Radiation Protection Dosimetry - current issue

Introductory Remarks

Menzel, H., Schonbacher, H., Vylet, V., Ulrici, L., Rokni, S. — Mon, 16 Nov 2009 09:54:48 PST

Operational radiation protection in high-energy physics accelerators

Rokni, S. H., Fasso, A., Liu, J. C. — Mon, 16 Nov 2009 09:54:48 PST

An overview of operational radiation protection (RP) policies and practices at high-energy electron and proton accelerators used for physics research is presented. The different radiation fields and hazards typical of these facilities are described, as well as access control and radiation control systems. The implementation of an operational RP programme is illustrated, covering area and personnel classification and monitoring, radiation surveys, radiological environmental protection, management of induced radioactivity, radiological work planning and control, management of radioactive materials and wastes, facility dismantling and decommissioning, instrumentation and training.

Operational radiation protection in synchrotron light and free electron laser facilities

Liu, J. C., Rokni, S. H., Vylet, V. — Mon, 16 Nov 2009 09:54:48 PST

The third-generation synchrotron radiation (SR) facilities are storage ring-based facilities with many insertion devices and photon beamlines, and have low injection beam power, but extremely high stored beam power. The fourth-generation X-ray free electron laser (FEL) facilities are based on an electron Linac with a long undulator and have high injection beam power. Due to its electron and photon beam characteristics and modes of operation, storage ring and photon beamlines have unique safety aspects, which are the main subjects of this paper. The shielding design limits, operational modes and beam losses are reviewed. Shielding analysis (source terms and methodologies) and interlocked safety systems for storage ring and photon beamlines (including SR and gas bremsstrahlung) are described. Specific safety issues for storage ring top-off injection and FEL facilities are discussed. Operational safety programme elements, e.g. operation authorisation, commissioning, training and radiation measurements, for SR facilities are also presented.

Operational radiation protection issues specific to high-intensity beams

Nakashima, H. — Mon, 16 Nov 2009 09:54:48 PST

This paper describes operational radiation protection issues specific to high-intensity accelerators, aimed at the radiological safety of high-intensity accelerators during construction and operation. The paper is composed of chapters on safety characteristics, radiological safety design and safety management systems of high-intensity accelerators. The Japan Proton Accelerator Research Complex (J-PARC) is taken as a reference, because J-PARC was recently completed after collecting and referring to experiences with existing accelerator facilities all over the world.

Instrument response in complex radiation fields

Agosteo, S., Silari, M., Ulrici, L. — Mon, 16 Nov 2009 09:54:49 PST

This paper aims at giving an overview of the main issues for estimating the radiation protection quantities in complex radiation fields. The measurability (or non-measurability) of the radiation protection quantities is discussed together with the main approaches for their estimate. The main mechanisms through which the various components of complex radiation fields are generated are also outlined. The main instruments employed for estimating the radiation protection quantities are described and discussed together with their response. Finally, a practical example is given, by discussing the results of an inter-comparison exercise held at the Gesellschaft für Schwerionenforschung mbH in Darmstadt (Germany) in the framework of the COordinated Network for RAdiation Dosimetry project, funded by the European Commission.

Individual monitoring at accelerator centres

Wernli, C. — Mon, 16 Nov 2009 09:54:49 PST

The accurate determination of personal dose equivalent requires the proper use of appropriate radiological quantities and units, knowledge of the dose equivalent response of the personal dosemeters used and detailed information on the fluence as well as dose equivalent spectra at the workplaces. This information can then be used to select the appropriate dosemeters, to set up the optimum calibration conditions and to introduce, in case of need, normalisation factors for application in specific radiation fields. High-energy neutrons contribute significantly to the radiation fields around high-energy particle accelerators. Examples for procedures and methods to determine personal dose equivalent at accelerator centres are given.

High-level dosimetric methods

Schonbacher, H., Furstner, M., Vincke, H. — Mon, 16 Nov 2009 09:54:49 PST

This article gives an overview of selected high-dose dosimetric methods suitable for use in accelerators in research and medicine for reference, transfer and routine dosimetry. This comprises solid state, glass, plastic and liquid chemical systems as well as ionisation chambers and calorimeters. The dose covered varies from 0.1 Gy to the MGy range. A summary comparing the main characteristics of these dosemeters is also given.

Operational radiation protection in high-energy physics accelerators: implementation of ALARA in design and operation of accelerators

Fasso, A., Rokni, S. — Mon, 16 Nov 2009 09:54:49 PST

This paper considers the historical evolution of the concept of optimisation of radiation exposures, as commonly expressed by the acronym ALARA, and discusses its application to various aspects of radiation protection at high-energy accelerators.

