The 42nd Lauriston S. Taylor Lecture: Radiation Dosimetry Research for Medicine and Protection-A European Journey

The assessment of doses related to exposures to ionizing radiation is an essential part of all applications of ionizing radiation including radiation medicine, radiation protection, radiation biology, radiation epidemiology, and also industrial uses of radiation. Absorbed dose is generally considered to be the fundamental quantity of radiation dosimetry. It is a metrologically sound quantity for which even primary standards exist for some materials, and it is used routinely in practice. However, there is no unique correlation between absorbed dose and the radiation-induced biological effect considered. There are also different objectives of radiation dosimetry for different applications. In radiation protection, quantities are required to set meaningful exposure limits and to implement the principle of optimization. In radiation therapy, the dependence of clinical outcomes on temporal aspects of the irradiations must be accounted for. In radiation diagnostics, quantities are needed to enable and monitor optimization of radiation dose and image quality. In radiation protection and in therapy with high linear-energy-transfer radiations, appropriate methods and parameters are needed to account for differences in radiation quality. These limitations of the quantity absorbed dose have led to the use of a multiplicity of dose quantities and dose modification factors. Radiation dosimetry continues, therefore, to be a field of active research regarding fundamental and conceptual aspects, taking account of advances in technologies, of novel methods in radiation therapy and diagnostics, and of progress in computational dosimetry. Dosimetry of high-energy radiations such as cosmic radiation encountered at flight altitudes and during space missions as well as at high-energy accelerators has become an important issue. In Europe, collaboration and coordination of radiation research in general, and dosimetry research in particular, are playing an important role. Dedicated research programs of the European Commission have been and still are very valuable and include collaborations with institutes in Eastern Europe and non-European countries. Several current and recent research topics in radiation dosimetry are addressed based on research carried out within European research programs, at European research centers including the European Organization for Nuclear Research (known as CERN), in European particle therapy projects, and at national metrological institutes. One focus is the quantification of radiation quality in radiation protection and in high linear-energy-transfer radiation therapy with emphasis on measurements with low-pressure proportional counters. Another focus is dosimetry of high-energy radiations with respect to measurements of cosmic radiation and at CERN's high-energy accelerators.

Twenty five years of the National Academy of Medical Sciences of Ukraine - progress and priorities for future of radiation medicine and biology

