One of these deposits is exposed along with the fission neutron dosimeter, whereas the second deposit is subsequently used for observation of background. P.sub.Z', A' is then determined by conducting a second irradiation, wherein both the irradiated and unirradiated fission deposits are used in solid state track recorder dosimeters for observation of the absolute number of fissions per unit volume. The difference between the latter determines P.sub.Z', A' since the thermal neutron cross section is known. F.sub.Z', A' is obtained by using a fission neutron dosimeter for this specific isotope, which is exposed along with the original threshold fission neutron dosimeter to experience the same neutron flux-time history at the same location. In order to determine the fissions per unit volume produced in the isotope (Z', A') as it ingrows during the irradiation, B.sub.Z', A', from these observations, the neutron field must generally be either time independent or a separable function of time t and neutron energy E.

  12. The Neutron Energy Response of the Panasonic Model 809 Personnel Dosimeter

    SciTech Connect

    Frederick Cummings

    2010-04-01

    In 2010, the U.S. Department of Energy will adopt a new set of radiation weighting factors and quality factors to be consistent with values recommended by the International Commission on Radiological Protection. The change will affect the magnitude of occupational exposure assigned to radiation workers exposed to neutron radiation. Understanding the energy response of the dosimeter and the effect of the new quantities is critical to accurately ensuring that occupational exposure remains below the established regulatory limits. Therefore, the factors used to interpret dosimeter readings must be re-evaluated for each irradiation field over the range of neutron energies in which the dosimeter is used. This paper describes one method of determining the neutron response of the dosimeter. A Monte Carlo approach was used to model the energy response of the Panasonic Model 809 dosimeter over the range of energies from 1.0 x 10^-8 to 20 MeV. The response, normalized to the response at 2.1 MeV, ranged from approximately 0.5 at 20 MeV to approximately 26 at 1 eV. The response was then divided at each energy by the appropriate dose conversion coefficient to determine the dose response of the dosimeter. The dose responses, normalized to the response at 2.1 MeV, ranged from approximately 0.4 at 20 MeV to 765 at 1 eV. Dose conversion factors were determined for various reference neutron spectra and plotted on the dose response curve. Good agreement was observed except for the case of D2Omoderated 252Cf.

  13. The energy dependence of lithium formate and alanine EPR dosimeters for medium energy x rays

    SciTech Connect

    Waldeland, Einar; Hole, Eli Olaug; Sagstuen, Einar; Malinen, Eirik

    2010-07-15

    Purpose: To perform a systematic investigation of the energy dependence of alanine and lilthium formate EPR dosimeters for medium energy x rays. Methods: Lithium formate and alanine EPR dosimeters were exposed to eight different x-ray beam qualities, with nominal potentials ranging from 50 to 200 kV. Following ionometry based on standards of absorbed dose to water, the dosimeters were given two different doses of approximately 3 and 6 Gy for each radiation quality, with three dosimeters for each dose. A reference series was also irradiated to three different dose levels at a {sup 60}Co unit. The dose to water energy response, that is, the dosimeter reading per absorbed dose to water relative to that for {sup 60}Co {gamma}-rays, was estimated for each beam quality. In addition, the energy response was calculated by Monte Carlo simulations and compared to the experimental energy response. Results: The experimental energy response estimates ranged from 0.89 to 0.94 and from 0.68 to 0.90 for lithium formate and alanine, respectively. The uncertainties in the experimental energy response estimates were typically 3%. The relative effectiveness, that is, the ratio of the experimental energy response to that following Monte Carlo simulations was, on average, 0.96 and 0.94 for lithium formate and alanine, respectively. Conclusions: This work shows that lithium formate dosimeters are less dependent on x-ray energy than alanine. Furthermore, as the relative effectiveness for both lithium formate and alanine were systematically less than unity, the yield of radiation-induced radicals is decreased following x-irradiation compared to irradiation with {sup 60}Co {gamma}-rays.

  14. 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

  15. Initial Characterization of a Gel Patch Dosimeter for In Vivo Dosimetry

    PubMed Central

    Matrosic, C; Culberson, W; Rosen, B; Madsen, E; Frank, G; Bednarz, B

    2016-01-01

    In vivo dosimetry is a greatly underutilized tool for patient safety in clinical external beam radiotherapy treatments, despite being recommended by several national and international organizations (AAPM, ICRU, IAEA, NACP). The reasons for this underutilization mostly relate to the feasibility and cost of in vivo dosimetry methods. Due to the increase in the number of beam angles and dose per fraction in modern treatments, there is a compelling need for a novel dosimeter that is robust and affordable while able to operate properly in these complex conditions. This work presents a gel patch dosimeter as a novel method of in vivo dosimetry. DEFGEL, a 6%T normoxic polyacrylamide gel, was injected into 1-cm thick acrylic molds to create 1-cm thick small cylindrical patch dosimeters. To evaluate the change in optical density due to radiation induced polymerization, dosimeters were scanned before and after irradiation using an in-house developed laser densitometer. The dose-responses of three separate batches of gel were evaluated and compared to check for linearity and repeatability. The response development time was evaluated to ensure that the patch dosimeter could be high throughput. Additionally, the potential of this system to be used as an in vivo dosimeter was tested with a clinically relevant end-to-end in vivo phantom test. All irradiations were performed with a Varian Clinac 21EX at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The dose response of all three batches of gel was found to be linear within the range of 2–20 Gy. At doses below 0.5 Gy the statistical uncertainties were prohibitively large to make quantitative assessments of the results. The three batches demonstrated good repeatability in the range of 2 Gy to up to 10 Gy, with only slight variations in response at higher doses. For low doses the dosimeter fully developed within an hour while at higher doses they fully developed within four hours. During the in vivo

  16. Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms.

    PubMed

    Koivisto, Juha H; Wolff, Jan E; Kiljunen, Timo; Schulze, Dirk; Kortesniemi, Mika

    2015-07-08

    The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in

  17. A Bremsstrahlung spectrometer using k-edge and differential filters with image plate dosimeters

    SciTech Connect

    Chen, C. D.; Porkolab, M.; King, J. A.; Beg, F. N.; Key, M. H.; Chen, H.; Mackinnon, A. J.; MacPhee, A. G.; Patel, P. K.; Akli, K. U.; Stephens, R. B.; Freeman, R. R.; Link, A.; Van Woerkom, L. D.

    2008-10-15

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with image plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code INTEGRATED TIGER SERIES 3.0 and the dosimeters calibrated with radioactive sources. An electron distribution with a slope temperature of 1.3 MeV is inferred from the Bremsstrahlung spectra.

  18. A Bremsstrahlung Spectrometer using k-edge and Differential Filters with Image plate dosimeters

    SciTech Connect

    Chen, C; Mackinnon, A; Beg, F; Chen, H; Key, M; King, J A; Link, A; MacPhee, A; Patel, P; Porkolab, M; Stephens, R; VanWoerkom, L; Akli, K; Freeman, R

    2008-05-02

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with Image Plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code Integrated Tiger Series 3.0 and the dosimeters calibrated with radioactive sources. Electron distributions with slope temperatures in the MeV range are inferred from the Bremsstrahlung spectra.

  19. Experimental determination of the influence of oxygen on the PRESAGE® dosimeter.

    PubMed

    Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

    2016-01-21

    It is generally accepted that the PRESAGE(®) radiochromic dosimeter is not sensitive to oxygen, however, this claim has not been supported or verified experimentally. Therefore, the aim of this study was to experimentally determine the potential influence of oxygen on dose sensitivity of the PRESAGE(®) dosimeter and its reporting system. Batches of PRESAGE(®) and its radical initiator-leuco dye reporting system were prepared in aerobic and anaerobic conditions. The anaerobic batches were deoxygenated by bubbling nitrogen through the dosimeter precursors or reporting system for 10 min. The dosimeters and reporting systems were prepared in spectrophotometric cuvettes and glass vials, respectively, and were irradiated with 6 MV photons to various radiation doses. Changes in optical density of the dosimeters and reporting system before and after irradiation were measured using a spectrophotometer. The overall results show that oxygen has some influence on the dosimetric characteristics of PRESAGE(®), although the radical initiator does appear to oxidize the leucomalachite green even in the presence of oxygen. Deoxygenation of the reporting system leads to an increase in sensitivity to radiation dose by ~30% when compared to the non-deoxygenated system. A minor increase in sensitivity (~5%) was also achieved by deoxygenating the PRESAGE(®) precursor prior to casting. In addition, dissolved oxygen measurements revealed low levels of dissolved oxygen (0.40 ± 0.04 mg l(-1)) in the polyurethane precursor used to fabricate the PRESAGE(®) dosimeters, as compared to water (8.60 ± 0.03 mg l(-1)) and the reporting system alone (1.30 ± 0.10 mg l(-1)). The results suggest that the presence of oxygen does not inhibit the radiochromic properties of the PRESAGE(®) system. However, deoxygenation of the dosimeter precursors prior to casting improves the dosimeters dose sensitivity by ~5%, which might be particularly useful for measuring low radiation doses. Nevertheless, we

  20. On the response of electronic personal dosimeters in constant potential and pulsed x- ray beams

    NASA Astrophysics Data System (ADS)

    Guimarães, M. C.; Silva, C. R. E.; Oliveira, P. M. C.; da Silva, T. A.

    2016-07-01

    Electronic personal dosimeters (EPDs) based on solid state detectors have widely been used but some deficiencies in their response in pulsed radiation beams have been reported. Nowadays, there is not an international standard for pulsed x-ray beams for calibration or type testing of dosimeters. Irradiation conditions for testing the response of EPDs in both the constant potential and pulsed x-ray beams were established in CDTN. Three different types of EPDs were tested in different conditions in similar ISO and IEC x-ray qualities. Results stressed the need of performing additional checks before using EPDs in constant potential or pulsed x-rays.

  1. Initial characterization of a gel patch dosimeter for in vivo dosimetry

    NASA Astrophysics Data System (ADS)

    Matrosic, C.; Culberson, W.; Rosen, B.; Madsen, E.; Frank, G.; Bednarz, B.

    2016-05-01

    In vivo dosimetry is a greatly underutilized tool for patient safety in clinical external beam radiotherapy treatments, despite being recommended by several national and international organizations (AAPM, ICRU, IAEA, NACP). The reasons for this underutilization mostly relate to the feasibility and cost of in vivo dosimetry methods. Due to the increase in the number of beam angles and dose per fraction in modern treatments, there is a compelling need for a novel dosimeter that is robust and affordable while able to operate properly in these complex conditions. This work presents a gel patch dosimeter as a novel method of in vivo dosimetry. DEFGEL, a 6% T normoxic polyacrylamide gel, was injected into 1 cm thick acrylic molds to create 1 cm thick small cylindrical patch dosimeters. To evaluate the change in optical density due to radiation induced polymerization, dosimeters were scanned before and after irradiation using an in-house developed laser densitometer. The dose–responses of three separate batches of gel were evaluated and compared to check for linearity and repeatability. The response development time was evaluated to ensure that the patch dosimeter could be high throughput. Additionally, the potential of this system to be used as an in vivo dosimeter was tested with a clinically relevant end-to-end in vivo phantom test. All irradiations were performed with a Varian Clinac 21EX at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The dose–response of all three batches of gel was found to be linear within the range of 2–20 Gy. At doses below 0.5 Gy the statistical uncertainties were prohibitively large to make quantitative assessments of the results. The three batches demonstrated good repeatability in the range of 2 Gy to up to 10 Gy, with only slight variations in response at higher doses. For low doses the dosimeter fully developed within an hour while at higher doses they fully developed within four hours. During the in

  2. Neutron dosimetry at commercial nuclear plants. Final report of Subtask B: dosimeter response

    SciTech Connect

    Cummings, F.M.; Endres, G.W.R.; Brackenbush, L.W.

    1983-03-01

    As part of a larger program to evaluate personnel neutron dosimetry at commercial nuclear power plants, this study was designed to characterize neutron dosimeter responses inside the containment structure of commercial nuclear plants. In order to characterize those responses, dosimeters were irradiated inside containment at 2 pressurized water reactors and at pipe penetrations outside the biological shield at two boiling water reactors. The reactors were operating at full power during the irradiations. Measurements were also performed with electronic instruments, the tissue equivalent proportional counter (TEPC), and portable remmeters, SNOOPY, RASCAL and PNR-4.

  3. Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms.

    PubMed

    Koivisto, Juha H; Wolff, Jan E; Kiljunen, Timo; Schulze, Dirk; Kortesniemi, Mika

    2015-01-01

    The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in

  4. Novel Multicompartment 3-Dimensional Radiochromic Radiation Dosimeters for Nanoparticle-Enhanced Radiation Therapy Dosimetry

    SciTech Connect

    Alqathami, Mamdooh; Blencowe, Anton; Yeo, Un Jin; Doran, Simon J.; Qiao, Greg; Geso, Moshi

    2012-11-15

    Purpose: Gold nanoparticles (AuNps), because of their high atomic number (Z), have been demonstrated to absorb low-energy X-rays preferentially, compared with tissue, and may be used to achieve localized radiation dose enhancement in tumors. The purpose of this study is to introduce the first example of a novel multicompartment radiochromic radiation dosimeter and to demonstrate its applicability for 3-dimensional (3D) dosimetry of nanoparticle-enhanced radiation therapy. Methods and Materials: A novel multicompartment phantom radiochromic dosimeter was developed. It was designed and formulated to mimic a tumor loaded with AuNps (50 nm in diameter) at a concentration of 0.5 mM, surrounded by normal tissues. The novel dosimeter is referred to as the Sensitivity Modulated Advanced Radiation Therapy (SMART) dosimeter. The dosimeters were irradiated with 100-kV and 6-MV X-ray energies. Dose enhancement produced from the interaction of X-rays with AuNps was calculated using spectrophotometric and cone-beam optical computed tomography scanning by quantitatively comparing the change in optical density and 3D datasets of the dosimetric measurements between the tissue-equivalent (TE) and TE/AuNps compartments. The interbatch and intrabatch variability and the postresponse stability of the dosimeters with AuNps were also assessed. Results: Radiation dose enhancement factors of 1.77 and 1.11 were obtained using 100-kV and 6-MV X-ray energies, respectively. The results of this study are in good agreement with previous observations; however, for the first time we provide direct experimental confirmation and 3D visualization of the radiosensitization effect of AuNps. The dosimeters with AuNps showed small (<3.5%) interbatch variability and negligible (<0.5%) intrabatch variability. Conclusions: The SMART dosimeter yields experimental insights concerning the spatial distributions and elevated dose in nanoparticle-enhanced radiation therapy, which cannot be performed using any of

  5. Initial characterization of a gel patch dosimeter for in vivo dosimetry

    NASA Astrophysics Data System (ADS)

    Matrosic, C.; Culberson, W.; Rosen, B.; Madsen, E.; Frank, G.; Bednarz, B.

    2016-05-01

    In vivo dosimetry is a greatly underutilized tool for patient safety in clinical external beam radiotherapy treatments, despite being recommended by several national and international organizations (AAPM, ICRU, IAEA, NACP). The reasons for this underutilization mostly relate to the feasibility and cost of in vivo dosimetry methods. Due to the increase in the number of beam angles and dose per fraction in modern treatments, there is a compelling need for a novel dosimeter that is robust and affordable while able to operate properly in these complex conditions. This work presents a gel patch dosimeter as a novel method of in vivo dosimetry. DEFGEL, a 6% T normoxic polyacrylamide gel, was injected into 1 cm thick acrylic molds to create 1 cm thick small cylindrical patch dosimeters. To evaluate the change in optical density due to radiation induced polymerization, dosimeters were scanned before and after irradiation using an in-house developed laser densitometer. The dose-responses of three separate batches of gel were evaluated and compared to check for linearity and repeatability. The response development time was evaluated to ensure that the patch dosimeter could be high throughput. Additionally, the potential of this system to be used as an in vivo dosimeter was tested with a clinically relevant end-to-end in vivo phantom test. All irradiations were performed with a Varian Clinac 21EX at the University of Wisconsin Medical Radiation Research Center (UWMRRC). The dose-response of all three batches of gel was found to be linear within the range of 2-20 Gy. At doses below 0.5 Gy the statistical uncertainties were prohibitively large to make quantitative assessments of the results. The three batches demonstrated good repeatability in the range of 2 Gy to up to 10 Gy, with only slight variations in response at higher doses. For low doses the dosimeter fully developed within an hour while at higher doses they fully developed within four hours. During the in vivo

  6. Experimental determination of the influence of oxygen on the PRESAGE® dosimeter

    NASA Astrophysics Data System (ADS)

    Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

    2016-01-01

    It is generally accepted that the PRESAGE® radiochromic dosimeter is not sensitive to oxygen, however, this claim has not been supported or verified experimentally. Therefore, the aim of this study was to experimentally determine the potential influence of oxygen on dose sensitivity of the PRESAGE® dosimeter and its reporting system. Batches of PRESAGE® and its radical initiator-leuco dye reporting system were prepared in aerobic and anaerobic conditions. The anaerobic batches were deoxygenated by bubbling nitrogen through the dosimeter precursors or reporting system for 10 min. The dosimeters and reporting systems were prepared in spectrophotometric cuvettes and glass vials, respectively, and were irradiated with 6 MV photons to various radiation doses. Changes in optical density of the dosimeters and reporting system before and after irradiation were measured using a spectrophotometer. The overall results show that oxygen has some influence on the dosimetric characteristics of PRESAGE®, although the radical initiator does appear to oxidize the leucomalachite green even in the presence of oxygen. Deoxygenation of the reporting system leads to an increase in sensitivity to radiation dose by ~30% when compared to the non-deoxygenated system. A minor increase in sensitivity (~5%) was also achieved by deoxygenating the PRESAGE® precursor prior to casting. In addition, dissolved oxygen measurements revealed low levels of dissolved oxygen (0.40  ±  0.04 mg l-1) in the polyurethane precursor used to fabricate the PRESAGE® dosimeters, as compared to water (8.60  ±  0.03 mg l-1) and the reporting system alone (1.30  ±  0.10 mg l-1). The results suggest that the presence of oxygen does not inhibit the radiochromic properties of the PRESAGE® system. However, deoxygenation of the dosimeter precursors prior to casting improves the dosimeters dose sensitivity by ~5%, which might be particularly useful for measuring low radiation doses

  7. Characteristics of optically stimulated luminescence dosimeters in the spread-out Bragg peak region of clinical proton beams

    SciTech Connect

    Kerns, James R.; Kry, Stephen F.; Sahoo, Narayan

    2012-04-15

    Purpose: Optically stimulated luminescent detectors (OSLDs) have a number of advantages in radiation dosimetry making them excellent dosimeters for quality assurance and patient dose verification. Although the dosimeters have been investigated in several modalities, relatively little work has been done in examining the dosimeters for use in clinical proton beams. This study examined a number of characteristics of the response of the dosimeters in the spread-out Bragg peak (SOBP) region of clinical proton beams. Methods: Optically stimulated luminescence (OSL) dosimeters from Landauer, Inc., specifically the nanoDot dosimeter, were investigated. These dosimeters were placed in a special phantom with a recess to fit the dosimeters without an air gap. Beams with nominal energies of 160, 200, and 250 MeV were used in the passively-scattered proton beam at the MD Anderson Cancer Center Proton Therapy Center. Dosimetric properties including linearity, field size dependence, energy dependence, residual signal as a function of cumulative dose, and postirradiation fading were investigated by taking measurements at the center of SOBPs. Results: The dosimeters showed 1% supralinearity at 200 cGy and 5% supralinearity at 1000 cGy. No noticeable field size dependence of the detector was found for field sizes from 2 x 2 cm{sup 2} to 18 x 18 cm{sup 2}. Residual signal as a function of cumulative dose showed a small increase for measurements up to 1000 cGy. Readout signal depletion of the dosimeters after consecutive readings showed a slightly larger depletion in protons for doses up to 500 cGy but not by a clinically significant amount. Within the center of various SOBP widths and proton energies the variation in response was less than 2%. An average beam quality factor of 1.089 with experimental standard deviation of 0.007 was determined and applied to the data such that the results were within 1.2% of ion chamber data. Conclusions: The nanoDot OSL dosimeter characteristics were

  8. Evaluation of the neutron dosimeter used by Martin Marietta Energy Systems, Inc., ability to meet the requirements of the American National Standard for Personnel Neutron Dosimeters (neutron energies less than 20 MeV) ANSI N319-1976

    SciTech Connect

    Gunter, R.J.

    1994-07-01

    An evaluation of the neutron dosimeter used by the Centralized External Dosimetry System of Martin Marietta Energy Systems, Inc., was performed, and the dosimeter was shown to meet the requirements of the American National Standard for Personnel Neutron Dosimeters, ANSI N319-1976. This report details the requirements of the Standard, describes the tests performed, and evaluates the results of testing. To demonstrate compliance with the Standard, dosimeters were irradiated with a {sup 252}Cf source while mounted on a standard phantom. Dose was measured using the routine methodology employed by the Centralized External Dosimetry System for neutron dosimetry. The ability to accurately measure neutron dose was compared to specific performance criteria from the Standard. This includes testing the lower limit of detection, upper limit of detection, precision of results, and the capability to detect neutrons in a high gamma dose environment. In addition to neutron exposure, the dosimeters were required to be exposed to environmental factors including temperature extremes, high humidity, exposure to room light, and a drop to a hard surface. Only after exposure to these conditions were the dosimeters read, with results compared to the requirements of the Standard. Normal use factors of routine neutron dosimetry influencing the accuracy, sensitivity, or precision of the dosimetry system were also evaluated to measure their impact on dosimeter response.

  9. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    NASA Astrophysics Data System (ADS)

    Pilařová (Vávrů), Kateřina; Kozubíková, Petra; Šolc, Jaroslav; Spěváček, Václav

    2014-11-01

    The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

  10. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 1999

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2000-09-19

    In January 1993, PNNL established an area monitoring dosimeter program in accordance with Article 514 of the DOE Radiological Control Manual. This program was to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the DOE Standard Radiological Control, personnel dosimetry shall be provided to 1) radiological workers who are likely to receive at least 100 mrem annually and 2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-1998 confirmed that personnel dosimetry was not needed for individuals located in areas monitored by the program. A total of 123 area thermoluminescent dosimeters (TLDs) were placed in PNNL facilities during calendar year 1999. The TLDs were exchanged and analyzed quarterly. All routine area monitoring TLD results were less than 50 mrem annually after correcting for worker occupancy. The results support the conclusion that personnel dosimeters are not necessary for staff, declared pregnant workers, minors, or members of the public in these monitored areas.

  11. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 1998

    SciTech Connect

    SR Bivins; GA Stoetzel

    1999-06-17

    In January 1993, Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM). The purpose of the program was to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the RCM, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-1997 confirmed that personnel dosimetry was not needed for individuals located in areas monitored by the program. A total of 97 area thermoluminescent dosimeters (TLDs) were placed in PNNL facilities during calendar year 1998. The TLDs were exchanged and analyzed quarterly. All routine area monitoring TLD results were less than 50 mrem annually after correcting for worker occupancy. The results support the conclusion that personnel dosimeters are not necessary for staff, declared pregnant workers, minors, or members of the public in these monitored areas.

  12. Dose algorithm for EXTRAD 4100S extremity dosimeter for use at Sandia National Laboratories.

    SciTech Connect

    Potter, Charles Augustus

    2011-05-01

    An updated algorithm for the EXTRAD 4100S extremity dosimeter has been derived. This algorithm optimizes the binning of dosimeter element ratios and uses a quadratic function to determine the response factors for low response ratios. This results in lower systematic bias across all test categories and eliminates the need for the 'red strap' algorithm that was used for high energy beta/gamma emitting radionuclides. The Radiation Protection Dosimetry Program (RPDP) at Sandia National Laboratories uses the Thermo Fisher EXTRAD 4100S extremity dosimeter, shown in Fig 1.1 to determine shallow dose to the extremities of potentially exposed individuals. This dosimeter consists of two LiF TLD elements or 'chipstrates', one of TLD-700 ({sup 7}Li) and one of TLD-100 (natural Li) separated by a tin filter. Following readout and background subtraction, the ratio of the responses of the two elements is determined defining the penetrability of the incident radiation. While this penetrability approximates the incident energy of the radiation, X-rays and beta particles exist in energy distributions that make determination of dose conversion factors less straightforward in their determination.

  13. Thermal neutron fluence measurement in a research reactor using thermoluminescence dosimeter TLD-600.

    PubMed

    Torkzadeh, F; Manouchehri, F

    2006-03-01

    A thermal neutron fluence in the range between 10(11) and 10(13) n cm(-2) in the reactor core of the Tehran research reactor has been measured using TLD-600 thermoluminescence dosimeters. After a thermal treatment of 1 h at 400 degrees C followed by 20 h cooling down to room temperature of pre-exposed dosimeters in the reactor, the accumulated TL light was measured after periods of storage of 24, 48 and 72 h. The influence of the irradiation-induced damage effect on the response of TLDs and their subsequent readings has been minimized in this manner. The induced TL light due to self-activity in the TLD-600 dosimeters, which is dependent on the neutron fluence, caused a conveniently measurable TL glow curve. The induced TL in the dosimeter due to the Q-value for the beta-decay of tritium Ebeta-max = 18.6 keV has been reproduced separately by a beta source to check the proportions of radionuclides in the chip. A short theoretical treatment is also presented.

  14. Area monitoring dosimeter program for the Pacific Northwest National Laboratory: Results for CY 1997

    SciTech Connect

    Bivins, S.R.; Stoetzel, G.A.

    1998-07-01

    In January 1993, Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the US Department of Energy (DOE) Radiological Control Manual (RCM). The purpose of the program was to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a) (1)--(3) and Article 511.1 of the RCM, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually, and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years (CY) 1993--1996 confirmed that personnel dosimetry was not needed for individuals located in areas monitored by the program. A total of 93 area thermoluminescent dosimeters (TLDs) were placed in PNNL facilities during CY 1997. The TLDs were exchanged and analyzed quarterly. All routine area monitoring TLD results were less than 50 mrem annually after correcting for worker occupancy. The results support the conclusions that personnel dosimeters are not necessary for staff, declared pregnant workers, minors, or members of the public in these monitored areas.

  15. Feasibility of reading LiF thermoluminescent dosimeters by electron spin resonance.

    PubMed

    Breen, S L; Battista, J J

    1999-08-01

    Lithium fluoride is a commonly used solid state dosimeter. During irradiation, electrons and holes become trapped in crystal imperfections; thermoluminescence dosimetry measures their thermally induced recombination. Electron paramagnetic resonance (EPR) spectroscopy can be used to measure the resonant absorption of microwaves by the unpaired electrons trapped in LiF. In an effort to extend the use of LiF dosimeters to smaller sizes and to the harsh environments encountered in internal dosimetry, EPR was evaluated as an alternative technique to read the radiation dose delivered to TLD-100 dosimeters. TLD-100 rods were irradiated with a 60Co source to doses of 10 Gy to 100 Gy. A radiation-induced signal (with a g-value of 2.002) could be detected only at liquid nitrogen temperatures at doses above 20 Gy. The EPR spectrum of irradiated LiF contains three components, one of which correlates positively with dose. However, the low sensitivity of the technique, and difficulty in interpreting the EPR spectrum from polycrystalline dosimeters, preclude its use as a dosimetry technique.

  16. Neutron Unfolding Code System for Calculating Neutron Flux Spectra from Activation Data of Dosimeter Foils.

    1982-04-30

    Version 00 As a part of the measurement and analysis plan for the Dosimetry Experiment at the "JOYO" experimental fast reactor, neutron flux spectral analysis is performed using the NEUPAC (Neutron Unfolding Code Package) code system. NEUPAC calculates the neutron flux spectra and other integral quantities from the activation data of the dosimeter foils.

  17. Considerations in the application of the electronic dosimeter to dose of record

    SciTech Connect

    Swinth, K.L.

    1997-12-01

    This report describes considerations for application of the electronic dosimeter (ED) as a measurement device for the dose of record (primary dosimetry). EDs are widely used for secondary dosimetry and advances in their reliability and capabilities have resulted in interest in their use to meet the needs of both primary and secondary dosimetry. However, the ED is an active device and more complex than the thermoluminescent and film dosimeters now in use for primary dosimetry. The user must evaluate the ED in terms of reliability, serviceability and radiations detected its intended application(s). If an ED is selected for primary dosimetry, the user must establish methods both for controlling the performance of the ED to ensure long term reliability of the measurements and for their proper use as a primary dosimeter. Regulatory groups may also want to develop methods to ensure adequate performance of the ED for dose of record. The purpose of the report is to provide an overview of considerations in the use of the ED for primary dosimetry. Considerations include recognizing current limitations, type testing of EDs, testing by the user, approval performance testing, calibration, and procedures to integrate the dosimeter into the users program.

