Contemporary Radiobiology

Total Page:16

File Type:pdf, Size:1020Kb

Contemporary Radiobiology Contemporary Radiobiology Contemporary Radiobiology By Kenshi Komatsu Contemporary Radiobiology By Kenshi Komatsu This book first published 2019 Cambridge Scholars Publishing Lady Stephenson Library, Newcastle upon Tyne, NE6 2PA, UK British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Copyright © 2019 by Kenshi Komatsu All rights for this book reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. ISBN (10): 1-5275-3882-6 ISBN (13): 978-1-5275-3882-5 CONTENTS Preface ...................................................................................................... xiv Part I: Physical Properties of Radiation Chapter One ................................................................................................. 2 The Nature of Radiation 1.1 The discovery of radiation 1.1.1 Radiation and radioactivity 1.1.2 Different types of radiation and their penetration abilities 1.2 Mechanisms of ionization and radiation units 1.2.1 How radiation causes ionization 1.2.2 Radioactivity and radiation units 1.3 Radiation dosimeters 1.3.1 Radiation dosimeters which use ionization 1.3.2 Radiation dosimeters using semiconductors 1.3.3 Radiation dosimeters which use scintillation 1.3.4 Radiation dosimeters that utilize light emission from glass 1.3.5 Background radiation and counting efficiency Commentary 1: Another Poincaré conjecture Chapter Two .............................................................................................. 21 Utilizing Nuclear reactions 2.1 Natural decay of radionuclides 2.1.1Types of nuclear decay and the radioactive nucleus 2.1.2 Natural decay of radionuclides and half-lives 2.2 Mechanisms of nuclear power generation and waste disposal 2.2.1 Artificial nuclear fission 2.2.2 How a nuclear power plant generates electricity 2.2.3 The nuclear fuel cycle 2.2.4 Waste disposal problems 2.3 Military uses of nuclear reactions 2.3.1 Nuclear fission used in A-bombs 2.3.2 Nuclear fusion used in H-bombs 2.4 Industrial and academic uses of radiation 2.4.1 Industrial applications vi Contents 2.4.2 Agricultural uses 2.4.3 Radiocarbon dating Commentary 2: Decimal notation for half-lives Questions & Answers Part II: Radiation and Biology Chapter Three ............................................................................................ 46 Effect of Radiation on Cells 3.1 Cleavage of DNA strands by radiation 3.1.1 Time course of radiation’s biological actions 3.1.2 DNA damage is caused by direct and indirect action 3.1.3 The chemical structure at the ends of DNA strand breaks 3.2 Mathematical models and the evaluation of biological effects 3.2.1 Reproductive death measured with the colony assays 3.2.2 SLD recovery is an indicator of the effects of chronic irradiation 3.2.3 Mathematical descriptions of cell survival curves 3.3 Factors that modify biological effects 3.3.1 Radioprotectors and mitigators can reduce radiation effects 3.3.2 Oxygen enhances radiation effects 3.3.3 Differences in biological effects due to linear energy transfer (LET) Commentary 3: Radicals and the ozone hole Chapter Four .............................................................................................. 67 DNA Repair and Protection from Radiation 4.1 Repair of DNA double-strand breaks 4.1.1 Studies of repair pathways using radiation sensitive cells 4.1.2 Two types of DNA repair are involved in the rejoining of DNA double-strand breaks 4.2 Initial cellular responses to DNA double-strand breaks 4.2.1 Checkpoints lead to a pause in cell proliferation 4.2.2 Chromatin remodeling relaxes DNA structures 4.2.3 Apoptosis promotes cell death rather than DNA repair 4.3 Side effects of DNA repair 4.3.1 Variation of radiation sensitivity in the cell cycle and SLD recovery 4.3.2 Radiation mutagenesis Commentary 4: Gene nomenclature and protein designation Commentary 5: Why do elephants not develop cancer more often Contemporary Radiobiology vii Chapter Five .............................................................................................. 