After the creation of the Academy of Medical Sciences of Ukraine in 1993 the Research Center for Radiation Medicine was among the first institutions to join the Academy (fig. 1). Estab lishing the Academy was among the first steps of the independent Ukrainian government and aimed to provide a high level health care for population. It was extremely needed for the minimization of Chornobyl medical consequences. This choice was related to a growing recognition of the scientific research in fulfilling the Сenter's mission - study of the effects of low dose radiation on human body and radiation protection of the exposed population.The Center entered the Academy as a potent insti tution. Director General Dr. Anatoly Romanenko and his first deputy prof. Oles Pyatak were lucky to concentrate in three institutes of the Center a talent ed workforce including director of the Institute of Clinical Radiology prof Volodymyr Bebeshko, director of the Institute of Epidemiology and Prophylaxis of radiation Injuries prof. Volodymyr Buzunov, director of the Institute of Experimental Radiology prof. Mikhail Rudnev. Drs. T. Azaren kova, S. Galkina, V. Boer, T. Treskunova were appointed as scientific secretaries. Dosimetry divi sion was headed by brilliant prof Ilya Likhtarev and his staff Drs. I. Los, V. Korzun, V. Repin, O. Pere voznikov, O. Bondarenko, V. Chumak and others.The Center met creation of the Academy with expe rienced research and clinical staff encountering 1587 members, including 272 research staff, 28 doctors of science and 98 PhDs, modern diagnostic and labo ratory equipment, 300 beds in clinical departments and construction of hospital and out patient hospi tal in Svyatoshin. Scientific staff included experi enced prof. I. Khomaziuk, prof. B. Prevarsky, prof. V. Zamostian, prof. P. Chayalo, prof. M. Omelya nets, prof. A. Prysyazhnyuk. Dr. A. Niagu, Dr. E. Stepanova, Dr. A.Chumak, Dr. V. Klymenko, Dr. D. Komarenko, M. Pilinska, L.Ovsiannikova, O. Pi rogova. were among the first academic supervisors in studies of Chornobyl health effects and got professor certificates in this new area. First PhD theses were successfully passed by Dr. E. Gorbov, and Dr. of Sciences - by Dr. D. Bazyka. Basics of future aca demic research directions were elaborated that time by Drs. O. Kovalenko, Zh. Minchenko, V. Talko, I. Holyavka, D. Belyi, D. Yakimenko, E. Mikhai lovska, V. Malyzhev, V. Sushko, A. Cheban, K. Lo ganovsky, K. Bruslova, I. Dyagil, T. Liubarets, O. Kucher, G. Chobotko, and others. Later the major ity of these studies formed a background for Chornobyl legislation, regulatory directives, pre sented as dissertations.A quarter of century passed. The Center as a part of the National Academy of Medical Sciences resisted the challenges and moved forward, was recognized worldwide and fulfilled its main mission - providing highly qualified health care to radiation exposed. Staff numbers decreased (1,091), but work amount has increased. Since 2000, new premises were installed - a hospital with the biggest in Ukraine outpatient clin ic, new laboratory facilities, the last of which was in troduced in 2013. The Academy became a national one and since 2011 the Center was recognized as a national research institution (NRCRM), staff mem bers received 3 State Awards of Ukraine in the Field of Science and Technology, numerous personal awards.During this period, NRCRM staff conducted and published priority research data on radiation risks and molecular mechanisms of leukemia, including chronic lymphocytic, myelodysplastic syndrome, multiple myeloma, thyroid cancer, breast cancer in Chornobyl accident cleanup workers. Studies of the mechanisms of non tumor pathology - cardio vascular, cerebrovascular, cognitive disorders are in process. Of high importance are studies of possible transgenerational effects of radiation. The devel oped new technologies and protocols for the advanced care of radiation exposed were intro duced to the general health care system, the addi tional departments of oncology and chemotherapy were equipped and started activities, databases of cancer cases in exposed population and separate groups of exposed were introduced, as well as an international database of radiation injuries. The Clinical and Epidemiological registry of the NRCRM is in function and developed. An adapta tion of research directions with a respect to the pathomorphosis of radiation induced diseases in the remote period after irradiation will continue.Performed complex studies of the effects of incorporation of 131I on the fetus and the next gen eration of experimental animals became important for understanding the mechanisms of formation of radiation effects. Introduction of new foodstuffs and supplements with radiation protective proper ties was of positive effect for population protection during the first years.In the area of dosimetry a substantial progress has been achieved in reconstruction of thyroid doses in the Ukrainian population, dosimetric passportisation of settlements, radiochemistry, the creation of new methods for reconstructive dosimetry for cleanup workers - SEAD, RADRUE, and ROCKVILLE. All developments are implemented to practice, tens of thousands of doses have been restored. International recognition has received for the method of in utero doses reconstruction. As editor in chief, I regard it successful to incorporate our bilingual edition «Problems of Radiation Medicine and Radiobiology» into the NCBI MedLine, SCOPUS and other data bases, that creates an unique opportunity to widely disseminate results of the Center's research.Strategies for the future. Ukraine belongs to countries with a priority development of nuclear energy. Even with the increase in the production of clean energy, there is no other way than the further deployment of a complete nuclear fuel cycle and energy industrial complex, the expansion of the nuclear technologies to all sectors of the economy.The main potential threats to radiation safety include the aging of the material base of the NPPs with the prolongation of the working life for nuclear reactors with the expired terms of exploitation; the existence of a «nuclear legacy» sites of the former USSR in the territories of enterprises for the extrac tion and processing of uranium ores. About 5,000 institutions and enterprises use more than 25,000 sources of ionizing radiation in general. The use of radiological technologies and sources of ionizing radiation in medicine is increasing, in particular the burden on patients and staff in invasive cardiac sur gery. This will require significant efforts from the NRCRM to ensure an adequate radiation protec tion of the population, taking into account the experience collected during the mitigation of health effects of Chornobyl. Radiological threats of malev olent use of nuclear technology hasn't be forgotten.The mission of the NRCRM is to expand basic research of the health effects of ionizing radiation, elaboration and implementation of the care and radiation protection of population. Background for future is paved by a successful implementation of a special program of medical and biophysical control of personnel during transformation of the Shelter object into an environmentally safe sys tem, the State social program of increasing safty, labor hygiene and environment for 2014-2018; many years of successful cooperation with the State Nuclear Regulatory Inspectorate, the Natio nal Commission for Radiation Protection, «Ener goatom» company, the relevant departments of the Ministry of Health, international organizations such as WHO, UNSCEAR, IAEA, IARC, the US National Cancer Institute, IRSN, Nagasaki, Hiroshima, Fukushima universities and others.From the editorial board I congratulate the staff of the Center with the twenty fifth anniversary of the Academy. I would like also to wish the National Academy of Medical Sciences of Ukraine new ad vances in medical science and practice, sustainabil ity, unity, development and worldwide recognition.

