Tutorial on Neutron Physics in Dosimetry

Almost since the time of the discovery of the neutron more than 70 years ago, efforts have been made to understand the effects of neutron radiation on tissue and, eventually, to use neutrons for cancer treatment. In contrast to charged particle or photon radiations which directly lead to release of electrons, neutrons interact with the nucleus and induce emission of several different types of charged particles such as protons, alpha particles or heavier ions. Therefore, a fundamental understanding of the neutron-nucleus interaction is necessary for dose calculations and treatment planning with the needed accuracy. We will discuss the concepts of dose and kerma, neutron-nucleus interactions and have a brief look at nuclear data needs and experimental facilities and set-ups where such data are measured.Comment: Invited talk at the 11th Neutron and Ion Dosimetry Symposium NEUDOS-11, October 11-16, 2009, Cape Town, South Africa. 14 pages, 8 figures; submitted to Radiation Measurement

Methodology to address radioprotection and safety issues in the IFMIF/EVEDA accelerator prototype

In the IFMIF/EVEDA accelerator prototype, deuterons (with energies up to 9 MeV) interact with the materials of the accelerator components due to beam losses and in the beam dump, where the beam is stopped. The productions of neutrons/photons together with radioactive inventories due to deuteron-induced reactions are some major issues for radioprotection and safety assessment. Here, we will focus on the proposal of a computational approach able to simulate deuteron transport and evaluate deuteron interactions and production of secondary particles with acceptable precision. Current Monte Carlo codes, such as MCNPX or PHITS, when applied for deuteron transport calculation, use built-in semi-analytical models to describe deuteron interactions. These models are found unreliable in predicting neutron and photon generated by low energy deuterons, typically present in the IFMIF/EVEDA prototype accelerator. In this context, a new computational methodological approach is proposed based on the use of an extended version of current MC codes capable to use evaluated deuteron libraries for neutron (and gamma) production. The TALYS nuclear reaction code is found to be an interesting potential candidate to produce the evaluated data for double-differential neutron and photon emission cross sections for incident deuterons in the energy range of interest for IFMIF/EVEDA applications. The recently-released deuteron Talys-based Evaluated Nuclear Data Library, TENDL-2009, is considered a good starting point in the road to achieve deuteron data files of enough quality for deuteron transport problems in EVEDA. Unfortunately, current Monte Carlo transport codes are not able to handle light ion libraries except for protons. To overcome this drawback the MCNPX code has been extended to handle deuteron (also triton, helion and alpha) nuclear data libraries. In this new extended MCNPX version called MCUNED, a new variance reduction technique has also been implemented for the production of secondary particles induced by light ions nuclear reactions, which allow reducing drastically the computing time needed in transport and nuclear response function calculations. Verification of these new capabilities for Monte 2 Carlo simulation of deuteron transport and secondary products generation included in MCUNED is successfully achieved. The existence of the MCUNED code allows us for the first time testing the deuteron crosssection TENDL package by simulation of integral experiments. Some preliminary efforts are addressed to compare existing experimental data on thick target neutron yields for Copper with those computed by the MCUNED code using TENDL cross sections

Deuteron cross section evaluation for safety and radioprotection calculations of IFMIF/EVEDA accelerator prototype

under construction in Japan. Interaction of these deuterons with matter will generate high levels of neutrons and induced activation, whose predicted yields depend strongly on the models used to calculate the different cross sections. A benchmark test was performed to validate these data for deuteron energies up to 20 MeV and to define a reasonable methodology for calculating the cross sections needed for EVEDA. Calculations were performed using the nuclear models included in MCNPX and PHITS, and the dedicated nuclear model code TALYS. Although the results obtained using TALYS (global parameters) or Monte Carlo codes disagree with experimental values, a solution is proposed to compute cross sections that are a good fit to experimental data. A consistent computational procedure is also suggested to improve both transport simulations/prompt dose and activation/residual dose calculations required for EVEDA

Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status

Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low energy thresholds and for a wide angular range (20-160 degrees). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature.Comment: 21 pages, 28 figure

Investigation on the potential of improvement in the field of medical applications of ionizing radiation via the future European Metrology Network

