Search

Previously, we have developed DynamicMC for modeling relative movement of Oak Ridge National Laboratory phantom in a radiation field for the Monte Carlo N-Particle package (Health Physics. 2023,124(4):301-309). Using this software, three-dimensional dose distributions in a phantom irradiated by a certain mono-energetic (Mono E) source can be deduced through its graphical user interface. In this study, we extended DynamicMC to be used in combination with the Particle and Heavy Ion Transport code System (PHITS) by providing it with a higher flexibility for dynamic movement for an anthropomorphic phantom. For this purpose, we implemented four new functions into the software, which are (1) to generate not only Mono E sources but also those having an energy spectrum of an arbitrary radioisotope (2) to calculate the absorbed doses for several radiologically important organs (3) to automatically average the calculated absorbed doses along the path of the phantom and (4) to generate user-defined slab shielding materials. The first and third items utilize the PHITS-specific modalities named radioisotope-source and sumtally functions, respectively. The computational cost and complexity can be dramatically reduced with these features. We anticipate that the present work and the developed open-source tools will be in the interest of nuclear radiation physics community for research and teaching purposes., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Abstract: Public communication about radiation is tricky business. Members of the public are frequently skeptical about messages from scientific sources, particularly when it comes to radiation. As radiation protection professionals, it is our job to relay scientifically sound information in a simple, clear, and concise manner. This paper discusses the Health Physics Society's "Ask The Experts" feature, the society's most successful public education endeavor with over one million visitors annually. The keys to effective communication of technical information are demonstrating empathy and compassion, keeping the language simple and concise, and offering sources of additional information to empower the individual to learn more on their own. The two most common categories of questions-radiation exposures from diagnostic imaging procedures and radiation exposures to the fetus-are discussed in detail, and some general information on how to respond to these types of questions is provided. A template for responding to public questions is provided, along with some examples., Competing Interests: The author declares no conflicts of interest., (Copyright © 2021 Health Physics Society.)

Purpose: To investigate a new clinical role for medical physicists in direct patient care with a prospective phase 2 clinical trial., Materials and Methods: Medical physicists participated in the Physics Direct Patient Care (PDPC) protocol, establishing independent professional relationships with radiation oncology patients. After attending a dedicated patient communication training program, medical physicists routinely met with patients for 2 physicist-patient consults to explain the treatment planning and delivery process, review the patient's treatment plan, and answer all technical questions. The first physicist-patient consult took place immediately before the computed tomography simulation, and the second took place immediately before the first treatment. Questionnaires were administered to each patient on the PDPC protocol at 3 time points to assess both anxiety and satisfaction. The first questionnaire was given shortly after the first physicist-patient consult, the second questionnaire was given shortly after the second physicist-patient consult, and the third questionnaire was given after the last treatment appointment, with no associated physicist-patient consult., Results: The mean patient anxiety score was considered to be low at all questionnaire time points. There was a statistically significant decrease (P < .0001) in anxiety from the simulation time point to the first treatment time point. The mean patient technical satisfaction score was considered to be high at all measurement time points. There was a statistically significant increase (P = .0012) in technical satisfaction from the simulation time point to the first treatment time point. There was a statistically significant decrease (P < .023) in technical satisfaction from the first treatment time point to the last treatment time point., Conclusions: Establishing a new clinical role for medical physicists and investigating its effects on patient anxiety and satisfaction have created the foundation for future studies. Based on the results of this trial, the PDPC protocol will be expanded to a larger group of medical physicists, radiation oncologists, and patient disease sites and investigated with a randomized phase 3 clinical trial., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Science and technology have outpaced our human ability to process and analyze the myriad data systems that extend throughout an enterprise of health care networks. Medical physicists must learn to work collaboratively with computer programmers, data scientists, administrators, and health care providers in the data-rich environment of modern health care, embracing and practicing a new discipline: cloud-based medical physics. This article addresses four distinct topics: (1) Evolution of health care systems, networks and electronic medical records (EMR); (2) Evolution of medical physics with scientific discoveries and technological advancements; (3) Evolution of information technology including; metadata, enterprise and the cloud; and (4) Medical physics enterprise: adaptive approach to quality and safety for the 21st Century.