Neutron Metrology in the United States-Where We've Been, Where We Are Now and What We Need to Do Moving Forward

Neutron metrology in the United States must be based on traceability to standards maintained by the National Institute of Standards and Technology (NIST). This article reviews the history of NIST's neutron-metrology efforts, the loss of those capabilities, and attempts to restore them. Recommendations are made to ensure that neutron dosimetry performed in the United States meets the requirements set forth by the International Standards Organization and other international and national authorities.

Consequences of the radiation accident at the Mayak production association in 1957 (the 'Kyshtym Accident')

This paper presents an overview of the nuclear accident that occurred at the Mayak Production Association (PA) in the Russian Federation on 29 September 1957, often referred to as 'Kyshtym Accident', when 20 MCi (740 PBq) of radionuclides were released by a chemical explosion in a radioactive waste storage tank. 2 MCi (74 PBq) spread beyond the Mayak PA site to form the East Urals Radioactive Trace (EURT). The paper describes the accident and gives brief characteristics of the efficacy of the implemented protective measures that made it possible to considerably reduce doses to the exposed population. The paper also provides retrospective dosimetry estimates for the members of the EURT Cohort (EURTC) which comprises approximately 21 400 people. During the first two years after the accident a decrease in the group average leukocyte (mainly due to neutrophils and lymphocytes) and thrombocyte count was observed in the population. At later dates an increased excess relative risk of solid cancer incidence and mortality was found in the EURTC.

Twelfth Annual Warren K. Sinclair Keynote Address--the Influence of the NCRP on Radiation Protection in the United States: Guidance and Regulation

The Warren K. Sinclair Keynote Address for the 2015 Annual Meeting of the National Council on Radiation Protection and Measurements (NCRP) describes the Council's influence in the development of radiation protection guidance in the United States since its founding in 1929 as the U.S. Advisory Committee on X-Ray and Radium Protection. The National Bureau of Standards (NBS) was the coordinating agency for the Advisory Committee, and its reports were published as NBS handbooks. In 1946, the Advisory Committee was renamed the National Committee on Radiation Protection and remained so until NCRP was chartered by the U.S. Congress in 1964. In 1931, the U.S. Advisory Committee on X-Ray and Radium Protection proposed the first formal standard for protecting people from radiation sources as NBS Handbook 15 and issued the first handbook on radium protection, NBS Handbook 18. Revised recommendations for external exposure were issued in 1936 and for radium protection in 1938 and remained in force until 1948. Throughout its 86 y history, the Council and its predecessors have functioned as effective advisors to the nation on radiation protection issues and have provided the fundamental guidance and recommendations necessary for the regulatory basis of the control of radiation exposure, radiation-producing devices, and radioactive materials in the United States.

