Superheated drop detector for determination of neutron dose equivalent to patients undergoing high-energy x-ray and electron radiotherapy

1993 ◽  
Vol 20 (3) ◽  
pp. 781-787 ◽  
Author(s):  
Ravinder Nath ◽  
Ali S. Meigooni ◽  
Christopher R. King ◽  
Stuart Smolen ◽  
Francesco d'Errico
Keyword(s):  
High Energy ◽  
Neutron Dose ◽  
Dose Equivalent ◽  
X Ray ◽  
Neutron Dose Equivalent ◽  
Electron Radiotherapy

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

scholarly journals Photo neutron dose equivalent rate in 15 MV X-ray beam from a Siemens Primus Linac

2015 ◽  
Vol 40 (2) ◽  
pp. 90 ◽  
Author(s):  
TAllahverdi Pourfallah ◽  
MR Akbari ◽  
H Babapour ◽  
M Shahidi ◽  
A Ghasemi
Keyword(s):  
Neutron Dose ◽  
Dose Equivalent ◽  
X Ray ◽  
Equivalent Rate ◽  
Neutron Dose Equivalent

scholarly journals The influence of shielding reinforcement in a vault with limited dimensions on the neutron dose equivalent in vicinity of medical electron linear accelerator

2020 ◽  
Vol 54 (2) ◽  
pp. 247-252
Author(s):  
Ana Ivkovic ◽  
Dario Faj ◽  
Mladen Kasabasic ◽  
Marina Poje Sovilj ◽  
Ivana Krpan ◽  
...  
Keyword(s):  
Neutron Energy ◽  
Linear Accelerator ◽  
High Energy ◽  
Neutron Dose ◽  
University Hospital ◽  
Fast Neutrons ◽  
Dose Equivalent ◽  
Electron Linear Accelerator ◽  
Neutron Spectra ◽  
Neutron Dose Equivalent

AbstractBackgroundHigh energy electron linear accelerators (LINACs) producing photon beams with energies higher than 10 MeV are widely used in radiation therapy. In these beams, fast neutrons are generated, which results in undesired contamination of the therapeutic beam. In this study, measurements and Monte Carlo (MC) simulations were used to obtain neutron spectra and dose equivalents in vicinity of linear accelerator.Materials and methodsLINAC Siemens Oncor Expression in Osijek University Hospital is placed in vault that was previously used for 60Co machine. Then, the shielding of the vault was enhanced using lead and steel plates. Measurements of neutron dose equivalent around LINAC and the vault were done using CR-39 solid state nuclear track detectors. To compensate energy dependence of detectors, neutron energy spectra was calculated in measuring positions using MC simulations.ResultsThe vault is a source of photoneutrons, but a vast majority of neutrons originates from accelerator head. Neutron spectra obtained from MC simulations show significant changes between the measuring positions. Annual neutron dose equivalent per year was estimated to be less than 324 μSv in the measuring points outside of the vault.ConclusionsSince detectors used in this paper are very dependent on neutron energy, it is extremely important to know the neutron spectra in measuring points. Though, patient dosimetry should include neutrons, estimated annual neutron doses outside the vault were far below exposure limit of ionizing radiation for workers.

Experimental and computational determination of neutron dose equivalent around radiotherapy accelerators

2003 ◽  
Vol 107 (4) ◽  
pp. 225-232 ◽  
Author(s):  
E. J. Waller ◽  
T. J. Jamieson ◽  
D. Cole ◽  
T. Cousins ◽  
R. B. Jammal
Keyword(s):  
Neutron Dose ◽  
Dose Equivalent ◽  
Neutron Dose Equivalent

scholarly journals Potential benefit of retrospective use of neutron monitors in improving ionising radiation exposure assessment on international flights: issues raised by neutron passive dosimeter measurements and EPCARD simulations during sudden changes in solar activity

2020 ◽  
Vol 71 (2) ◽  
pp. 152-157
Author(s):  
Marina Poje Sovilj ◽  
Branko Vuković ◽  
Vanja Radolić ◽  
Igor Miklavčić ◽  
Denis Stanić
Keyword(s):  
Solar Activity ◽  
High Energy ◽  
Ionising Radiation ◽  
Neutron Dose ◽  
Flight Crew ◽  
Dose Equivalent ◽  
Ambient Dose Equivalent ◽  
Neutron Dose Equivalent ◽  
Neutron Component ◽  
Ambient Dose

AbstractSince air transport became more accessible, more and more people have been exposed to ionising radiation of cosmic origin. Measuring the neutron dose equivalent is a good approximation of total ambient dose equivalent, as neutrons carry about 50 % of the dose at flight altitudes. The aim of our study was to compare our measurements of the neutron component of secondary cosmic radiation dose, taken with passive dosimeters, with the data obtained from a simulation generated by EPCARD software, which is common in assessing flight crew exposure to ionising radiation. We observed deviations (both above and below) from the expected proportion of the neutron component (between 40 and 80 %), which pointed to certain issues with actual passive dosimeter measurement and the EPCARD simulation. The main limitation of the dosimeter are large uncertainties in high energy neutron response, which may result in underestimation of neutron dose equivalent. The main drawback of the software simulation is monthly averaging of solar potential in calculations, which can neglect sporadic high energy events. Since airlines worldwide almost exclusively use software (due to costs and convenience) to estimate the dose received by their crew, it is advisable to retrospectively recalculate the dose taking into account neutron monitor readings when solar activity changes.

scholarly journals The neutron dose equivalent around high energy medical electron linear accelerators

2014 ◽  
Vol 29 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Marina Poje ◽  
Ana Ivkovic ◽  
Slaven Jurkovic ◽  
Gordana Zauhar ◽  
Branko Vukovic ◽  
...  
Keyword(s):  
Neutron Radiation ◽  
Medical Personnel ◽  
Dose Dependence ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Equivalent ◽  
Linear Accelerators ◽  
Dose Rates ◽  
Neutron Dose Equivalent ◽  
Conservative Estimation

The measurement of neutron dose equivalent was made in four dual energy linear accelerator rooms. Two of the rooms were reconstructed after decommissioning of 60Co units, so the main limitation was the space. The measurements were performed by a nuclear track etched detectors LR-115 associated with the converter (radiator) that consist of 10B and with the active neutron detector Thermo BIOREM FHT 742. The detectors were set at several locations to evaluate the neutron ambient dose equivalent and/or neutron dose rate to which medical personnel could be exposed. Also, the neutron dose dependence on collimator aperture was analyzed. The obtained neutron dose rates outside the accelerator rooms were several times smaller than the neutron dose rates inside the accelerator rooms. Nevertheless, the measured neutron dose equivalent was not negligible from the aspect of the personal dosimetry with almost 2 mSv a year per person in the areas occupied by staff (conservative estimation). In rooms with 15 MV accelerators, the neutron exposure to the personnel was significantly lower than in the rooms having 18 MV accelerators installed. It was even more pronounced in the room reconstructed after the 60Co decommissioning. This study confirms that shielding from the neutron radiation should be considered when building vaults for high energy linear accelerators, especially when the space constraints exist.

X‐ray determination of the Debye temperature at high pressure using high‐energy synchrotron radiation

1990 ◽  
Vol 68 (6) ◽  
pp. 2719-2722 ◽  
Author(s):  
A. Matsumuro ◽  
M. Kobayashi ◽  
T. Kikegawa ◽  
M. Senoo
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Debye Temperature ◽  
High Energy ◽  
X Ray
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