Purpose: The purpose of this study is to evaluate the usefulness of the design of experiments in the analysis of multiparametric problems related to the quality assurance in radiotherapy. The main motivation is to use this statistical method to optimize the quality assurance processes in the validation of beam models., Method: Considering the Varian Eclipse system, eight parameters with several levels were selected: energy, MLC, depth, X, Y 1 and Y 2 jaw dimensions, wedge and wedge jaw. A Taguchi table was used to define 72 validation tests. Measurements were conducted in water using a CC04 on a TrueBeam STx, a TrueBeam Tx, a Trilogy and a 2300IX accelerator matched by the vendor. Dose was computed using the AAA algorithm. The same raw data was used for all accelerators during the beam modelling., Results: The mean difference between computed and measured doses was 0.1±0.5% for all beams and all accelerators with a maximum difference of 2.4% (under the 3% tolerance level). For all beams, the measured doses were within 0.6% for all accelerators. The energy was found to be an influencing parameter but the deviations observed were smaller than 1% and not considered clinically significant., Conclusion: Designs of experiment can help define the optimal measurement set to validate a beam model. The proposed method can be used to identify the prognostic factors of dose accuracy. The beam models were validated for the 4 accelerators which were found dosimetrically equivalent even though the accelerator characteristics differ., (Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Gioacchino Failla was initially appointed to operate the radon plant at Memorial Hospital in 1916. What to most people would have been a part-time temporary position was to him a career. He was not satisfied to simply fabricate radon seeds, he wanted to understand the physics and biology of the radiation emitted by the progeny of radium. His was not the first medical physics group in the United States, though it was one of the earliest, but it was the first to put such emphasis on the biological effects. After more than 28 years at Memorial Hospital, Failla moved his research group to Columbia University Medical Center and his pioneering work, blending physics and biology, has continued to date at Columbia by those that he trained or inspired, under three directors that followed him.

Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Medical physics, both as a scientific discipline and clinical service, hugely contributed and still contributes to the advances in the radiotherapy of prostate cancer. The traditional translational role in developing and safely implementing new technology and methods for better optimizing, delivering and monitoring the treatment is rapidly expanding to include new fields such as quantitative morphological and functional imaging and the possibility of individually predicting outcome and toxicity. The pivotal position of medical physicists in treatment personalization probably represents the main challenge of current and next years and needs a gradual change of vision and training, without losing the traditional and fundamental role of physicists to guarantee a high quality of the treatment. The current focus issue is intended to cover traditional and new fields of investigation in prostate cancer radiation therapy with the aim to provide up-to-date reference material to medical physicists daily working to cure prostate cancer patients. The papers presented in this focus issue touch upon present and upcoming challenges that need to be met in order to further advance prostate cancer radiation therapy. We suggest that there is a smart future for medical physicists willing to perform research and innovate, while they continue to provide high-quality clinical service. However, physicists are increasingly expected to actively integrate their implicitly translational, flexible and high-level skills within multi-disciplinary teams including many clinical figures (first of all radiation oncologists) as well as scientists from other disciplines., (Copyright © 2016. Published by Elsevier Ltd.)

Partial differential equations are often used in the field of medical physics. In this (final) issue, the methods for solving the partial differential equations were introduced, which include separation of variables, integral transform (Fourier and Fourier-sine transforms), Green's function, and series expansion methods. Some examples were also introduced, in which the integral transform and Green's function methods were applied to solving Pennes' bioheat transfer equation and the Fourier series expansion method was applied to Navier-Stokes equation for analyzing the wall shear stress in blood vessels.Finally, the author hopes that this series will be helpful for people who engage in medical physics.

In this issue, simultaneous differential equations were introduced. These differential equations are often used in the field of medical physics. The methods for solving them were also introduced, which include Laplace transform and matrix methods. Some examples were also introduced, in which Laplace transform and matrix methods were applied to solving simultaneous differential equations derived from a three-compartment kinetic model for analyzing the glucose metabolism in tissues and Bloch equations for describing the behavior of the macroscopic magnetization in magnetic resonance imaging.In the next (final) issue, partial differential equations and various methods for solving them will be introduced together with some examples in medical physics.