Experimental microdosimetry: history, applications and recent technical advances

The invention of tissue-equivalent proportional counters simulating micrometre diameter volumes, intended to measure the linear energy transfer of a radiation field, resulted in a practical demonstration of the stochastic nature of energy deposition in small volumes. Besides contributing to a better understanding of the interactions between ionising radiation and biological systems, these detectors have had a significant impact on applied radiation dosimetry. The initial instruments were elegant but suitable only for laboratory experiments because of their sensitivity to environmental conditions and the complex support systems they required. However, their ability to separate the dose due to neutrons from that delivered by photons motivated detector design modifications that eventually resulted in robust detectors suitable for use as radiation survey instruments. Proportional counters simulating micrometre tissue volumes turned out to be the ideal detectors for monitoring the complex radiation environments, including on the space shuttle and International Space Station, and have served as the primary active dosimeters in space for nearly two decades. The need for more sophisticated measurements has led to further improvements in detector design, and the need for smaller and lighter dosimeters is motivating further developments in both detectors and data processing systems.

38th Lauriston S. Taylor lecture: on the shoulders of giants - radiation protection over 50 years

Most advances in science, technology, and radiation protection are not truly new ideas but rather build upon a foundation of prior work and achievements by earlier generations of scientists and researchers. This paper summarizes major achievements over the last 50-70 y in the various areas involved in radiation protection as well as giving information about some of those who were, and are, significant contributors.

Exerpts from the history of alpha recoils

Any confined air volume holding radon ((222)Rn) gas bears a memory of past radon concentrations due to (210)Pb (T(1/2) = 22 y) and its progenies entrapped in all solid objects in the volume. The efforts of quantifying past radon exposures by means of the left-behind long-lived radon progenies started in 1987 with this author's unsuccessful trials of removing (214)Po from radon exposed glass objects. In this contribution the history and different techniques of assessing radon exposure to man in retrospect will be overviewed. The main focus will be on the implantation of alpha recoils into glass surfaces, but also potential traps in radon dwellings will be discussed. It is concluded that for a successful retrospective application, three crucial imperatives must be met, i.e. firstly, the object must persistently store a certain fraction of the created (210)Pb atoms, secondly, be resistant over decades towards disturbances from the outside and thirdly, all (210)Pb atoms analysed must originate from airborne radon only. For large-scale radon epidemiological studies, non-destructive and inexpensive measurement techniques are essential. Large-scale studies cannot be based on objects rarely found in dwellings or not available for measurements.

Fifty years of individual monitoring of ionising radiation in Switzerland: history, trends and perspectives

In the last 50 y, individual monitoring of ionising radiation in Switzerland underwent substantial development, strongly influenced by type of applications of ionising radiation, monitoring technologies, knowledge of health risks, protection philosophies and regulatory frameworks. The role of individual monitoring in the system of radiation protection moved from a passive, a posteriori control of limits towards an important and more interactive tool for optimisation. Dose trends for occupational exposures document these developments. In the future, new and emerging dose intensive applications in medicine and an increasing demand for international harmonisation, particularly in Europe, will pose new challenges in individual monitoring.

A Brazilian government external individual monitoring service: experience since 1972

Instituto de Radioproteção e Dosimetria, a Brazilian government research institute, provides individual monitoring services since 1972. Its dosemeters are: film-based thorax for whole body photons, thermoluminescence dosimetry (TLD) albedo for whole body neutrons and TLD ring for extremity photons. About 6000 radiation workers are currently being monitored with film dosemeters in 256 different facilities in Brazil, most of them working in health-related activities. Around 400 Brazilian radiation workers are monitored with TLD albedo neutron monitor and about 500 workers use TLD rings. This paper describes the monitoring systems used, presents the results obtained in internal quality programs and in intercomparison exercises and analyses the measured dose values from 1985 to 2009.

Astronomical fire: Richard Carrington and the solar flare of 1859

An explosion on the Sun in 1859, serendipitously witnessed by amateur astronomer Richard Carrington, plunged telegraphic communications into chaos and bathed two thirds of the Earth's skies in aurorae. Explaining what happened to the Sun and how it could affect Earth, 93 million miles away, helped change the direction of astronomy. From being concerned principally with charting the stars to aid navigation, astronomers became increasingly concerned with what the celestial objects were, how they behaved and how they might affect life on Earth.