Due to constant development in radiodiagnostic and radiotherapy procedures with increasing complexity, a need for high-level coordination of the ionizing radiation metrology community was recognized to better respond to the needs of end users. In order to facilitate knowledge dissemination and improve communication between stakeholders involved in medical applications of ionizing radiation, a Joint Network Project was started in 2020. One of the specific objectives of Work Package 2 of the project 19NET04 MIRA, “Support for a European Metrology Network on the medical use of ionizing radiation” is to support the developing states, ensuring that the planned EMN is inclusive through improvements in the medical use of ionizing radiation [1]. Czech Republic, Romania and Serbia were defined as countries of interest to conduct the survey and collect relevant data from stakeholders in the category of medical staff and professionals, so that the potential for improvement for medical applications of ionizing radiation can be evaluated. For the purpose of data collection, an online questionnaire was prepared and distributed to the stakeholders. The questionnaire was structured in such a way to allow easier collection of information regarding availability of (1) calibration services; (2) documented technical protocols; (3) standard documentation in the establishments for different ionizing radiation applications. Implementation of a Quality assurance (QA) programme was investigated, as well as the consistency in realization of proficiency testing (PT) or audits. The stakeholders were asked if additional workshops or training programmes are needed in their area of expertise. The radiodiagnostic modalities included in the questionnaire were the general radiography, mammography, computed tomography and interventional procedures, while radiotherapy modalities included external beam radiotherapy (teletherapy) and brachytherapy. Although nuclear medicine (therapy and diagnostic) procedures were part of the questionnaire, none of the respondents have capabilities for these applications. Based on the information collected via the online questionnaire, calibration services are available for most of the modalities, except for brachytherapy where traceability is not established. QA and PT are regularly performed in radiotherapy, while it is not the case in radiodiagnostic modalities. Improvement in knowledge transfer is needed for all of the applications investigated. Considering the acquired information, there is a clear need for EMN to support knowledge transfer, communication and technical exchange between the metrology community and the stakeholders involved in the medical applications of ionizing radiation. The forthcoming European Metrology Network will further elaborate the knowledge dissemination and stakeholder dialogue through its stakeholder panels and joint training effortsX JUBILEE International Conference on Radiation in Various Fields of Research : RAD 2022 (Spring Edition) : book of abstracts; June 13-17, 2022; Herceg Novi, Montenegr

Neutron-induced Light Ion Production From Fe, Pb And U At 96 Mev

Double-differential cross sections for light-ion production (up to A=4) induced by 96 MeV neutrons have been measured for $^{nat}$Fe, $^{nat}$Pb and $^{nat}$U. The experiments have been performed at the The Svedberg Laboratory in Uppsala, using two independent devices, MEDLEY and SCANDAL. The recorded data cover a wide angular range (20º - 160º) with low energy thresholds. The work was performed within the HINDAS collaboration studying three of the most important nuclei for incineration of nuclear waste with accelerator-driven systems (ADS). The obtained cross section data are of particular interest for the understanding of the so-called pre-equilibrium stage in a nuclear reaction and are compared with model calculations performed with the GNASH, TALYS and PREEQ code

A Novel Fast Neutron Detector For Nuclear Data Measurements

International audienceAccelerator driven system will use a heavy element target such as lead. Many calculations are available to simulate high-energy spallation neutron induced reactions, but little data are available for comparison with the simulations. In order to constrain the simulation tools we have measured (n,Xn) double differential cross section on different targets at The Svedberg Laboratory, Uppsala, Sweden. For neutron energy above 40 MeV, we have developed a novel detector, CLODIA, based on proton recoil and drift chambers to determine neutron energy. CLODIA (Chamber for LOcalization with DrIft and Amplification) is able to track recoil protons with energy up to 90 MeV with spatial resolution of about one millimeter and a detection efficiency of 99% for each drift chamber. Using CLODIA coupled with the SCANDAL set-up, we have been able to measure double differential (n,Xn) cross section on lead and iron for incident neutron energy in the 40-95 MeV energy region

VERIDIC: validation and estimation of radiation skin dose in interventional cardiology

Interventne procedure u radiologiji i kardiologiji povezani su sa visokim dozama za kožu pacijenta i potencijalnim radijacionim povredama kože. Različita metodologije i rešenja razvijene us za procenu maksimalne doze za kožu, čija se svojsvta, uključujuši i tačnost značajno razlikuju. U radu su prokazani ciljevi, metode i preminiran a rešenja projekta VERIDIC usmerenoj na validaciju zaličitih ofline i online softvera za procenu doze za kožu pacijenta u intervenatnoj kardiologiji.In interventional cardiology (IC), patients may be exposed to high doses to the skin resulting in tissue reactions (skin burns) following single or multiple procedures. To address this issue, online and offline software has been developed to estimate the maximum skin dose (MSD) to the patient from IC procedures. However, the capabilities and accuracy of such skin dose calculation (SDC) software to estimate MSD and 2D dose distributions markedly differ among vendors. Hence, this project focuses onthe harmonisation of RDSR (radiation dose structured report) and on the validation of SDC software products in IC, which will optimise radiation protection of patients. The outcome of the project will include the standards for digital dose reporting, development of protocols for acceptance testing and Quality Control (QC)of SDC software and setting of diagnostic reference levels per clinical complexity, assessing thefrequency of high-dose procedures as well as dose reduction strategies based on the multi-centric data collection. This paper focuses on the work performed to investigate performance of solid state dosimeters used in clinical environment.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј