TY  - JOUR
AB  - Microbeam radiotherapy is a novel type of radiotherapy in which narrow beams of radiation (typically less than 500 mu m) are spatially fractionated, delivering a non-uniform distribution to the target tumour volume. Due to the very high dose gradients and very small beams involved, new dosimetric techniques are required for translation into clinical practise. Current real-time beam monitoring is typically performed using 1 dimensional silicon strip detectors or wire chambers, with 2D beam information measured offline using radiochromic film (requiring a minimum of 24 h to self-develop).Using an Xstrahl SARRP X-ray irradiation device with a bespoke microbeam collimator at the Technical University of Munich, Germany, the newly developed vM1212 detector was exposed to a variety of microbeams (220 kV, nominal slit widths 0-100 mu m) for evaluation of in vivo real time verification.The performance of the detector was assessed by changing the collimator slit width (and thus microbeam FWHM) mid-irradiation. Microbeam FWHMs of 130-190 mu m could be measured in this manner in addition to temporally monitoring other basic parameters such as the radiation intensity. More advanced parameters could be calculated as the tungsten slits within the microbeam collimator opened and closed such as the rate of change of FWHM; the peak-valley-dose-ratio (PVDR); and the sub-pixel movement of each microbeam peak.This work demonstrates the potential of radiation hard CMOS sensors in radiotherapy for in vivo real-time monitoring of X-ray microbeams FWHM, intensity and position.
AU  - Flynn, S.*
AU  - Price, T.*
AU  - Allport, P.P.*
AU  - Patallo, I.S.*
AU  - Thomas, R.*
AU  - Subiel, A.*
AU  - Bartzsch, S.
AU  - Treibel, F.*
AU  - Ahmed, M.*
AU  - Jacobs-Headspith, J.*
AU  - Edwards, T.*
AU  - Jones, I.*
AU  - Cathie, D.*
AU  - Guerrini, N.*
AU  - Sedgwick, I.*
C1  - 59762
C2  - 49045
CY  - Radarweg 29, 1043 Nx Amsterdam, Netherlands
TI  - First demonstration of real-time in-situ dosimetry of X-ray microbeams using a large format CMOS sensor.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 978
PB  - Elsevier
PY  - 2020
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - There is a high demand in modern medical applications for dosimetry sensors with a small footprint allowing for unobtrusive or high spatial resolution detectors. To this end we characterize the sensoric response of radiation resistant high mobility AlGaN/GaN semiconductor devices when exposed to β--emitters. The samples were operated as a floating gate transistor, without a field effect gate electrode, thus excluding any spurious effects from β--particle interactions with a metallic surface covering. We demonstrate that the source-drain current is modulated in dependence on the kinetic energy of the incident β--particles. Here, the signal is shown to have a linear dependence on the absorbed energy calculated from Monte Carlo simulations. Additionally, a stable and reproducible sensor performance as a β--dose monitor is shown for individual radioisotopes. Our experimental findings and the characteristics of the AlGaN/GaN high mobility layered devices indicate their potential for future applications where small sensor size is necessary, like for instance brachytherapy.
AU  - Schmid, M.
AU  - Howgate, J.
AU  - Rühm, W.
AU  - Thalhammer, S.*
C1  - 48087
C2  - 39901
CY  - Amsterdam
SP  - 14-19
TI  - High mobility AlGaN/GaN devices for β--dosimetry.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 819
PB  - Elsevier Science Bv
PY  - 2016
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.
AU  - Caresana, M.*
AU  - Denker, A.*
AU  - Esposito, A.*
AU  - Ferrarini, M.*
AU  - Golnik, N.*
AU  - Hohmann, E.*
AU  - Leuschner, A.*
AU  - Luszik-Bhadra, M.*
AU  - Manessi, G.*
AU  - Mayer, S.*
AU  - Ott, K.*
AU  - Röhrich, J.*
AU  - Silari, M.*
AU  - Trompier, F.*
AU  - Volnhals, M.
AU  - Wielunski, M.
C1  - 29158
C2  - 31055
SP  - 203-213
TI  - Intercomparison of radiation protection instrumentation in a pulsed neutron field.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 737
PB  - Elsevier Science
PY  - 2014
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - The authors measured the neutron energy spectra of a quasi-monoenergetic Li-7(p,n) neutron source with 246 and 389 MeV protons set at seven angles (0 degrees, 2.5 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees and 30 degrees), using a time-of-flight (TOF) method employing organic scintillators NE213 at the Research Center for Nuclear Physics (RCNP) of Osaka University. The energy spectra of the source neutrons were precisely deduced down to 2 MeV at 0 degrees and 10 MeV at other angles. The cross-sections of the peak neutron production reaction at 0 degrees were on the 35-40 mb line of other experimental data, and the peak neutron angular distribution agreed well with the Taddeucci formula. Neutron energy spectra below 100 MeV at all angles were comparable, but the shapes of the continuum above 150 MeV changed considerably with the angle. In order to consider the correction required to derive the response in the peak region from the measured total response for high-energy neutron monitors such as DARWIN and Wendi-2, the authors showed the subtractions of H* (10) obtained at larger angles (10 degrees, 15 degrees, 20 degrees and 30 degrees) from the 0 degrees data in the continuum part for the 246 and 389 MeV Li-7(p,n) reactions. It was found that subtracting the dose equivalent at about 20 degrees from the 0 degrees data almost eliminates the continuum component. This method has potential to eliminate problems associated with continuum correction for high-energy neutron monitors.