Patient and staff radiation doses from early radiological examinations (1899−1902)

A source of data on radiographic and fluoroscopic examinations, including radiographic technique factors, was used in conjunction with information about cold-cathode X-ray apparatus to estimate patient and staff radiation doses for the years 1899 to 1902 at the Forth Banks Infirmary, Newcastle-upon-Tyne. Physical evidence from representative apparatus of the period was used with a beam spectral simulation program to characterize the X-ray beam, and information about the electrical supply waveform was produced by experimental operation of a contemporary induction coil. Results are given in terms of skin entrance dose, and these are compared with modern values. An estimate of the annual dose received by the radiographer known to have carried out all of the examinations within this period is also given.

Review and history of photon cross section calculations

Photon (x-ray, gamma-ray, bremsstrahlung) mass attenuation coefficients, mu/rho, are among the most widely used physical parameters employed in medical diagnostic and therapy computations, as well as in diverse applications in other fields such as nuclear power plant shielding, health physics and industrial irradiation and monitoring, and in x-ray crystallography. This review traces the evolution of this data base from its empirical beginnings totally derived from measurements beginning in 1907 by Barkla and Sadler and continuing up through the 1935 Allen compilation (published virtually unchanged in all editions up through 1971-1972 of the Chemical Rubber Handbook), to the 1949 semi-empirical compilation of Victoreen, as our theoretical understanding of the constituent Compton scattering, photoabsorption and pair production interactions of photons with atoms became more quantitative. The 1950s saw the advent of completely theoretical (guided by available measured data) systematic compilations such as in the works of Davisson and Evans, and by White-Grodstein under the direction of Fano, using mostly theory developed in the 1930s (pre-World War II) by Sauter, Bethe, Heitler and others. Post-World War II new theoretical activity, and the introduction of the electronic automatic computer, led to the more extensive and more accurate compilations in the 1960s and 1970s by Storm and Israel, and by Berger and Hubbell. Today's mu/rho compilations by Cullen et al, by Seltzer, Berger and Hubbell, and by others, collectively spanning the ten decades of photon energy from 10 eV to 100 GeV, for all elements Z= 1 to 100, draw heavily on the 1970s shell-by-shell photoabsorption computations of Scofield, the 1960s coherent and incoherent scattering computations of Cromer et al, and the 1980 computations of electron-positron pair and triplet computations of Hubbell, Gimm and Øverbø, these names being representative of the vast legions of other researchers whose work fed into these computations.

Fission, critical mass and safety--a historical review

Since the discovery of fission, the notion of a chain reaction in a critical mass releasing massive amounts of energy has haunted physicists. The possibility of a bomb or a reactor prompted much of the early work on determining a critical mass, but the need to avoid an accidental critical excursion during processing or transport of fissile material drove much that took place subsequently. Because of the variety of possible situations that might arise, it took some time to develop adequate theoretical tools for criticality safety and the early assessments were based on direct experiment. Some extension of these experiments to closely similar situations proved possible, but it was not until the 1960s that theoretical methods (and computers to run them) developed enough for them to become reliable assessment tools. Validating such theoretical methods remained a concern, but by the end of the century they formed the backbone of criticality safety assessment. This paper traces the evolution of these methods, principally in the UK and USA, and summarises some related work concerned with the nature of criticality accidents and their radiological consequences. It also indicates how the results have been communicated and used in ensuring nuclear safety.

A history of radiation detection instrumentation

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

A history of radiation detection instrumentation

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

Radioactive contamination in the upper part of the Techa river: stirring-up of bottom sediments and precipitation of suspended particles. Analysis of the data obtained in 1949-1951

A hydrodynamic model of the upper part of the Techa river was developed on the basis of the river valley geometry as well as data of hydrological conditions and of the granulometric composition of bottom sediments. The model describes the transport of radioactivity by suspended sediments with different granulometric compositions (clay, silt) in the early 1950s. It includes the stirring-up of bottom sediments and the precipitation of suspended sediments as a function of water discharge rate and water level in the investigated part of the river. The results allow to specify the development of the river system contamination as a result of inflow of suspended sediments contaminated with radionuclides. In the period of liquid radioactive waste (LRW) discharges, the water of the Techa river contained a large fraction of finely dispersed particles of less than 5 micro m diameter. At the site of LRW discharge 80% of the discharged activity was adsorbed to these particles. Depending on the water flow, 40-80% of the suspensions precipitated at the bottom of subsequent sedimentation reservoirs. A total of about 1.6 MCi adsorbed to the suspended particles entered the open hydrographic system of the Techa river. The conclusion that the largest part of the activity was adsorbed on the suspended particles contradicts the assumption in the Techa river dosimetry system, TRDS-2000, that most of the released activity entered the Techa river in soluble form. For a correct reconstruction of the doses received by the Techa river population it is, therefore, essential to consider hydrodynamic models that take into account the transport of radionuclides adsorbed on the suspended particles.

The birth of nuclear medicine instrumentation: Blumgart and Yens, 1925

In 1925, Hermann Blumgart performed the first diagnostic procedure using radioactive indicators on humans; this first is well recognized. Less well recognized is the fact that Blumgart and his coworker Otto C. Yens, then a medical student, developed the first instrumentation used in a diagnostic procedure involving radioactive indicators. The instrumentation, a modified Wilson cloud chamber, turned out to be the detector most suitable for their purpose. Blumgart also showed remarkable foresight in outlining the requirements both for a satisfactory indicator (tracer) and for a satisfactory detector--requirements that still hold true today. The Blumgart-Yens modified cloud chamber was the birth of nuclear medicine instrumentation.

The evolution of medical imaging: from Geiger counters to MRI--a personal saga

This article traces the evolution of medical imaging, from the crude images of the thyroid gland obtained using Geiger and scintillation counters, to the automatic scanners built to image brain tumors and organs, to gamma cameras, to digital imaging. A computed tomography scanner built in Aberdeen in the late 1960s led to the present-day gamma-camera tomographs, the main workhorse of nuclear medicine. The gradual evolution of the steps needed for clinical magnetic resonance imaging (MRI) are described, along with the rapid development of this novel form of body imaging. A brief account is also given of the present-day use of MRI in clinical medicine worldwide, with some modern cutting-edge applications, and its possible future.

The development of field-based measurement methods for radioactive fallout assessment

An overview is provided on the development of field equipment, instrument systems, and methods of analyses that were used to assess the impact of radioactive fallout from atmospheric weapons tests. Included in this review are developments in fallout collection, aerosols measurements in surface air, and high-altitude sampling with aircraft and balloons. In addition, developments in radiation measurements are covered in such areas as survey and monitoring instruments, in situ gamma-ray spectrometry, and aerial measurement systems. The history of these developments and the interplay with the general advances in the field of radiation and radioactivity metrology are highlighted. An emphasis is given as to how the modifications and improvements in the instruments and methods over time led to their adaptation to present-day applications to radiation and radioactivity measurements.

Microdosimetry: reflections on Harald Rossi

This and twelve previous Symposia reflect the evolution of microdosimetry, a field of research that has determined major new developments in radiation research, radiation protection, and radiology during the past four decades. The concepts of microdosimetry and its techniques were developed almost single handedly by H. H. Rossi. This memorial lecture outlines some of the ideas and some of the work of Harald Rossi that led to microdosimetry. It describes its major impact on radiobiology and, especially, its impact on studies with fast neutrons and on risk assessment. Microdosimetry was primarily designed as a tool for the elucidation of basic mechanisms of radiation action, but it has found its most important applications in the dosimetric measurement techniques that have become indispensable in radiation protection and in the dosimetry for radiation therapy. The advances of molecular biology are now providing new possibilities for a quantitative application of microdosimetry to radiobiology along the lines that Harald Rossi defined.