DICOM2PHITS and PSFC4PHITS are user assistance programs for medical physics PHITS applications. DICOM2PHITS is a program to construct the voxel PHITS simulation geometry from patient CT DICOM image data by using a conversion table from CT number to material composition. PSFC4PHITS is a program to convert the IAEA phase-space file data to PHITS format to be used as a simulation source of PHITS. Both of the programs are useful for users who want to apply PHITS simulation to verification of the treatment planning of radiation therapy. We are now developing a program to convert dose distribution obtained by PHITS to DICOM RT-dose format. We also want to develop a program which is able to implement treatment information included in other DICOM files (RT-plan and RT-structure) as a future plan.

Continuing Professional Development (CPD) is vital to the medical physics profession if it is to embrace the pace of change occurring in medical practice. As CPD is the planned acquisition of knowledge, experience and skills required for professional practice throughout one's working life it promotes excellence and protects the profession and public against incompetence. Furthermore, CPD is a recommended prerequisite of registration schemes (Caruana et al. 2014) and is implied in the Council Directive 2013/59/EURATOM (EU BSS) and the International Basic Safety Standards (BSS). It is to be noted that currently not all national registration schemes require CPD to maintain the registration status necessary to practise medical physics. Such schemes should consider adopting CPD as a prerequisite for renewing registration after a set period of time. This EFOMP Policy Statement, which is an amalgamation and an update of the EFOMP Policy Statements No. 8 and No. 10, presents guidelines for the establishment of national schemes for CPD and activities that should be considered for CPD., (Copyright © 2016. Published by Elsevier Ltd.)

Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist is responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography.

Preventive Medicine Specialists (military occupational specialty [MOS] 68S) with the health physics specialist (N4) qualification identifier possess a unique force health protection skill set. In garrison, they ensure radiation exposures to patients, occupational workers and the public from hospital activities such as radioisotope therapy and x-ray machines do not to exceed Federal law limits and kept as low as reasonably achievable. Maintaining sufficient numbers of health physics specialists (HPSs) to fill authorizations has been a consistent struggle for the Army Medical Department due to the rigorous academic requirements of the additional skill identifier-producing program. This shortage has limited MOS 68SN4 deployment opportunities in the past and prevented medical planners from recognizing the capabilities these Soldiers can bring to the fight. In 2014, for the first time, HPSs were sourced to deploy as an augmentation capability to the 172nd Preventive Medicine Detachment (PM Det), the sole PM Det supporting the Combined Joint Operations Area-Afghanistan. Considerable successes in bettering radiation safety practices and improvements in incident and accident response were achieved as a result of their deployment. The purposes of this article are to describe the mission services performed by HPSs in Afghanistan, discuss the benefits of deploying HPSs with PM Dets, and demonstrate to senior medical leadership the importance of maintaining a health physics capability in a theater environment.

The Encyclopaedia of Medical Physics EMITEL was developed under the EU pilot project European Medical Imaging Technology e-Encyclopaedia for Lifelong Learning. This large reference material includes 3400 articles on 2100 pages supported by thousands of illustrations. All materials are available free at the website, www.emitel2.eu. The articles are grouped in seven categories--physics of: X-ray diagnostic radiology, nuclear medicine, radiotherapy, magnetic resonance imaging, ultrasound imaging, radiation protection and general terms. The radiation protection part of EMITEL includes 450 articles. These were organised in several sub-groups including: nuclear and atomic physics; ionizing radiation interactions and biological effects; radiation detection and measurement; dosimetric quantities and units; and general radiation protection and international bodies. EMITEL project was developed over 3 y and attracted as contributors 250+ senior specialists from 35 countries. After its successful launching, EMITEL is actively used by thousands of professionals around the world., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Performing health physics and radiation safety functions under a special nuclear material license and a research and test reactor license at a major government research and development laboratory encompasses many elements not encountered by industrial, general, or broad scope licenses. This article reviews elements of the health physics and radiation safety program at the NIST Center for Neutron Research, including the early history and discovery of the neutron, applications of neutron research, reactor overview, safety and security of radiation sources and radioactive material, and general health physics procedures. These comprise precautions and control of tritium, training program, neutron beam sample processing, laboratory audits, inventory and leak tests, meter calibration, repair and evaluation, radioactive waste management, and emergency response. In addition, the radiation monitoring systems will be reviewed including confinement building monitoring, ventilation filter radiation monitors, secondary coolant monitors, gaseous fission product monitors, gas monitors, ventilation tritium monitor, and the plant effluent monitor systems.

PHITS is a general purpose Monte Carlo particle transport simulation code developed through the collaboration of several institutes mainly in Japan. It can analyze the motion of nearly all radiations over wide energy ranges in 3-dimensional matters. It has been used for various applications including medical physics. This paper reviews the recent improvements of the code, together with the biological dose estimation method developed on the basis of the microdosimetric function implemented in PHITS.

In this issue, symbolic methods for solving differential equations were firstly introduced. Of the symbolic methods, Laplace transform method was also introduced together with some examples, in which this method was applied to solving the differential equations derived from a two-compartment kinetic model and an equivalent circuit model for membrane potential. Second, series expansion methods for solving differential equations were introduced together with some examples, in which these methods were used to solve Bessel's and Legendre's differential equations. In the next issue, simultaneous differential equations and various methods for solving these differential equations will be introduced together with some examples in medical physics.

Purpose: A novel (32)P brachytherapy source has been in use at our institution intraoperatively for temporary radiation therapy of the spinal dura and other localized tumors. We describe the dosimetry and clinical implementation of the source., Methods and Materials: Dosimetric evaluation for the source was done with a complete set of MCNP5 Monte Carlo calculations preceding clinical implementation. In addition, the depth dose curve and dose rate were measured by use of an electron field diode to verify the Monte Carlo calculations. Calibration procedures using the diode in a custom-designed phantom to provide an absolute dose calibration and to check dose uniformity across the source area for each source before treatment were established., Results: Good agreement was established between the Monte Carlo calculations and diode measurements. Quality assurance measurements results are provided for about 100 sources used to date. Clinical source calibrations were usually within 10% of manufacturer specifications. Procedures for safe handling of the source are described., Discussion: Clinical considerations for using the source are discussed., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Utilization of differential equations and methods for solving them in medical physics are presented. First, the basic concept and the kinds of differential equations were overviewed. Second, separable differential equations and well-known first-order and second-order differential equations were introduced, and the methods for solving them were described together with several examples. In the next issue, the symbolic and series expansion methods for solving differential equations will be mainly introduced.

Operation of the NIF requires a large and varied number of routine and infrequent activities involving contaminated and radioactive systems, both in servicing online equipment and offline refurbishment of components. Routine radiological operations include up to several dozen entries into contaminated systems per day, multiple laboratories refurbishing radiologically impacted parts, handling of tens of curies of tritium, and (eventually) tens of workers spending most of their day working in radiation areas and handling moderately activated parts. Prior to the introduction of radioactive materials and neutron producing experiments (capable of causing activation), very few of the operating staff had any radiological qualifications or experience. To support the full NIF operating program, over 600 radiological workers needed to be trained, and a functional and large-scale radiological protection program needed to be put in place. It quickly became evident that there was a need to supplement the LLNL site radiological protection staff with additional radiological controls technicians and a radiological protection staff within NIF operations to manage day-to-day activities. This paper discusses the approach taken to stand up the radiological protection program and some lessons learned.

PHITS is a general purpose Monte Carlo particle transport simulation code to analyze the transport in three-dimensional phase space and collisions of nearly all particles, including heavy ions, over wide energy range up to 100 GeV/u. Various quantities, such as particle fluence and deposition energies in materials, can be deduced using estimator functions "tally". Recently, a microdosimetric tally function was also developed to apply PHITS to medical physics. Owing to these features, PHITS has been used for medical applications, such as radiation therapy and protection.