AU  - Iwamoto, Y.*
AU  - Hagiwara, M.*
AU  - Satoh, D.*
AU  - Iwase, H.*
AU  - Yashima, H.*
AU  - Itoga, T.*
AU  - Sato, T.*
AU  - Nakane, Y.*
AU  - Nakashima, H.*
AU  - Sakamoto, Y.*
AU  - Matsumoto, T.*
AU  - Masuda, A.*
AU  - Nishiyama, J.*
AU  - Tamii, A.*
AU  - Hatanaka, K.*
AU  - Theis, C.*
AU  - Feldbaumer, E.*
AU  - Jaegerhofer, L.*
AU  - Pioch, C.
AU  - Mares, V.
AU  - Nakamura, T.*
C1  - 6128
C2  - 28440
CY  - Amsterdam, Netherlands
SP  - 43-49
TI  - Quasi-monoenergetic neutron energy spectra for 246 and 389 MeV Li-7(p,n) reactions at angles from 0 degrees to 300 degrees.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 629
IS  - 1
PB  - Elsevier
PY  - 2011
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - In 2007, a Bonner spheres spectrometer (BSS) was installed in Ny-Ålesund, Spitsbergen, at about 79°N. The spectrometer allows continuous measurement of the spectral fluence rate distribution of secondary neutrons from cosmic radiation in absolute terms. In this way, the system complements a neutron monitor (NM) that was installed in 2005, in Barentsburg, Spitsbergen, at about 78°N. To compare the readings of both systems, the NM response functions to neutrons and protons were calculated by means of the GEANT4 code, in the energy range between 10 meV and 100 GeV, and between 40 MeV and 10 GeV, respectively, using different intra-nuclear cascade (INC) models at energies above 20 MeV. Sample spectral fluence distributions as measured by means of the BSS system for neutrons in November and December 2007 were used and folded with the calculated GEANT4 NM response. The resulting calculated NM count rates were then compared to those actually measured by the NM system and a reasonable agreement between 7% and 43% was obtained, depending on the nuclear models used in the GEANT4 calculations and the assumed 10B enrichment of the NM counters used to detect the neutrons.
AU  - Pioch, C.
AU  - Mares, V.
AU  - Vashenyuk, E.V.*
AU  - Balabin, Y.V.*
AU  - Rühm, W.
C1  - 5463
C2  - 27811
SP  - 51-57
TI  - Measurement of cosmic ray neutrons with Bonner sphere spectrometer and neutron monitor at 79°N.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 626-627
IS  - 1
PB  - Elsevier
PY  - 2011
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - The neutron field condition in and around the treatment room of the neutron therapy facility at the research reactor FRM in Garching-Miinchen was studied for radiation protection purposes. Neutron spectrometry was conducted by using a 15-channel multisphere spectrometer. From the unfolded spectral shapes, averaged dose conversion coefficients were derived and correction factors for the reading of two neutron monitors obtained. These results were compared with further measurements done at a medical linear accelerator where the neutrons are produced by (gamma, n) processes in the irradiation head.
AU  - Schraube, H.
AU  - Kneschaurek, P.*
AU  - Schraube, G.
AU  - Wagner, F.M.*
AU  - Weitzenegger, E.
C1  - 9971
C2  - 20019
SP  - 463-467
TI  - Neutron spectra around medical treatment facilities.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
PB  - North-Holland Publ. Co.
PY  - 2002
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01-1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3 % over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration.
AU  - Hayes, R.B.*
AU  - Haskell, E.H.*
AU  - Wieser, A.
AU  - Romanyukha, A.A.*
AU  - Hardy, B.L.*
AU  - Barrus, J.K.*
C1  - 9972
C2  - 19204
SP  - 453-461
TI  - Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 440
PB  - North-Holland Publ. Co.
PY  - 2000
SN  - 0168-9002
ER  - 

TY  - JOUR
AU  - Mares, V.
AU  - Schraube, G.
AU  - Schraube, H.
C1  - 19001
C2  - 12039
SP  - 398-412
TI  - Calculated neutron response of a Bonner sphere spectrometer with 3He counter.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - A307
PY  - 1991
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - The neutron response matrix for a Bonner sphere spectrometric system with a 3.2 cm diameter 3He proportional counter is calculated applying the MCNP Monte Carlo code. The effects of variations in density of the polyethylene moderators and in gas pressure of the 3He counter are also discussed.
AU  - Mares, V.
AU  - Schraube, G.
AU  - Schraube, H.
C1  - 40714
C2  - 40173
SP  - 398-412
TI  - Calculated neutron response of a Bonner sphere spectrometer with 3He counter.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 307
IS  - 2-3
PY  - 1991
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - A thin-walled parallel-plate ionization chamber with high bandwidth is described by means of which (using O2 filling) the presentation of the beam time profile of linear accelerator pulses of a few 10 ns duration is achieved. Filled with air the chamber can be used for the presentation of μm pulses. The intensity limits and the time resolution of the method are discussed.