  18. A Prototype RF Dosimeter for Independent Measurement of the Average Specific Absorption Rate (SAR) During MRI

    PubMed Central

    Stralka, John P; Bottomley, Paul A

    2008-01-01

    Purpose To develop a scanner-independent dosimeter for measuring the average radio frequency (RF) power deposition and specific absorption rates (SAR) for human MRI exposure. Materials and Methods A prototype dosimeter has a transducer with orthogonal conducting loops surrounding a small signal-generating MRI sample. The loops contain resistors whose values are adjusted to load the scanner’s MRI coils equivalent to an average head or body during MRI. The scanner adjusts its power output to normal levels during setup, using the MRI sample. Following calibration, the total power and average SAR deposited in the transducer are measured from the root-mean-square (rms) power induced in the transducer during MRI. Results A 1.5 Tesla head transducer was adjusted to elicit the same load as the average of nine adult volunteers. Once adjusted, the transducer loads other head coils the same as the head does. The dosimeter is calibrated at up to 20 W total deposited power and 4.5 W/kg SAR in the average head, with about 5% accuracy. Conclusion This dosimeter provides a simple portable means of measuring the power deposited in a body-equivalent sample load, independent of the scanner. Further work will develop SAR dosimetry for the torso and for higher fields. PMID:17969145

  19. A Novel Twin-TLD Radiation Dosimeter for Astronauts during LEO Missions

    NASA Astrophysics Data System (ADS)

    Mukherjee, Bhaskar; Lambert, Jamil; Fuentes, Carolina; Sunil, C.; Tripathy, Sam; Sarkar, Pradip Kumar

    2012-07-01

    During low earth orbiting (LEO) missions space vehicles are continuously bombarded with energetic protons from the sun and in the events of solar flare (SFE), the proton flux sporadically increases by many orders of magnitudes. The solar protons interact with the containment wall of the vehicle producing high-energy neutrons with a broad energy distribution as well as gamma rays, which result in a high radiation exposure to astronauts. By implementing pairs of TLD-700 (7LiF:Ti, Mg) and TLD-500 (alpha: Al2O3-C) chips we have developed a personal dosimeter for an accurate assessment of biological dose of high-energy mixed radiation field. Dosimeters were irradiated with high-energy neutrons produced by bombarding a 25*25*35 cm3 polystyrene plate phantom with high-energy therapeutic protons at Westdeutsches Protonentherapiezentrum Essen (WPE). The radiation field was simulated using the FLUKA code and the dosimeters were calibrated in-situ with a tissue equivalent proportional counter (TEPC). The operation principle of the novel twin-TLD personal dosimeter for astronauts will be highlighted in our presentation.

  20. Clinical application of radiophotoluminescent glass dosimeter for dose verification of prostate HDR procedure

    SciTech Connect

    Hsu, Shih-Ming; Yeh, Chien-Yi; Yeh, Tien-Chi; Hong, Ji-Hong; Tipton, Annie Y. H.; Chen, Wei-Li; Sun, Shung-Shung; Huang, David Y. C.

    2008-12-15

    High dose rate brachytherapy (HDR-BT) is one of the many modalities for prostate cancer treatment. Due to the nature of HDR-BT, in vivo dosimetry is feasible and can be used to verify consistent dose delivery. In order to validate a dose verification system for HDR-BT prostate cancer treatment, a radiophotoluminescent glass dosimeter (RPLGD) was used and the measurements were compared with those from a thermoluminescent dosimeter. The RPLGD shows many advantages in HDR-BT dose measurement, such as repeatability, stability, and small effective size. These advantages make the RPLGD a superior option for use as a dosimeter in HDR-BT. The results described here show that the difference between the measured dose and the treatment planned dose is less than 5%. A Monte Carlo simulation for the dose was performed using Monte Carlo N -particle to investigate position error. This study concludes that the RPLGD is a promising and reliable dosimeter for HDR-BT in vivo dosimetry with clinically acceptable accuracy.

  1. Validation of dose measurements by scintillating fiber optic dosimeters for medical applications

    NASA Astrophysics Data System (ADS)

    Correia, A.; Pirraco, R.; Rosa, C. C.

    2013-11-01

    Organic scintillators have been promoted and widely used in scintillating fiber-optic dosimeters (SFOD) due to their tissue-equivalent characteristics, small sensitive volume combined with high spatial resolution, and emission of visible light proportional to the absorbed electron and gamma dose rate. In this paper we will present the validation of Monte Carlo simulations of dose measurements assisted by scintillating fiber optic dosimeters operating in the visible spectral range, in the context of the development of fiber optic dosimeters targeted to Brachytherapy. The Monte Carlo simulation results are compared to measurements performed with SFOD test probes, assembled with BCF-60 (Saint Gobain) samples of 1 mm diameter and 0.35 to 1.5 cm length, coupled to PMMA optical fiber. The optical signal resulting from scintillation and Cherenkov light is transmitted through an additional optical fiber link to a remote measuring device. For SFOD probes irradiation a dedicated PMMA phantom was used. The results were validated against measurements obtained with a properly calibrated pinpoint ionization chamber (PTW). The probes were positioned in a radial arrangement, with a radioactive source at its center point. The γ-rays source is a Nucletron Microselectron-V2 192Ir. The dose curves are obtained according to the different positions in the phantom with the SFOD dosimeters. The system is able to use a Fiber Optic Multiplexer (FOM) controlled with Labview software.

  2. Method and apparatus for passive optical dosimeter comprising caged dye molecules

    DOEpatents

    Sandison, David R.

    2001-07-03

    A new class of ultraviolet dosimeters is made possible by exposing caged dye molecules, which generate a dye molecule on exposure to ultraviolet radiation, to an exterior environment. Applications include sunburn monitors, characterizing the UV exposure history of UV-sensitive materials, especially including structural plastics, and use in disposable `one-use` optical equipment, especially medical devices.

  3. Feasibility of CBCT dosimetry for IMRT using a normoxic polymethacrylic-acid gel dosimeter

    NASA Astrophysics Data System (ADS)

    Bong, Ji Hye; Kwon, Soo-Il; Kim, Kum Bae; Kim, Mi Suk; Jung, Hai Jo; Ji, Young Hoon; Ko, In Ok; Park, Ji Ae; Kim, Kyeong Min

    2013-09-01

    The purpose of this study is to evaluate the availability of cone-beam computed tomography(CBCT) for gel dosimetry. The absorbed dose was analyzed by using intensity-modulated radiation therapy(IMRT) to irradiate several tumor shapes with a calculated dose and several tumor acquiring images with CBCT in order to verify the possibility of reading a dose on the polymer gel dosimeter by means of the CBCT image. The results were compared with those obtained using magnetic resonance imaging(MRI) and CT. The linear correlation coefficients at doses less than 10 Gy for the polymer gel dosimeter were 0.967, 0.933 and 0.985 for MRI, CT and CBCT, respectively. The dose profile was symmetric on the basis of the vertical axis in a circular shape, and the uniformity was 2.50% for the MRI and 8.73% for both the CT and the CBCT. In addition, the gradient in the MR image of the gel dosimeter irradiated in an H shape was 109.88 while the gradients of the CT and the CBCT were 71.95 and 14.62, respectively. Based on better image quality, the present study showed that CBCT dosimetry for IMRT could be restrictively performed using a normoxic polymethacrylic-acid gel dosimeter.

  4. Implementation of the Panasonic TLD (Thermoluminescent Dosimeter) system for personnel monitoring at the Nevada Test Site

    SciTech Connect

    DeMarre, M.; Teasdale, C.L.; Sygitowicz, L.S.

    1988-01-01

    In January 1987, the dosimetry system at the Nevada Test Site changed from a film badge dosimetry program to the Panasonic Thermoluminescent Dosimeter (TLD) system to monitor external radiation exposure to personnel working at the Nevada Test Site. In order to implement the Panasonic TLD system, a combination dosimeter and security credential badge holder had to be developed, a computer processing system developed, a dose processing algorithm developed and enough Panasonic UD802AS2 TLDs purchased to support a large quarterly exchange. Problems that had to be resolved during the first year of operation were: processing approximately 15,000 dosimeters per quarter; multiple exchange of the same dosimeter in the same quarter due to incoming visitors and vendors; late returns due to the unique user community at the Nevada Test Site; TLD damage experience and unusual TLD anomalies. The experience from the original planning stages for conversion to the TLD system to the reality of the implementation of this system will be discussed.

  5. Measuring Day-Night Noise Levels (DNL) using the metrosonics db-310 sound level analyzer (Dosimeter)

    NASA Astrophysics Data System (ADS)

    Ali, Ali Y.

    1989-09-01

    The Metrosonics db-310 Dosimeter does not provide automatic calculation of DNLs for environmental noise surveys. Previous environmental noise surveys using the db-310 Dosimeter required DNL values to be calculated manually from the paper printout of sound levels. Manual calculations proved to be both laborious and monotonous; worse, one missed key stroke would require a restart of this whole calculation. In addition, the quality of the printouts are very poor if reproduction is required. The manual method of DNL calculating made long term environmental noise monitoring tedious and labor intensive with many opportunities for error. This report presents a program listing, setup requirements, procedures and operating instructions for DNL calculations using the Metrosonics db-310 Noise Dosimeter, a Z-248 or Z-184 Microcomputer, ENABLE software, and a BASIC program. Procedures and operating instructions describe: (1) programming the Metrosonics db-310 Dosimeter parameters for environmental noise measurements, (2) down loading its data to a Zenith Z-248 or Z-184 Computer using ENABLE, and (3) running a BASIC program which calculates the DNL and provides a hard copy of the results.

  6. Effects of refractive index mismatch in optical CT imaging of polymer gel dosimeters

    SciTech Connect

    Manjappa, Rakesh; Makki S, Sharath; Kanhirodan, Rajan; Kumar, Rajesh

    2015-02-15

    Purpose: Proposing an image reconstruction technique, algebraic reconstruction technique-refraction correction (ART-rc). The proposed method takes care of refractive index mismatches present in gel dosimeter scanner at the boundary, and also corrects for the interior ray refraction. Polymer gel dosimeters with high dose regions have higher refractive index and optical density compared to the background medium, these changes in refractive index at high dose results in interior ray bending. Methods: The inclusion of the effects of refraction is an important step in reconstruction of optical density in gel dosimeters. The proposed ray tracing algorithm models the interior multiple refraction at the inhomogeneities. Jacob’s ray tracing algorithm has been modified to calculate the pathlengths of the ray that traverses through the higher dose regions. The algorithm computes the length of the ray in each pixel along its path and is used as the weight matrix. Algebraic reconstruction technique and pixel based reconstruction algorithms are used for solving the reconstruction problem. The proposed method is tested with numerical phantoms for various noise levels. The experimental dosimetric results are also presented. Results: The results show that the proposed scheme ART-rc is able to reconstruct optical density inside the dosimeter better than the results obtained using filtered backprojection and conventional algebraic reconstruction approaches. The quantitative improvement using ART-rc is evaluated using gamma-index. The refraction errors due to regions of different refractive indices are discussed. The effects of modeling of interior refraction in the dose region are presented. Conclusions: The errors propagated due to multiple refraction effects have been modeled and the improvements in reconstruction using proposed model is presented. The refractive index of the dosimeter has a mismatch with the surrounding medium (for dry air or water scanning). The algorithm

  7. Remote auditing of radiotherapy facilities using optically stimulated luminescence dosimeters

    SciTech Connect

    Lye, Jessica Dunn, Leon; Kenny, John; Alves, Andrew; Lehmann, Joerg; Williams, Ivan; Kron, Tomas; Oliver, Chris; Butler, Duncan; Johnston, Peter; Franich, Rick

    2014-03-15

    Purpose: On 1 July 2012, the Australian Clinical Dosimetry Service (ACDS) released its Optically Stimulated Luminescent Dosimeter (OSLD) Level I audit, replacing the previous TLD based audit. The aim of this work is to present the results from this new service and the complete uncertainty analysis on which the audit tolerances are based. Methods: The audit release was preceded by a rigorous evaluation of the InLight® nanoDot OSLD system from Landauer (Landauer, Inc., Glenwood, IL). Energy dependence, signal fading from multiple irradiations, batch variation, reader variation, and dose response factors were identified and quantified for each individual OSLD. The detectors are mailed to the facility in small PMMA blocks, based on the design of the existing Radiological Physics Centre audit. Modeling and measurement were used to determine a factor that could convert the dose measured in the PMMA block, to dose in water for the facility's reference conditions. This factor is dependent on the beam spectrum. The TPR{sub 20,10} was used as the beam quality index to determine the specific block factor for a beam being audited. The audit tolerance was defined using a rigorous uncertainty calculation. The audit outcome is then determined using a scientifically based two tiered action level approach. Audit outcomes within two standard deviations were defined as Pass (Optimal Level), within three standard deviations as Pass (Action Level), and outside of three standard deviations the outcome is Fail (Out of Tolerance). Results: To-date the ACDS has audited 108 photon beams with TLD and 162 photon beams with OSLD. The TLD audit results had an average deviation from ACDS of 0.0% and a standard deviation of 1.8%. The OSLD audit results had an average deviation of −0.2% and a standard deviation of 1.4%. The relative combined standard uncertainty was calculated to be 1.3% (1σ). Pass (Optimal Level) was reduced to ≤2.6% (2σ), and Fail (Out of Tolerance) was reduced to >3

  8. Solid-state dosimeters: A new approach for mammography measurements

    SciTech Connect

    Brateman, Libby F.; Heintz, Philip H.

    2015-02-15

    Purpose: To compare responses of modern commercially available solid-state dosimeters (SStDs) used in mammography medical physics surveys for two major vendors of current digital mammography units. To compare differences in dose estimates among SStD responses with ionization chamber (IC) measurements for several target/filter (TF) combinations and report their characteristics. To review scientific bases for measurements of quantities required for mammography for traditional measurement procedures and SStDs. Methods: SStDs designed for use with modern digital mammography units were acquired for evaluation from four manufacturers. Each instrument was evaluated under similar conditions with the available mammography beams provided by two modern full-field digital mammography units in clinical use: a GE Healthcare Senographe Essential (Essential) and a Hologic Selenia Dimensions 5000 (Dimensions), with TFs of Mo/Mo, Mo/Rh; and Rh/Rh and W/Rh, W/Ag, and W/Al, respectively. Measurements were compared among the instruments for the TFs over their respective clinical ranges of peak tube potentials for kVp and half-value layer (HVL) measurements. Comparisons for air kerma (AK) and their associated relative calculated average glandular doses (AGDs), i.e., using fixed mAs, were evaluated over the limited range of 28–30 kVp. Measurements were compared with reference IC measurements for AK, reference HVLs and calculated AGD, for two compression paddle heights for AK, to evaluate scatter effects from compression paddles. SStDs may require different positioning from current mammography measurement protocols. Results: Measurements of kVp were accurate in general for the SStDs (within −1.2 and +1.1 kVp) for all instruments over a wide range of set kVp’s and TFs and most accurate for Mo/Mo and W/Rh. Discrepancies between measurements and reference values were greater for HVL and AK. Measured HVL values differed from reference values by −6.5% to +3.5% depending on the SStD and

  9. Characteristics of a novel polymer gel dosimeter formula for MRI scanning: Dosimetry, toxicity and temporal stability of response.

    PubMed

    Abtahi, S M

    2016-09-01

    The present study intended to investigate the composition of a new polymer gel dosimeter. The new composition would be more suitable for a wide range of applications in comparison to polyacrylamide gel dosimeter since its extremely toxic acrylamide has been replaced with less harmful monomer i.e. 2-Acrylamido-2-MethylPropane Sulfonic acid (AMPS). To this end, the PAGAT gel dosimeter formula was used as a basis to test the new formulation of polymer gel dosimeter with a different monomer (AMPS) instead of acrylamide by using the %6T and %50C to the formula. The new formulation was named PAMPSGAT (Poly AMPS, Gelatin and THPC) polymer gel dosimeter. Moreover, the MRI response (R2) of dosimeters was analyzed in terms of different dose range as well as post-irradiation time. The results indicated that the dose-response (R2) of AMPS/Bis had a linear trend over a wide dose range. Furthermore, the results showed an acceptable temporal stability for the new polymer gel dosimeter.

  10. Determining the applicability of the Landauer nanoDot as a general public dosimeter in a research imaging facility.

    PubMed

    Charlton, Michael A; Thoreson, Kelly F; Cerecero, Jennifer A

    2012-11-01

    The Research Imaging Institute (RII) building at the University of Texas Health Science Center at San Antonio (UTHSCSA) houses two cyclotron particle accelerators, positron emission tomography (PET) machines, and a fluoroscopic unit. As part of the radiation protection program (RPP) and meeting the standard for achieving ALARA (as low as reasonably achievable), it is essential to minimize the ionizing radiation exposure to the general public through the use of controlled areas and area dose monitoring. Currently, thirty-four whole body Luxel+ dosimeters, manufactured by Landauer, are being used in various locations within the RII to monitor dose to the general public. The intent of this research was to determine if the nanoDot, a single point dosimeter, can be used as a general public dosimeter in a diagnostic facility. This was tested by first verifying characteristics of the nanoDot dosimeter including dose linearity, dose rate dependence, angular dependence, and energy dependence. Then, the response of the nanoDot dosimeter to the Luxel+ dosimeter when placed in a continuous, low dose environment was investigated. Finally, the nanoDot was checked for appropriate response in an acute, high dose environment. Based on the results, the current recommendation is that the nanoDot should not replace the Luxel+ dosimeter without further work to determine the energy spectra in the RII building and without considering the limitation of the microStar reader, portable on-site OSL reader, at doses below 0.1 mGy (10 mrad). PMID:23026976

  11. Characteristics of a novel polymer gel dosimeter formula for MRI scanning: Dosimetry, toxicity and temporal stability of response.

    PubMed

    Abtahi, S M

    2016-09-01

    The present study intended to investigate the composition of a new polymer gel dosimeter. The new composition would be more suitable for a wide range of applications in comparison to polyacrylamide gel dosimeter since its extremely toxic acrylamide has been replaced with less harmful monomer i.e. 2-Acrylamido-2-MethylPropane Sulfonic acid (AMPS). To this end, the PAGAT gel dosimeter formula was used as a basis to test the new formulation of polymer gel dosimeter with a different monomer (AMPS) instead of acrylamide by using the %6T and %50C to the formula. The new formulation was named PAMPSGAT (Poly AMPS, Gelatin and THPC) polymer gel dosimeter. Moreover, the MRI response (R2) of dosimeters was analyzed in terms of different dose range as well as post-irradiation time. The results indicated that the dose-response (R2) of AMPS/Bis had a linear trend over a wide dose range. Furthermore, the results showed an acceptable temporal stability for the new polymer gel dosimeter. PMID:27542576

  12. Use of multi-element beta dosimeters for measuring dose rates in the TMI-2 containment building

    SciTech Connect

    Scherpelz, R I; Endres, G W.R.; Rathbun, L A

    1983-09-01

    The use of thermoluminescent dosimeters (TLDs) for beta dosimetry has traditionally involved inaccuracies due to the energy-dependent response of the TLDs. In order to correct for the beta energy spectrum, researchers at the Pacific Northwest Laboratory (PNL - operated by Battelle Memorial Institute) have developed a dosimeter using TLDs under a number of different thickness of aluminum shields. The PNL multi-element beta dosimeter has been used in four-element and seven-element configurations. Design considerations, analysis procedures, quality assurance, and error determinations for the dosimeters are described in this report. The methods of data analysis used for converting TLD response to dose are also described. These multi-element dosimeters have been used to measure beta and gamma doses resulting from radioactive contaminants in the Three Mile Island Unit 2 containment building. Over 100 dosimeters have been used in three sets of experiments at a number of locations in the building. This report documents the experiments and presents the doses evaluated by the dosimeters.

  13. Dose evaluation of an NIPAM polymer gel dosimeter using gamma index

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Jen; Lin, Jing-Quan; Hsieh, Bor-Tsung; Yao, Chun-Hsu; Chen, Chin-Hsing

    2014-11-01

    An N-isopropylacrylamide (NIPAM) polymer gel dosimeter has great potential in clinical applications. However, its three-dimensional dose distribution must be assessed. In this work, a quantitative evaluation of dose distributions was performed to evaluate the NIPAM polymer gel dosimeter using gamma analysis. A cylindrical acrylic phantom filled with NIPAM gel measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by a 4×4 cm2 square light field. The irradiated gel phantom was scanned using an optical computed tomography (optical CT) scanner (OCTOPUS™, MGS Research, Inc., Madison, CT, USA) at 1 mm resolution. The projection data were transferred to an image reconstruction program, which was written using MATLAB (The MathWorks, Natick, MA, USA). The program reconstructed the image of the optical density distribution using the algorithm of a filter back-projection. Three batches of replicated gel phantoms were independently measured. The average uncertainty of the measurements was less than 1%. The gel was found to have a high degree of spatial uniformity throughout the dosimeter and good temporal stability. A comparison of the line profiles of the treatment planning system and of the data measured by optical CT showed that the dose was overestimated in the penumbra region because of two factors. The first is light scattering due to changes in the refractive index at the edge of the irradiated field. The second is the edge enhancement caused by free radical diffusion. However, the effect of edge enhancement on the NIPAM gel dosimeter is not as significant as that on the BANG gel dosimeter. Moreover, the dose uncertainty is affected by the inaccuracy of the gel container positioning process. To reduce the uncertainty of 3D dose distribution, improvements in the gel container holder must be developed.

  14. Water-equivalent dosimeter array for small-field external beam radiotherapy

    SciTech Connect

    Archambault, Louis; Beddar, A. Sam; Gingras, Luc; Lacroix, Frederic; Roy, Rene; Beaulieu, Luc

    2007-05-15

    With the increasing complexity of dose patterns external beam radiotherapy, there is a great need for new types of dosimeters. We studied the first prototype of a new dosimeter array consisting of water-equivalent plastic scintillating fibers for dose measurement in external beam radiotherapy. We found that this array allows precise, rapid dose evaluation of small photon fields. Starting with a dosimeter system constructed with a single scintillating fiber coupled to a clear optical fiber and read using a charge coupled device camera, we looked at the dosimeter's spatial resolution under small radiation fields and angular dependence. Afterward, we analyzed the camera's light collection to determine the maximum array size that could be built. Finally, we developed a prototype made of ten scintillating fiber detectors to study the behavior and precision of this system in simple dosimetric situations. The scintillation detector showed no measurable angular dependence. Comparison of the scintillation detector and a small-volume ion chamber showed agreement except for 1x1 and 0.5x5.0 cm{sup 2} fields where the output factor measured by the scintillator was higher. The actual field of view of the camera could accept more than 4000 scintillating fiber detectors simultaneously. Evaluation of the dose profile and depth dose curve using a prototype with ten scintillating fiber detectors showed precise, rapid dose evaluation even with placement of more than 75 optical fibers in the field to simulate what would happen in a larger array. We concluded that this scintillating fiber dosimeter array is a valuable tool for dose measurement in external beam radiotherapy. It possesses the qualities necessary to evaluate small and irregular fields with various incident angles such as those encountered in intensity-modulated radiotherapy, radiosurgery, and tomotherapy.

  15. Investigation of the effect of some irradiation parameters on the response of various types of dosimeters to electron irradiation

    NASA Astrophysics Data System (ADS)

    Farah, K.; Kuntz, F.; Kadri, O.; Ghedira, L.

    2004-09-01

    Several undyed and dyed polymer films are commercially available for dosimetry in intense radiation fields, especially for radiation processing of food and sterilisation of medical devices. The effects of temperature during irradiation and post-irradiation stability, on the response of these dosimeters are of importance to operators of irradiation facilities. The present study investigates the effects of temperature during irradiation by 2.2 MeV electrons beam accelerator and post irradiation storage on the response of several types of dosimeter films. All dosimeters showed a significant effect of temperature during irradiation and post-irradiation storage.

  16. Evaluation of LLNL's Nuclear Accident Dosimeters at the CALIBAN Reactor September 2010

    SciTech Connect

    Hickman, D P; Wysong, A R; Heinrichs, D P; Wong, C T; Merritt, M J; Topper, J D; Gressmann, F A; Madden, D J

    2011-06-21

    The Lawrence Livermore National Laboratory uses neutron activation elements in a Panasonic TLD holder as a personnel nuclear accident dosimeter (PNAD). The LLNL PNAD has periodically been tested using a Cf-252 neutron source, however until 2009, it was more than 25 years since the PNAD has been tested against a source of neutrons that arise from a reactor generated neutron spectrum that simulates a criticality. In October 2009, LLNL participated in an intercomparison of nuclear accident dosimeters at the CEA Valduc Silene reactor (Hickman, et.al. 2010). In September 2010, LLNL participated in a second intercomparison of nuclear accident dosimeters at CEA Valduc. The reactor generated neutron irradiations for the 2010 exercise were performed at the Caliban reactor. The Caliban results are described in this report. The procedure for measuring the nuclear accident dosimeters in the event of an accident has a solid foundation based on many experimental results and comparisons. The entire process, from receiving the activated NADs to collecting and storing them after counting was executed successfully in a field based operation. Under normal conditions at LLNL, detectors are ready and available 24/7 to perform the necessary measurement of nuclear accident components. Likewise LLNL maintains processing laboratories that are separated from the areas where measurements occur, but contained within the same facility for easy movement from processing area to measurement area. In the event of a loss of LLNL permanent facilities, the Caliban and previous Silene exercises have demonstrated that LLNL can establish field operations that will very good nuclear accident dosimetry results. There are still several aspects of LLNL's nuclear accident dosimetry program that have not been tested or confirmed. For instance, LLNL's method for using of biological samples (blood and hair) has not been verified since the method was first developed in the 1980's. Because LLNL and the other DOE

  17. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy

    NASA Astrophysics Data System (ADS)

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,θ0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380 MeV) was established by interpolating between G-values obtained for Co-60 and 250 kV x-rays. An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength. Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3 mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%. Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%. The combined standard uncertainty in the determination of absorbed dose to water

  18. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy.

    PubMed

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,θ0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380 MeV) was established by interpolating between G-values obtained for Co-60 and 250 kV x-rays.An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength.Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3 mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%.Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%.The combined standard uncertainty in the determination of absorbed dose to water at

  19. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters.

    PubMed

    Chan, Maria F; Song, Yulin; Dauer, Lawrence T; Li, Jingdong; Huang, David; Burman, Chandra

    2012-01-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar™ DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium (∼2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by ± 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., ∼d(max) of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  20. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters

    SciTech Connect

    Chan, Maria F.; Song, Yulin; Dauer, Lawrence T.; Li Jingdong; Huang, David; Burman, Chandra

    2012-10-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar Trade-Mark-Sign DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium ({approx}2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by {+-} 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., {approx}d{sub max} of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  1. Comparative sensitivity study and reading correction of various albedo dosimeters in neutron fields on the U-400M accelerator

    NASA Astrophysics Data System (ADS)

    Mokrov, Yu. V.; Morozov, S. V.; Shchegolev, V. Yu.

    2013-03-01

    The sensitivities of three types of albedo dosimeters are experimentally studied in U-400M accelerator radiation fields in the experimental hall (one point) and behind its shielding (three points). It is shown that the ratios of the sensitivity of the albedo dosimeter (AD) and the combined personal dosimeter (CPD) used earlier at the Joint Institute for Nuclear Research (JINR) to the sensitivity of the DVGN-01 dosimeter are constant within 25%. This allows the AD and CPD sensitivities obtained earlier at the JINR facilities to be used for correcting readings of the DVGN-01 now used at JINR for personal radiation monitoring. Correction coefficients are found for DVGN-01 readings behind the U-400M shielding. This has allowed a more reliable correction coefficient to be established for the Flerov Laboratory of Nuclear Reactions (FLNR).

  2. Hydrolyzable hemoglobin adducts of polyfunctional monocyclic N-substituted arenes as dosimeters of exposure and markers of metabolism.

    PubMed Central

    Zwirner-Baier, I; Kordowich, F J; Neumann, H G

    1994-01-01

    Hemoglobin adducts of 10 polyfunctional amino- and nitro-substituted benzenes and toluenes were analyzed: 2,4,6-trinitrotoluene, 2,4- and 2,6-dinitrotoluene, 2-amino-4-nitrotoluene, 4-amino-2-nitrotoluene, 2,4- and 2,6-diaminotoluene, 1,3-dinitrobenzene, 1-amino-3-nitrobenzene, and 1,3-diaminobenzene. A single dose (0.5 mmole/kg) of the test compounds was administered to female Wistar rats by gavage, and blood extracted and hemoglobin prepared after 24 hr. One or more cleavage products could be obtained in each case by hydrolyzing hemoglobin (Hb). Hemoglobin binding indices (HBI: binding [mmole/mole Hb]/dose [mmole/kg]) and the ratios of hydrolyzable adducts were determined. The HBI ranged between < 0.02 and 69.0. The results indicate the in vivo formation of several, covalently bound, hydrolyzable hemoglobin adducts. Conclusions on prevailing metabolic pathways can be drawn. Total binding of several compounds seems sufficient for biomonitoring of human blood samples. These chemicals are considered representative for environmental contamination with explosives of this type, and we propose their Hb adducts be used as dosimeters for human exposure to these suspected carcinogens. PMID:7889857

  3. Hydrolyzable hemoglobin adducts of polyfunctional monocyclic N-substituted arenes as dosimeters of exposure and markers of metabolism.

    PubMed

    Zwirner-Baier, I; Kordowich, F J; Neumann, H G

    1994-10-01

    Hemoglobin adducts of 10 polyfunctional amino- and nitro-substituted benzenes and toluenes were analyzed: 2,4,6-trinitrotoluene, 2,4- and 2,6-dinitrotoluene, 2-amino-4-nitrotoluene, 4-amino-2-nitrotoluene, 2,4- and 2,6-diaminotoluene, 1,3-dinitrobenzene, 1-amino-3-nitrobenzene, and 1,3-diaminobenzene. A single dose (0.5 mmole/kg) of the test compounds was administered to female Wistar rats by gavage, and blood extracted and hemoglobin prepared after 24 hr. One or more cleavage products could be obtained in each case by hydrolyzing hemoglobin (Hb). Hemoglobin binding indices (HBI: binding [mmole/mole Hb]/dose [mmole/kg]) and the ratios of hydrolyzable adducts were determined. The HBI ranged between < 0.02 and 69.0. The results indicate the in vivo formation of several, covalently bound, hydrolyzable hemoglobin adducts. Conclusions on prevailing metabolic pathways can be drawn. Total binding of several compounds seems sufficient for biomonitoring of human blood samples. These chemicals are considered representative for environmental contamination with explosives of this type, and we propose their Hb adducts be used as dosimeters for human exposure to these suspected carcinogens.

  4. Hydrolyzable hemoglobin adducts of polyfunctional monocyclic N-substituted arenes as dosimeters of exposure and markers of metabolism

    SciTech Connect

    Zwirner-Baier, I.; Kordowich, F.J.; Neumann, H.G.

    1994-10-01

    Hemoglobin adducts of 10 polyfunctional amino- and nitro-substituted benzenes and toluenes were analyzed: 2,4,6-trinitrotoluene, 2,4- and 2,6-dinitrotoluene. 2-amino-4-nitrotoluene, 4-amino-2-nitrotoluene, 2,4- and 2,6-diaminotoluene, 1,3-dinitrobenzene, 1-amino-3-nitrobenzene, and 1,3-diaminobenzene. A single dose (0.5 mmole/kg) of the test compounds was administered to female Wistar rats by gavage, and blood extracted and hemoglobin prepared after 24 hr. One or more cleavage products could be obtained in each case by hydrolyzing hemoglobin (Hb). Hemoglobin binding indices (HBl); binding (mmole/mole Hbl/dose [mmole/kg]) and the ratios of hydrolyzable adducts were determined. The HBl ranged between <0/.02 and 69.0. The results indicate the in vivo formation of several, convalently bound, hydrolyzable hemoglobin adducts. Conclusion on prevailing metabolic pathways can be drawn. Total binding of several compounds seems sufficient for biomonitoring of human blood samples. These chemicals are considered representative for environmental contamination with explosives of this type, and we propose their Hb adducts be used as dosimeters for human exposure to these suspected carcinogens. 8 refs., 2 figs., 2 tabs.

  5. Impact of reading pre-irradiation background signal on the post-irradiation glow curves of thermoluminescence dosimeters.

    PubMed

    Abd El-Hafez, A I; Maghraby, A

    2011-10-01

    Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescence dosimeters are widely used in many applications. It was noticed that post-irradiation glow curves of LiF dosimeters that had undergone pre-irradiation background dose measurements dramatically differed from the curves of dosimeters irradiated without such preliminary measurements. Three types of dosimeters were studied in this respect, namely, TLD-700, TLD-600, and TLD-100. Impact of pre-irradiation background measurements on the glow curve areas, peak positions, and individual peak intensities were investigated using computerized glow curve analysis. Similarities in the behavior of the dosimeters of all three types were found. Areas of the glow peaks P₂a, P₃, P₄, P₅, and P₆ increased. Peak P₃ grew most significantly, followed by P₂, and P₅. Also, one of the common features was a shift of T(max) of P₅ to higher temperatures. Pre-irradiation background readings increase the total area of the glow curve in general and affect relative intensities and positions of specific peaks, which changes the shape of the glow curve. It is strongly recommended to perform pre-irradiation background measurements for all LiF-based dosimeters regardless of the values of the background doses relative to the radiation doses to be given.

  6. In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

    NASA Astrophysics Data System (ADS)

    Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

    2016-06-01

    Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

  7. Effects of computational phantoms on the effective dose and two-dosimeter algorithm for external photon beams.

    PubMed

    Karimi-Shahri, K; Rafat-Motavalli, L; Miri-Hakimabad, H; Liu, L; Li, J

    2016-09-01

    In this study, the effect of computational phantoms on the effective dose (E), dosimeter responses positioned on the front (chest) and back of phantom, and two-dosimeter algorithm was investigated for external photon beams. This study was performed using Korean Typical MAN-2 (KTMAN-2), Chinese Reference Adult Male (CRAM), ICRP male reference, and Male Adult meSH (MASH) reference phantoms. Calculations were performed for beam directions in different polar and azimuthal angles using the Monte Carlo code of MCNP at energies of 0.08, 0.3, and 1MeV. Results show that the body shape significantly affects E and two-dosimeter responses when the dosimeters are indirectly irradiated. The acquired two-dosimeter algorithms are almost the same for all the mentioned phantoms except for KTMAN-2. Comparisons between the obtained E and estimated E (Eest), acquired from two-dosimeter algorithm, illustrate that the Eest is overestimated in overhead (OH) and underfoot (UF) directions. The effect of using one algorithm for all phantoms was also investigated. Results show that application of one algorithm to all reference phantoms is possible. PMID:27389880

  8. Evaluation of the radiation-sensitizer/protector and/or antioxidant efficiencies using Fricke and PAG dosimeters

    NASA Astrophysics Data System (ADS)

    Meesat, Ridthee; Jay-Gerin, Jean-Paul; Khalil, Abdelouahed; Lepage, Martin

    2009-05-01

    In this study, our aim is to assess the potential of Fricke and polyacrylamide gel (PAG) dosimeters to quantitatively evaluate the efficiency of potential radiation sensitizers/protectors and antioxidants. These compounds are of importance in radiotherapy as well as in disease prevention and promotion of health. The basic principle of the Fricke dosimeter is the radiation-induced oxidation of Fe2+ to Fe3+ in an aerated aqueous 0.4 M H2SO4. The production of ferric ions is most sensitive to the radical species produced in the radiolysis of water. Using this method, we observed that cystamine (one of the best of the known radioprotectors) can prevent oxydation of Fe2+ from reactive radiolysis species. However, one obvious disadvantage of the Fricke dosimeter is that it operates under highly acidic conditions (pH 0.46), which may degrade biological compounds. In contrast, the pH of the polyacrylamide gel (PAG) dosimeter is almost neutral, such that degradation of compounds is less probable. A change in R2-dose sensitivity was observed in the presence of radiosensitizers/radioprotectors and antioxidants. The protective effect of Trolox (a well-known antioxidant) and thiourea (a radioprotector) was readily observed using the PAG dosimeter. Incorporation of iodinated radiation sensitizers such as NaI and an iodine contrast agent led to a quantifiable sensitizer enhancement ratio. These studies suggest that the Fricke and the PAG dosimeters have the potential to evaluate the efficiency of radiation sensitizers/protectors and antioxidants.

  9. The behaviour of alanine dosimeters at temperatures between 100 and 300 K

    NASA Astrophysics Data System (ADS)

    Sharpe, P. H. G.; Sephton, J. P.; Gouldstone, C. A.

    2009-07-01

    A cryostat has been constructed to enable irradiations in a MDS Nordion Gammacell 220 irradiator to be carried out at selected temperatures between 100 and 300 K. The principle of operation and the performance of this cryostat are described and results are given of a study into the behaviour of alanine dosimeters at cryogenic temperatures. This work extends previously published data to the region between solid CO 2 and liquid N 2 temperatures and has demonstrated complex dose-dependent behaviour. A sharp discontinuity in the effect of temperature on alanine dosimeter response has been found in the region between 150 and 180 K, with no further influence of irradiation temperature on response observed below this point.

  10. Design and construct optimum dosimeter to detect airborne radon and thoron gas: Experimental study

    NASA Astrophysics Data System (ADS)

    Ismail, Asaad H.; Jaafar, Mohamad S.

    2011-02-01

    Aim of this work is to design and select optimum dimension of a radon and thoron dosimeter within the measure optimum value of the calibration factor, using CR-39 Nuclear Track Detectors (NTDs). The results show that the best dimension to detect and measure real values of airborne radon and thoron concentrations is 6 cm and 7 cm for diameter and height, respectively. Calibration factors (K) for radon and thoron at this dimension were 2.68 ± 0.03 cm and 0.83 ± 0.01 cm, respectively, and these factors relatively depend on the detector efficiency. Therefore, the efficiency of CR-39NTDs to register alpha particles and their effects on the calibration factor estimated. It is found that the calibration factor increased exponentially with detector efficiency. Moreover, detector efficiency was equal to 80.3 ± 1.23% at the optimum dosimeter.

  11. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2006

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2007-07-19

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to 1) radiological workers who are likely to receive at least 100 mrem annually, and 2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2005 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  12. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2000

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2001-07-05

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a) (1)-(4) and Article 511.1 of the DOE Standard Radiological Control, personnel dosimetry shall be provided to 1) radiological workers who are likely to receive at least 100 mrem annually, and 2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2000 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  13. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2001

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2002-07-08

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the U.S. Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a) (1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to 1) radiological workers who are likely to receive at least 100 mrem annually, and 2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2001 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  14. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2005

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2006-06-21

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually, and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2005 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program

  15. Influence of gelling agents on the dosimetric performance of the Turnbull Blue gel dosimeter

    NASA Astrophysics Data System (ADS)

    Šolc, Jaroslav; Sochor, Vladimír; Spěváček, Václav

    2010-11-01

    Gelling agents such as agarose, phytagel, and several types of gelatin were used for preparation of Turnbull Blue radiochromic gel dosimeter. Their influence on gel dose response and background value was assessed. It was found that all gelatins cause significant increase of background in a short period of time after gel preparation therefore gelatin is not a suitable gelling agent for this dosimeter. Phytagel and agarose gels exhibit low and stable background and higher dose sensitivity than gelatin gels; however, the disadvantage is increased scattered light intensity in the gel in comparison to gelatin gels. A simple measurement was done demonstrating that the scattered light intensity significantly increases in phytagel and agarose gel in comparison to gelatin gels.

  16. Improved dose sensitivity of normoxic polyacrylamide gelatin gel dosimeter with sucrose

    NASA Astrophysics Data System (ADS)

    Yoshioka, M.; Hayashi, S.; Usui, S.; Haneda, K.; Kondo, T.; Numasaki, H.; Teshima, T.; Tominaga, T.

    2010-11-01

    To improve the dose sensitivity of normoxic polyacrylamide gelatin gel (nPAG) dosimeter, the effect of sucrose as an additive is investigated. The dose-transverse relaxation rate (R2) characteristics of the samples of nPAG with different sucrose concentrations were examined, and temperature increases due to exothermic polymerization reaction in the irradiated gel were also measured. As the result, the dose-R2 sensitivity increased (~3 times) with increasing sucrose concentrations (0-25%), while other characteristics of dose response, such as dose integral property, dose rate dependence and temporal stability, were consistent with those of typical nPAG dosimeter. And as the sucrose concentrations increased, a larger temperature increase was observed. These results clearly indicate that the polymerization rate is increased with increasing sucrose concentrations.

  17. Response of the alanine/ESR dosimeter to radiation from an Ir-192 HDR brachytherapy source.

    PubMed

    Anton, M; Hackel, T; Zink, K; von Voigts-Rhetz, P; Selbach, H-J

    2015-01-01

    The response of the alanine dosimeter to radiation from an Ir-192 source with respect to the absorbed dose to water, relative to Co-60 radiation, was determined experimentally as well as by Monte Carlo simulations. The experimental and Monte Carlo results for the response agree well within the limits of uncertainty. The relative response decreases with an increasing distance between the measurement volume and the source from approximately 98% at a 1 cm distance to 96% at 5 cm. The present data are more accurate, but agree well with data published by Schaeken et al (2011 Phys. Med. Biol. 56 6625-34). The decrease of the relative response with an increasing distance that had already been observed by these authors is confirmed. In the appendix, the properties of the alanine dosimeter with respect to volume and sensitivity corrections are investigated. The inhomogeneous distribution of the detection probability that was taken into account for the analysis was determined experimentally.

  18. An automated system for the measurement of alanine/EPR dosimeters

    PubMed

    Sharpe; Sephton

    2000-05-01

    NPL for several years has offered mailed reference dosimetry services based on alanine/EPR dosimeters, both at industrial and therapy dose levels. Compared to other methods of reference dosimetry, operator involvement in alanine/EPR has been found to be relatively high, and contributes significantly to the overall economics of the process. Commercially available sample changers are not suitable for high accuracy applications, and it has proved necessary to develop a dedicated automation system to handle NPL alanine dosimeter pellets. In this paper we describe an automatic sample changer for placing and retrieving alanine pellets into and out of the cavity of a standard research grade EPR spectrometer. Up to 32 pellets can be held in each removable sample tray. The sample changer software has been interfaced into the spectrometer control software to enable complete automation of the measurement process, including the optimization of spectrometer settings and rotation of the sample within the cavity.

  19. Response of the alanine/ESR dosimeter to radiation from an Ir-192 HDR brachytherapy source

    NASA Astrophysics Data System (ADS)

    Anton, M.; Hackel, T.; Zink, K.; von Voigts-Rhetz, P.; Selbach, H.-J.

    2015-01-01

    The response of the alanine dosimeter to radiation from an Ir-192 source with respect to the absorbed dose to water, relative to Co-60 radiation, was determined experimentally as well as by Monte Carlo simulations. The experimental and Monte Carlo results for the response agree well within the limits of uncertainty. The relative response decreases with an increasing distance between the measurement volume and the source from approximately 98% at a 1 cm distance to 96% at 5 cm. The present data are more accurate, but agree well with data published by Schaeken et al (2011 Phys. Med. Biol. 56 6625-34). The decrease of the relative response with an increasing distance that had already been observed by these authors is confirmed. In the appendix, the properties of the alanine dosimeter with respect to volume and sensitivity corrections are investigated. The inhomogeneous distribution of the detection probability that was taken into account for the analysis was determined experimentally.

  20. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2003

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2004-08-18

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually, and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2003 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  1. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2002

    SciTech Connect

    Bivins, Steven R.; Stoetzel, Gregory A.

    2003-07-09

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually, and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2002 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  2. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: Results for CY 2004

    SciTech Connect

    Bivens, Steven A.; Stoetzel, Gregory A.

    2005-06-28

    Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM) in January 1993. This program is to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a)(1)-(4) and Article 511.1 of the PNNL Radiological Control Program Description, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually, and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993-2004 confirm that personnel dosimetry is not needed for individuals located in areas monitored by the program.

  3. Responses of a direct ion storage dosimeter (DIS-1) to heavy charged particles.

    PubMed

    Yasuda, H

    2001-12-01

    The responses of a direct ion storage dosimeter (DIS-1) to energetic heavy charged particles were examined using (4)He, (12)C, (40)Ar and (56)Fe ion beams at the HIMAC at the National Institute of Radiological Sciences. The efficiency of the DIS-1 on the basis of absorbed dose was almost unity for the helium and carbon ions and was slightly decreased for the argon and iron ions. The linearity in the dose response and the angular independence for these heavy ions were fairly good. Although further studies are necessary, these results suggest that the DIS-1 would be a suitable passive dosimeter for measurements of absorbed dose in a field dominated by heavy charged particles such as the space environment. PMID:11741505

  4. Best fit refractive index of matching liquid for 3D NIPAM gel dosimeters using optical CT

    NASA Astrophysics Data System (ADS)

    Chen, Chin-Hsing; Wu, Jay; Hsieh, Bor-Tsung; Chen, De-Shiou; Wang, Tzu-Hwei; Chien, Sou-Hsin; Chang, Yuan-Jen

    2014-11-01

    The accuracy of an optical computed tomography (CT)-based dosimeter is significantly affected by the refractive index (RI) of the matching liquid. Mismatched RI induces reflection and refraction as the laser beam passes through the gel phantom. Moreover, the unwanted light rays collected by the photodetector produce image artifacts after image reconstruction from the collected data. To obtain the best image quality, this study investigates the best-fit RI of the matching liquid for a 3D NIPAM gel dosimeter. The three recipes of NIPAM polymer gel used in this study consisted of 5% gelatin, 5% NIPAM and 3% N,N'-methylene bisacrylamide, which were combined with three compositions (5, 10, and 20 mM) of Tetrakis (hydroxymethyl) phosphonium chloride. Results were evaluated using a quantitative evaluation method of the gamma evaluation technique. Results showed that the best-fit RI for the non-irradiated NIPAM gel ranges from 1.340 to 1.346 for various NIPAM recipes with sensitivities ranging from 0.0113 to 0.0227. The greatest pass rate of 88.00% is achieved using best-fit RI=1.346 of the matching liquid. The adoption of mismatching RI decreases the gamma pass rate by 2.63% to 16.75% for all three recipes of NIPAM gel dosimeters. In addition, the maximum average deviation is less than 0.1% for the red and transparent matching liquids. Thus, the color of the matching liquid does not affect the measurement accuracy of the NIPAM gel dosimeter, as measured by optical CT.

  5. Thermoluminescent Dosimeter Use for Environmental Surveillance at the Hanford Site, 1971–2005

    SciTech Connect

    Antonio, Ernest J.; Poston, Ted M.; Rathbone, Bruce A.

    2010-03-01

    This report describes the use of thermo luminescent dosimeters for environmental surveillance of external radiation on and around the Hanford Site for the period of 1970 to 2005. It addresses changes in the technology and associated quality control and assurance used in this work and summarizes the results of the 35 year period of external radiation surveillance. The appendices to this report provide trend plots for each location that comprised the shoreline, onsite, perimeter, and offsite sample design.

  6. DETECTORS AND EXPERIMENTAL METHODS: Online measurement of the BEPC II background using RadFET dosimeters

    NASA Astrophysics Data System (ADS)

    Gong, Hui; Li, Jin; Gong, Guang-Hua; Li, Yu-Xiong; Hou, Lei; Shao, Bei-Bei

    2009-09-01

    To monitor the integral dose deposited in the BESIII electromagnetic calorimeter whose performance degrades due to exposure to the BEPC II background, a 400 nm IMPL RadFET dosimeter-based integral dose online monitor system is built. After calibration with the 60Co source and verification with TLD in the pulse radiation fields, an experiment was arranged to measure the BEPC II background online. The results are presented.

  7. Determination of possible damage/degradation of the Sandia National Laboratories Personal Nuclear Accident Dosimeter (PNAD).

    SciTech Connect

    Potter, Charles Augustus; Ward, Dann C.

    2008-05-01

    This report describes the results of an inspection performed on the existing stock of SNL Personal Nuclear Accident Dosimeters (PNADs). The current stock is approximately 20 years old, and has not been examined since their initial acceptance. A small random sample of PNADs were opened (a destructive process) and the contents visually examined. Sample contents were not degraded and indicate that the existing stock of SNL PNADs is acceptable for continued use.

  8. An investigation of the pre-irradiation temporal stability of PAGAT gel dosimeter

    NASA Astrophysics Data System (ADS)

    Khoei, S.; Moorrees, J. B.; Langton, C. M.; Trapp, J. V.

    2010-11-01

    In this work we examine two aspects of the PAGAT gel dosimeter. The first aspect studied is determination of a stable range of concentrations of the anti-oxidant Tetrakis Hydroxy Phosphonium Chloride (THPC). Once the desired THPC concentration is determined, we proceed to an investigation into the effect of pre-irradiation storage time and how this affects the dose response of the gel.

  9. Uncertainties encountered in implementation of adaptive planning with in vivo dosimeters.

    PubMed

    Studenski, M T; Gardner, S J; Den, R B

    2015-01-01

    Under a previously approved institutional review board protocol for prostate cancer patients, implanted metal-oxide semiconductor field-effect transistor dosimeters (dose verification system, Sicel Technologies) were used for measurement of the in vivo delivered daily dose. This dosimetric information provided the ability to adapt the plan if the measured doses did not match the dose expected from the planning system. Due to the inherent uncertainty in the dosimeters, the decision to adapt the treatment plan was made only if readings differed by more than 7 % for three consecutive days. To validate this method, we acquired daily cone beam computed tomography images for five patients, and the dose delivered to the dosimeters was calculated by use of (1) an automated procedure (MIM Maestro, MIM Software) and (2) the treatment planning system (XIO, Elekta). 72 % of the doses calculated automatically fell within 1 % of the doses calculated in the planning system, and 99 % agreed within 2 %. When compared to the calculated dose, 53 % of the in vivo measurements fell within 3 % of the calculated dose, 80 % fell within 5 %, and 9.8 % were greater than 7 %, but never on three consecutive days. The measured doses agreed reasonably well with the calculated doses, supporting the decision to adapt the plan only if there were discrepancies of more than 7 % over three consecutive days. Even with the inherent uncertainty in the dosimeters, this adaptive planning method can detect delivery inaccuracies that would not otherwise be caught with the use of only daily image guidance or other dose calculation surrogates.

  10. A response function calculation for a dose-equivalent neutron dosimeter using superheated drops

    SciTech Connect

    Wang, C.K. )

    1991-01-01

    A neutron dosimeter using superheated drops in gel was invented by Apfel. The SDD-100 or BD-100, which uses Freon-12 (CF{sub 2}Cl{sub 2}) for the superheated drops, is most useful in neutron dosimetry because it was claimed that the neutron response function of such a dosimeter is nearly dose equivalent. An ideal dose-equivalent neutron dosimeter should be totally independent of the energies of incident neutrons. Lo and Apfel have performed calculations and experiments to study the neutron response functions for various types of superheated drops, including Freon-12. Both their calculational and the experimental results demonstrated the dose-equivalent-like response function for the Freon-12. The agreement between the calculational results and the experimental results is not satisfactory, however, especially for neutrons with energies < 100 keV. One important factor, which was not considered and may have contributed to the disagreement, is the neutron-slowing-down effect. That is, kilo-electron-volt neutrons, although not energetic enough to trigger bubbles in Freon-12, have a short mean-free-path (< 1 cm) and can easily slow down or thermalize in the gel matrix and then trigger bubbles in Freon-12 via a {sup 35}Cl(n,p){sup 35}S reaction. To consider the slowing-down effect in the dosimeter, a neutron transport calculation must be performed. This paper describes the set of Monte Carlo neutron transport calculations that were performed to calculate the response function for a bare SDD-100 surrounded with various thicknesses of polyethylene (CH{sub 2}).

  11. Does nitrogen gas bubbled through a low density polymer gel dosimeter solution affect the polymerization process?

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Gholami, Mehrdad; Pourfallah, Tayyeb Allahverdi; Keshtkar, Mohammad

    2015-01-01

    Background: On account of the lower electron density in the lung tissue, the dose distribution in the lung cannot be verified with the existing polymer gel dosimeters. Thus, the aims of this study are to make a low density polymer gel dosimeter and investigate the effect of nitrogen gas bubbles on the R2 responses and its homogeneity. Materials and Methods: Two different types of low density polymer gel dosimeters were prepared according to a composition proposed by De Deene, with some modifications. In the first type, no nitrogen gas was perfused through the gel solution and water. In the second type, to expel the dissolved oxygen, nitrogen gas was perfused through the water and gel solution. The post-irradiation times in the gels were 24 and 5 hours, respectively, with and without perfusion of nitrogen gas through the water and gel solution. Results: In the first type of gel, there was a linear correlation between the doses and R2 responses from 0 to 12 Gy. The fabricated gel had a higher dynamic range than the other low density polymer gel dosimeter; but its background R2 response was higher. In the second type, no difference in R2 response was seen in the dose ranges from 0 to 18 Gy. Both gels had a mass density between 0.35 and 0.45 g.cm-3 and CT values of about -650 to -750 Hounsfield units. Conclusion: It appeared that reactions between gelatin-free radicals and monomers, due to an increase in the gel temperature during rotation in the household mixer, led to a higher R2-background response. In the second type of gel, it seemed that the collapse of the nitrogen bubbles was the main factor that affected the R2-responses. PMID:26015914

  12. Polyvinyl butyral films containing leuco-malachite green as low-dose dosimeters

    NASA Astrophysics Data System (ADS)

    Mai, Hoang Hoa; Solomon, H. M.; Taguchi, M.; Kojima, T.

    2008-04-01

    Thin films containing leuco-malachite green (LMG) dye in polyvinyl butyral (PVB) have been developed for dose measurements of a few hundreds Gy level. The film shows significant color change in the visible range, and the sensitivity of the film to absorbed dose was enhanced by addition of chloride-containing compounds, such as chloral hydrate or 2,2,2-trichloroethanol. The film is suitable as dosimeters for dose measurements, e.g. in food irradiation and environmental protection.

  13. Dose mapping of the rectal wall during brachytherapy with an array of scintillation dosimeters

    SciTech Connect

    Cartwright, L. E.; Suchowerska, N.; Yin, Y.; Lambert, J.; Haque, M.; McKenzie, D. R.

    2010-05-15

    Purpose: In pelvic brachytherapy treatments, the rectum is an organ at risk. The authors have developed an array of scintillation dosimeters suitable for in vivo use that enables quality assurance of the treatment delivery and provides an alert to potential radiation accidents. Ultimately, this will provide evidence to direct treatment planning and dose escalation and correlate dose with the rectal response. Methods: An array of 16 scintillation dosimeters in an insertable applicator has been developed. The dosimeters were calibrated simultaneously in a custom designed circular jig before use. Each dosimeter is optically interfaced to a set of pixels on a CCD camera located outside the treatment bunker. A customized software converts pixel values into dose rate and accumulates dose for presentation during treatment delivery. The performance of the array is tested by simulating brachytherapy treatments in a water phantom. The treatment plans were designed to deliver a known dose distribution on the surface of the rectal applicator, assumed to represent the dose to the rectal wall. Results: The measured doses were compared to those predicted by the treatment plan and found to be in agreement to within the uncertainty in measurement, usually within 3%. The array was also used to track the progression of the source as it moved along the catheter. The measured position was found to agree with the position reported by the afterloader to within the measurement uncertainty, usually within 2 mm. Conclusions: This array is capable of measuring the actual dose received by each region of the rectal wall during brachytherapy treatments. It will provide real time monitoring of treatment delivery and raise an alert to a potential radiation accident. Real time dose mapping in the clinical environment will give the clinician additional confidence to carry out dose escalation to the tumor volume while avoiding rectal side effects.

  14. Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy.

    PubMed

    Kumar, A Sathish; Singh, I Rabi Raja; Sharma, S D; Ravindran, B Paul

    2015-01-01

    The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom. PMID:26500397

  15. Uncertainties encountered in implementation of adaptive planning with in vivo dosimeters.

    PubMed

    Studenski, M T; Gardner, S J; Den, R B

    2015-01-01

    Under a previously approved institutional review board protocol for prostate cancer patients, implanted metal-oxide semiconductor field-effect transistor dosimeters (dose verification system, Sicel Technologies) were used for measurement of the in vivo delivered daily dose. This dosimetric information provided the ability to adapt the plan if the measured doses did not match the dose expected from the planning system. Due to the inherent uncertainty in the dosimeters, the decision to adapt the treatment plan was made only if readings differed by more than 7 % for three consecutive days. To validate this method, we acquired daily cone beam computed tomography images for five patients, and the dose delivered to the dosimeters was calculated by use of (1) an automated procedure (MIM Maestro, MIM Software) and (2) the treatment planning system (XIO, Elekta). 72 % of the doses calculated automatically fell within 1 % of the doses calculated in the planning system, and 99 % agreed within 2 %. When compared to the calculated dose, 53 % of the in vivo measurements fell within 3 % of the calculated dose, 80 % fell within 5 %, and 9.8 % were greater than 7 %, but never on three consecutive days. The measured doses agreed reasonably well with the calculated doses, supporting the decision to adapt the plan only if there were discrepancies of more than 7 % over three consecutive days. Even with the inherent uncertainty in the dosimeters, this adaptive planning method can detect delivery inaccuracies that would not otherwise be caught with the use of only daily image guidance or other dose calculation surrogates. PMID:25236778

  16. TH-C-17A-08: Monte Carlo Based Design of Efficient Scintillating Fiber Dosimeters

    SciTech Connect

    Wiles, A; Loyalka, S; Rangaraj, D; Izaguirre, E

    2014-06-15

    Purpose: To accurately predict Cherenkov radiation generation in scintillating fiber dosimeters. Quantifying Cherenkov radiation provides a method for optimizing fiber dimensions, orientation, optical filters, and photodiode spectral sensitivity to achieve efficient real time imaging dosimeter designs. Methods: We develop in-house Monte Carlo simulation software to model polymer scintillation fibers' fluorescence and Cherenkov emission in megavoltage clinical beams. The model computes emissions using generation probabilities, wavelength sampling, fiber photon capture, and fiber transport efficiency and incorporates the fiber's index of refraction, optical attenuation in the Cherenkov and visible spectrum and fiber dimensions. Detector component selection based on parameters such as silicon photomultiplier efficiency and optical coupling filters separates Cherenkov radiation from the dose-proportional scintillating emissions. The computation uses spectral and geometrical separation of Cherenkov radiation, however other filtering techniques can expand the model. Results: We compute Cherenkov generation per electron and fiber capture and transmission of those photons toward the detector with incident electron beam angle dependence. The model accounts for beam obliquity and nonperpendicular electron fiber impingement, which increases Cherenkov emission and trapping. The rotational angle around square fibers shows trapping efficiency variation from the normally incident minimum to a maximum at 45 degrees rotation. For rotation in the plane formed by the fiber axis and its surface normal, trapping efficiency increases with angle from the normal. The Cherenkov spectrum follows the theoretical curve from 300nm to 800nm, the wavelength range of interest defined by silicon photomultiplier and photodiode spectral efficiency. Conclusion: We are able to compute Cherenkov generation in realistic real time scintillating fiber dosimeter geometries. Design parameters incorporate

  17. The feasibility of the polycarbonate Durolon(TM) as a thermal neutron dosimeter.

    PubMed

    Pugliesi, F; Pereira, M A Stanojev; Pugliesi, R; Dias, M S

    2014-07-01

    The feasibility of Durolon as a thermal neutron dosimeter was studied. As experimentally determined the proposed methodology covers a wide range of doses, from 0.1 mSv

  18. Radiological properties of nanocomposite Fricke gel dosimeters for heavy ion beams

    PubMed Central

    Maeyama, Takuya; Fukunishi, Nobuhisa; Ishikawa, Kenichi L.; Fukasaku, Kazuaki; Fukuda, Shigekazu

    2016-01-01

    The radiological properties of nanocomposite Fricke gel (NC-FG) dosimeters prepared with different concentrations of nano-clay, perchloric acid and ferrous ions in deaerated conditions were investigated under carbon and argon ion beam irradiation covering a linear-energy-transfer (LET) range of 10 to 3000 eV/nm. We found that NC-FG exhibits radiological properties distinct from those of conventional Fricke gel. The radiation sensitivity of NC-FG is independent of the LET and is nearly constant even at very high LET (3000 eV/nm) values in the Bragg peak region of the argon ion beam. In addition, whereas conventional Fricke gel dosimeters only operate under acidic conditions, NC-FG dosimeters function under both acidic and neutral conditions. The radiation sensitivity decreases with decreasing nano-clay concentration in NC-FG, which indicates that the nano-clay plays a vital role in the radiation-induced oxidation of Fe2+. PMID:26968632

  19. Area monitoring dosimeter program for the Pacific Northwest National Laboratory: Results for CY 1996

    SciTech Connect

    Bivins, S R; Stoetzel, G A

    1997-06-01

    In January 1993, Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM). The purpose of the program was to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological buffer Areas are negligible. In accordance with 10 CFR Part 835.402 (a) (1)-(3) and Article 511.1 of the RCM, personnel dosimetry shall be provided to (1) radiological workers who are likely to receive at least 100 mrem annually and (2) declared pregnant workers, minors, and members of the public who are likely to receive at least 50 mrem annually. Program results for calendar years 1993, 1994, and 1995 confirmed that personnel dosimetry was not needed for individuals located in areas monitored by the program. A total of 108 area TLDs were placed in PNNL facilities during CY 1996. The TLDs were exchanged and analyzed quarterly. All routine area monitoring TLD results were less than 50 mrem annually after correcting for worker occupancy. The results support the conclusion that personnel dosimeters are not necessary for staff, declared pregnant workers, minors, or members of the public in these monitored areas.