[The "recommendations of 1928" and its background]

In the "recommendations of the International X-ray Units Committee" published in 1928, the first international unit "Roentgen" was given without any specific definition of the physical quantity represented by the unit. This introduced confusion into the subsequent history of radiation units. The "recommendations" had another distinctive feature, i.e., more than half of the recommendations were concerned with the problems of X-ray measurement. Around 1925, almost all Roentgen societies and physics societies in the world regarded the ionization of air by X-ray as a basic phenomenon for the establishment of the unit. Many devices were proposed for counting the number of ions. O. Glasser and his joint research workers examined the accuracy of each apparatus to choose the best one. The results of their study were adopted in the "recommendations of 1928". In the meantime, owing to the Compton effect discovered in 1923, it had become difficult to relate the X-ray dose unconditionally with air ionization quantity. Consequently, the physical quantity represented by the unit "Roentgen" became difficult to specify, and much time was needed to resolve these problemss. Various sicknesses and lesions had been caused by the misuse of X-ray. To avoid the damage and to reproduce the conditions of treatment, physicians took it as a matter of urgency to standardize the international units. They thought that practical convenience should be given priority over the pursuit of physical precision in the standardization of units and measurements. These factors led to the vagueness of the physical quantity represented by "Roentgen" in the "recommendations of 1928".

AAPM protocol for 40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology

The American Association of Physicists in Medicine (AAPM) presents a new protocol, developed by the Radiation Therapy Committee Task Group 61, for reference dosimetry of low- and medium-energy x rays for radiotherapy and radiobiology (40 kV < or = tube potential < or = 300 kV). It is based on ionization chambers calibrated in air in terms of air kerma. If the point of interest is at or close to the surface, one unified approach over the entire energy range shall be used to determine absorbed dose to water at the surface of a water phantom based on an in-air measurement (the "in-air" method). If the point of interest is at a depth, an in-water measurement at a depth of 2 cm shall be used for tube potentials > or = 100 kV (the "in-phantom" method). The in-phantom method is not recommended for tube potentials < 100 kV. Guidelines are provided to determine the dose at other points in water and the dose at the surface of other biological materials of interest. The protocol is based on an up-to-date data set of basic dosimetry parameters, which produce consistent dose values for the two methods recommended. Estimates of uncertainties on the final dose values are also presented.

The history and future of accelerator radiological protection

The development of accelerator radiological protection from the mid-1930s, just after the invention of the cyclotron, to the present day is described. Three major themes--physics, personalities and politics--are developed. In the sections describing physics the development of shielding design though measurement, radiation transport calculations, the impact of accelerators on the environment and dosimetry in accelerator radiation fields are described. The discussion is limited to high-energy, high-intensity electron and proton accelerators. The impact of notable personalities on the development of both the basic science and on the accelerator health physics profession itself is described. The important role played by scholars and teachers is discussed. In the final section. which discusses the future of accelerator radiological protection, some emphasis is given to the social and political aspects that must he faced in the years ahead.

The 1999 Lauriston S. Taylor lecture--back to background: natural radiation and radioactivity exposed

I am profoundly grateful for being chosen as the twenty-third presenter of the Lauriston S. Taylor Lecture, and I share this honor with a list of distinguished scientists, including my husband, who pay tribute to the premier leader in radiation protection. In 1938, Laurie was working for the National Bureau of Standards and chaired the Advisory Committee on X-ray and Radium Protection, a group of 8 persons, who set the pace for all forthcoming radiation standards. NBS had, since 1913, been standardizing essentially all of the radium offered for sale in the U.S., and the problem arose to revise the handbook on proper conditions for handling radium based on the then current knowledge. This resulted in Handbook 23 (1938) superseding the 1934 work. At the time Laurie was a scientist working in the measurements side of radiation and though he contributed much to that field, his name is inseparably linked with guidance in radiation protection. Today we pay tribute for his leadership that he carried out with intelligence, grace, and personal warmth. My talk today deals mostly with measured data for naturally occurring internal radiation emitters and how these data can be used for predictive purposes in estimating the dose and risk from internal body contamination. This stresses the "and Measurements" part of the Council's title. The topic of this year's NCRP Annual Meeting is "Radiation Protection in Medicine: Contemporary Issues." I believe that physicians and State and Federal agencies will have to cope with complaints following various exposure situations resulting from the cleanup of background radionuclides during closure at nuclear facilities, military use of radioactivity, and occurrences of high natural background in some locations. They will find comfort in the knowledge that existing background radiation data can be the basis for predictions of realistic dose and risk in most situations.