AU  - Balk, O.A.
AU  - Hochhäuser, E.
AU  - Arnold, W.R.*
AU  - Schneider, H.G.*
C1  - 42324
C2  - 40238
SP  - 93-100
TI  - Monitoring of ten-nanoseconds radiation pulses using ionization electrons.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 294
IS  - 1-2
PY  - 1990
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - A windowless gas-flow proportional counter for the measurement of 241Pu electrodeposited on stainless steel discs is described. The lower limit of detection is found to be 5 mBq at 60000 s counting time.
AU  - Winkler, R.A.
AU  - Rosner, G.
C1  - 33650
C2  - 36582
SP  - 359-361
TI  - Proportional counter for low-level 241Pu measurement.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 274
IS  - 1-2
PY  - 1989
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - Ionometric measurements in the beams of linear accelerators can be carried out even at high pulse dose rates if one considers the ionic recombination within the ionization chamber. It is shown that this in turn provides the knowledge of the electron component collected in the chamber. We used a chamber developed for that very purpose, which allows a direct measurement of the electron component. Results up to a pulse dose of 1.1 × 10−2 C kg−1 (approximately 43 R) are presented.
AU  - Hochhäuser, E.
AU  - Balk, O.
AU  - Ebel, F.
AU  - Schneider, H.
AU  - Arnold, W.
C1  - 17194
C2  - 10260
SP  - 542-549
TI  - Dosymetry in the Bremsstrahlung Beam of an 65 MeV Electron linear Accelerator Using an Ionization Ion-Electron Chamber.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 270
IS  - 2-3
PY  - 1988
SN  - 0168-9002
ER  - 

TY  - JOUR
AU  - Hochhäuser, E.
AU  - Balk, O.
C1  - 17645
C2  - 10570
SP  - 493-498
TI  - A Foil Calorimeter for Dosimetry of Short Impulse Electron Radiation of High Dose Rate.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 263
PY  - 1988
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - The Monte Carlo neutron and photon transport code SAM-CE has been used to calculate the photon radiation field in the air-over-ground geometry. It is shown that the external gamma exposure from Gaussian clouds is, for low energies, considerably reduced by the presence of the ground. Organ dose from point sources in the air and from plane sources on the ground have been calculated for several hundreds of radionuclides. In the second case, compared to results of other authors, higher doses were found for medium and high gamma energies, since the relatively low self-shielding of the human body against horizontal irradiations has been accounted for in this paper. For low gamma energies the doses are considerably reduced due to the, in this energy range, stronger shielding of surface roughness of the air-ground interface.
AU  - Jacob, P.
AU  - Paretzke, H.G.
C1  - 33134
C2  - 35558
SP  - 156-159
TI  - Dose-rate conversion factors for external gamma exposure.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 255
IS  - 1-2
PY  - 1987
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - The shielding of gamma radiation by typical European houses has been investigated using a Monte Carlo photon transport code. Sources of the gamma radiation are activity deposited on the building and its surroundings and air-borne radionuclides in an semi-infinite cloud. Results are given for different source energies and at various locations inside and outside of the buildings. The effects of deposition on nearby trees and of shielding by neighbouring buildings was investigated. A comparison has been made with results obtained for the same buildings by the point kernel buildup factor method. More than an order of magnitude underestimations by the point kernel method are shown to arise in certain cases.
AU  - Meckbach, R.
AU  - Jacob, P.
AU  - Paretzke, H.G.
C1  - 42303
C2  - 36204
SP  - 160-164
TI  - Shielding of gamma radiation by typical European houses.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 255
IS  - 1-2
PY  - 1987
SN  - 0168-9002
ER  - 

TY  - JOUR
AB  - A low-power, plasma-type sputter source for the production of positive ions of non-volatile elements has been constructed and tested. Argon and copper were employed as support gas and sample material, respectively. The source output was measured as a function of the discharge current, the axial magnetic field, the sputter voltage, the spacing between the sputter sample and the source exit, the diameter of the sputter sample, and the argon pressure. It was found that the Cu+ current, ICu, increases with increasing discharge current id as ICu ∝ id n, where n ≥ 2. ICu increases with decreasing sample-to-exit spacing s. For not too small spacings, ICu ∝ s-2. Cu+ currents of up to 6 μA were produced at a total power consumption of less than 60 W. The simultaneous prese nce of an intense Ar+ component in the beam causes space charge expansion which becomes significant at low energies and large ratios of the drift length to the beam-size defining apertures. Loss of target current may also be caused by neutralization of ions in charge-transfer collisions outside of the source.
AU  - Wach, W.
AU  - Wittmaack, K.
C1  - 41660
C2  - 38488
SP  - 1-8
TI  - Performance characteristics of a plasma-type sputter ion source.
JO  - Nucl. Instrum. Methods Phys. Res. Sect. A
VL  - 228
IS  - 1
PY  - 1984
SN  - 0168-9002
ER  -