Calibration of PADC-based neutron area dosemeters in the neutron field produced in the treatment room of a medical LINAC

Bedogni, R.; Domingo, C.; Esposito, A.; Gentile, A.; García-Fusté, M.J.; de-San-Pedro, M.; Tana, L.; D’Errico, Francesco; Ciolini, Riccardo; Fulvio, Angela Di

doi:10.1016/j.radmeas.2012.04.009

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…The contribution of neutron activation reactions as a source of induced activity in air was also considered by applying previous measurements of neutron flux and neutron energy spectrum around the 15 MV Varian Clinac accelerator (Bedogni et al 2013). It was found to be negligible with respect to the air photoneutron activation.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of air photoactivation at linear accelerators for radiotherapy

et al. 2015

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High-energy x-rays produced by radiotherapy accelerators operating at potentials above 10 MV may activate the air via (γ, n) reactions with both oxygen and nitrogen. While the activation products are relatively short-lived, personnel entering the accelerator room may inhale some radioactive air, which warrants internal dosimetry assessments. This work illustrates a method based on the use of ammonium nitrate solutions for the evaluation of photon-induced air activation and for the estimate of internal doses to radiotherapy personnel. Air activation and internal dosimetry assessments based on our method are presented for some widespread radiotherapy linear accelerator models. Our results indicate that the equivalent dose to the lungs of radiotherapy personnel is negligible for beam energies below 18 MeV.

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Section: Resultsmentioning

confidence: 99%

Evaluation of air photoactivation at linear accelerators for radiotherapy

et al. 2015

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“…Some few facilities are already equipped with specific installations for calibration purposes simulating more realistic workplace fields, such as IRSN/CANEL, NPL, PTB and CERF (Lacoste 2010, Lacoste et al 2011. Another solution sometimes employed in practice is to directly calibrate at the workplace or to determine an additional correction factor k, specific from the workplace field to take into account the differences between this and the calibration field, and those between the curve of conversion coefficients and the detector response (Mayer et al 2007, Bedogni et al 2013, Luszik-Bhadra 2016. This correction factor must be determined in situ by means of spectrometric measurements or MC methods.…”

Section: R E R E H E mentioning

confidence: 99%

Study of the responses and calibration procedures of neutron and gamma area and environmental detectors for use in proton therapy

et al. 2019

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Ambient dose equivalent measurements with radiation protection instruments are associated to large uncertainties, mostly due to the energy dependence of the instrument response and to the dissimilarity between the spectra of the standard calibration source and the workplace field. The purpose of this work is to evaluate its impact on the performance of area and environmental detectors in the proton therapy environment, and to provide practical solutions whenever needed and possible. The study was carried out at the Centre Antoine Lacassagne (CAL) proton therapy site, and included a number of commercially available area detectors and a home-made environmental thermoluminescent dosimeter based on a polyethylene moderator loaded with TLD600H/TLD700H pairs. Monte Carlo simulations were performed with MCNP to calculate, first, missing or partially lacking instrument responses, covering the range of energies involved in proton therapy. Second, neutron and gamma spectra were computed at selected positions in and outside the CAL proton therapy bunkers. Appropriate correction factors were then derived for each detector, workplace location and calibration radionuclide source, which amounts to up to 1.9 and 1.5 for neutron and photon area detectors, respectively, and suggest that common ambient dose equivalent instruments might not meet IEC requirements. The TLD environmental system was calibrated in situ and appropriate correction factors were applied to account for the cosmic spectra. Measurements performed with this system from 2014 to 2017 around the installation were consistent with reference natural background dose data and with pre-operational levels registered at the site before the construction of the building in 1988, showing thus no contribution from the site clinical activities. An in situ verification procedure for the radiation protection instruments was also implemented in 2016 at the low energy treatment room using the QA beam reference conditions. The method presents main methodological, practical and economic advantages over external verifications.

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“…Photoneutrons are measured using CR-39 SSNTD (solid state neutron track detector) for high energy and mixed-energy plans in uniform water equivalent phantom for single fraction at isocenter distance with gantry angle merged to zero degree. Films (Intercast Europe S.p.A, Italy) are etched (track forming) in 6.25 N NaOH solution for 8 hours at 70 ∘ C [21]. Neutron tracks are counted using Olympus microscope with 1000x zooming.…”

Section: Neutron Measurementsmentioning

confidence: 99%

Dosimetric Studies of Mixed Energy Intensity Modulated Radiation Therapy for Prostate Cancer Treatments

Haneefa

Shakir

Siddhartha

et al. 2014

Journal of Radiotherapy

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Dosimetric studies of mixed field photon beam intensity modulated radiation therapy (IMRT) for prostate cancer using pencil beam (PB) and collapsed cone convolution (CCC) algorithms using Oncentra MasterPlan treatment planning system (v. 4.3) are investigated in this study. Three different plans were generated using 6 MV, 15 MV, and mixed beam (both 6 and 15 MV). Fifteen patients with two sets of plans were generated: one by using PB and the other by using CCC for the same planning parameters and constraints except the beam energy. For each patient’s plan of high energy photons, one set of photoneutron measurements using solid state neutron track detector (SSNTD) was taken for this study. Mean percentage ofV66 Gyin the rectum is18.55±2.8,14.58±2.1, and16.77±4.7for 6 MV, 15 MV, and mixed-energy plans, respectively. Mean percentage ofV66 Gyin bladder is16.54±2.1,17.42±2.1,and16.94±41.9for 6 MV, 15 MV, and mixed-energy plans, respectively. Mixed fields neutron contribution at the beam entrance surface is 45.62% less than at 15 MV photon beam. Our result shows that, with negligible neutron contributions, mixed field IMRT has considerable dosimetric advantage.

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Calibration of PADC-based neutron area dosemeters in the neutron field produced in the treatment room of a medical LINAC

Cited by 12 publications

References 15 publications

Evaluation of air photoactivation at linear accelerators for radiotherapy

Evaluation of air photoactivation at linear accelerators for radiotherapy

Study of the responses and calibration procedures of neutron and gamma area and environmental detectors for use in proton therapy

Dosimetric Studies of Mixed Energy Intensity Modulated Radiation Therapy for Prostate Cancer Treatments

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