From dating to biophysics--20 years of progress in applied ESR spectroscopy

ESR spectroscopy represents a tool for quantitative radiation analysis that was developed somehow simultaneously for dating purposes in Japan and in Germany for high-level standardization, in the mid-seventies. Meanwhile, ESR dosimetry has reached an established metrology level. Present research fields of ESR dosimetry consider post-accident dose reconstruction in the environment, and biophysical dosimetry using human tissues. The latter promises a re-definition of radiation risk for chronicle exposure to be derived from individuals of the early nuclear facilities in Russia, and hopefully United States in the future. An attempt is made to sketch development and potential future of the ESR technique.

Radiation hormesis: its historical foundations as a biological hypothesis

This paper represents the first systematic effort to describe the historical foundations of radiation hormesis. Spanning the years from 1898 to the early 1940's the paper constructs and assesses the early history of such research and evaluates how advances in related scientific fields affected the course of hormetic related research. The present effort was designed to not only address this gap in current knowledge, but to offer a toxicological basis for how the concept of hormetic dose-response relationships may affect the nature of the bioassay and its role in the risk assessment process.

Bioelectromagnetics, Carl Durney, and dosimetry: some historical remarks

The contributions of Carl Durney to dosimetry have decisively advanced the bioelectromagnetics field and led to significant revisions of relevant health standards. Three items come to mind while studying his work: 1. The work of Carl Durney and his colleagues in dosimetry has advanced the bioelectromagnetics field most significantly whereas more abundant work of a biomedical nature has had less impact. More biophysics work is desirable. 2. The rationale for the specific absorption rate as a basis of health standards needs further elaboration. The need for scaling animal results is stressed. 3. Dosimetry at the cellular level (microdosimetry) is essential if one cares to discuss direct field interactions at the cellular and macromolecular level. Carl Durney's recognition of this need is stated. Carl Durney's wide range of productive interests is indicated by several tables. They summarize his many contributions to electrical engineering, education, bioelectromagnetic dosimetry, hyperthermia, NMR, and field-induced biophysical phenomena at the molecular and cellular level. His scientific work is summarized, including how his interest changed with time. His scientific accomplishment and productive interaction with students, colleagues, and society sets an example to be admired.

The Radiofrequency Radiation Dosimetry Handbook: reminiscences

This paper traces the history of the development of the Radiofrequency Radiation Dosimetry Handbook and its subsequent impact on radio frequency radiation exposure standards. The author's recollections are used to illustrate the behind the scenes efforts of the individuals involved in this project. The development of models at the University of Utah and confirmation of these results by various experimenters led to the publication of four editions of the Radiofrequency Radiation Dosimetry Handbook, i.e., "The RFR Experimenters Bible."

Radiographic exposure slide rules

Before automatic exposure control was fitted to diagnostic X-ray sets, radiographers were faced with the problem of choosing the parameters that would give the best radiographic image. For a new X-ray set whose performance was unknown, this was no easy matter, and often required considerable trial and error because of the number of variables involved. To reduce the amount of work, special slide rules were invented which calculated the effect of some of these variables. Five such slide rules, dating from between about 1910 and 1950, are illustrated and discussed, including the light they shed on changes in radiographic practice over the years.

New dosimetry of atomic bomb radiations

The reassessment of the radiation dosimetry from the Hiroshima and Nagasaki atomic bombs is almost complete. Since atomic bomb survivors provide a major source of data for estimates of risk of cancer induction by radiation the impact of the new dosimetry on risk estimates and radiation protection standards is important. The changes include an increase of about 20% in the estimated yield of the Hiroshima bomb and a reduction in the estimated doses from neutrons in both cities. The estimated neutron dose for Hiroshima is about 10% of the previous estimate. The neutron doses are now so small that direct estimates of neutron relative biological effectiveness may be precluded or be much more difficult. There is little change in most of the gamma ray organ doses because various changes in the new estimates tend to cancel each other out. The new estimate of the attenuation of the free-in-air kerma by the walls of the homes is about twice that used in the previous dosimetry. But the transmission of gamma radiation to the deep organs such as bone marrow is significantly greater than earlier estimates. Probably future risk estimates for radiogenic cancer will be somewhat higher because of both the new dosimetry and the new cancer mortality data. New risk estimates should be available in 1988.