  20. Development of an alanine dosimeter for gamma dosimetry in mixed environments

    SciTech Connect

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

    1992-12-31

    L-{alpha}a-Alanine, a nontoxic polycrystalline amino acid, has been investigated for use in high-precision, high-level absorbed-dose measurements in mixed neutron/photon environments such as research and test reactors. The technique is based on the use of electron paramagnetic resonance (EPR) spectroscopy to determine the extent of free radical production in a sample exposed to ionizing radiation, and has been successfully used for photon absorbed-dose measurements at levels exceeding 10{sup 5} Gy with high measurement precision. Application of the technique to mixed environments requires knowledge of the energy-dependent response of the dosimeter for both photons and neutrons. Determination of the dosimeter response to photons is accomplished by irradiations in {sup 60}Co and bremsstrahlung sources and by calculations of energy-dependent photon kerma. Neutron response is determined by calculations in conjunction with CaF{sub 2}:Mn thermoluminescence dosimeters and by calculations of energy-dependent neutron kerma. Several neutron environments are used, including the ACRR and SPR-III reactors.

  1. Development of an alanine dosimeter for gamma dosimetry in mixed environments -- Summary of research

    SciTech Connect

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

    1994-02-01

    L-{alpha}-alanine, a nontoxic polycrystalline amino acid, has been investigated for use in high-precision, high-level absorbed-dose measurements in mixed neutron/photon environments such as research and test reactors. The technique is based on the use of electron paramagnetic resonance spectroscopy to determine the extent of free radical production in a sample exposed to ionizing radiation, and has been successfully used for photon absorbed-dose measurements at levels exceeding 10{sup 5} Gy with high measurement precision. Application of the technique to mixed environments requires knowledge of the energy-dependent response of the dosimeter for both photons and neutrons. Determination of the dosimeter response to photons is accomplished by irradiations in {sup 60}Co and bremsstrahlung sources and by calculations of energy-dependent photon kerma. Neutron response is determined by irradiations in conjunction with CaF{sub 2}:Mn thermoluminescence dosimeters and by calculations of energy-dependent neutron kerma. Several neutron environments are used, including those provided by the Annular Core Research Reactor and Sandia Pulsed Reactor.

  2. Calorimetry of electron beams and the calibration of dosimeters at high doses

    NASA Astrophysics Data System (ADS)

    Humphreys, J. C.; McLaughlin, W. L.

    Graphite or metal calorimeters are used to make absolute dosimetric measurements of high-energy electron beams. These calibrated beams are then used to calibrate several types of dosimeters for high-dose applications such as medical-product sterilization, polymer modification, food processing, or electronic-device hardness testing. The electron beams are produced either as continuous high-power beams at approximately 4.5 MeV by d.c. type accelerators or in the energy range of approximately 8 to 50 MeV using pulsed microwave linear accelerators (linacs). The continuous beams are generally magnetically scanned to produce a broad, uniform radiation environment for the processing of materials of extended lateral dimensions. The higher-energy pulsed beams may also be scanned for processing applications or may be used in an unscanned, tightly-focused mode to produce maximum absorbed dose rates such as may be required for electronic-device radiation hardness testing. The calorimeters are used over an absorbed dose range of 10 2 to 10 4 Gy. Intercomparison studies are reported between National Institute of Standards and Technology (NIST) and UK National Physical Laboratory (NPL) graphite disk calorimeters at high doses, using the NPL 10-MeV linac, and agreement was found within 1.5%. It was also shown that the electron-beam responses of radiochromic film dosimeters and alanine pellet dosimeters can be accurately calibrated by comparison with calorimeter readings.

  3. Leuco-crystal-violet micelle gel dosimeters: I. Influence of recipe components and potential sensitizers.

    PubMed

    Nasr, A T; Alexander, K; Schreiner, L J; McAuley, K B

    2015-06-21

    Radiochromic leuco crystal violet (LCV) micelle gel dosimeters are promising three-dimensional radiation dosimeters because of their spatial stability and suitability for optical readout. The effects of surfactant type and surfactant concentration on dose sensitivity of LCV micelle gels are tested, demonstrating that dose sensitivity and initial colour of the gel increases with increasing Triton x-100 (Tx100) concentration. Using Cetyl Trimethyl Ammonium Bromide (CTAB) in place of Tx100 produces gels that are nearly colourless prior to irradiation, but reduces the dose sensitivity. The separate effects of Tri-chloro acetic acid concentration and pH are investigated, revealing that controlling the pH near 3.6 is crucial for achieving high dose sensitivity. The sensitizing effect of chlorinated species on dose sensitivity is tested using 2,2,2-trichloroethanol (TCE), chloroform, and 1,1,1-trichloro-2-methyl-2-propanol hemihydrate. TCE gives the largest improvement in dose sensitivity and is recommended for use in micelle gel dosimeters because it is less volatile and safer to use than chloroform. Preliminary experiments on a new gel containing CTAB as the surfactant and TCE show that this new gel gives a dose sensitivity that is 24% higher than that of previous LCV micelle gels and is nearly colourless prior to irradiation. PMID:26020840

  4. Dyed polyvinyl chloride films for use as high-dose routine dosimeters in radiation processing

    NASA Astrophysics Data System (ADS)

    Mai, Hoang Hoa; Duong, Nguyen Dinh; Kojima, Takuji

    2004-04-01

    Characteristics of the polyvinyl chloride (PVC) films containing 0.11 wt% of malachite green oxalate or 6GX-setoglausine and about 100 μm in thickness were studied for use as routine dosimeters in radiation processing. These films show basically color bleaching under irradiation with 60Co γ-rays in a dose range of 5-50 kGy. The sensitivity of the dosimeters and the linearity of dose-response curves are improved by adding 2.5% of chloral hydrate [CCl 3CH(OH) 2] and 0.15% hydroquinone [HOC 6H 4OH]. These additions extend the minimum dose limit to 1 kGy covering dosimetry requirements of the quality assurance in radiation processing of food and healthcare products. The dose responses of both dyed PVC films at irradiation temperatures from 20°C to 35°C are constant relative to those at 25°C, and the temperature coefficients for irradiation temperatures from 35°C to 55°C were estimated to be (0.43±0.01)%/°C. The dosimeter characteristics are stable within 1% at 25°C before and 60 days after the end of irradiation.

  5. Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry

    NASA Astrophysics Data System (ADS)

    Jafari, S. M.; Alalawi, A. I.; Hussein, M.; Alsaleh, W.; Najem, M. A.; Hugtenburg, R. P.; Bradley, D. A.; Spyrou, N. M.; Clark, C. H.; Nisbet, A.

    2014-11-01

    An investigation has been made of glass beads and optical fibres as novel dosimeters for small-field photon radiation therapy dosimetry. Commercially available glass beads of largest dimension 1.5 mm and GeO2-doped SiO2 optical fibres of 5 mm length and 120 µm diameter were characterized as thermoluminescence dosimeters. Results were compared against Monte-Carlo simulations with BEAMnrc/DOSXYZnrc, EBT3 Gafchromic film, and a high-resolution 2D-array of liquid-filled ionization chambers. Measurements included relative output factors and dose profiles for square-field sizes of 1, 2, 3, 4, and 10 cm. A customized Solid-Water® phantom was employed, and the beads and fibres were placed at defined positions along the longitudinal axis to allow accurate beam profile measurement. Output factors and the beam profile parameters were compared against those calculated by BEAMnrc/DOSXYZnrc. The output factors and field width measurements were found to be in agreement with reference measurements to within better than 3.5% for all field sizes down to 2 cm2 for both dosimetric systems, with the beads showing a discrepancy of no more than 2.8% for all field sizes. The results confirm the potential of the beads and fibres as thermoluminescent dosimeters for use in small photon radiation field sizes.

  6. Leuco-crystal-violet micelle gel dosimeters: I. Influence of recipe components and potential sensitizers

    NASA Astrophysics Data System (ADS)

    Nasr, A. T.; Alexander, K.; Schreiner, L. J.; McAuley, K. B.

    2015-06-01

    Radiochromic leuco crystal violet (LCV) micelle gel dosimeters are promising three-dimensional radiation dosimeters because of their spatial stability and suitability for optical readout. The effects of surfactant type and surfactant concentration on dose sensitivity of LCV micelle gels are tested, demonstrating that dose sensitivity and initial colour of the gel increases with increasing Triton x-100 (Tx100) concentration. Using Cetyl Trimethyl Ammonium Bromide (CTAB) in place of Tx100 produces gels that are nearly colourless prior to irradiation, but reduces the dose sensitivity. The separate effects of Tri-chloro acetic acid concentration and pH are investigated, revealing that controlling the pH near 3.6 is crucial for achieving high dose sensitivity. The sensitizing effect of chlorinated species on dose sensitivity is tested using 2,2,2-trichloroethanol (TCE), chloroform, and 1,1,1-trichloro-2-methyl-2-propanol hemihydrate. TCE gives the largest improvement in dose sensitivity and is recommended for use in micelle gel dosimeters because it is less volatile and safer to use than chloroform. Preliminary experiments on a new gel containing CTAB as the surfactant and TCE show that this new gel gives a dose sensitivity that is 24% higher than that of previous LCV micelle gels and is nearly colourless prior to irradiation.

  7. Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry.

    PubMed

    Jafari, S M; Alalawi, A I; Hussein, M; Alsaleh, W; Najem, M A; Hugtenburg, R P; Bradley, D A; Spyrou, N M; Clark, C H; Nisbet, A

    2014-11-21

    An investigation has been made of glass beads and optical fibres as novel dosimeters for small-field photon radiation therapy dosimetry. Commercially available glass beads of largest dimension 1.5 mm and GeO2-doped SiO2 optical fibres of 5 mm length and 120 µm diameter were characterized as thermoluminescence dosimeters. Results were compared against Monte-Carlo simulations with BEAMnrc/DOSXYZnrc, EBT3 Gafchromic film, and a high-resolution 2D-array of liquid-filled ionization chambers. Measurements included relative output factors and dose profiles for square-field sizes of 1, 2, 3, 4, and 10 cm. A customized Solid-Water® phantom was employed, and the beads and fibres were placed at defined positions along the longitudinal axis to allow accurate beam profile measurement. Output factors and the beam profile parameters were compared against those calculated by BEAMnrc/DOSXYZnrc. The output factors and field width measurements were found to be in agreement with reference measurements to within better than 3.5% for all field sizes down to 2 cm2 for both dosimetric systems, with the beads showing a discrepancy of no more than 2.8% for all field sizes. The results confirm the potential of the beads and fibres as thermoluminescent dosimeters for use in small photon radiation field sizes.

  8. A small animal image guided irradiation system study using 3D dosimeters

    NASA Astrophysics Data System (ADS)

    Qian, Xin; Admovics, John; Wuu, Cheng-Shie

    2015-01-01

    In a high resolution image-guided small animal irradiation platform, a cone beam computed tomography (CBCT) is integrated with an irradiation unit for precise targeting. Precise quality assurance is essential for both imaging and irradiation components. The conventional commissioning techniques with films face major challenges due to alignment uncertainty and labour intensive film preparation and scanning. In addition, due to the novel design of this platform the mouse stage rotation for CBCT imaging is perpendicular to the gantry rotation for irradiation. Because these two rotations are associated with different mechanical systems, discrepancy between rotation isocenters exists. In order to deliver x-ray precisely, it is essential to verify coincidence of the imaging and the irradiation isocenters. A 3D PRESAGE dosimeter can provide an excellent tool for checking dosimetry and verifying coincidence of irradiation and imaging coordinates in one system. Dosimetric measurements were performed to obtain beam profiles and percent depth dose (PDD). Isocentricity and coincidence of the mouse stage and gantry rotations were evaluated with starshots acquired using PRESAGE dosimeters. A single PRESAGE dosimeter can provide 3 -D information in both geometric and dosimetric uncertainty, which is crucial for translational studies.

  9. Effect of driving pressure and nebulizer model on aerosol output during intermittent delivery with a dosimeter.

    PubMed

    Alkins, Stephan A; Hurwitz, Kenneth M; Sierra, Angel

    2002-01-01

    Recent guidelines reinforce the need for a standardized technique during inhalational bronchoprovocation challenge testing. We investigated the effects of nebulizer model and dosimeter driving pressure on nebulizer output using a nebulized saline model. Four nebulizers (Hudson 1720, Salter 8900, Baxter Airlife, and DeVilbiss 644) were evaluated at two driving pressures (20 and 50 pounds per square inch [psi]) via a dosimeter (Salter 700) that delivered a 0.6-sec actuation. Output was determined gravimetrically after 20 actuations of saline at constant respiratory flow and volume. Output per actuation at 20 psi was 2.83 +/- 0.41 mg (mean +/- SD), 4.58 +/- 0.66, 4.75 +/- 0.42, and 4.75 +/- 1.37 for the Hudson, Salter, Baxter, and DeVilbiss, respectively, and 6.75 +/- 0.61 mg, 9.17 +/- 0.88, 9.42 +/- 1.32, and 9.83 +/- 1.75 at 50 psi. The Hudson delivered a lower volume than the other nebulizers (p < 0.0005). At 20 psi, output from the DeVilbiss had greater variability (coefficient of variation = 28.8%) compared to the Baxter (CV = 8.8%; p = 0.045). The output was greater at 50 psi than 20 psi for all models (p < 0.0005). These results demonstrate that, when choosing a nebulizer driven by a dosimeter, it is important to base that selection on published data describing aerosol output under different driving pressures.

  10. Response of Panasonic dosimeters to submersion exposure by sup 133 Xe

    SciTech Connect

    Hoffman, J.M.; Catchen, G.L. )

    1990-01-01

    The dose response to {sup 133}Xe radiation of several types of Panasonic 800 series thermoluminescent dosimeters (TLD) were evaluated. The dosimeters were exposed by submersion in {sup 133}Xe gas. The relative sensitivities of the lithium borate and the calcium sulfate phosphors were determined for several configurations. The TLDs were exposed in the holders (as the devices came from the vendor) with various shields covering the elements, and they were exposed with the TLDs removed from the holders. Some dosimeters were exposed, both in holders and out of holders (TL insert only configuration), both in plastic bags and free in air. For the in-holder configuration, the responses of the heavily shielded (greater than 170 mg cm-2) elements were used to obtain the photon dose-rate component, and the responses of the lightly shielded (less than 13 mg cm-2) element were used to obtain the beta component. Similarly, for the insert-only configurations, the observed over-response of the calcium sulfate phosphors to low-energy photons could be used to separate the beta dose rate component. By using the calculated beta doses, correction factors were determined for the apparent under-responses of the elements to beta radiation. The results of both methods are consistent. These results also suggest that the beta component could be used in environmental monitoring as a more sensitive means to determine {sup 133}Xe activities in clouds and to separate some of the effects of submersion exposure from those of distant exposure.

  11. r and s-processes: Chronometers, thermometers and neutron dosimeters

    SciTech Connect

    Winters, R.R.

    1985-01-20

    Recent measurements of neutron cross sections have provided new data which can be incorporated into models of nucleosynthesis to allow more reliable estimates of the duration and physical conditions under which the heavier chemical elements formed. Measurements of various neutron capture and scattering cross sections for the osmium isotopes have greatly reduced the uncertainty associated with the use of the Re/Os beta decay as a nucleosynthetic chronometer. In particular, measurements of the /sup 189/Os(n,n') and /sup 189/Os(n,..gamma..) cross sections appear to support the use of the optical model and the Brink-Axel hypothesis to calculate neutron and gamma ray transmission factors needed to estimate the effects of the first excited state in /sup 187/Os on neutron capture in a stellar environment. Our latest results imply that the laboratory cross section should be enhanced by about 20% as estimated by Woosley and Fowler and, hence, the age of the chemical elements is estimated to be (17 +- 3) byr. Branchings in the s-process path can provide information about the temperature and/or neutron density during nucleosynthesis. Recent measurements of the neutron capture cross sections of the samarium isotopes imply a branch at /sup 147/Nd partly bypassing /sup 148/Sm. Analysis of this branching yield an estimate for the s-process neutron density of approx.10/sup 8/ cm/sup -3/.

  12. Red emission phosphor for real-time skin dosimeter for fluoroscopy and interventional radiology

    SciTech Connect

    Nakamura, Masaaki Chida, Koichi; Zuguchi, Masayuki

    2014-10-15

    Purpose: There are no effective real-time direct skin dosimeters for interventional radiology. Such a scintillation dosimeter would be available if there was a suitable red emission phosphor in the medical x-ray range, since the silicon photodiode is a highly efficient device for red light. However, it is unknown whether there is a suitable red emission phosphor. The purpose of this study is to find a suitable red emission phosphor that can be used in x-ray dosimeters. Methods: Five kinds of phosphors which emit red light when irradiated with electron beams or ultraviolet rays in practical devices were chosen. For the brightness measurement, phosphor was put into transparent plastic cells or coated onto plastic sheets. The phosphors were irradiated with medical range x-rays [60–120 kV(peak), maximum dose rate of 160 mGy min{sup −1}], and the emission was measured by a luminance meter. Several characteristics, such as brightness, dose rate dependence, tube voltage dependence, and brightness stability, were investigated. Results: The luminescence of Y V O{sub 4}:Eu, (Y,Gd,Eu) BO{sub 3}, and Y{sub 2}O{sub 3}:Eu significantly deteriorated by 5%–10% when irradiated with continuous 2 Gy x-rays. The 0.5MgF{sub 2}⋅3.5MgO⋅GeO{sub 2}:Mn phosphor did not emit enough. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration, and it had a linear relationship so that the x-ray dose rate could be determined from the brightness with sufficient accuracy. For the tube voltage dependence of the Y{sub 2}O{sub 2}S:Eu,Sm phosphor, the brightness per unit dose rate with 120 kV(peak) x-rays was 30% higher than that with 60 kV(peak) x-rays. Conclusions: Five kinds of phosphors were chosen as an x-ray scintillator for a real-time direct skin dosimeter. The Y V O{sub 4}:Eu, (Y,Gd,Eu)BO{sub 3}, and Y{sub 2}O{sub 3}:Eu phosphors had brightness deterioration caused by the x-rays. Only the Y{sub 2}O{sub 2}S:Eu,Sm phosphor had hardly any brightness deterioration

  13. Characterization of MOSFET Dosimeter Angular Response Using a Spherical Phantom for Fluoroscopic Dosimetry.

    PubMed

    Wang, Chu; Hill, Kevin; Yoshizumi, Terry

    2016-01-01

    Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) dosimeters, placed in anthropomorphic phantoms, are a standard method for organ dosimetry in medical x-ray imaging applications. However, many x-ray applications, particularly fluoroscopy procedures, use variable projection angles. During dosimetry, the MOSFET detector active area may not always be perpendicular to the x-ray beam. The goal of this study was to characterize the dosimeter's angular response in the fluoroscopic irradiation involved in pediatric cardiac catheterization procedures, during which a considerable amount of fluoroscopic x-ray irradiation is often applied from various projection angles. A biological x-ray irradiator was used to simulate the beam quality of a biplane fluoroscopy imaging system. A custom-designed acrylic spherical scatter phantom was fabricated to measure dosimeter response (in mV) in two rotational axes, axial (ψ) and normal-to-axial (θ), in 30° increments, as well as four common oblique angles used in cardiac catheterization: a) 90° Left Anterior Oblique (LAO); b) 70° LAO/ 20° Cranial; c) 20° LAO/ 15° Cranial; and d) 30° Right Anterior Oblique (RAO). All results were normalized to the angle where the dosimeter epoxy is perpendicular to the beam or the Posterior-Anterior projection angle in the clinical setup. The relative response in the axial rotation was isotropic (within ± 10% deviation); that in the normal-to-axial rotation was isotropic in all angles except the ψ = 270° angle, where the relative response was 83 ± 9%. No significant deviation in detector response was observed in the four common oblique angles, with their relative responses being: a) 102 ± 3%; b) 90 ± 3%; c) 92 ± 3%; and d) 95 ± 3%, respectively. These angular correction factors will be used in future dosimetry studies for fluoroscopy. The spherical phantom may be useful for other applications, as it allows the measurement of dosimeter response in virtually all angles in the 3

  14. Calibration and conformational studies in radiation dosimetry using polymer gel dosimeters

    NASA Astrophysics Data System (ADS)

    Cardenas, Richard L.

    2001-11-01

    The polymer gel dosimeter made its debut in the early 90's and dosimetrists and medical physicists alike were excited about the prospect of using the gel dosimeter as an effective and useful three-dimensional modeling tool. Research in the early to mid-90's brought on better polymer mixtures with greater sensitivity and shelf life. Nearly a decade later, these gels are not being used in a clinical setting. The question is, why are they not being routinely used in the clinical setting for modeling and quality assurance of radiation instrumentation and computer generated treatment plans? There are three main reasons and we address these reasons directly in this investigation. First, every promising experiment performed on these gels were done in ideal conditions. The problem ideal experimentation is that the conditions in a clinical setting are unpredictable hence these idealized protocols could not be easily used in practice. Second, attempts to use the gels in clinical settings had mixed results. There was no real consistency with the results based on calibration curves generated by the gel manufacturer and even based on additional calibration studies performed by the medical physicists. Third, there were no consistent and effective calculation programs that were flexible, rigorous, and consistent to use. Due to these main problems, medical physicists have begun to dismiss the gel dosimeter and reverted to traditional 1-dimensional and 2-dimensional verification methods. What we developed in this study is a means to put the polymer gel dosimeter back into the forefront of dosimetry. First, we performed experiments under a clinical setting. Then, we investigated three different calibration methods, including our very own normalized calibration protocol to identify calibration problems and offer up a solution to this problem. Finally, we also generated a good data processing program that is flexible, rigorous, and consistent to use in any setting. In addition to

  15. Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study.

    PubMed

    Al-Karmi, Anan M; Ayaz, Ali Asghar H; Al-Enezi, Mamdouh S; Abdel-Rahman, Wamied; Dwaikat, Nidal

    2015-09-01

    Alanine dosimeters in the form of pure alanine powder in PMMA plastic tubes were investigated for dosimetry in a clinical application. Electron paramagnetic resonance (EPR) spectroscopy was used to measure absorbed radiation doses by detection of signals from radicals generated in irradiated alanine. The measurements were performed for low-dose ranges typical for single-fraction doses often used in external photon beam radiotherapy. First, the dosimeters were irradiated in a solid water phantom to establish calibration curves in the dose range from 0.3 to 3 Gy for 6 and 18 MV X-ray beams from a clinical linear accelerator. Next, the dosimeters were placed at various locations in an anthropomorphic pelvic phantom to measure the dose delivery of a conventional four-field box technique treatment plan to the pelvis. Finally, the doses measured with alanine dosimeters were compared against the doses calculated with a commercial treatment planning system (TPS). The results showed that the alanine dosimeters have a highly sensitive dose response with good linearity and no energy dependence in the dose range and photon beams used in this work. Also, a fairly good agreement was found between the in-phantom dose measurements with alanine dosimeters and the TPS dose calculations. The mean value of the ratios of measured to calculated dose values was found to be near unity. The measured points in the in-field region passed dose-difference acceptance criterion of 3% and those in the penumbral region passed distance-to-agreement acceptance criterion of 3 mm. These findings suggest that the pure alanine powder in PMMA tube dosimeter is a suitable option for dosimetry of radiotherapy photon beams.

  16. Response verification of dose rate and time dependence of PAGAT polymer gel dosimeters by photon beams using magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Azadbakht, B.; Hadad, K.; Zahmatkesh, M. H.

    2009-05-01

    The purpose of this study was to evaluate dependence of PAGAT polymer gel dosimeter 1/T2 on different post time imaging as well as on different mean dose rates for a standard clinically used Co-60 therapy unit and an electa linear accelerator. Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2(1/T2) was determined to be 4.5% N,N'-methylen-bis-acrylamide(bis), 4.5% acrylamid(AA), 5% gelatine, 5 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC), 0.01 mM hydroquinone (HQ) and 86% HPLC(Water).When the preparation of final polymer gel solution is completed, it is transferred into phantoms and allowed to set by storage in a refrigerator at about 4°C. The sensitivity of the dosimeter was represented by the slope of calibration curve in the linear region measured for each modality. A calibration curve (in the linear region) based on 16 dosimeters (15 irradiated and one background) was obtained for 1.25 MV photon beam. To determine the calibration curve of the PAGAT polymer gel dosimeter, there are two linear responses between 2-10Gy and 10-30Gy and the R2-dose sensitivity showed stability with imaging post time after 38 days. Dose rate of dependence was studied in 6 MV photon beam with the use of dose rates 80, 160, 240, 320, 400 and 480 cGy/min. Evaluation of dosimeters were performed on Siemens Symphony, Germany 1.5T Scanner in the head coil. A multi echo sequence with 32 equidistant echoes was used for the evaluation of irradiated polymer gel dosimeters. The parameters of the sequence were as follows: TR 3000ms, TE 20ms, Slice Thickness 4 mm and FOV 256mm. No trend in polymer-gel dosimeter 1/T2 dependence was found on mean dose rate for photon beams.

  17. Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study.

    PubMed

    Al-Karmi, Anan M; Ayaz, Ali Asghar H; Al-Enezi, Mamdouh S; Abdel-Rahman, Wamied; Dwaikat, Nidal

    2015-09-01

    Alanine dosimeters in the form of pure alanine powder in PMMA plastic tubes were investigated for dosimetry in a clinical application. Electron paramagnetic resonance (EPR) spectroscopy was used to measure absorbed radiation doses by detection of signals from radicals generated in irradiated alanine. The measurements were performed for low-dose ranges typical for single-fraction doses often used in external photon beam radiotherapy. First, the dosimeters were irradiated in a solid water phantom to establish calibration curves in the dose range from 0.3 to 3 Gy for 6 and 18 MV X-ray beams from a clinical linear accelerator. Next, the dosimeters were placed at various locations in an anthropomorphic pelvic phantom to measure the dose delivery of a conventional four-field box technique treatment plan to the pelvis. Finally, the doses measured with alanine dosimeters were compared against the doses calculated with a commercial treatment planning system (TPS). The results showed that the alanine dosimeters have a highly sensitive dose response with good linearity and no energy dependence in the dose range and photon beams used in this work. Also, a fairly good agreement was found between the in-phantom dose measurements with alanine dosimeters and the TPS dose calculations. The mean value of the ratios of measured to calculated dose values was found to be near unity. The measured points in the in-field region passed dose-difference acceptance criterion of 3% and those in the penumbral region passed distance-to-agreement acceptance criterion of 3 mm. These findings suggest that the pure alanine powder in PMMA tube dosimeter is a suitable option for dosimetry of radiotherapy photon beams. PMID:26138456

  18. Dose response and post-irradiation characteristics of the Sunna 535-nm photo-fluorescent film dosimeter

    NASA Astrophysics Data System (ADS)

    Murphy, M. K.; Kovács, A.; Miller, S. D.; McLaughlin, W. L.

    2003-12-01

    Results of characterization studies on one of the first versions of the Sunna photo-fluorescent dosimeter™ have previously been reported, and the performance of the red fluorescence component described. This present paper describes dose response and post-irradiation characteristics of the green fluorescence component from the same dosimeter film ( Sunna Model γ), which is manufactured using the injection molding technique. This production method may supply batch sizes on the order of 1 million dosimeter film elements while maintaining a signal precision (1 σ) on the order of ±1% without the need to correct for variability of film thickness. The dosimeter is a 1 cm×3 cm polymeric film of 0.5-mm thickness that emits green fluorescence at intensities increasing almost linearly with dose. The data presented include dose response, post-irradiation growth, heat treatment, dosimeter aging, dose rate dependence, energy dependence, dose fractionation, variation of response within a batch, and the stability of the fluorimeter response. The results indicate that, as a routine dosimeter, the green signal provides a broad range of response at food irradiation (0.3-5 kGy), medical sterilization (5-40 kGy), and polymer cross-linking (40-250 kGy) dose levels.

  19. High-precision dosimetry for radiotherapy using the optically stimulated luminescence technique and thin Al2O3:C dosimeters

    NASA Astrophysics Data System (ADS)

    Yukihara, E. G.; Yoshimura, E. M.; Lindstrom, T. D.; Ahmad, S.; Taylor, K. K.; Mardirossian, G.