Purpose: Failure mode and effects analysis (FMEA) represents a prospective approach for risk assessment. A multidisciplinary working group of the Italian Association for Medical Physics applied FMEA to electron beam intraoperative radiation therapy (IORT) delivered using mobile linear accelerators, aiming at preventing accidental exposures to the patient., Methods and Materials: FMEA was applied to the IORT process, for the stages of the treatment delivery and verification, and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system, based on the product of three parameters (severity, frequency of occurrence and detectability, each ranging from 1 to 10); 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125., Results: Twenty-four subprocesses were identified. Ten potential failure modes were found and scored, in terms of RPN, in the range of 42-216. The most critical failure modes consisted of internal shield misalignment, wrong Monitor Unit calculation and incorrect data entry at treatment console. Potential causes of failure included shield displacement, human errors, such as underestimation of CTV extension, mainly because of lack of adequate training and time pressures, failure in the communication between operators, and machine malfunctioning. The main effects of failure were represented by CTV underdose, wrong dose distribution and/or delivery, unintended normal tissue irradiation. As additional safety measures, the utilization of a dedicated staff for IORT, double-checking of MU calculation and data entry and finally implementation of in vivo dosimetry were suggested., Conclusions: FMEA appeared as a useful tool for prospective evaluation of patient safety in radiotherapy. The application of this method to IORT lead to identify three safety measures for risk mitigation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

This paper discusses various concepts involved in the counting losses of pulse-counting health physics instrumentation when used within the pulsed radiation environments of typical accelerator fields in order to preestablish appropriate limitations in use. Discussed are the "narrow" pulse and the "wide" pulse cases, the special effect of neutron moderating assemblies, and the effect of pulse fine microstructure on the counting losses of the pulse-counting instrumentation. In the narrow-pulse case, the accelerator pulse width is less than or equal to the instrument's dead time; whereas in the wide-pulse case, the accelerator pulse width is significantly longer than the instrument's dead time. Examples are provided that highlight the various concepts and limitations.

The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future.

The graphics processing unit (GPU) has emerged as a competitive platform for computing massively parallel problems. Many computing applications in medical physics can be formulated as data-parallel tasks that exploit the capabilities of the GPU for reducing processing times. The authors review the basic principles of GPU computing as well as the main performance optimization techniques, and survey existing applications in three areas of medical physics, namely image reconstruction, dose calculation and treatment plan optimization, and image processing.

The Standard Model of Particle Physics is reviewed with an emphasis on its relationship to the physics supporting the health physics profession. Concepts important to health physics are emphasized and specific applications are presented. The capability of the Standard Model to provide health physics relevant information is illustrated with application of conservation laws to neutron and muon decay and in the calculation of the neutron mean lifetime.

An x-ray tube mainly emits low-energy X-rays, with few maximum energy E₀ (equal in keV to the voltage U in kV) x-rays. Aluminium filtration (mandatory minimum thickness of 1.5 to 2.5 mm based on tube voltage) reduces soft X-rays and provides a mean energy equal to 2/3 E₀. The half value layer of a reference material characterizes the spectrum. X-ray attenuation in tissues is due to secondary electron interactions: photoelectric effect at low-energy, especially in dense materials with high Z number; compton effect at intermediate-energy, proportional to density. The optimization of acquisition parameters of a medically necessary examination is based on appropriate selection of the highest voltage (U in kV) providing the best contrast and lowest tube current (Q in mAs) providing a diagnostic image.