Radiation safety system

Vylet, V., Liu, J. C., Walker, L. S. — Mon, 16 Nov 2009 09:54:49 PST

The goal of this work is to provide an overview of a Radiation safety system (RSS) designed for protection from prompt radiation hazard at accelerator facilities. RSS design parameters, functional requirements and constraints are derived from hazard analysis and risk assessment undertaken in the design phase of the facility. The two main subsystems of a RSS are access control system (ACS) and radiation control system (RCS). In this text, a common approach to risk assessment, typical components of ACS and RCS, desirable features and general design principles applied to RSS are described.

Understanding and characterisation of the risks to human health from exposure to low levels of radiation

Goodhead, D. T. — Mon, 16 Nov 2009 09:54:49 PST

Exposure to ionising radiation can lead to a wide variety of health effects. Cancer is judged to be the main risk from radiation at low doses and low dose rates, and controlling this risk has been the main factor in developing radiation protection practice. Conventional paradigms of radiobiology and radiation carcinogenesis have served to guide extrapolations of epidemiological data on exposed human populations, so as to estimate risks at low doses and low dose rates, to other types of ionising radiation and to non-uniform exposures. These paradigms are founded on a century of experimental and theoretical studies, but nevertheless there remain many uncertainties. Major assumptions and simplifications have been introduced to achieve a practical system of additive doses (and implied risks) for radiation protection. Advancing epidemiological studies and experimental research continue to reduce uncertainties in some areas while, in others, they raise new challenges to the generality and applicability of the conventional paradigms.

Radiation transport calculations and simulations

Fasso, A., Ferrari, A., Sala, P. R. — Mon, 16 Nov 2009 09:54:49 PST

This article is an introduction to the Monte Carlo method as used in particle transport. After a description at an elementary level of the mathematical basis of the method, the Boltzmann equation and its physical meaning are presented, followed by Monte Carlo integration and random sampling, and by a general description of the main aspects and components of a typical Monte Carlo particle transport code. In particular, the most common biasing techniques are described, as well as the concepts of estimator and detector. After a discussion of the different types of errors, the issue of quality assurance is briefly considered.

Programmes for the evaluation of the environmental impact

Vojtyla, P. — Mon, 16 Nov 2009 09:54:49 PST

The article provides an overview of the different components of programmes for the evaluation of the environmental impact of accelerator facilities. The starting point is the knowledge of radiation and radionuclides that may be encountered in the environment of accelerators. The second step is an efficient environmental monitoring programme suitable for the given source term. The results of the monitoring programme provide an input for models calculating the maximum effective dose received by members of the public, so expressing the dosimetric impact of the facility.

Radioactive waste management and decommissioning of accelerator facilities

Ulrici, L., Magistris, M. — Mon, 16 Nov 2009 09:54:49 PST

During the operation of high-energy accelerators, the interaction of radiation with matter can lead to the activation of the machine components and of the surrounding infrastructures. As a result of maintenance operation and during decommissioning of the installation, considerable amounts of radioactive waste are evacuated and shall be managed according to the radiation-protection legislation. This paper gives an overview of the current practices in radioactive waste management and decommissioning of accelerators.

Carbon-ion radiotherapy: clinical aspects and related dosimetry

Mon, 16 Nov 2009 09:54:49 PST

The features of relativistic carbon-ion beams are attractive from the viewpoint of radiotherapy. They exhibit not only a superior physical dose distribution but also an increase in biological efficiency with depth, because energy loss of the beams increases as they penetrate the body. This paper reviews clinical aspects of carbon-beam radiotherapy using the experience at the National Institute of Radiological Sciences. The paper also outlines the dosimetry related to carbon-beam radiotherapy, including absolute dosimetry of the carbon beam, neutron measurements and radiation protection measurements.

Medical physics aspects of particle therapy

Jakel, O. — Mon, 16 Nov 2009 09:54:49 PST

Charged particle beams offer an improved dose conformation to the target volume when compared with photon radiotherapy, with better sparing of normal tissue structures close to the target. In addition, beams of heavier ions exhibit a strong increase of the linear energy transfer in the Bragg peak when compared with the entrance region. These physical and biological properties make ion beams more favourable for radiation therapy of cancer than photon beams. As a consequence, particle therapy with protons and heavy ions has gained increasing interest worldwide. This contribution summarises the physical and biological principles of charged particle therapy with ion beams and highlights some of the developments in the field of beam delivery, the principles of treatment planning and the determination of absorbed dose in ion beams. The clinical experience gathered so far with carbon ion therapy is briefly reviewed.

Radiation protection constraints for use of proton and ion accelerators in medicine

Agosteo, S. — Mon, 16 Nov 2009 09:54:49 PST

This paper gives some guidelines for radiation protection at proton therapy facilities. The energy and angular distribution of secondary radiation from thick iron and tissue targets bombarded by 250-MeV protons were calculated with Monte Carlo simulations in order to emphasise the influence of the various components of the radiation field on the shielding design. The main constraints for radiation protection (e.g. workload, use and occupancy factors, etc.), shielding design (including access mazes) and the estimate of material activation are also discussed with some practical examples.