    2005-12-01

    The potential of using the optically stimulated luminescence (OSL) technique with aluminium oxide (Al2O3:C) dosimeters for a precise and accurate estimation of absorbed doses delivered by high-energy photon beams was investigated. This study demonstrates the high reproducibility of the OSL measurements and presents a preliminary determination of the depth-dose curve in water for a 6 MV photon beam from a linear accelerator. The uncertainty of a single OSL measurement, estimated from the variance of a large sample of dosimeters irradiated with the same dose, was 0.7%. In the depth-dose curve obtained using the OSL technique, the difference between the measured and expected doses was <=0.7% for depths between 1.5 and 10 cm, and 1.1% for a depth of 15 cm. The readout procedure includes a normalization of the response of the dosimeter with respect to a reference dose in order to eliminate variations in the dosimeter mass, dosimeter sensitivity, and the reader's sensitivity. This may be relevant for quality assurance programmes, since it simplifies the requirements in terms of personnel training to achieve the precision and accuracy necessary for radiotherapy applications. We concluded that the OSL technique has the potential to be reliably incorporated in quality assurance programmes and dose verification.

  20. Characterization of a medical X-ray machine for testing the response of electronic dosimeters in pulsed radiation fields

    NASA Astrophysics Data System (ADS)

    Guimarães, Margarete C.; Da Silva, Teógenes A.

    2014-11-01

    Electronic personal dosimeters (EPD) based on solid state detectors have been used for personnel monitoring for radiation protection purpose; their use has been extended to practices with pulsed radiation beams although their performance is not well known. Deficiencies in the EPD response in pulsed radiation fields have been reported; they were not detected before since type tests and calibrations of EPDs were established in terms of continuous X and gamma reference radiations. An ISO working group was formed to elaborate a standard for test conditions and performance requirements of EPDs in pulsed beams; the PTB/Germany implemented a special X-ray facility for generating the reference pulsed radiation beams. In this work, an 800 Plus VMI medical X-ray machine of the Dosimeter Calibration Laboratory of CDTN/CNEN was characterized to verify its feasibility to perform EPD tests. Characterization of the x-ray beam was done in terms of practical peak voltage, half-value layer, mean energy and air kerma rate. Reference dosimeters used for air kerma measurements were verified as far their metrological coherence and a procedure for testing EDPs was established. Electronic personal dosimeters (EPD) have been used for personnel monitoring. EPD use has been extended to pulsed radiation beams. Deficiencies in the EPD response in pulsed beams have been reported. The feasibility of using a medical X-ray machine to perform EPD tests was studied. Reference dosimeters were verified and EPD testing procedure was established.

  1. The role of the spectral sensitivity curve in the selection of relevant biological dosimeters for solar UV monitoring.

    PubMed

    Modos, K; Gaspar, S; Kerekgyarto, T; Vink, A A; Roza, L; Fekete, A

    1999-01-01

    To estimate the risk of enhanced UV-B radiation due to stratospheric ozone depletion, phage T7 and uracil thin-layer biological dosimeters have been developed, which weight the UV irradiance according to induced DNA damage. To study the molecular basis of the biological effects observed after UV irradiation, the spectral sensitivity curves of the two dosimeters and induction of the two major DNA photoproducts, cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts ((6-4)PDs), in phage T7 have been determined for polychromatic UV sources. CPDs and (6-4)PDs are determined by lesion-specific monoclonal antibodies in an immunodotblot assay. Phage T7 and uracil biological dosimeters together with a Robertson-Berger (RB) meter have been used for monitoring environmental radiation from the polar region to the equator. The biologically effective dose (BED) established with the three different dosimeters increases according to the changes in the solar angle and ozone column, but the degree of the change differs significantly. The results can be explained based on the different spectral sensitivities of the dosimeters. A possible method for determining the trend of the increase in the biological risk due to ozone depletion is suggested.

  2. Radiation-induced refraction artifacts in the optical CT readout of polymer gel dosimeters

    SciTech Connect

    Campbell, Warren G.; Jirasek, Andrew; Wells, Derek M.

    2014-11-01

    Purpose: The objective of this work is to demonstrate imaging artifacts that can occur during the optical computed tomography (CT) scanning of polymer gel dosimeters due to radiation-induced refractive index (RI) changes in polyacrylamide gels. Methods: A 1 L cylindrical polyacrylamide gel dosimeter was irradiated with 3 × 3 cm{sup 2} square beams of 6 MV photons. A prototype fan-beam optical CT scanner was used to image the dosimeter. Investigative optical CT scans were performed to examine two types of rayline bending: (i) bending within the plane of the fan-beam and (ii) bending out the plane of the fan-beam. To address structured errors, an iterative Savitzky–Golay (ISG) filtering routine was designed to filter 2D projections in sinogram space. For comparison, 2D projections were alternatively filtered using an adaptive-mean (AM) filter. Results: In-plane rayline bending was most notably observed in optical CT projections where rays of the fan-beam confronted a sustained dose gradient that was perpendicular to their trajectory but within the fan-beam plane. These errors caused distinct streaking artifacts in image reconstructions due to the refraction of higher intensity rays toward more opaque regions of the dosimeter. Out-of-plane rayline bending was observed in slices of the dosimeter that featured dose gradients perpendicular to the plane of the fan-beam. These errors caused widespread, severe overestimations of dose in image reconstructions due to the higher-than-actual opacity that is perceived by the scanner when light is bent off of the detector array. The ISG filtering routine outperformed AM filtering for both in-plane and out-of-plane rayline errors caused by radiation-induced RI changes. For in-plane rayline errors, streaks in an irradiated region (>7 Gy) were as high as 49% for unfiltered data, 14% for AM, and 6% for ISG. For out-of-plane rayline errors, overestimations of dose in a low-dose region (∼50 cGy) were as high as 13 Gy for

  3. Temporal signal stability of KCl:Eu{sup 2+} storage phosphor dosimeters

    SciTech Connect

    Xiao Zhiyan; Hansel, Rachael; Chen Haijian; Du Dongsu; Yang Deshan; Li, H. Harold

    2013-02-15

    Purpose: Current KCl:Eu{sup 2+} prototype dosimeters require a wait time of 12 h between irradiation and dosimetric readout. Although irradiating the dosimeters in the evening and reading on the following day works well in the clinical schedule, reducing the wait time to few hours is desirable. The purposes of this work are to determine the origin of the unstable charge-storage centers and to determine if these centers respond to optical or thermal excitation prior to dosimetric readout. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters were fabricated in-house for this study. A 6 MV photon beam was used to irradiate the dosimeters. After x ray irradiation, dosimeters were subjected to external excitation with near-infrared (NIR) light, ultraviolet (UV) light, or thermal treatment. Photostimulated luminescence (PSL) signal's temporal stability was subsequently measured at room temperature over a few hours using a laboratory PSL readout system. The dosimeters were also placed in a cryostat to measure the temperature dependence of the temporal stability down to 10 K. Results: Strong F-band was present in the PSL stimulation spectrum, indicating that F-centers were the electron-storage centers in KCl:Eu{sup 2+} where an electron was stored at a chlorine anion vacancy. Due to deep energy-depth (2.2 eV), F-centers were probably not responsible for the fast fading in the first a few hours post x ray irradiation. In addition, weak NIR bands were present. However, there was no change in PSL stabilization rate with intense NIR excitation, suggesting that the NIR bands played no role in the PSL fading. At temperatures lower than 77 K there was almost no signal fading with time. Noticeable PSL was observed for undoped KCl samples at room temperature, suggesting that Cl{sub 2}{sup -} V{sub k} centers served as hole-storage centers for both undoped and doped KCl where a hole was trapped by a chlorine molecular ion. V{sub k} centers were stable at low temperature and became mobile

  4. SU-E-T-511: Do Presage 3D Dosimeters Show Dose Fractionation Sensitivity?

    SciTech Connect

    Klawikowski, S; Alqathami, M; Ibbott, G; Adamovics, J; Benning, R

    2014-06-01

    Purpose: To determine whether Presage 3D polymer dosimeter dose response is sensitive to dose delivery fractionation. Bang gels have demonstrated a dose fractionation related dependence in which a single 400 cGy irradiation would produce a different detector response than four 100 cGy irradiations even if delivered closely in time to one another. Such a fractional dependent response in Presage would be detrimental for measuring multi-beam irradiations. Methods: Two separate batches of Presage were poured into cuvettes, and a third batch was molded into cuvette shaped blocks. A total of 37 cuvettes/blocks were irradiated in a Cobalt-60 irradiator to 400 cGy within solid water phantoms in either one, eight, or sixteen fractions. Another group of 15 cuvettes were also kept unirradiated and used for background subtraction between the pre-scan and post-scan results. The times between fractional deliveries were held constant at 30 seconds and the Cobalt irradiator dose rate was 49 cGy/min. Each Presage batch has a separate dose sensitivity and therefore fractionation response comparisons were only performed within the same batch. The cuvettes were first pre-scanned the day prior to irradiation and post-scanned the day after irradiation. Other than approximately 3 hours warming time prior to each irradiation and optical density measurement the cuvettes were stored in a refrigerator. All cuvettes were stored in a lightless environment throughout manufacturing and testing. The cuvettes’ optical densities were optically measured at 632 nm with a spectrophotometer. Results: No noticeable dose fractionation dependence was detected for any of the three independent batches of Presage for either the eight or sixteen fraction irradiation schemes. Conclusion: These results indicate using Presage 3D dosimeters to measure multi-beam photon irradiations common in IMRT, Gamma Knife, and Cyberknife treatment delivery schemes. Presage dosimeters are made by and trademarked by Heuris

  5. Investigation of the dose characteristics of an n-NIPAM gel dosimeter with computed tomography

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Yu; Shih, Tian-Yu; Hsieh, Bor-Tsung; Chang, Shu-Jun; Liu, Yan-Lin; Wu, Tung-Hsin; Wu, Jay

    2011-10-01

    Nowadays, radiotherapy attempts to deliver complex three-dimensional (3-D) dose distribution. The gel dosimeter, which can measure the 3-D dose output, is suitable for clinical use. This study developed an n-NIPAM gel dosimeter based on an N-isopropyl-acrylamide monomer, and used computed tomography (CT) to evaluate the characteristics of n-NIPAM gels. The n-NIPAM gel consisted of 6% gelatin, 5% monomer, and 2.5% cross-linker combined with 5 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC) for deoxygenation. Dose responses of 2-15 Gy delivered by a linear accelerator were examined. Temporal instability, energy dependence, dose rate dependence, and spatial resolution were evaluated as well. Temporal instability appeared before 24 h post-irradiation. The maximum difference of sensitivity reached 33% for various dose rates from 100 to 500 cGy min -1, while it was within 10% for X-ray energies from 6 to 15 MV. The average sensitivity of n-NIPAM under 6 MV and 400 cGy min -1 was 0.5689 HU Gy -1, and the linearity ( R2=0.998) was comparable to that of the conventional NIPAM gels. For the spatial resolution, the edge spread distances were generally shorter than 6.5 mm for adjacent quadrants with different dose gradients of 5/10, 5/15, 10/20, and 15/20 Gy. We conclude that n-NIPAM has high linearity and high sensitivity. Although the energy dependence is minor, there is a slight dose rate dependence. The proposed dosimeter with CT readout is suitable in clinical radiotherapy to increase the accuracy of dose verification.

  6. A Comprehensive Evaluation of NIPAM Polymer Gel Dosimeters on Three Orthogonal Planes and Temporal Stability Analysis.

    PubMed

    Cheng, Kai-Yuan; Hsieh, Ling-Ling; Shih, Cheng-Ting

    2016-01-01

    Polymer gel dosimeters have been proven useful for dose evaluation in radiotherapy treatments. Previous studies have demonstrated that using a polymer gel dosimeter requires a 24 h reaction time to stabilize and further evaluate the measured dose distribution in two-dimensional dosimetry. In this study, the short-term stability within 24 h and feasibility of N-isopropylacrylamide (NIPAM) polymer gel dosimeters for use in three-dimensional dosimetry were evaluated using magnetic resonance imaging (MRI). NIPAM gels were used to measure the dose volume in a clinical case of intensity-modulated radiation therapy (IMRT). For dose readouts, MR images of irradiated NIPAM gel phantoms were acquired at 2, 5, 12, and 24 h after dose delivery. The mean standard errors of dose conversion from using dose calibration curves (DRC) were calculated. The measured dose volumes at the four time points were compared with those calculated using a treatment planning system (TPS). The mean standard errors of the dose conversion from using the DRCs were lower than 1 Gy. Mean pass rates of 2, 5, 12, and 24 h axial dose maps calculated using gamma evaluation with 3% dose difference and 3 mm distance-to-agreement criteria were 83.5% ± 0.9%, 85.9% ± 0.6%, 98.7% ± 0.3%, and 98.5% ± 0.9%, respectively. Compared with the dose volume histogram of the TPS, the absolute mean relative volume differences of the 2, 5, 12, and 24 h measured dose volumes were lower than 1% for the irradiated region with an absorbed dose higher than 2.8 Gy. It was concluded that a 12 h reaction time was sufficient to acquire accurate dose volume using the NIPAM gels with MR readouts. PMID:27192217

  7. A Comprehensive Evaluation of NIPAM Polymer Gel Dosimeters on Three Orthogonal Planes and Temporal Stability Analysis

    PubMed Central

    Shih, Cheng-Ting

    2016-01-01

    Polymer gel dosimeters have been proven useful for dose evaluation in radiotherapy treatments. Previous studies have demonstrated that using a polymer gel dosimeter requires a 24 h reaction time to stabilize and further evaluate the measured dose distribution in two-dimensional dosimetry. In this study, the short-term stability within 24 h and feasibility of N-isopropylacrylamide (NIPAM) polymer gel dosimeters for use in three-dimensional dosimetry were evaluated using magnetic resonance imaging (MRI). NIPAM gels were used to measure the dose volume in a clinical case of intensity-modulated radiation therapy (IMRT). For dose readouts, MR images of irradiated NIPAM gel phantoms were acquired at 2, 5, 12, and 24 h after dose delivery. The mean standard errors of dose conversion from using dose calibration curves (DRC) were calculated. The measured dose volumes at the four time points were compared with those calculated using a treatment planning system (TPS). The mean standard errors of the dose conversion from using the DRCs were lower than 1 Gy. Mean pass rates of 2, 5, 12, and 24 h axial dose maps calculated using gamma evaluation with 3% dose difference and 3 mm distance-to-agreement criteria were 83.5% ± 0.9%, 85.9% ± 0.6%, 98.7% ± 0.3%, and 98.5% ± 0.9%, respectively. Compared with the dose volume histogram of the TPS, the absolute mean relative volume differences of the 2, 5, 12, and 24 h measured dose volumes were lower than 1% for the irradiated region with an absorbed dose higher than 2.8 Gy. It was concluded that a 12 h reaction time was sufficient to acquire accurate dose volume using the NIPAM gels with MR readouts. PMID:27192217

  8. Design of an advanced TLD-based fixed nuclear accident dosimeter

    SciTech Connect

    Casson, W.H.; Mei, G.T.

    1993-08-01

    A new system has been designed for use as a fixed nuclear accident dosimeter based upon the thermoluminescent dosimeter (TLD) system used for personnel dosimetry at US Department of Energy facilities managed by Martin Marietta Energy Systems, Inc. The system is made up of a small phantom consisting of two main parts measuring 20 x 20 x 5 cm and made from polymethylmethacrylate. A neutron-sensitive TLD card is placed in the center between the two pieces. Also, TLD cards in standard holders are mounted on the front and back of the phantom. A derivation is made of a linear combination of the responses from the TLD elements which results in calculation of the neutron fluence, absorbed dose, and dose equivalent. By using the right linear combinations, a crude spectrum can be estimated, which allows further calculation of the average fluence-to-dose-equivalent conversion factor. The response of the system was tested and found to be applicable for the evaluation of typical nuclear accident spectra, although considerable improvement can be made by the addition of a sulfur pellet. The system was also tested for angular dependence. In order to move the development of this system from the proof-of-principle to full application, the calculation of the TLD resonse curves must be improved, additional measurements must be made, and the system must be tested in a simulated accident neutron field. The advantages of the new fixed dosimeter system are its simplicity, easy maintenance, and lower operational cost. The system uses standard TLD cards that are already in place throughout Energy Systems facilities. The TLD process personnel are famliiar with evaluating doses from TLDs and can provide information necessary to ensure timely and accurate assessment of exposures that may result from riticality accidents. Most of the quality control requirements are part of the existing personnel dosimetry system.

  9. Relative response of the alanine dosimeter to medium energy x-rays.

    PubMed

    Anton, M; Büermann, L

    2015-08-01

    The response of the alanine dosimeter to kilovoltage x-rays with respect to the dose to water was measured, relative to the response to Co-60 radiation.Two series of x-ray qualities were investigated, one ranging from 30 kV to 100 kV tube voltage (TW series), the other one ranging from 70 kV to 280 kV (TH series). Due to the use of the water calorimeter as a primary standard, the uncertainty of the delivered dose is significantly lower than for other published data. The alanine response was measured as described in a previous publication (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The uncertainty component due to the alanine measurement and analysis is ⩽0.4%, the major part of the combined uncertainty of the relative response originates from the uncertainty of the delivered dose. The relative uncertainties of the relative response vary from ⩽2% for the TW series to ⩽1.1% for the TH series.Different from the behaviour of the alanine dosimeter for megavoltage x-rays or electrons, the relative response drops significantly from unity for Co-60 radiation to less than 64% for the TW quality with a tube voltage of 30 kV. In order to reproduce this behaviour through Monte Carlo simulations, not only the ratio of the absorbed dose to alanine to the absorbed dose to water has to be known, but also the intrinsic efficiency, i.e. the dependence of the number of free radicals generated per unit of absorbed dose on the photon energy. This quantity is not yet accessible for the TW series.For a possible use of the alanine dosimeter for kilovoltage x-rays, for example in electronic brachytherapy, users should rely on the measured data for the relative response which have become available with this publication. PMID:26216572

  10. Relative response of the alanine dosimeter to medium energy x-rays

    NASA Astrophysics Data System (ADS)

    Anton, M.; Büermann, L.

    2015-08-01

    The response of the alanine dosimeter to kilovoltage x-rays with respect to the dose to water was measured, relative to the response to Co-60 radiation. Two series of x-ray qualities were investigated, one ranging from 30 kV to 100 kV tube voltage (TW series), the other one ranging from 70 kV to 280 kV (TH series). Due to the use of the water calorimeter as a primary standard, the uncertainty of the delivered dose is significantly lower than for other published data. The alanine response was measured as described in a previous publication (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The uncertainty component due to the alanine measurement and analysis is ⩽0.4%, the major part of the combined uncertainty of the relative response originates from the uncertainty of the delivered dose. The relative uncertainties of the relative response vary from ⩽2% for the TW series to ⩽1.1% for the TH series. Different from the behaviour of the alanine dosimeter for megavoltage x-rays or electrons, the relative response drops significantly from unity for Co-60 radiation to less than 64% for the TW quality with a tube voltage of 30 kV. In order to reproduce this behaviour through Monte Carlo simulations, not only the ratio of the absorbed dose to alanine to the absorbed dose to water has to be known, but also the intrinsic efficiency, i.e. the dependence of the number of free radicals generated per unit of absorbed dose on the photon energy. This quantity is not yet accessible for the TW series. For a possible use of the alanine dosimeter for kilovoltage x-rays, for example in electronic brachytherapy, users should rely on the measured data for the relative response which have become available with this publication.

  11. Relative response of the alanine dosimeter to medium energy x-rays.

    PubMed

    Anton, M; Büermann, L

    2015-08-01

    The response of the alanine dosimeter to kilovoltage x-rays with respect to the dose to water was measured, relative to the response to Co-60 radiation.Two series of x-ray qualities were investigated, one ranging from 30 kV to 100 kV tube voltage (TW series), the other one ranging from 70 kV to 280 kV (TH series). Due to the use of the water calorimeter as a primary standard, the uncertainty of the delivered dose is significantly lower than for other published data. The alanine response was measured as described in a previous publication (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The uncertainty component due to the alanine measurement and analysis is ⩽0.4%, the major part of the combined uncertainty of the relative response originates from the uncertainty of the delivered dose. The relative uncertainties of the relative response vary from ⩽2% for the TW series to ⩽1.1% for the TH series.Different from the behaviour of the alanine dosimeter for megavoltage x-rays or electrons, the relative response drops significantly from unity for Co-60 radiation to less than 64% for the TW quality with a tube voltage of 30 kV. In order to reproduce this behaviour through Monte Carlo simulations, not only the ratio of the absorbed dose to alanine to the absorbed dose to water has to be known, but also the intrinsic efficiency, i.e. the dependence of the number of free radicals generated per unit of absorbed dose on the photon energy. This quantity is not yet accessible for the TW series.For a possible use of the alanine dosimeter for kilovoltage x-rays, for example in electronic brachytherapy, users should rely on the measured data for the relative response which have become available with this publication.

  12. Investigation of the clinical performance of a novel solid-state diagnostic dosimeter.

    PubMed

    Tse, Jason; McLean, Donald

    2015-01-01

    This study investigated the clinical performance of a novel solid-state diagnostic dosimeter, the RaySafe Xi transparent detector, by comparing its performance to a reference-class ionization chamber. Firstly a comparison of dosimeter response "free-in-air" with standard beam qualities was made, followed by an investigation into its relative transparency in an X-ray field and angular sensitivity dependence. The second part of the study looked at the overall performance of the transparent detector under scatter conditions with a number of beam qualities, including standard beam and those hardened by copper (Cu) filtration of thickness up to 0.9 mm, as would be encountered in the equipment testing of fluoroscopy systems. Overall, the transparent detector has demonstrated equivalent measurement properties to the ionization chamber under standard conditions and provided similar X-ray attenuation as reflected by the nearly identical radiographic parameters selected for both dosimeters by the automatic dose rate control (ADRC) system. Yet, it also possessed an asymmetric angular response which respectively under- and overestimated the dose contribution from the rear and lateral directions by the same amount of 50%. The transparent detector provided comparable dose reading of ± 3% to the ionization chamber with standard beam qualities and backscatter radiation present. These results were in good agreement with those of free-in-air measurement, indicating that the angular under- and overresponse might potentially compensate one another for accurate measurement. However, for identical Cu filtered beam qualities and setups, the transparent detector on average overresponded by 5.4% across the useful tube voltage range. In conclusion, the transparent detector, with its novel design, is essentially equivalent, within a 5% tolerance, to an ionization chamber, except in situations where beams hardened with Cu filtration are used with backscatter radiation present requiring

  13. A Method of Determining Accuracy and Precision for Dosimeter Systems Using Accreditation Data

    SciTech Connect

    Rick Cummings and John Flood

    2010-12-01

    A study of the uncertainty of dosimeter results is required by the national accreditation programs for each dosimeter model for which accreditation is sought. Typically, the methods used to determine uncertainty have included the partial differentiation method described in the U.S. Guide to Uncertainty in Measurements or the use of Monte Carlo techniques and probability distribution functions to generate simulated dose results. Each of these techniques has particular strengths and should be employed when the areas of uncertainty are required to be understood in detail. However, the uncertainty of dosimeter results can also be determined using a Model II One-Way Analysis of Variance technique and accreditation testing data. The strengths of the technique include (1) the method is straightforward and the data are provided under accreditation testing and (2) the method provides additional data for the analysis of long-term uncertainty using Statistical Process Control (SPC) techniques. The use of SPC to compare variances and standard deviations over time is described well in other areas and is not discussed in detail in this paper. The application of Analysis of Variance to historic testing data indicated that the accuracy in a representative dosimetry system (Panasonic® Model UD-802) was 8.2%, 5.1%, and 4.8% and the expanded uncertainties at the 95% confidence level were 10.7%, 14.9%, and 15.2% for the Accident, Protection Level-Shallow, and Protection Level-Deep test categories in the Department of Energy Laboratory Accreditation Program, respectively. The 95% level of confidence ranges were (0.98 to 1.19), (0.90 to 1.20), and (0.90 to 1.20) for the three groupings of test categories, respectively.

  14. A method of determining accuracy and precision for dosimeter systems using accreditation data.

    PubMed

    Cummings, Frederick; Flood, John R

    2010-12-01

    A study of the uncertainty of dosimeter results is required by the national accreditation programs for each dosimeter model for which accreditation is sought. Typically, the methods used to determine uncertainty have included the partial differentiation method described in the U.S. Guide to Uncertainty in Measurements or the use of Monte Carlo techniques and probability distribution functions to generate simulated dose results. Each of these techniques has particular strengths and should be employed when the areas of uncertainty are required to be understood in detail. However, the uncertainty of dosimeter results can also be determined using a Model II One-Way Analysis of Variance technique and accreditation testing data. The strengths of the technique include (1) the method is straightforward and the data are provided under accreditation testing and (2) the method provides additional data for the analysis of long-term uncertainty using Statistical Process Control (SPC) techniques. The use of SPC to compare variances and standard deviations over time is described well in other areas and is not discussed in detail in this paper. The application of Analysis of Variance to historic testing data indicated that the accuracy in a representative dosimetry system (Panasonic® Model UD-802) was 8.2%, 5.1%, and 4.8% and the expanded uncertainties at the 95% confidence level were 10.7%, 14.9%, and 15.2% for the Accident, Protection Level-Shallow, and Protection Level-Deep test categories in the Department of Energy Laboratory Accreditation Program, respectively. The 95% level of confidence ranges were (0.98 to 1.19), (0.90 to 1.20), and (0.90 to 1.20) for the three groupings of test categories, respectively. PMID:21068596

  15. Dosimeter design, construction, and implantation. [for recording HZE cosmic particle tracks

    NASA Technical Reports Server (NTRS)

    Winter, D. L.; Suri, K.; Durso, J. A.; Cota, F. L.; Ashley, W. W.; Binnard, R. M.; Haymaker, W.; Benton, E. V.; Cruty, M. R.; Zeman, W.

    1975-01-01

    To detect the passage of cosmic ray particles through the heads of the pocket mice during the Apollo XVII flight, a 'monitor' (dosimeter) composed of plastics was prepared and implanted under the scalp. The monitor was mounted on a platform, the undersurface of which fitted the contour of the skull. Numerous tests were run to assure that the presence of the monitor assembly beneath the scalp would be compatible with the well-being of the mice and that the capacity of the monitor to detect the traversal of cosmic ray particles would be preserved over the several weeks during which it would remain under the scalp.

  16. A method to correct for stray light in telecentric optical-CT imaging of radiochromic dosimeters.

    PubMed

    Thomas, Andrew; Newton, Joseph; Oldham, Mark

    2011-07-21

    Radiochromic plastic and gel materials have recently emerged which can yield 3D dose information over clinical volumes in high resolution. These dosimeters can provide a much more comprehensive verification of complex radiation therapy treatments than can be achieved by conventional planar and point dosimeters. To achieve full clinical potential, these dosimeters require a fast and accurate read-out technology. Broad-beam optical-computed tomography (optical-CT) systems have shown promise, but can be sensitive to stray light artifacts originating in the imaging chain. In this work we present and evaluate a method to correct for stray light artifacts by deconvolving a measured, spatially invariant, point spread function (PSF). The correction was developed for the DLOS (Duke large field-of-view optical-CT scanner) in conjunction with radiochromic PRESAGE® dosimeters. The PSF was constructed from a series of acquisitions of projection images of various sized apertures placed in the optical imaging chain. Images were acquired with a range of exposure times, and for a range of aperture sizes (0.2-11 mm). The PSF is investigated under a variety of conditions, and found to be robust and spatially invariant, key factors enabling the viability of the deconvolution approach. The spatial invariance and robustness of the PSF are facilitated by telecentric imaging, which produces a collimated light beam and removes stray light originating upstream of the imaging lens. The telecentric capability of the DLOS therefore represents a significant advantage, both in keeping stray light levels to a minimum and enabling viability of an accurate PSF deconvolution method to correct for the residual. The performance of the correction method was evaluated on projection images containing known optical-density variations, and also on known 3D dose distributions. The method is shown to accurately account for stray light on small field dosimetry with corrections up to 3% in magnitude shown

  17. [Method for determination of radiation effects in cosmonauts by board dosimeter readings made during orbital mission].

    PubMed

    Kolomenskiĭ, A V; Petrov, V M; Shafirkin, A V

    1998-01-01

    A technique for calculating the SS MIR absorbed doses from the galactic cosmic rays, protons of the Earth's radiation belts and solar flares is described. Calculated daily doses for different compartments along the MIR main axis are compared with doses calculated for the location of board radiometer R-16 in various periods of solar activity. Maximal doses in MIR compartments (in the absence of phantom) were compared with the doses in referential depths of a spherical phantom representing the blood forming tissue, skin, enteric epithelium, and the absorbed dose in the dosimeter location. This comparison allows more precise estimation of radiation hazard to cosmonauts in space flight. PMID:9858987

  18. Radiation chemistry of heavy-particle tracks. II. Fricke dosimeter system

    SciTech Connect

    Chatterjee, A.; Magee, J.L.

    1980-12-25

    A heavy-particle-track model suggested by considerations presented in a companion paper is used in a calculation of the differential (G') and integral (G) yields of the Fricke dosimeter system for six selected particles over a wide range of energies. The particles are H, He, C, Ne, Ar, and Fm; the energy range for the first two is 10/sup -3/-10/sup 3/ MeV/n, and for the last four is 10/sup -1/-10/sup 3/ MeV/n. The calculated G' and G values are compared with experimental values as far as possible, and the heavy-particle-track model situation is discussed.