After a radiological dispersal device (RDD) event, it is possible for radionuclides to enter the human body through inhalation, ingestion, and skin and wound absorption. From a health physics perspective, it is important to know the magnitude of the intake to perform dosimetric assessments. From a medical perspective, removal of radionuclides leading to dose aversion (hence risk reduction) is of high importance. The efficacy of medical decorporation strategies is extremely dependent upon the time of treatment delivery after intake. The "golden hour," or more realistically 3-4 h, is optimal when attempting to increase removal of radionuclides from extracellular fluids prior to cellular incorporation. To assist medical first response personnel in making timely decisions regarding appropriate treatment delivery modes, it is desirable to have a software tool that compiles existing radionuclide decorporation therapy data and allows a user to perform simple diagnosis leading to optimized decorporation treatment strategies. In its most simple application, the software is a large database of radionuclide decorporation strategies and treatments. The software can also be used in clinical interactive mode, in which the user inputs the radionuclide, estimated activity, route of intake and time since exposure. The software makes suggestions as to the urgency of treatment (i.e., triage) and the suggested therapy. Current developments include risk assessment which impacts the potential risk of delivered therapy and resource allocation of therapeutic agents. The software, developed for the Canadian Department of National Defence (DND), is titled MEDECOR (MEdical DECORporation). The MEDECOR tool was designed for use on both personal digital assistant and laptop computer environments. The tool was designed using HTML/Jscript, to allow for ease of portability amongst different computing platforms. This paper presents the features of MEDECOR, results of testing at a major NATO exercise, and future development of this tool into MEDECOR2.

A short guidebook for medical professionals has been published in Finland, summarizing essential knowledge of radiation accidents, including diagnosis and treatment of radiation injuries. The work was undertaken by the Finnish Radiation and Nuclear Safety Authority (STUK), which is a liaison institution of the World Health Organization Radiation Emergency Medical Preparedness and Assistance Network. The booklet is available in all hospital emergency departments and health care centers throughout the country.

The possibility of the occurrence of radiation accidents is increasing in the Asian region. However, training/education programs for medical professionals have not been established to improve the medical preparedness for radiation emergencies in the Asian region. As one of the activities for radiation emergency medical preparedness, Korea and Japan have started training programs for radio-nuclear emergencies in the region. In this article, the medical response systems for radiation emergency in the two countries and the training programs for the Asian region will be introduced.

In the past, most emphasis in planning for and response to an emergency situation has been placed on selected protective measures in the early phase of an emergency to keep the doses received below levels where severe deterministic health effects can be excluded and/or where the risk of stochastic effects in the population is considered "acceptable". Less emphasis has been placed on the development of comprehensive protection strategies which include considerations of the consequences of all exposure pathways and all phases, e.g. long-term rehabilitation. In its new publication 103, ICRP proposed a coherent conceptual framework for protection in all types of exposure situations including "emergency exposure situations" and "existing exposure situations". In the context of developing protection strategies for these exposure situations, the Commission recommends that national authorities set reference levels between, typically, 20 mSv and 100 mSv annual effective dose (emergency exposure situation) and 1 mSv and 20 mSv (existing exposure situation). In order to optimise protection strategies, it is necessary to identify the dominant exposure pathways, the timescales over which the dose will be received, and the effectiveness of available protection options. The characteristics of the development and implementation of such protection strategies is described.

Radiation therapy aimed at curing prostate cancer forms a considerable workload in most contemporary radiation oncology departments. The wide range of currently available therapeutic strategies for this cancer and their increasing complexity further increases the impact these patients have within the treating unit. Grounded in basic anatomy, physiology and pathology, the rationale for the division of prostate cancers into different prognostic and therapeutic groups is discussed, and put into clinical context using the current research evidence base. Weaknesses in this evidence base are highlighted in relation to areas directly impacted on by the work of medical physics.

Radiation protection in medicine is underpinned by the concepts of justification and optimisation. Over the last 20 y much successful work has been devoted to developing and consolidating approaches to optimisation. A substantial knowledge base and a set of practical approaches have now been created to give effect to it. With respect to justification, less effort has been applied and the efforts applied have not yet been as successful. Authoritative sources suggest that a substantial fraction of radiological examinations may be unnecessary. In addition, a mainstream general medical journal has identified that few of those responsible for prescribing or performing examinations were familiar with the units used to specify the amount of radiation (and risk) received. This report sets out the conclusions of a consultation held in Vienna, by the International Atomic Energy Agency, dealing with the nature of justification and how to give effect to it in practice.