  19. Measurement of bow tie profiles in CT scanners using a real-time dosimeter

    SciTech Connect

    Whiting, Bruce R.; Evans, Joshua D.; Williamson, Jeffrey F.; Dohatcu, Andreea C.; Politte, David G.

    2014-10-15

    Purpose: Several areas of computed tomography (CT) research require knowledge about the intensity profile of the x-ray fan beam that is introduced by a bow tie filter. This information is considered proprietary by CT manufacturers, so noninvasive measurement methods are required. One method using real-time dosimeters has been proposed in the literature. A commercially available dosimeter was used to apply that method, and analysis techniques were developed to extract fan beam profiles from measurements. Methods: A real-time ion chamber was placed near the periphery of an empty CT gantry and the dose rate versus time waveform was recorded as the x-ray source rotated about the isocenter. In contrast to previously proposed analysis methods that assumed a pointlike detector, the finite-size ion chamber received varying amounts of coverage by the collimated x-ray beam during rotation, precluding a simple relationship between the source intensity as a function of fan beam angle and measured intensity. A two-parameter model for measurement intensity was developed that included both effective collimation width and source-to-detector distance, which then was iteratively solved to minimize the error between duplicate measurements at corresponding fan beam angles, allowing determination of the fan beam profile from measured dose-rate waveforms. Measurements were performed on five different scanner systems while varying parameters such as collimation, kVp, and bow tie filters. On one system, direct measurements of the bow tie profile were collected for comparison with the real-time dosimeter technique. Results: The data analysis method for a finite-size detector was found to produce a fan beam profile estimate with a relative error between duplicate measurement intensities of <5%. It was robust over a wide range of collimation widths (e.g., 1–40 mm), producing fan beam profiles that agreed with a relative error of 1%–5%. Comparison with a direct measurement technique on

  20. A method to correct for stray light in telecentric optical-CT imaging of radiochromic dosimeters

    PubMed Central

    Thomas, Andrew; Newton, Joseph

    2011-01-01

    Radiochromic plastic and gel materials have recently emerged which can yield 3D dose information over clinical volumes in high resolution. These dosimeters can provide a much more comprehensive verification of complex radiation therapy treatments than can be achieved by conventional planar and point dosimeters. To achieve full clinical potential, these dosimeters require a fast and accurate read-out technology. Broad-beam optical-computed tomography (optical-CT) systems have shown promise, but can be sensitive to stray light artifacts originating in the imaging chain. In this work we present and evaluate a method to correct for stray light artifacts by deconvolving a measured, spatially invariant, point spread function (PSF). The correction was developed for the DLOS (Duke large field-of-view optical-CT scanner) in conjunction with radiochromic PRESAGE® dosimeters. The PSF was constructed from a series of acquisitions of projection images of various sized apertures placed in the optical imaging chain. Images were acquired with a range of exposure times, and for a range of aperture sizes (0.2–11 mm). The PSF is investigated under a variety of conditions, and found to be robust and spatially invariant, key factors enabling the viability of the deconvolution approach. The spatial invariance and robustness of the PSF are facilitated by telecentric imaging, which produces a collimated light beam and removes stray light originating upstream of the imaging lens. The telecentric capability of the DLOS therefore represents a significant advantage, both in keeping stray light levels to a minimum and enabling viability of an accurate PSF deconvolution method to correct for the residual. The performance of the correction method was evaluated on projection images containing known optical-density variations, and also on known 3D dose distributions. The method is shown to accurately account for stray light on small field dosimetry with corrections up to 3% in magnitude shown

  1. NUCLEAR RADIATION DOSIMETER USING COMPOSITE FILTER AND A SINGLE ELEMENT FILTER

    DOEpatents

    Storm, E.; Shlaer, S.

    1964-04-21

    A nuclear radiation dosimeter is described that uses, in combination, a composite filter and a single element filter. The composite filter contains a plurality of comminuted metals having K-edges evenly distributed over the energy range of interest and the quantity of each of the metals is selected to result in filtering in an amount inversely proportional to the sensitivity of the film in the range over l00 kev. A copper filter is used that has a thickness to contribute the necessary additional correction in the interval between 40 and 100 kev. (AEC)

  2. Use of computer memory chips as the basis for a digital albedo neutron dosimeter.

    PubMed

    Davis, J L

    1985-08-01

    We have measured the sensitivity of commercially available dynamic random access memories (D-RAMs) to alpha particles. Using a beam of 14-meV neutrons and a 6LiF crystal as a converter we have measured sensitivities to neutron radiation as high as 9.25 memory errors per millirem. We estimate that an optimized converter would produce even higher sensitivities as an albedo dosimeter in realistic radiation fields. Such a device would have a number of operational advantages. PMID:4019197

  3. Energy response of LiF (TLD-100) and CaSO4:Dy TL dosimeters to different diagnostic spectra.

    PubMed

    Servomaa, A J

    1985-08-01

    Energy response of LiF (TLD-100) and CaSO4:Dy TL dosimeters to different diagnostic X-ray spectra has been studied. Through energy response the X-ray spectrum influences the dose to be measured with a thermoluminescence dosimeter. The energy responses of both dosimeters were calculated with typical diagnostic high voltages 60-140 kVp and with 1-50 mmAl total filtrations for 2-pulse and constant potential generators. Theoretical X-ray spectra were used. Pulse form and small differences in high voltage and in total filtration do not cause any significant error in measured dose due to energy response. The ratio of the energy responses of CaSO4: Dy and LiF does not produce a sufficiently strongly sloping curve as a function of high voltage for the determination of the half-value layer with typical diagnostic exposure values.

  4. Area Monitoring Dosimeter Program for the Pacific Northwest National Laboratory: results for CY 1993 and CY 1994

    SciTech Connect

    Bivins, S.R.; Stoetzel, G.A..

    1996-03-01

    In January 1993, Pacific Northwest National Laboratory (PNNL) established an area monitoring dosimeter program in accordance with Article 514 of the Department of Energy (DOE) Radiological Control Manual (RCM)(DOE 1994). The purpose of the program was to minimize the number of areas requiring issuance of personnel dosimeters and to demonstrate that doses outside Radiological Buffer Areas are negligible. Article 51 1. la of the RCM requires issuance of personnel dosimeters if individuals are likely to receive a dose of at least 100 mrem annually. The area monitoring TLD program was a useful tool in determining exposure trends in work areas located outside of radiological areas. In several situations, the information obtained from this program was used to relocate staff or radioactive material resulting in potential dose reductions for staff.

  5. Investigating the accuracy of microstereotactic-body-radiotherapy utilizing anatomically accurate 3D printed rodent-morphic dosimeters

    SciTech Connect

    Bache, Steven T.; Juang, Titania; Belley, Matthew D.; Koontz, Bridget F.; Yoshizumi, Terry T.; Kirsch, David G.; Oldham, Mark; Adamovics, John

    2015-02-15

    Purpose: Sophisticated small animal irradiators, incorporating cone-beam-CT image-guidance, have recently been developed which enable exploration of the efficacy of advanced radiation treatments in the preclinical setting. Microstereotactic-body-radiation-therapy (microSBRT) is one technique of interest, utilizing field sizes in the range of 1–15 mm. Verification of the accuracy of microSBRT treatment delivery is challenging due to the lack of available methods to comprehensively measure dose distributions in representative phantoms with sufficiently high spatial resolution and in 3 dimensions (3D). This work introduces a potential solution in the form of anatomically accurate rodent-morphic 3D dosimeters compatible with ultrahigh resolution (0.3 mm{sup 3}) optical computed tomography (optical-CT) dose read-out. Methods: Rodent-morphic dosimeters were produced by 3D-printing molds of rodent anatomy directly from contours defined on x-ray CT data sets of rats and mice, and using these molds to create tissue-equivalent radiochromic 3D dosimeters from Presage. Anatomically accurate spines were incorporated into some dosimeters, by first 3D printing the spine mold, then forming a high-Z bone equivalent spine insert. This spine insert was then set inside the tissue equivalent body mold. The high-Z spinal insert enabled representative cone-beam CT IGRT targeting. On irradiation, a linear radiochromic change in optical-density occurs in the dosimeter, which is proportional to absorbed dose, and was read out using optical-CT in high-resolution (0.5 mm isotropic voxels). Optical-CT data were converted to absolute dose in two ways: (i) using a calibration curve derived from other Presage dosimeters from the same batch, and (ii) by independent measurement of calibrated dose at a point using a novel detector comprised of a yttrium oxide based nanocrystalline scintillator, with a submillimeter active length. A microSBRT spinal treatment was delivered consisting of a 180

  6. SU-E-I-09: Application of LiF:Mg,Cu (TLD-100H) Dosimeters for in Diagnostic Radiology

    SciTech Connect

    Sina, S; Zeinali, B; Karimipourfard, M; Lotfalizadeh, F; Sadeghi, M; Faghihi, R

    2014-06-01

    Purpose: Accurate dosimetery is very essential in diagnostic radiology. The goal of this study is to verify the application of LiF:Mg,Cu,P (TLD100H) in obtaining the Entrance skin dose (ESD) of patients undergoing diagnostic radiology. The results of dosimetry performed by TLD-100H, were compared with those obtained by TLD100, which is a common dosimeter in diagnostic radiology. Methods: In this study the ESD values were measured using two types of Thermoluminescence dosimeters (TLD-100, and TLD-100H) for 16 patients undergoing diagnostic radiology (lumbar spine imaging). The ESD values were also obtained by putting the two types of TLDs at the surface of Rando phantom for different imaging techniques and different views (AP, and lateral). The TLD chips were annealed with a standard procedure, and the ECC values for each TLD was obtained by exposing the chips to equal amount of radiation. Each time three TLD chips were covered by thin dark plastic covers, and were put at the surface of the phantom or the patient. The average reading of the three chips was used for obtaining the dose. Results: The results show a close agreement between the dose measuered by the two dosimeters.According to the results of this study, the TLD-100H dosimeters have higher sensitivities (i.e.signal(nc)/dose) than TLD-100.The ESD values varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for measurements. Conclusion: The TLD-100H dosimeters are suggested as effective dosimeters for dosimetry in low dose fields because of their higher sensitivities.

  7. SU-E-T-230: Measurement of Proton-Activated Positron Emission with PRESAGE 3-D Dosimeters

    SciTech Connect

    Carroll, M; Mawlawi, O; Ibbott, G; Adamovics, J

    2014-06-01

    Purpose: Measurement of positron emission following proton beam irradiation of a target has been studied as a method of in-vivo dosimetry. Relative dosimetry studies between a phantom and treatment plan are susceptible to range uncertainties from material heterogeneities and setup error. By using the radiochromic polyurethane dosimeter PRESAGE, we can correlate the proton dose distribution to the PET activity measurement within a single detector. The PRESAGE formulation used was developed for high-LET proton radiotherapy, has similar density and RLSP to tissue, and consists of a greater carbon component, which gives it a higher positron signal than many other 3D detectors. Methods: Three cylindrical PRESAGE dosimeters were irradiated semi-uniformly to 500 cGy with 180- MeV protons. The beam was directed along the dosimeter axis and delivered a 2-cm SOBP at the center of the dosimeter. The dosimeters were rushed to a nearby PET/CT where imaging began within 15 minutes, less than a single half-life of 11C. A 3-hr measurement captured the full activation decay. Afterwards, the dose profiles were measured by optical-CT. A direct comparison between the measured dose and the positron emission was performed using CERR software. Results: The correlations between dose distributions and PET activity were consistent with previous studies in that the proximal region of the SOBP displayed the highest activity. The spatial distributions between the dose and activity were similar. Along the central axis of the beam, we found a shift in the distal 80% of 1 cm. The lateral profile showed good agreement between dose and activity. PET imaging times between 30-min and 3-hrs showed <5% discrepancy. Conclusion: PRESAGE dosimeters offer a strong and unique potential to accurately correlate dosimetric and PET activation information. Implementation in an anthropomorphic phantom could be used to study representative treatment plans. NIH grant 5R01CA100835.

  8. Performance Evaluation of a Multichannel All-In-One Phantom Dosimeter for Dose Measurement of Diagnostic X-ray Beam

    PubMed Central

    Jeon, Hyesu; Yoo, Wook Jae; Shin, Sang Hun; Kwon, Guwon; Kim, Mingeon; Kim, Hye Jin; Song, Young Beom; Jang, Kyoung Won; Youn, Won Sik; Lee, Bongsoo

    2015-01-01

    We developed a multichannel all-in-one phantom dosimeter system composed of nine sensing probes, a chest phantom, an image intensifier, and a complementary metal-oxide semiconductor (CMOS) image sensor to measure the dose distribution of an X-ray beam used in radiation diagnosis. Nine sensing probes of the phantom dosimeter were fabricated identically by connecting a plastic scintillating fiber (PSF) to a plastic optical fiber (POF). To measure the planar dose distribution on a chest phantom according to exposure parameters used in clinical practice, we divided the top of the chest phantom into nine equal parts virtually and then installed the nine sensing probes at each center of the nine equal parts on the top of the chest phantom as measuring points. Each scintillation signal generated in the nine sensing probes was transmitted through the POFs and then intensified by the image intensifier because the scintillation signal normally has a very low light intensity. Real-time scintillation images (RSIs) containing the intensified scintillation signals were taken by the CMOS image sensor with a single lens optical system and displayed through a software program. Under variation of the exposure parameters, we measured RSIs containing dose information using the multichannel all-in-one phantom dosimeter and compared the results with the absorbed doses obtained by using a semiconductor dosimeter (SCD). From the experimental results of this study, the light intensities of nine regions of interest (ROI) in the RSI measured by the phantom dosimeter were similar to the dose distribution obtained using the SCD. In conclusion, we demonstrated that the planar dose distribution including the entrance surface dose (ESD) can be easily measured by using the proposed phantom dosimeter system. PMID:26569252

  9. True 3D chemical dosimetry (gels, plastics): Development and clinical role

    NASA Astrophysics Data System (ADS)

    Schreiner, L. J.

    2015-01-01

    Since the introduction of volumetric chemical dosimetry with Fricke gel dosimeters in the 1980s, three-dimensional (3D) dosimetry has been a promising technique for the clinic, since it provides a unique methodology for 3D dose measurement of the complex conformal dose distributions achieved by modern techniques such as Intensity Modulated and Volumetric Arc Radiation Therapy. In the last decade, the potential for improved clinical applicability has been advanced by the development of improved 3D dosimeters such as normoxic polymer gel systems, radiochromic plastics (such as PRESAGE) and, recently, newer radiochromic gel dosimeters. Some of these new 3D dosimetry systems were enabled by the availability of optical computed tomography imaging systems for fast dose readout. However, despite its promise, true 3D dosimetry is still not widely practiced in the community. Its use has been confined primarily to select centres of expertise and to specialised quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. In this paper I review some of the current 3D chemical dosimeters available, discuss the requirements for their use and briefly review the roles that these systems can provide to complement the other dose delivery validation approaches available in the clinic. I conclude by describing two roles that may be uniquely served by 3D chemical dosimetry in end-to-end process testing and validation in the complex environment coming into play with the development of Image Guided Adaptive Radiation Therapy.

  10. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters.

    PubMed

    Kim, Jae Joon; Ha, Jun Mok; Lee, Hyeok Moo; Raza, Hamid Saeed; Park, Ji Won; Cho, Sung Oh

    2016-08-01

    The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor.

  11. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters.

    PubMed

    Kim, Jae Joon; Ha, Jun Mok; Lee, Hyeok Moo; Raza, Hamid Saeed; Park, Ji Won; Cho, Sung Oh

    2016-08-01

    The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor. PMID:27399874

  12. Evaluation of the response to xenon-133 radiations by thermoluminescent dosimeters used during the accident at Three Mile Island.

    PubMed

    Riley, R J; Zanzonico, P B; Masterson, M E; St Germain, J M; Laughlin, J S

    1982-03-01

    An evaluation is presented of the accuracy and sensitivity of three types of TLD's used during the accident at the Three Mile Island Nuclear Station. This evaluation indicated that, due to the method of calibration, all the dosimeters over-responded to 133Xe radiations. The response ranged from slightly above unity to almost two. Exposures of the TLD's were of two types, namely, the characteristic X-rays either were or were not filtered from the beam. The angular sensitivity of the dosimeters is also reported. PMID:7068394

  13. Use of a spherical albedo system for correcting the readings of albedo dosimeters in JINR phasotron neutron radiation fields

    NASA Astrophysics Data System (ADS)

    Mokrov, Yu. V.; Morozova, S. V.

    2014-03-01

    Results of calibrating a spherical albedo system in the radiation fields of a Pu-Be radionuclide neutron source are presented. It is shown that it can be used for correcting the readings of the DVGN-01 albedo dosimeter. The results of measurements with the system in JINR phasotron neutron fields for the purpose of correcting the DVGN-01 readings in these fields are given. The values of the correction factors for DVGN-01 albedo dosimeters when used in personnel neutron dosimetry (PD) on the JINR phasotron are determined.

  14. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region. PMID:26589210

  15. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  16. Use of MOSFET dosimeters to validate Monte Carlo radiation treatment calculation in an anthropomorphic phantom

    NASA Astrophysics Data System (ADS)

    Juste, Belén; Miró, R.; Abella, V.; Santos, A.; Verdú, Gumersindo

    2015-11-01

    Radiation therapy treatment planning based on Monte Carlo simulation provide a very accurate dose calculation compared to deterministic systems. Nowadays, Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) dosimeters are increasingly utilized in radiation therapy to verify the received dose by patients. In the present work, we have used the MCNP6 (Monte Carlo N-Particle transport code) to simulate the irradiation of an anthropomorphic phantom (RANDO) with a medical linear accelerator. The detailed model of the Elekta Precise multileaf collimator using a 6 MeV photon beam was designed and validated by means of different beam sizes and shapes in previous works. To include in the simulation the RANDO phantom geometry a set of Computer Tomography images of the phantom was obtained and formatted. The slices are input in PLUNC software, which performs the segmentation by defining anatomical structures and a Matlab algorithm writes the phantom information in MCNP6 input deck format. The simulation was verified and therefore the phantom model and irradiation was validated throughout the comparison of High-Sensitivity MOSFET dosimeter (Best medical Canada) measurements in different points inside the phantom with simulation results. On-line Wireless MOSFET provide dose estimation in the extremely thin sensitive volume, so a meticulous and accurate validation has been performed. The comparison show good agreement between the MOSFET measurements and the Monte Carlo calculations, confirming the validity of the developed procedure to include patients CT in simulations and approving the use of Monte Carlo simulations as an accurate therapy treatment plan.

  17. Monte Carlo Simulation of the Irradiation of Alanine Coated Film Dosimeters with Accelerated Electrons

    NASA Astrophysics Data System (ADS)

    Uribe, R. M.; Salvat, F.; Cleland, M. R.; Berejka, A.

    2009-03-01

    The Monte Carlo code PENELOPE was used to simulate the irradiation of alanine coated film dosimeters with electron beams of energies from 1 to 5 MeV being produced by a high-current industrial electron accelerator. This code includes a geometry package that defines complex quadratic geometries, such as those of the irradiation of products in an irradiation processing facility. In the present case the energy deposited on a water film at the surface of a wood parallelepiped was calculated using the program PENMAIN, which is a generic main program included in the PENELOPE distribution package. The results from the simulation were then compared with measurements performed by irradiating alanine film dosimeters with electrons using a 150 kW Dynamitron™ electron accelerator. The alanine films were placed on top of a set of wooden planks using the same geometrical arrangement as the one used for the simulation. The way the results from the simulation can be correlated with the actual measurements, taking into account the irradiation parameters, is described. An estimation of the percentage difference between measurements and calculations is also presented.

  18. Effect of composition interactions on the dose response of an N-isopropylacrylamide gel dosimeter.

    PubMed

    Chang, Yuan-Jen; Hsieh, Bor-Tsung

    2012-01-01

    In this study, a two-level full factorial design was used to identify the effects of the interactions between compositions in an N-isopropylacrylamide (NIPAM) gel dosimeter involving the following variables: (A) gelatin, (B) NIPAM, (C) the crosslinker N, N'-methylene-bis-acrylamide (Bis), and (D) the antioxidant tetrakis (hydroxymethyl) phosphonium chloride (THPC). The dose range was from 0 Gy to 5 Gy. Optical computed tomography was used to scan the polymer gel dosimeter. Each component was set to two levels for all four variables, including (A) 4% and 6%, (B) 4% and 6%, (C) 2% and 4%, as well as (D) 5 and 15 mM. Response surface methodology and a central composite design were adopted for the quantitative investigation of the respective interaction effects on the dose response curve of the gel. The results showed that the contributions of the interaction effects, i.e., AB (6.22%), AC (8.38%), AD (7.74%), BC (9.44%), ABC (18.24%), BCD (12.66%), and ABCD (13.4%), were greater than those of the four main effects, accounting for over 76.08% of the total variability. These results also indicated that the NIPAM gel recipe with the highest sensitivity was at 40%C (mass fraction of Bis). PMID:23077487

  19. Effect of Composition Interactions on the Dose Response of an N-Isopropylacrylamide Gel Dosimeter

    PubMed Central

    Chang, Yuan-Jen; Hsieh, Bor-Tsung

    2012-01-01

    In this study, a two-level full factorial design was used to identify the effects of the interactions between compositions in an N-isopropylacrylamide (NIPAM) gel dosimeter involving the following variables: (A) gelatin, (B) NIPAM, (C) the crosslinker N, N′-methylene-bis-acrylamide (Bis), and (D) the antioxidant tetrakis (hydroxymethyl) phosphonium chloride (THPC). The dose range was from 0 Gy to 5 Gy. Optical computed tomography was used to scan the polymer gel dosimeter. Each component was set to two levels for all four variables, including (A) 4% and 6%, (B) 4% and 6%, (C) 2% and 4%, as well as (D) 5 and 15 mM. Response surface methodology and a central composite design were adopted for the quantitative investigation of the respective interaction effects on the dose response curve of the gel. The results showed that the contributions of the interaction effects, i.e., AB (6.22%), AC (8.38%), AD (7.74%), BC (9.44%), ABC (18.24%), BCD (12.66%), and ABCD (13.4%), were greater than those of the four main effects, accounting for over 76.08% of the total variability. These results also indicated that the NIPAM gel recipe with the highest sensitivity was at 40%C (mass fraction of Bis). PMID:23077487

  20. In vivo dose measurement using TLDs and MOSFET dosimeters for cardiac radiosurgery.

    PubMed

    Gardner, Edward A; Sumanaweera, Thilaka S; Blanck, Oliver; Iwamura, Alyson K; Steel, James P; Dieterich, Sonja; Maguire, Patrick

    2012-05-10

    In vivo measurements were made of the dose delivered to animal models in an effort to develop a method for treating cardiac arrhythmia using radiation. This treatment would replace RF energy (currently used to create cardiac scar) with ionizing radiation. In the current study, the pulmonary vein ostia of animal models were irradiated with 6 MV X-rays in order to produce a scar that would block aberrant signals characteristic of atrial fibrillation. The CyberKnife radiosurgery system was used to deliver planned treatments of 20-35 Gy in a single fraction to four animals. The Synchrony system was used to track respiratory motion of the heart, while the contractile motion of the heart was untracked. The dose was measured on the epicardial surface near the right pulmonary vein and on the esophagus using surgically implanted TLD dosimeters, or in the coronary sinus using a MOSFET dosimeter placed using a catheter. The doses measured on the epicardium with TLDs averaged 5% less than predicted for those locations, while doses measured in the coronary sinus with the MOSFET sensor nearest the target averaged 6% less than the predicted dose. The measurements on the esophagus averaged 25% less than predicted. These results provide an indication of the accuracy with which the treatment planning methods accounted for the motion of the target, with its respiratory and cardiac components. This is the first report on the accuracy of CyberKnife dose delivery to cardiac targets.

  1. Monte Carlo Simulation of the Irradiation of Alanine Coated Film Dosimeters with Accelerated Electrons

    SciTech Connect

    Uribe, R. M.; Salvat, F.; Cleland, M. R.; Berejka, A.

    2009-03-10

    The Monte Carlo code PENELOPE was used to simulate the irradiation of alanine coated film dosimeters with electron beams of energies from 1 to 5 MeV being produced by a high-current industrial electron accelerator. This code includes a geometry package that defines complex quadratic geometries, such as those of the irradiation of products in an irradiation processing facility. In the present case the energy deposited on a water film at the surface of a wood parallelepiped was calculated using the program PENMAIN, which is a generic main program included in the PENELOPE distribution package. The results from the simulation were then compared with measurements performed by irradiating alanine film dosimeters with electrons using a 150 kW Dynamitron electron accelerator. The alanine films were placed on top of a set of wooden planks using the same geometrical arrangement as the one used for the simulation. The way the results from the simulation can be correlated with the actual measurements, taking into account the irradiation parameters, is described. An estimation of the percentage difference between measurements and calculations is also presented.

  2. Spectroscopic separation of Čerenkov radiation in high-resolution radiation fiber dosimeters

    NASA Astrophysics Data System (ADS)

    Darafsheh, Arash; Zhang, Rongxiao; Kanick, Stephen Chad; Pogue, Brian W.; Finlay, Jarod C.

    2015-09-01

    We have investigated Čerenkov radiation generated in phosphor-based optical fiber dosimeters irradiated with clinical electron beams. We fabricated two high-spatial resolution fiber-optic probes, with 200 and 400 μm core diameters, composed of terbium-based phosphor tips. A generalizable spectroscopic method was used to separate Čerenkov radiation from the transmitted signal by the fiber based on the assumption that the recorded signal is a linear superposition of two basis spectra: characteristic luminescence of the phosphor medium and Čerenkov radiation. We performed Monte Carlo simulations of the Čerenkov radiation generated in the fiber and found a strong dependence of the recorded Čerenkov radiation on the numerical aperture of the fiber at shallow phantom depths; however, beyond the depth of maximum dose that dependency is minimal. The simulation results agree with the experimental results for Čerenkov radiation generated in fibers. The spectroscopic technique used in this work can be used for development of high-spatial resolution fiber micro dosimeters and for optical characterization of various scintillating materials, such as phosphor nanoparticles, in ionizing radiation fields of high energy.

  3. Magnesium lactate mixed with EVA polymer/paraffin as an EPR dosimeter for radiation processing application

    NASA Astrophysics Data System (ADS)

    Soliman, Y. S.; Abdel-Fattah, A. A.

    2012-12-01

    The dosimetric characteristics of γ-radiation-induced defects in magnesium lactate (ML) rods (3.5 mm×10 mm) formulated by mixing ML with molten mixtures of paraffin wax and EVA copolymer have been investigated using electron paramagnetic resonance (EPR). The EPR spectrum of irradiated ML rods was characterized by a quartet signal with the spectroscopic splitting g-factor of 2.0048±0.0003 at 0.4 mT. The useful dose range of the rod dosimeter was 100 Gy to 80 kGy. The mass attenuation coefficient, μ/ρ, and the mass energy-absorption coefficient, μen/ρ, versus energy in the range of 10 keV to 20 MeV indicate that the prepared ML dosimeter is typically adipose tissue equivalent overall this energy range. The overall combined uncertainties (at 2σ) associated with routine dose monitoring in the dose range of 0.1-10 kGy and 10-80 kGy were found to be 6.14% and 6.36%, respectively.

  4. Latex Rubber Gloves as a Sampling Dosimeter Using a Novel Surrogate Sampling Device.

    PubMed

    Sankaran, Gayatri; Lopez, Terry; Ries, Steve; Ross, John; Vega, Helen; Eastmond, David A; Krieger, Robert I

    2015-01-01

    Pesticide exposure during harvesting of crops occurs primarily to the workers' hands. When harvesters wear latex rubber gloves for personal safety and hygiene harvesting reasons, gloves accumulate pesticide residues. Hence, characterization of the gloves' properties may be useful for pesticide exposure assessments. Controlled field studies were conducted using latex rubber gloves to define the factors that influence the transfer of pesticides to the glove and that would affect their use as a residue monitoring device. A novel sampling device called the Brinkman Contact Transfer Unit (BCTU) was constructed to study the glove characteristics and residue transfer and accumulation under controlled conditions on turf. The effectiveness of latex rubber gloves as sampling dosimeters was evaluated by measuring the transferable pesticide residues as a function of time. The validation of latex rubber gloves as a residue sampling dosimeter was performed by comparing pesticide transfer and dissipation from the gloves, with the turf transferable residues sampled using the validated California (CA) Roller, a standard measure of residue transfer. The observed correlation (Pearson's correlation coefficient R(2)) between the two methods was .84 for malathion and .96 for fenpropathrin, indicating that the BCTU is a useful, reliable surrogate tool for studying available residue transfer to latex rubber gloves under experimental conditions. Perhaps more importantly, these data demonstrate that latex gloves worn by workers may be useful quantifiable matrices for measuring pesticide exposure.

  5. A self-checking fiber optic dosimeter for monitoring common errors in brachytherapy applications

    SciTech Connect

    Yin, Y.; Lambert, J.; Yang, S.; McKenzie, D. R.; Jackson, M.; Suchowerska, N.

    2009-07-15

    Scintillation dosimetry with optical fiber readout [fiber optic dosimetry (FOD)] requires accurate measurement of light intensity. It is therefore vulnerable to loss of calibration if any changes occur in the efficiency of the optical pathway between the scintillator and the light detector. The authors show in this article that common types of errors that arise during clinical use for brachytherapy applications can be quantified using a light emitting diode to stimulate the scintillator, the so-called LED-FOD method, in an integrated and easy-to-use control unit that incorporates a compact peripheral component interconnect extension for instrumentation. Common sources of error include bending and mechanical compression of the fiber optic components and changes in the temperature of the scintillator. The authors show that the method can detect all the common errors studied in this work and that different types of errors can result in different correlations between the LED stimulated signal and the brachytherapy source signal. For a single-type error the LED-FOD can be used easily for system diagnosis and validation with the possibility to correct the dosimeter reading if the correlation between the LED stimulated signal and the brachytherapy source signal can be defined. For more complex errors, resulting from two or more errors occurring simultaneously, the LED-FOD method can also allow the clinician to make a judgment on the reliability of the dosimeter reading. This self-checking method can enhance the clinical robustness of the FOD for achieving accurate dose control.

  6. Investigation of a pulsed current annealing method in reusing MOSFET dosimeters for in vivo IMRT dosimetry

    SciTech Connect

    Luo, Guang-Wen; Qi, Zhen-Yu Deng, Xiao-Wu; Rosenfeld, Anatoly

    2014-05-15

    Purpose: To explore the feasibility of pulsed current annealing in reusing metal oxide semiconductor field-effect transistor (MOSFET) dosimeters forin vivo intensity modulated radiation therapy (IMRT) dosimetry. Methods: Several MOSFETs were irradiated atd{sub max} using a 6 MV x-ray beam with 5 V on the gate and annealed with zero bias at room temperature. The percentage recovery of threshold voltage shift during multiple irradiation-annealing cycles was evaluated. Key dosimetry characteristics of the annealed MOSFET such as the dosimeter's sensitivity, reproducibility, dose linearity, and linearity of response within the dynamic range were investigated. The initial results of using the annealed MOSFETs for IMRT dosimetry practice were also presented. Results: More than 95% of threshold voltage shift can be recovered after 24-pulse current continuous annealing in 16 min. The mean sensitivity degradation was found to be 1.28%, ranging from 1.17% to 1.52%, during multiple annealing procedures. Other important characteristics of the annealed MOSFET remained nearly consistent before and after annealing. Our results showed there was no statistically significant difference between the annealed MOSFETs and their control samples in absolute dose measurements for IMRT QA (p = 0.99). The MOSFET measurements agreed with the ion chamber results on an average of 0.16% ± 0.64%. Conclusions: Pulsed current annealing provides a practical option for reusing MOSFETs to extend their operational lifetime. The current annealing circuit can be integrated into the reader, making the annealing procedure fully automatic.

  7. Radiological characteristics of charged particle interactions in the first clay-nanoparticle dichromate gel dosimeter

    NASA Astrophysics Data System (ADS)

    Taylor, M. L.; Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Fukasaku, K.; Furuta, T.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

    2013-06-01

    The incorporation of clay nanoparticles into gel dosimeters shows promise for significant diffusion reduction - but to what extent does the presence of the nano-clay influence charged particle interactions and, in particular, what is the impact on water equivalence? In this work, we quantify the radiological characteristics of electron, proton and carbon ion interactions in the RIKEN dichromate nanoclay gel and specifically evaluate the water equivalence over a broad energy range. Results indicate that the radiological properties are sufficiently representative of tissues that this low-diffusion gel could readily be used for validation of complex dose distributions. Electron and proton ranges are within 1 % of those in water. Mean effective atomic numbers for electron interactions in the range 10 keV - 10 GeV are within 1 % of those of water which, coupled with the similar mass density, ultimately means the overall impact on dose distributions is not great. The range of C6+ ions in the nanoclay gel is closer to that of water (< 4 %) than a common polymer gel dosimeter (< 7 %), though experimentally measured R1 values indicate an over-response at low doses.

  8. Response of biological uv dosimeters to the simulated extraterrestrial uv radiation

    NASA Astrophysics Data System (ADS)

    Bérces, A.; Rontó, G.; Kerékgyártó, T.; Kovács, G.; Lammer, H.

    In the Laboratory polycrystalline uracil thin layer and bacteriophage T7 detectors have been developed for UV dosimetry on the EarthSs surface. Exponential response of the uracil polycrystal has been detected both by absorption spectroscopy and measurements of the refractive index under the influence of terrestrial solar radiation or using UV-C sources. In UV biological dosimetry the UV dose scale is additive starting at a value of zero according to the definition of CIE (Technical Report TC-6-18). The biological dose can be defined by a measured end-effect. In our dosimeters (phage T7 and uracil dosimeter) exposed to natural (terrestrial) UV radiation the proportion of pyrimidin photoproducts among the total photoproducts is smaller than 0.1 and the linear correlation between the biological and physical dose is higher than 0.9. According to the experimental data this linear relationship is often not valid. We observed that UV radiation did not only induce dimerisation but shorter wavelengths caused monomerisation of pyrimidin dimers. Performing the irradiation in oxygen free environment and using a Deuterium lamp as UV source, we could increase monomerisation against dimerisation thus the DNA-based dosimetrySs additivity rule is not fulfilled in these conditions. In this study we will demonstrate those non-linear experiments which constitute the basis of our biological experiments on the International Space Station.

  9. Feasibility study of CaSO4:Tb,Yb as a thermoluminescent dosimeter

    NASA Astrophysics Data System (ADS)

    Junot, Danilo O.; Santos, Max A.; Chagas, Marcos A. P.; Couto dos Santos, Marcos A.; Nunes, Luiz A. O.; Souza, Divanizia N.

    2014-02-01

    A new composite based on CaSO4, using terbium as dopant and ytterbium as co-dopant (CaSO4:Tb,Yb), was developed for employment as a thermoluminescent (TL) dosimeter. The crystals used in this work were grown using a production route based on the Yamashita method (Yamashita et al., 1968). Crystal powder was calcined at 600 °C for 1 h. Pellets were made by adding commercial and colorless glass to improve physical resistance and sintered at 700 °C for 6 h. All samples were irradiated by a beta source (90Sr/90Y) and received doses from 1 Gy to 5 Gy. TL analyses have been performed and characteristics such as sensitivity, reproducibility, linearity, and fading have been studied. The CaSO4:Tb,Yb pellets glow curves presented two peaks, the first at around 115 °C, and the second at around 200 °C. The highest intensity was shown for CaSO4:Tb,Yb with a concentration of 0.1 mol% of Tb and Yb together. In all the samples the TL response was proportional to the absorbed dose. Therefore, the CaSO4:Tb,Yb has potential to be used as a thermoluminescent dosimeter.

  10. EPR and UV spectroscopic study of table sugar as a high-dose dosimeter

    NASA Astrophysics Data System (ADS)

    Yordanov, N. D.; Gancheva, V.; Georgieva, E.

    2002-10-01

    The possibilities for the estimation of the absorbed dose for high-energy radiation with a new self-calibrated dosimeter containing table sugar as a radiation-sensitive material and Mn 2+/MgO as an internal standard by the method of electron paramagnetic resonance (EPR) is reported. The dose response of this dosimeter is represented as the ratio between the EPR signal intensities of sugar and Mn 2+ versus absorbed dose. Because the EPR spectra of both substances are simultaneously recorded, the influence of some related instrumental setting parameters were investigated. UV spectral studies on water solutions of irradiated solid sugar were also performed. In all solutions of irradiated sugar samples a band at 267 nm was recorded as linearly increasing intensity with the absorbed dose. The minimum detectable dose using the UV spectrum of water solutions of irradiated sugar is 100 Gy. Combination of EPR and UV spectral data is possible to use for independent internal or international calibration and control of dose estimations.

  11. The use of commercial glass as a potential gamma accidental dosimeter through the absorption spectra

    NASA Astrophysics Data System (ADS)

    Kharita, M. H.; Yousef, S.; Bakr, S.

    2012-05-01

    Various types of commercial glass (ordinary windows, cathode ray tubes, glass kitchenware) have been studied as potential accidental radiation dosimeters. The proposed method utilizes the changes in the glasses' absorption spectra as a result of irradiation. A 60Co gamma irradiation cell has been used to irradiate samples with doses ranging from 5 to 200 Gy. The transmittance was measured using a photospectrometer (UV-visible spectrometry). The results demonstrate that the transmittance spectra of most of the glass samples change in linear proportion to the exposure dose. Moreover, the study considers the fading effect on the absorption spectra of the irradiated samples for fading times up to 100 days at room temperature. The results of this work demonstrate that several widely used types of glass can be used as high-dose accidental dosimeters for doses ranging between 8 and 200 Gy. A reasonable calibration line can be established for any irradiated glass sample by heating, re-irradiating with standard doses and measuring the related absorption coefficient. Further investigations are needed to decrease the minimum detectable dose of the proposed method and to study the effect of glass composition on radiation response.

  12. Design of an ultra low power CMOS pixel sensor for a future neutron personal dosimeter

    SciTech Connect

    Zhang, Y.; Hu-Guo, C.; Husson, D.; Hu, Y.

    2011-07-01

    Despite a continuously increasing demand, neutron electronic personal dosimeters (EPDs) are still far from being completely established because their development is a very difficult task. A low-noise, ultra low power consumption CMOS pixel sensor for a future neutron personal dosimeter has been implemented in a 0.35 {mu}m CMOS technology. The prototype is composed of a pixel array for detection of charged particles, and the readout electronics is integrated on the same substrate for signal processing. The excess electrons generated by an impinging particle are collected by the pixel array. The charge collection time and the efficiency are the crucial points of a CMOS detector. The 3-D device simulations using the commercially available Synopsys-SENTAURUS package address the detailed charge collection process. Within a time of 1.9 {mu}s, about 59% electrons created by the impact particle are collected in a cluster of 4 x 4 pixels with the pixel pitch of 80 {mu}m. A charge sensitive preamplifier (CSA) and a shaper are employed in the frond-end readout. The tests with electrical signals indicate that our prototype with a total active area of 2.56 x 2.56 mm{sup 2} performs an equivalent noise charge (ENC) of less than 400 e - and 314 {mu}W power consumption, leading to a promising prototype. (authors)

  13. Personal dose equivalent for photons and its variation with dosimeter position.

    PubMed

    Zankl, M

    1999-02-01

    This work presents conversion coefficients per air kerma free-in-air for the personal dose equivalent, Hp(10), calculated according to its definition by the International Commission on Radiation Units and Measurements as a quantity in the human body. The values were calculated using Monte Carlo methods for various dosimeter positions in the trunk of a voxel model of an adult male, and they are given for various directions of incidence of broad parallel photon beams with energies between 10 keV and 10 MeV. It is shown that the numerical values of the personal dose equivalent depend on the exact position of the dosimeter, with maximum differences between 12% and 80%, depending on the beam geometry. It is further shown that the recommended calibration quantity Hp slab(10), which has been used in ICRP Publication 74 and ICRU Report 57 in the absence of data in the human body to approximate personal dose equivalent, does represent the latter quantity in a sensible way for some, but not all, beam geometries. Comparison of the values for the personal dose equivalent of this work with effective dose revealed that Hp(10) is a conservative estimate or close approximation of E for most irradiation geometries and photon energies. PMID:9929127

  14. Radiation dosimeter

    DOEpatents

    Fox, Richard J.

    1983-01-01

    A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even though the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

  15. Radiation dosimeter

    DOEpatents

    Fox, R.J.

    1981-09-01

    A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even through the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

  16. Neutron contribution to CaF2:Mn thermoluminescent dosimeter response in mixed (n/y) field environments.

    SciTech Connect

    DePriest, Kendall Russell; Griffin, Patrick Joseph

    2003-07-01

    Thermoluminescent dosimeters (TLDs), particularly CaF{sub 2}:Mn, are often used as photon dosimeters in mixed (n/{gamma}) field environments. In these mixed field environments, it is desirable to separate the photon response of a dosimeter from the neutron response. For passive dosimeters that measure an integral response, such as TLDs, the separation of the two components must be performed by postexperiment analysis because the TLD reading system cannot distinguish between photon- and neutron-produced response. Using a model of an aluminum-equilibrated TLD-400 (CaF{sub 2}:Mn) chip, a systematic effort has been made to analytically determine the various components that contribute to the neutron response of a TLD reading. The calculations were performed for five measured reactor neutron spectra and one theoretical thermal neutron spectrum. The five measured reactor spectra all have experimental values for aluminum-equilibrated TLD-400 chips. Calculations were used to determine the percentage of the total TLD response produced by neutron interactions in the TLD and aluminum equilibrator. These calculations will aid the Sandia National Laboratories-Radiation Metrology Laboratory (SNL-RML) in the interpretation of the uncertainty for TLD dosimetry measurements in the mixed field environments produced by SNL reactor facilities.

  17. Neutron Contribution to CaF2:Mn Thermoluminescent Dosimeter Response in Mixed (n/y) Field Environments

    SciTech Connect

    DEPRIEST, KENDALL R.

    2002-11-01

    Thermoluminescent dosimeters (TLDs), particularly CaF{sub 2}:Mn, are often used as photon dosimeters in mixed (n/{gamma}) field environments. In these mixed field environments, it is desirable to separate the photon response of a dosimeter from the neutron response. For passive dosimeters that measure an integral response, such as TLDs, the separation of the two components must be performed by post-experiment analysis because the TLD reading system cannot distinguish between photon and neutron produced response. Using a model of an aluminum-equilibrated TLD-400 chip, a systematic effort has been made to analytically determine the various components that contribute to the neutron response of a TLD reading. The calculations were performed for five measured reactor neutron spectra and one theoretical thermal neutron spectrum. The five measured reactor spectra all have dosimetry quality experimental values for aluminum-equilibrated TLD-400 chips. Calculations were used to determined the percentage of the total TLD response produced by neutron interactions in the TLD and aluminum equilibrator. These calculations will aid the Sandia National Laboratories-Radiation Metrology Laboratory (SNL-RML) in the interpretation of the uncertainty for TLD dosimetry measurements in the mixed field environments produced by SNL reactor facilities.

  18. A standard Fricke dosimeter compared to an ionization chamber used for dosimetric characterization of 60Co photon beam

    NASA Astrophysics Data System (ADS)

    Moussous, Ouiza; Medjadj, Toufik

    2016-06-01

    The main objective of this study was to investigate the Fricke dosimeter water equivalent system for measurement of dosimetric parameters for photon beam. The parameters measured with the Fricke dosimeter were compared to those obtained with an ionization chamber. In this work characteristics for 60Co γ-rays of field sizes ranging from 5 × 5 cm2 to 20 × 20 cm2 are reported. The measurements were carried out in the secondary standard dosimetry laboratory using a collimated 60Co gamma source therapy unit. The 60Co beam output in terms of absorbed dose to water was obtained as per IAEA TRS 398 recommendations using cylindrical ionization chamber, whose ND,w has been supplied by the IAEA's reference laboratory. Specific quantities measured include: output factors, peak scatter factor, lateral beam profiles and percentage depth dose. The Fricke dosimeters were irradiated in a water phantom using the suitable poly (methyl methacrylate), PMMA stand. Our results demonstrate that Fricke dosimeter and ionization chamber agree with each other.

  19. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  20. Potential of a New Technique for Remote Sensing of Hydrocarbon Accumulations and Blind Uranium Deposits: Buried Lif Thermoluminescence Dosimeters

    NASA Technical Reports Server (NTRS)

    Siegel, F. R.; Vaz, J. E.; Lindholm, R. C.

    1982-01-01

    Buried thermoluminescence dosimeters may be useful in remote sensing of petroleum and natural gas accumulations and blind uranium deposits. They act as integrating detectors that smooth out the effects of environmental variations that affect other measuring systems and result in irregularities and poor repeatability in measurements made during gas and radiometric surveys.

  1. A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

    PubMed Central

    Zhang, Da; Li, Xinhua; Gao, Yiming; Xu, X. George; Liu, Bob

    2013-01-01

    Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord

  2. Evaluation of alanine as a reference dosimeter for therapy level dose comparisons in megavoltage electron beams

    NASA Astrophysics Data System (ADS)

    McEwen, Malcolm; Sharpe, Peter; Vörös, Sándor

    2015-04-01

    When comparing absorbed dose standards from different laboratories (e.g. National Measurement Institutes, NMIs, for Key or Supplementary comparisons) it is rarely possible to carry out a direct comparison of primary standard instruments, and therefore some form of transfer detector is required. Historically, air-filled, unsealed ionization chambers have been used because of the long history of using these instruments, very good stability over many years, and ease of transport. However, the use of ion chambers for therapy-level comparisons is not without its problems. Findings from recent investigations suggest that ion chambers are prone to non-random variations, they are not completely robust to standard courier practices, and failure at any step in a comparison can render all measurements potentially useless. An alternative approach is to identify a transfer system that is insensitive to some of these concerns—effectively a dosimeter that is inexpensive, simple to use, robust, but with sufficient precision and of a size relevant to the disseminated quantity in question. The alanine dosimetry system has been successfully used in a number of situations as an audit dosimeter and therefore the purpose of this investigation was to determine whether alanine could also be used as the transfer detector for dosimetric comparisons, which require a lower value for the measurement uncertainty. A measurement protocol was developed for comparing primary standards of absorbed dose to water in high-energy electron beams using alanine pellets irradiated in a water-equivalent plastic phantom. A trial comparison has been carried out between three NMIs and has indicated that alanine is a suitable alternative to ion chambers, with the system used achieving a precision of 0.1%. Although the focus of the evaluation was on the performance of the dosimeter, the comparison results are encouraging, showing agreement at the level of the combined uncertainties (~0.6%). Based on this

  3. A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

    SciTech Connect

    Zhang, Da; Li, Xinhua; Liu, Bob; Gao, Yiming; Xu, X. George

    2013-08-15

    Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future.Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations.Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated

  4. Functional Evaluation of the DOZA DKG-05D Electronic Dosimeter System

    SciTech Connect

    Piper, Roman K.; Scherpelz, Robert I.

    2009-11-04

    The DOZA DKG-05D electronic personal dosimeter (EPD) was the subject of a limited type-test evaluation in support of Plutonium Production Reactor Agreement (PPRA) Implementation. The primary goal of this evaluation was to provide confidence in the functionality of the dosimeter and identify potential weaknesses in PPRA applications. The tests were based on IEC-61526, recommendations of the International Electrotechnical Commission pertaining to EPDs. All tests were performed in Pacific Northwest National Laboratory’s (PNNL) Radiological Calibrations and Standards Facility in the 318 building. The first testing category was functional considerations. The tests found that the mechanical characteristics of the DKG-05D support usability. However, user controls are not intuitive and straightforward, and the user instructions were unclear and difficult to follow. The unit functioned in a variety of humidity conditions. In high temperature conditions it performed well. However, in cold conditions the display began to fade, which limits its usefulness below about 5 °C. The vendor claims that the unit functions to -20 °C, and it may be correctly recording doses at that low temperature, but the doses cannot be read in real time. Testing found that battery life is generally good, operating for 200 hours on a full charge. This is far more than needed for the intended application. Charging the battery, however, had some pitfalls resulting from two charging modes. The high-current mode would be automatically selected if the battery charge fell below a threshold value when inserted in the charger. Otherwise, a low-current mode would be selected. In some cases a battery needing recharging would not get sufficient current to fully charge in a reasonable time period. There were also problems found in the low-battery indication and there was a possibility for data loss in the low-battery condition. The EPD generally performed well in measuring dose and dose rate. There were some

  5. Study of suitability of Fricke-gel-layer dosimeters for in-air measurements to characterise epithermal/thermal neutron beams for NCT.

    PubMed

    Gambarini, G; Artuso, E; Giove, D; Felisi, M; Volpe, L; Barcaglioni, L; Agosteo, S; Garlati, L; Pola, A; Klupak, V; Viererbl, L; Vins, M; Marek, M

    2015-12-01

    The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing (10)B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed.

  6. Effects of smartphone diaries and personal dosimeters on behavior in a randomized study of methods to document sunlight exposure.

    PubMed

    Køster, Brian; Søndergaard, Jens; Nielsen, Jesper Bo; Allen, Martin; Bjerregaard, Mette; Olsen, Anja; Bentzen, Joan

    2016-06-01

    Dosimeters and diaries have previously been used to evaluate sun-related behavior and UV exposure in local samples. However, wearing a dosimeter or filling in a diary may cause a behavioral change. The aim of this study was to examine possible confounding factors for a questionnaire validation study. We examined the effects of wearing dosimeters and filling out diaries, measurement period and recall effect on the sun-related behavior in Denmark in 2012. Our sample included 240 participants eligible by smartphone status and who took a vacation during weeks 26-32 in 2012, randomized by gender, age, education and skin type to six groups: 1) Control + diary, 2) Control, 3) 1-week dosimetry measurement, 4) 1-week dosimetry measurement + diary, 5) 3-week dosimetry measurement and 6) 1-week dosimetry measurement with 4 week delayed questionnaire. Correlation coefficients between reported outdoor time and registered outdoor time for groups 3-6 were 0.39, 0.45, 0.43 and 0.09, respectively. Group 6 was the only group not significantly correlated. Questionnaire reported outdoor exposure time was shorter in the dosimeter measurement groups (3-6) than in their respective controls. We showed that using a dosimeter or keeping a diary seems to increase attention towards the behavior examined and therefore may influence this behavior. Receiving the questionnaire with 4 week delay had a significant negative influence on correlation and recall of sunburn. When planning future UV behavior questionnaire validations, we suggest to use a 1-week interval for dosimetry measurements, no diary, and to minimize the time from end of measurement to filling out questionnaires. PMID:27419038

  7. Application of optically stimulated luminescence technique to evaluate simultaneously accumulated and single doses with the same dosimeter

    NASA Astrophysics Data System (ADS)

    Malthez, Anna Luiza M. C.; Freitas, Marcelo B.; Yoshimura, Elisabeth M.; Button, Vera L. S. N.

    2014-02-01

    Optically stimulated luminescence dosimeters (OSLD) can be read several times with a negligible loss (degradation) of signal. In this work, we explore this OSL property to estimate simultaneously the accumulated and single doses using a unique Al2O3 dosimeter, irradiated repeated times along over 4 months. This was done through several irradiations of OSLD (Landauer Luxel Dots) with two energies (28 keV X-rays and 1.25 MeV Co-60 gamma rays) and several doses distributed over time. Thermoluminescent dosimeters (TLD) were used as a reference to compare the estimated doses obtained with OSLD. For each irradiation, and both energies, a calibration curve was evaluated with OSLD and TLD to estimate the dose values. The OSL readouts were made with a MicroStar (Landauer) OSL reader. To estimate background (BG) over time, a set of OSLD and TLD (Bycron TLD100) was not irradiated and BG was monitored at each readout section. After irradiations, the OSL and TL signals were converted to dose and values were compared. As a set of OSLD suffered no bleaching after the readouts, it was possible to estimate simultaneously the accumulated and single doses with a unique OSLD. Each single dose was estimated through the subtraction of successive accumulated doses determined for each single OSLD. We concluded that the single doses determined by OSL and TL techniques were compatible, and that the accumulated dose, obtained with OSL technique was comparable to the sum of single doses determined with TLD. We can conclude that using OSL technique and Al2O3 dosimeters it is possible to estimate simultaneously accumulated and single doses with the same dosimeter irradiated with low or high energy photons.

  8. Dosimetry for small fields in stereotactic radiosurgery using gafchromic MD-V2-55 film, TLD-100 and alanine dosimeters.

    PubMed

    Massillon-J L, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

    2013-01-01

    This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in (60)Co gamma-ray and 6 MV x-ray reference (10×10 cm(2)) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields

  9. Dosimetry for Small Fields in Stereotactic Radiosurgery Using Gafchromic MD-V2-55 Film, TLD-100 and Alanine Dosimeters

    PubMed Central

    Massillon-JL, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

    2013-01-01

    This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in 60Co gamma-ray and 6 MV x-ray reference (10×10 cm2) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields

  10. Investigation of thermoluminescence properties of mobile phone screen displays as dosimeters for accidental dosimetry

    NASA Astrophysics Data System (ADS)

    Mrozik, Anna; Marczewska, B.; Bilski, P.; Kłosowski, M.

    2014-11-01

    The rapid assessment of the radiation dose after unexpected exposure is a task of accidental dosimetry. In case of a radiological accident glasses originating from mobile phone screens, placed usually near the human body, could be used as emergency thermoluminescent (TL) personal dosimeters. The time between irradiation and TL readout is crucial and therefore preparation of the mobile phone screens and their readout conditions should be optimized. The influence of the samples etching, bleaching and selection of the optical filters based on measurement of the emission spectrum of irradiated glass samples during heating for different types of mobile phones were the subjects of our investigation. Obtained results showed that glasses extracted from different brands of mobile phones have different dosimetric properties but all of them give a luminescent signal which can be used to calculate the dose.

  11. Measurements for dose distribution with a photo-stimulated luminescence dosimeter sheet

    NASA Astrophysics Data System (ADS)

    Kurokawa, C.; Urushiyama, A.

    2013-06-01

    Dose distributions for photon beam were measured using a Photo-Stimulated Luminescence Dosimeter (PSLD) sheet, which has 18 × 24 cm2 dimension and 0.2 mm thickness. Its density and effective atomic number are 1.0 g/cm3 and 7.6, respectively. The read out was performed by blue LED lights for 20 seconds, which was much shorter than the readout time for TLD. The percent depth dose and dose profile were obtained as smooth curve after the calibration and it reproduced the measurements with ionization chamber, except for the tail region in the dose profile. We demonstrated the measurement of the prostate VMAT dose distribution also. The result reproduces the calculation by treatment planning system (TPS) qualitatively. It is shown that the PSLD sheet has the potential to measure the dose distribution.

  12. Space charge dosimeters for extremely low power measurements of radiation in shipping containers

    DOEpatents

    Britton, Jr.; Charles L.; Buckner, Mark A.; Hanson, Gregory R.; Bryan, William L.

    2011-04-26

    Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes in situ polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

  13. Space charge dosimeters for extremely low power measurements of radiation in shipping containers

    DOEpatents

    Britton, Jr., Charles L.; Buckner, Mark A.; Hanson, Gregory R.; Bryan, William L.

    2011-05-03

    Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

  14. Dosimetric assessment of the PRESAGE dosimeter for a proton pencil beam

    NASA Astrophysics Data System (ADS)

    Wuu, C.-S.; Xu, Y.; Qian, X.; Adamovics, J.; Cascio, E.; Lu, H.-M.

    2013-06-01

    The objective of this study is to assess the feasibility of using PRESAGE dosimeters for proton pencil beam dosimetry. Two different formulations of phantom materials were tested for their suitability in characterizing a single proton pencil beam. The dosimetric response of PRESAGE was found to be linear up to 4Gy. First-generation optical CT scanner, OCTOPUSTM was used to implement dose distributions for proton pencil beams since it provides most accurate readout. Percentage depth dose curves and beam profiles for two proton energy, 110 MeV, and 93 MeV, were used to evaluate the dosimetric performance of two PRESAGE phantom formulas. The findings from this study show that the dosimetric properties of the phantom materials match with basic physics of proton beams.

  15. Radiation chemistry of heavy-particle tracks. 2. Fricke dosimeter system

    SciTech Connect

    Chatterjee, Aloke; Magee, John L.

    1980-12-01

    A heavy-particle track model suggested by considerations presented in a companion paper is used in a calculation of the differential (G') and integral (G) yields of the Fricke dosimeter system for six selected particles over a wide range of energies. The particles are H, He, C, Ne, Ar, and Fm; the energy range for the first two is 10{sup -3} MeV/n to 10{sup 3} MeV/n, and for the last four is 10{sup -1} MeV/n to 10{sup 3} MeV/n. The calculated G' and G values are compared with experimental values as far as possible, and the heavy-particle track model situation is discussed.

  16. Space charge dosimeters for extremely low power measurements of radiation in shipping containers

    SciTech Connect

    Buckner, Mark A; Hanson, Gregory R; Bryan, William L

    2009-04-28

    Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

  17. Evaluation of Exposure From a Low Energy X-Ray Device Using Thermoluminescent Dosimeters

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Harris, William S., Jr.

    1997-01-01

    The exposure from an electron beam welding device was evaluated using thermoluminescent dosimeters (TLDs). The device generated low energy X-rays which the current dose equivalent conversion algorithm was not designed to evaluate making it necessary to obtain additional information relating to TLD operation at the photon energies encountered with the device. This was accomplished by performing irradiations at the National Institute of Standards and Technology (NIST) using low energy X-ray techniques. The resulting data was used to determine TLD badge response for low energy X-rays and to establish the relationship between TLD element response and the dose equivalent at specific depths in tissue for these photon energies. The new energy/dose equivalent calibration data was used to calculate the shallow and eye dose equivalent of badges exposed to the device.

  18. Modelling optical scattering artefacts for varying pathlength in a gel dosimeter phantom

    NASA Astrophysics Data System (ADS)

    Bosi, Stephen G.; Brown, Saxby; Sarabipour, Sarvenaz; DeDeene, Yves; Baldock, Clive

    2009-01-01

    A gelatin phantom containing an optically scattering funnel-shaped region of elevated optical density (OD) was used to examine light-scattering-induced artefacts in a cone-beam optical CT scanner used for gel dosimetry. To simulate polymer gel dosimeters, the opacity was introduced by adding a colloidal scatterer to the gelatin. Scatter results in an underestimate of OD (hence dose). In line profiles of OD taken from 3D reconstructions of the funnel, those profiles with a long pathlength through high OD regions exhibited a 'dishing' (or 'cupping') artefact, while those of short pathlength exhibited the opposite effect—'doming'. These phenomena are accounted for by a model that includes the effect of stray, scattered light.

  19. Miniature Tissue Equivalent Proportional Counter dosimeter for active personal radiation monitoring of astronauts

    NASA Astrophysics Data System (ADS)

    Watson Huber, Aubrey

    The accurate measurement of spaceflight crew radiation exposure is of utmost importance. If onboard instrumentation shows that the pre-determined limit for radiation exposure has been met or exceeded during a mission, that mission can be greatly affected by the implementation of precautionary measures, or, in more extreme cases, the crew's health being negatively affected. Large active regional monitors determine real-time radiation risks of the crew during spaceflight, while small passive personal badges detect individual astronaut total exposure levels upon their return to Earth. At present, there are no personal active radiation dosimeters that can assess the continuous radiation risk to individual astronauts during spaceflight. Personal active radiation devices would be ideal for current operations in low-Earth orbit (LEO), as well as upcoming extravehicular activities on the Moon, Mars, or other planetary bodies. This project focused on the miniaturization of the Tissue Equivalent Proportional Counters (TEPCs) presently being utilized on the International Space Station (ISS) and Space Shuttle, enabling them to become personal crew dosimeters. The miniaturized TEPC prototype design has dimensions of 7.6 x 10.1 x 2.54 cm (3 x 4 x 1 in). It is composed of a 3 x 4 array of 1.27 cm (0.5 in) spherical detectors for measurements equivalent to a 4.39 cm (1.73 in) spherical detector, with an additional standalone sphere of diameter 1.27 cm (0.5 in) for taking measurements in high-flux environments. The detector simulates a tissue-equivalent diameter of 2 microns, is sensitive to lineal energies of 0.3 -- 1000 keV/micron, and can measure charged particles and neutrons ranging from 0.01 -- 100 mGy/hr.

  20. Stored-fluorography mode reduces radiation dose during cardiac catheterization measured with OSLD dosimeter

    NASA Astrophysics Data System (ADS)

    Ting, Chien-Yi; Chen, Zhih-Cherng; Tang, Kuo-Ting; Liu, Wei-Chung; Lin, Chun-Chih; Wang, Hsin-Ell

    2015-12-01

    Coronary angiogram is an imperative tool for diagnosis of coronary artery diseases, in which cine-angiography is a commonly used method. Although the angiography proceeds under radiation, the potential risk of radiation exposure for both the patients and the operators was seldom noticed. In this study, the absorbed radiation dose in stored-fluorography mode was compared with that in cine-angiography mode by using optically simulated luminescent dosimeters to realize their effects on radiation dose. Patients received coronary angiogram via radial artery approach were randomized into the stored-fluorography group (N=30) or the cine-angiography group (N=30). The excluded criteria were: 1. women at pregnancy or on breast feeding, 2. chronic kidney diseases with glomerular filtration rate less than 60 mL/min. During the coronary angiogram, absorbed dose of the patients and the operator radiation exposure was measured with optically simulated luminescent dosimeter (OSLD). The absorbed dose of the patients in the stored-fluorography group (3.13±0.25 mGy) was apparently lower than that in the cine-angiography group (65.57±5.37 mGy; P<0.001). For the operator, a statistical difference (P<0.001) was also found between the stored-fluorography group (0.09163 μGy) and the cine-angiography (0.6519μGy). Compared with traditional cine-angiography mode, the stored-fluorography mode can apparently reduce radiation exposure of the patients and the operator in coronary angiogram.

  1. Evaluation of dose variation during total skin electron irradiation using thermoluminescent dosimeters

    SciTech Connect

    Weaver, R.D.; Gerbi, B.J.; Dusenbery, K.E.

    1995-09-30

    The purpose of this study was to determine acceptable dose variation using thermoluminescent dosimeters (TLD) in the treatment of Mycosis Fungoides with total skin electron beam (TSEB) irradiation. From 1983 to 1993, 22 patients were treated with total skin electron beam therapy in the standing position. A six-field technique was used to deliver 2 Gy in two days, treating 4 days per week, to a total dose of 35 to 40 Gy using a degraded 9 MeV electron beam. Thermoluminescent dosimeters were placed on several locations of the body and the results recorded. The variations in these readings were analyzed to determine normal dose variation for various body location during TSEB. The dose to flat surfaces of the body was essentially the same as the dose to the prescription point. The dose to tangential surfaces was within {plus_minus} 10% of the prescription dose, but the readings showed much more variation (up to 24%). Thin areas of the body showed large deviations from the prescription dose along with a large amount of variation in the readings (up to 22%). Special areas of the body, such as the perineum and eyelid, showed large deviations from the prescription dose along with very large (up to 40%) variations in the readings. The TLD results of this study will be used as a quality assurance check for all new patients treated with TSEB. The results of the TLDs will be compared with this baseline study to determine if the delivered dose is within acceptable ranges. If the TLD results fall outside the acceptable limits established above, then the patient position can be modified or the technique itself evaluated. 4 refs., 5 tabs.

  2. Tracking and Monitoring with Dosimeter-Enabled ARG-US RFID System - 12009

    SciTech Connect

    Anderson, J.; Lee, H.; De Lurgio, P.; Kearney, C.M.; Craig, B.; Soos, I.H.; Tsai, H.; Liu, Y.; Shuler, J.

    2012-07-01

    Automated monitoring and tracking of materials with radio frequency identification (RFID) technology can significantly improve both the operating efficiency of radiological facilities and the application of the ALARA (as low as reasonably achievable) principle in them. One such system, called ARG-US, has been developed by Argonne National Laboratory for the U.S. Department of Energy (DOE) Packaging and Certification Program to use in managing sensitive nuclear and radioactive materials. Several ARG-US systems are in various stages of deployment and advanced testing across DOE sites. ARG-US utilizes sensors in the tags to continuously monitor the state of health of the packaging and promptly disseminates alarms to authorized users. In conjunction with global positioning system (GPS) tracking provided by TRANSCOM, the system can also monitor and track packages during transport. A compact dosimeter has been incorporated in the ARG-US tags via an onboard universal asynchronous receiver/transmitter interface. The detector has a wide measurement range for gamma radiation - from 0.1 mSv/h to 8 Sv/h. The detector is able to generate alarms for both high and low radiation and for a high cumulative dose. In a large installation, strategically located dosimeter-enabled tags can yield an accurate, real-time, 2D or 3D dose field map that can be used to enhance facility safety, security, and safeguards. This implementation can also lead to a reduced need for manned surveillance and reduced exposure of personnel to radiation, consistent with the ALARA principle at workplaces. (authors)

  3. SU-E-T-451: Accuracy and Application of the Standard Imaging W1 Scintillator Dosimeter

    SciTech Connect

    Kowalski, M; McEwen, M

    2014-06-01

    Purpose: To evaluate the Standard Imaging W1 scintillator dosimeter in a range of clinical radiation beams to determine its range of possible applications. Methods: The W1 scintillator is a small perturbation-free dosimeter which is of interest in absolute and relative clinical dosimetry due to its small size and water equivalence. A single version of this detector was evaluated in Co-60 and linac photon and electron beams to investigate the following: linearity, sensitivity, precision, and dependence on electrometer type. In addition, depth-dose and cross-plane profiles were obtained in both photon and electron beams and compared with data obtained with wellbehaved ionization chambers. Results: In linac beams the precision and linearity was very impressive, with typical values of 0.3% and 0.1% respectively. Performance in a Co-60 beam was much poorer (approximately three times worse) and it is not clear whether this is due to the lower signal current or the effect of the continuous beam (rather than pulsed beam of the linac measurements). There was no significant difference in the detector reading when using either the recommended SI Supermax electrometer or two independent high-quality electrometers, except for low signal levels, where the Supermax exhibited an apparent threshold effect, preventing the measurement of the bremsstrahlung background in electron depth-dose curves. Comparisons with ion chamber measurements in linac beams were somewhat variable: good agreement was seen for cross-profiles (photon and electron beams) and electron beam depth-dose curves, generally within the 0.3% precision of the scintillator but systematic differences were observed as a function of measurement depth in photon beam depth-dose curves. Conclusion: A first look would suggest that the W1 scintillator has applications beyond small field dosimetry but performance appears to be limited to higher doserate and/or pulsed radiation beams. Further work is required to resolve

  4. Evaluation of various polyethylene as potential dosimeters by attenuated total reflectance-Fourier-transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Halperin, Fred; Collins, Greta; DiCicco, Michael; Logar, John

    2014-12-01

    Various types of polyethylene (PE) have been evaluated in the past for use as a potential dosimeter, chiefly via the formation of an unsaturated transvinylene (TV) double-bond resulting from exposure to ionizing radiation. The utilization of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy in characterizing TV formation in irradiated PE for a potential dosimeter has yet to be fully developed. In this initial investigation, various PE films/sheets were exposed to ionizing radiation in a high-energy 5 megaelectron volt (MeV) electron beam accelerator in the 10-500 kilogray (kGy) dose range, followed by ATR-FTIR analysis of TV peak formation at the 965 cm-1 wavenumber. There was an upward trend in TV formation for low-density polyethylene (LDPE) films and high-density polyethylene (HDPE) sheets as a function of absorbed dose in the 10-50 kGy dose range, however, the TV response could not be equated to a specific absorbed dose. LDPE film displayed a downward trend from 50 kGy to 250 kGy and then scattering up to 500 kGy; HDPE sheets demonstrated an upward trend in TV formation up to 500 kGy. For ultra-high molecular weight polyethylene (UHMWPE) sheets irradiated up to 150 kGy, TV response was equivalent to non-irradiated UHMWPE, and a minimal upward trend was observed for 200 kGy to 500 kGy. The scatter of the data for the irradiated PE films/sheets is such that the TV response could not be equated to a specific absorbed dose. A better correlation of the post-irradiation TV response to absorbed dose may be attained through a better understanding of variables.

  5. Prototype CMOS SSPM solar particle dosimeter with tissue-equivalent sensor

    NASA Astrophysics Data System (ADS)

    Stapels, C. J.; Johnson, E. B.; Mukhopadhyay, S.; Chapman, E. C.; Christian, J. F.; Benton, Eric

    2009-08-01

    A dosimeter-on-a-chip (DoseChip) comprised of a tissue-equivalent scintillator coupled to a solid-state photomultiplier (SSPM) built using CMOS (complementary metal-oxide semiconductor) technology represents an ideal technology for a space-worthy, real-time solar-particle monitor for astronauts. It provides a tissue-equivalent response to the relevant energies and types of radiation for Low-Earth Orbit (LEO) and interplanetary space flight to the moon or Mars. The DoseChip will complement the existing Crew Passive Dosimeters by providing real-time dosimetry and as an alarming monitor for solar particle events (SPEs).[1] A prototype of the DoseChip, comprised of a 3 x 3 x 3 mm3 cube of BC-430 plastic scintillator coupled to a 2000-pixel SSPM, has successfully demonstrated response to protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory and at the HIMAC facility in Japan. The dynamic range of the dose has been verified over four orders of magnitude for particles with LET ranging from 0.2 keV/μm to 200 keV/μm, which includes 1-GeV protons to 420-MeV/n Fe nuclei. To exploit the benefits of the CMOS SSPM, we have developed our first autonomous prototype using the DoseChip. An analog circuit is used to process the signals from the SSPM, and an on-board microprocessor is used to digitize and store the pulse height information. Power is distributed over the device from a single dual voltage supply through various regulators and boost converters to appropriate supply voltages to each of the components.

  6. Small field in-air output factors: The role of miniphantom design and dosimeter type

    SciTech Connect

    Warrener, Kirbie; Hug, Benjamin; Ebert, Martin A.; Liu, Paul; McKenzie, David R.; Ralston, Anna; Suchowerska, Natalka

    2014-02-15

    Purpose: The commissioning of treatment planning systems and beam modeling requires measured input parameters. The measurement of relative output in-air, S{sub c} is particularly difficult for small fields. The purpose of this study was to investigate the influence of miniphantom design and detector selection on measured S{sub c} values for small fields and to validate the measurements against Monte Carlo simulations. Methods: Measurements were performed using brass caps (with sidewalls) or tops (no sidewalls) of varying heights and widths. The performance of two unshielded diodes (60012 and SFD), EBT2 radiochromic film, and a fiber optic dosimeter (FOD) were compared for fields defined by MLCs (5–100 mm) and SRS cones (4–30 mm) on a Varian Novalis linear accelerator. Monte Carlo simulations were performed to theoretically predict S{sub c} as measured by the FOD. Results: For all detectors, S{sub c} agreed to within 1% for fields larger than 10 mm and to within 2.3% for smaller fields. Monte Carlo simulation matched the FOD measurements for all size of cone defined fields to within 0.5%. Conclusions: Miniphantom design is the most important variable for reproducible and accurate measurements of the in-air output ratio, S{sub c}, in small photon fields (less than 30 mm). Sidewalls are not required for fields ≤ 30 mm and tops are therefore preferred over the larger caps. Unlike output measurements in water, S{sub cp,} the selection of detector type for S{sub c} is not critical, provided the active dosimeter volume is small relative to the field size.

  7. Glycol ethers--validation procedures for tube/pump and dosimeter monitoring methods.

    PubMed

    Langhorst, M L

    1984-06-01

    Methods were developed and validated for personal monitoring of exposures to airborne glycol ethers, both short-term and long-term time-weighted-averages. Either a 600 mg charcoal tube or a 780 mg silica gel tube is recommended for monitoring nine glycol ethers, depending upon the humidity and other organic compounds to be monitored. The charcoal tube allows maximum sensitivity and is unaffected by high humidity conditions. Two-phase solvent desorption with CS2 and water allows aqueous phase recoveries of DOWANOL EM, PM, EE, DM, DPM, and TM glycol ethers. DOWANOL EB, DB and TPM glycol ethers are partitioned between the two layers, necessitating chromatographic analysis of both layers. The silica gel tube method can be used to monitor all nine glycol ethers tested, but is affected by high humidity conditions, resulting in significant breakthrough of the more volatile glycol ethers. The 3M organic vapor monitor can accurately and conveniently determine exposure concentrations for DOWANOL EM, EE, and PM glycol ethers, but sensitivities may be inadequate for sampling periods less than one hour. These methods were validated at levels down to 0.1 times the Dow internal exposure guidelines for those substances with Dow exposure guidelines and well above the current ACGIH and OSHA guidelines. This paper also illustrates validation procedures for tube/pump and dosimeter methods, allowing good definition of method accuracy and precision. Some screening experiments are described for diffusional dosimeters to check the most important parameters in a minimum of time. This methodology will allow assessment of human airborne exposures relative to the new toxicology data available on animals. PMID:6331145

  8. Exposure of arctic field scientists to ultraviolet radiation evaluated using personal dosimeters.

    PubMed

    Cockell, C S; Scherer, K; Horneck, G; Rettberg, P; Facius, R; Gugg-Helminger, A; Driscoll, C; Lee, P

    2001-10-01

    During July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum für Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degrees N) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythemally weighted exposure, as measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies (typically 7-8 okta of stratus) reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive approximately 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second time-scales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as medics and computer scientists, who spent the majority of their time in tents. PMID:11683037

  9. Influence of electrodes on the photon energy deposition in CVD-diamond dosimeters studied with the Monte Carlo code PENELOPE.

    PubMed

    Górka, B; Nilsson, B; Fernández-Varea, J M; Svensson, R; Brahme, A

    2006-08-01

    A new dosimeter, based on chemical vapour deposited (CVD) diamond as the active detector material, is being developed for dosimetry in radiotherapeutic beams. CVD-diamond is a very interesting material, since its atomic composition is close to that of human tissue and in principle it can be designed to introduce negligible perturbations to the radiation field and the dose distribution in the phantom due to its small size. However, non-tissue-equivalent structural components, such as electrodes, wires and encapsulation, need to be carefully selected as they may induce severe fluence perturbation and angular dependence, resulting in erroneous dose readings. By introducing metallic electrodes on the diamond crystals, interface phenomena between high- and low-atomic-number materials are created. Depending on the direction of the radiation field, an increased or decreased detector signal may be obtained. The small dimensions of the CVD-diamond layer and electrodes (around 100 microm and smaller) imply a higher sensitivity to the lack of charged-particle equilibrium and may cause severe interface phenomena. In the present study, we investigate the variation of energy deposition in the diamond detector for different photon-beam qualities, electrode materials and geometric configurations using the Monte Carlo code PENELOPE. The prototype detector was produced from a 50 microm thick CVD-diamond layer with 0.2 microm thick silver electrodes on both sides. The mean absorbed dose to the detector's active volume was modified in the presence of the electrodes by 1.7%, 2.1%, 1.5%, 0.6% and 0.9% for 1.25 MeV monoenergetic photons, a complete (i.e. shielded) (60)Co photon source spectrum and 6, 18 and 50 MV bremsstrahlung spectra, respectively. The shift in mean absorbed dose increases with increasing atomic number and thickness of the electrodes, and diminishes with increasing thickness of the diamond layer. From a dosimetric point of view, graphite would be an almost perfect

  10. Influence of electrodes on the photon energy deposition in CVD-diamond dosimeters studied with the Monte Carlo code PENELOPE

    NASA Astrophysics Data System (ADS)

    Górka, B.; Nilsson, B.; Fernández-Varea, J. M.; Svensson, R.; Brahme, A.

    2006-08-01

    A new dosimeter, based on chemical vapour deposited (CVD) diamond as the active detector material, is being developed for dosimetry in radiotherapeutic beams. CVD-diamond is a very interesting material, since its atomic composition is close to that of human tissue and in principle it can be designed to introduce negligible perturbations to the radiation field and the dose distribution in the phantom due to its small size. However, non-tissue-equivalent structural components, such as electrodes, wires and encapsulation, need to be carefully selected as they may induce severe fluence perturbation and angular dependence, resulting in erroneous dose readings. By introducing metallic electrodes on the diamond crystals, interface phenomena between high- and low-atomic-number materials are created. Depending on the direction of the radiation field, an increased or decreased detector signal may be obtained. The small dimensions of the CVD-diamond layer and electrodes (around 100 µm and smaller) imply a higher sensitivity to the lack of charged-particle equilibrium and may cause severe interface phenomena. In the present study, we investigate the variation of energy deposition in the diamond detector for different photon-beam qualities, electrode materials and geometric configurations using the Monte Carlo code PENELOPE. The prototype detector was produced from a 50 µm thick CVD-diamond layer with 0.2 µm thick silver electrodes on both sides. The mean absorbed dose to the detector's active volume was modified in the presence of the electrodes by 1.7%, 2.1%, 1.5%, 0.6% and 0.9% for 1.25 MeV monoenergetic photons, a complete (i.e. shielded) 60Co photon source spectrum and 6, 18 and 50 MV bremsstrahlung spectra, respectively. The shift in mean absorbed dose increases with increasing atomic number and thickness of the electrodes, and diminishes with increasing thickness of the diamond layer. From a dosimetric point of view, graphite would be an almost perfect electrode

  11. An evaluation of the impact of urban air pollution on paint dosimeters by tracking changes in the lipid MALDI-TOF mass spectra profile.

    PubMed

    Herrera, A; Navas, N; Cardell, C

    2016-08-01

    We evaluated the impact of urban air pollution on egg yolk tempera paint dosimeters (binary mixture samples made with historic artist´s blue, red and white pigments) by tracking changes over time in their lipid matrix-assisted laser desorption ionization time-of-flight mass spectra (MALDI-TOF-MS) profiles. We studied triacylglycerols (TGs), phospholipids (PLs) and their oxidation by-products from paint dosimeters that had been exposed outdoors for six months to the polluted atmosphere in the city center of Granada (Spain). Four types of chickens' eggs were also analyzed to find out whether their lipid mass spectra (lipid fingerprints) varied significantly. The ultimate goal of this research is to provide a precise analytical protocol to show whether the changes in the egg yolk identified in paint dosimeters are due to pigment-binder interactions. The Bligh-Dyer (BD) method was optimized for the extraction of the lipids. This innovative procedure included a washing-step prior to the mass spectrometric analysis, which proved crucial for obtaining higher quality lipid fingerprints. A novel interpretation of the results is proposed by applying the BD method, which suggests that transesterification processes occurred in the lipid fractions that were catalyzed by the pigments in the paint dosimeters. In blank dosimeters specific ions produced by oxidative cleavage of PLs and/or TGs may be used as markers of the presence of egg yolk binders. The composition and structure of the specific lipid compounds are also tentatively proposed. In aged dosimeters the intact content of the TGs and PLs decreased; however, we propose that short-chain oxidative products arising from TGs and PLs are present in all the samples, except for the white lead based dosimeter. We end with a new explanation as to why this dosimeter behaves differently from the others.

  12. Preliminary investigation of the NMR, optical and x-ray CT dose-response of polymer gel dosimeters incorporating cosolvents to improve dose sensitivity

    NASA Astrophysics Data System (ADS)

    Koeva, V. I.; Olding, T.; Jirasek, A.; Schreiner, L. J.; McAuley, K. B.

    2009-05-01

    This study reports on efforts to increase the dose sensitivity of polymer gel dosimeters used in 3D radiation dosimetry. The potential of several different cosolvents is investigated, with the aim of increasing the solubility of N,N'-methylene-bisacrylamide crosslinker in polymer gel dosimeters. Glycerol and isopropanol increase the limit for the crosslinker solubility from approximately 3% to 5% and 10% by weight, respectively. This enables the manufacture of polymer gel dosimeters with much higher levels of crosslinking than was previously possible. New dosimeter recipes containing up to 5 wt% N,N'-methylene-bisacrylamide were subjected to spatially uniform radiation and were studied using nuclear magnetic resonance (NMR), as well as x-ray and optical CT techniques. The resulting dosimeters exhibit dose sensitivities that are up to 2.7 times higher than measured for a typical dosimeters with 3% N,N'-methylene-bisacrylamide without the addition of cosolvent. Two additional cosolvents (n-propanol and sec-butanol) were deemed unsuitable for practical dosimeters due to incompatibility with gelatin, cloudiness prior to irradiation, and immiscibility with water when large quantities of cosolvent were used. The dosimeters with high N,N'-methylene-bisacrylamide content that used isopropanol or glycerol as cosolvents had high optical clarity prior to irradiation, but did not produce suitable optical CT results for non-uniformly irradiated gels due to polymer development outside of the high dose regions of the pencil beams and significant light scatter. Further experiments are required to determine whether cosolvents can be used to manufacture gels with sufficiently high dose sensitivity for readout using x-ray computed tomography.

  13. An evaluation of the impact of urban air pollution on paint dosimeters by tracking changes in the lipid MALDI-TOF mass spectra profile.

    PubMed

    Herrera, A; Navas, N; Cardell, C

    2016-08-01

    We evaluated the impact of urban air pollution on egg yolk tempera paint dosimeters (binary mixture samples made with historic artist´s blue, red and white pigments) by tracking changes over time in their lipid matrix-assisted laser desorption ionization time-of-flight mass spectra (MALDI-TOF-MS) profiles. We studied triacylglycerols (TGs), phospholipids (PLs) and their oxidation by-products from paint dosimeters that had been exposed outdoors for six months to the polluted atmosphere in the city center of Granada (Spain). Four types of chickens' eggs were also analyzed to find out whether their lipid mass spectra (lipid fingerprints) varied significantly. The ultimate goal of this research is to provide a precise analytical protocol to show whether the changes in the egg yolk identified in paint dosimeters are due to pigment-binder interactions. The Bligh-Dyer (BD) method was optimized for the extraction of the lipids. This innovative procedure included a washing-step prior to the mass spectrometric analysis, which proved crucial for obtaining higher quality lipid fingerprints. A novel interpretation of the results is proposed by applying the BD method, which suggests that transesterification processes occurred in the lipid fractions that were catalyzed by the pigments in the paint dosimeters. In blank dosimeters specific ions produced by oxidative cleavage of PLs and/or TGs may be used as markers of the presence of egg yolk binders. The composition and structure of the specific lipid compounds are also tentatively proposed. In aged dosimeters the intact content of the TGs and PLs decreased; however, we propose that short-chain oxidative products arising from TGs and PLs are present in all the samples, except for the white lead based dosimeter. We end with a new explanation as to why this dosimeter behaves differently from the others. PMID:27216656

  14. Spectral response of solvent-cast polyvinyl chloride (PVC) thin film used as a long-term UV dosimeter.

    PubMed

    Amar, Abdurazaq; Parisi, Alfio V

    2013-08-01

    The spectral response of solvent-cast polyvinyl chloride (PVC) thin film suitable for use as a long-term UV dosimeter has been determined by measuring the UV induced change in the 1064 cm(-1) peak intensity of the PVC's infrared (IR) spectra as a function of the wavelength of the incident radiation. Measurements using cut-off filters, narrow band-pass filters and monochromatic radiation showed that the 16 μm PVC film responds mainly to the UVB band. The maximum response was at 290 nm and decreasing exponentially with wavelength up to about 340 nm independent of temperature and exposure dose. The most suitable concentration (W/V%) of PVC/Tetrahydrofuran solution was found to be 10% and the best thickness for the dosimeter was determined as 16 μm.

  15. Development of an energy discriminate CR-39(®) nuclear track etch dosimeter for Radon-220 gas measurements.

    PubMed

    Brown, J M C; Solomon, S; Tinker, R A

    2011-10-01

    An energy discriminate CR-39(®) nuclear track etch dosimeter for use in a (220)Rn and (222)Rn gas monitor has been developed and experimentally assessed. It utilises a thin film of Mylar(®) C to attenuate the alpha particle energies to allow only the damage tracks created by the 8.785 MeV alpha particles emitted from (212)Po of the (232)Th decay chain to be registered in the CR-39(®) plaque, allowing for the direct measurement of (220)Rn gas concentrations. The dosimeter was developed through a combination of experimental investigations and theoretical simulations using the Monte Carlo ion transport modelling program Stopping and Range of Ions in Materials (SRIM 2008). A film thickness of 54 μm has been shown to attenuate all alpha energies less then 7.7 MeV. PMID:20980083

  16. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

    PubMed

    Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

    2015-01-01

    The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

  17. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy

    PubMed Central

    Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

    2015-01-01

    The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (−50 to −6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

  18. The Observed Variance Between Predicted and Measured Radiation Dose in Breast and Prostate Patients Utilizing an in-vivo Dosimeter

    PubMed Central

    Scarantino, Charles W.; Prestidge, Bradley R.; Anscher, Mitchel S.; Ferree, Carolyn R.; Kearns, William T.; Black, Robert D.; Bolick, Natasha G.; Beyer, Gloria P.

    2008-01-01

    Purpose Report the results of using a permanently implantable dosimeter in radiation therapy: determine specific adverse events, degree of migration, and acquire dose measurements during treatment to determine difference between expected and measured dose. Methods and Materials DVS (Dose Verification System) is a wireless, permanently implantable MOSFET dosimeter using a bidirectional antenna for power and data transfer. The study cohort includes 36 breast (33 received 2 devices) and 29 prostate (21 received 2 devices) cancer patients. A total of 1783 and 1749 daily dose measurements were obtained on breast and prostate patients, respectively. The measurements were compared to the planned expected dose. Bi-weekly CT scans were obtained to evaluate migration and NCI CTCv3 used to evaluate adverse events. Results Only grade I/II adverse events of pain and bleeding were noted. There were only four instances of dosimeter migration of >5mm due to known factors. A deviation of ≥7% in cumulative dose was noted in 7 of 36 (19%) for breast cancer patients. In prostate cancer patients, a ≥7% deviation was noted in 6 of 29 (21%) and 8 of 19 (42%) during initial and boost irradiation, respectively. The two patterns of dose deviation were random and systematic. Some causes for these differences could involve organ movement, patient movement and/or treatment plan considerations. Conclusions The DVS was not associated with significant adverse events or migration. The dosimeter can measure dose in situ on a daily basis. The accuracy and utility of the DVS complements current IGRT and IMRT techniques. PMID:18793963

  19. SU-E-CAMPUS-T-02: Exploring Radiation Acoustics CT Dosimeter Design Aspects for Proton Therapy

    SciTech Connect

    Alsanea, F; Moskvin, V; Stantz, K

    2014-06-15

    Purpose: Investigate the design aspects and imaging dose capabilities of the Radiation Acoustics Computed Tomography (RA CT) dosimeter for Proton induced acoustics, with the objective to characterize a pulsed pencil proton beam. The focus includes scanner geometry, transducer array, and transducer bandwidth on image quality. Methods: The geometry of the dosimeter is a cylindrical water phantom (length 40cm, radius 15cm) with 71 ultrasound transducers placed along the length and end of the cylinder to achieve a weighted set of projections with spherical sampling. A 3D filtered backprojection algorithm was used to reconstruct the dosimetric images and compared to MC dose distribution. First, 3D Monte Carlo (MC) Dose distributions for proton beam energies (range of 12cm, 16cm, 20cm, and 27cm) were used to simulate the acoustic pressure signal within this scanner for a pulsed proton beam of 1.8x107 protons, with a pulse width of 1 microsecond and a rise time of 0.1 microseconds. Dose comparison within the Bragg peak and distal edge were compared to MC analysis, where the integrated Gaussian was used to locate the 50% dose of the distal edge. To evaluate spatial fidelity, a set of point sources within the scanner field of view (15×15×15cm3) were simulated implementing a low-pass bandwidth response function (0 to 1MHz) equivalent to a multiple frequency transducer array, and the FWHM of the point-spread-function determined. Results: From the reconstructed images, RACT and MC range values are within 0.5mm, and the average variation of the dose within the Bragg peak are within 2%. The spatial resolution tracked with transducer bandwidth and projection angle sampling, and can be kept at 1.5mm. Conclusion: This design is ready for fabrication to start acquiring measurements. The 15 cm FOV is an optimum size for imaging dosimetry. Currently, simulations comparing transducer sensitivity, bandwidth, and proton beam parameters are being evaluated to assess signal-to-noise.

  20. An investigation of a PRESAGE® in-vivo dosimeter for brachytherapy

    PubMed Central

    Vidovic, A K; Juang, T; Meltsner, S; Adamovics, J; Chino, J; Steffey, B; Craciunescu, O; Oldham, M

    2014-01-01

    Determining accurate in-vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in-vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm x 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® In-Vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0–15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy·cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (~1mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in-vivo dose verification, although