87 Radiation Injuries to Tissues and Organs 5.1 Deterministic effects and stochastic effects 5.1.1 Radiation injuries are classified into deterministic effects and stochastic effects 5.1.2 Radiation sensitivity varies among tissues 5.1.3 Onset of radiation injuries 5.2 Radiation injuries in various organs 5.2.1 Skin injuries 5.2.2 Injuries to the testes and ovaries 5.2.3 Eye injuries 5.2.4 Others organs: lungs, kidney, thyroid, oral mucosa 5.3 Injuries to three critical organs which can lead to individual deaths after radiation exposures 5.3.1 Relationship between exposure dose and survival time 5.3.2 Bone marrow death 5.3.3 Intestinal death 5.3.4 Central nervous system death 5.3.5 Clinical treatments for radiation accidents at doses approaching LD50/60 Commentary 6: Stem cells, ES cells and iPS cells Commentary 7: Leukemia and the bone marrow Chapter Six .............................................................................................. 109 Radiation Carcinogenesis 6.1 The nature of spontaneous carcinogenesis and radiation carcinogenesis 6.1.1 Activation of oncogenes and the inactivation of tumor suppressor genes 6.1.2 Mechanisms leading to spontaneous carcinogenesis 6.1.3 Mechanisms involved in radiation carcinogenesis 6.2 Frequency of radiation carcinogenesis in humans 6.2.1 Useful epidemiological data 6.2.2 Development of leukemia 6.2.3 Development of solid cancers 6.3 Factors affecting radiation carcinogenesis 6.3.1 Effect of age at exposure 6.3.2 Effect of chronic exposures and the type of radiation 6.3.3 Other factors affecting radiation carcinogenesis 6.4 Radiation carcinogenesis risk and the LNT hypothesis 6.4.1 What is the LNT hypothesis viii Contents 6.4.2 Using the LNT model avoids unnecessary risks from exposures Commentary 8: Terms used to describe carcinogenesis and radiation exposure Commentary 9: Local distribution of deaths from spontaneous carcinogenesis in Japan Chapter Seven .......................................................................................... 129 Radiation and Birth Defects 7.1 The radiation sensitive fetal stage 7.1.1 Embryo death during the pre-implantation period 7.1.2 Congenital malformations during organogenesis 7.1.3 Microcephaly in the fetus 7.2 How hereditary effects occur 7.2.1 Chromosomal abnormalities due to radiation exposures 7.2.2 Mendelian inheritance in a single gene 7.2.3 Human hereditary diseases 7.3 Unexpectedly low risk of radiation-induced hereditary diseases 7.3.1 Methods used to estimate hereditary risk 7.3.2 The doubling dose for genetic mutations in mice 7.3.3 Evaluation of radiation risks for hereditary diseases 7.3.4 Hereditary effects have not been observed in A-bomb survivors 7.3.5 Radiation carcinogenesis in the fetus and trans-generational carcinogenesis Questions & Answers Part III: Radiation and Medicine Chapter Eight ........................................................................................... 154 Tumor Radiotherapy 8.1 Tumor radiobiology 8.1.1 Radiation is effective for treating tumors 8.1.2 Hypoxic cells and radiotherapy 8.1.3 Radiation sensitivity in tumors 8.1.4 Tolerable doses for normal organs 8.2 Modification of radiation sensitivity in tumors and normal tissues 8.2.1 Sequential reoxygenation of hypoxic cells 8.2.2 Combining antitumor drugs with radiotherapy 8.2.3 Reducing damage to normal tissues Contemporary Radiobiology ix 8.3 Alternative radiation modalities for tumor treatment 8.3.1 Three-dimensional conformal radiotherapy 8.3.2 Intensity modulated radiotherapy 8.3.3 Stereotactic radiotherapy 8.3.4 Proton beam therapy 8.3.5 Heavy particle beam therapy 8.3.6 Brachytherapy with small shielded radiation sources 8.3.7 Boron neutron capture therapy Chapter Nine ............................................................................................ 177 Diagnostic Uses of Radiation 9.1 Types of X-ray Diagnosis 9.1.1 Principles of X-ray photography 9.1.2 X-ray generators 9.1.3 Detecting X-rays 9.1.4 Mammography 9.1.5 X-ray CT 9.1.6 Interventional Radiology 9.2 Diagnosis using radionuclides 9.2.1 Single photon emission computed tomography (SPECT) 9.2.2 Positron emission tomography (PET) 9.3 Exposure doses received from diagnostic radiation Commentary 10: The Beatles and X-ray CT Questions & Answers Part IV: Life and Radiation Chapter Ten ............................................................................................. 202 DNA Base Repair and Life 10.1 Protecting DNA from solar ultraviolet light and smoking 10.1.1 Types of DNA base damage induced by solar ultraviolet light 10.1.2 DNA base damage due to smoking 10.1.3 Nucleotide excision repair 10.1.4 Translesion DNA synthesis 10.1.5 Skin cancer and Xeroderma Pigmentosum 10.2 Protecting DNA from oxygen toxicity 10.2.1 DNA base damage produced by oxidation 10.2.2 Base excision repair 10.2.3 Base excision repair and carcinogenesis x Contents 10.3 Protecting DNA from alcohol-induced damage 10.3.1 DNA interstrand cross-links are caused by alcohol metabolism 10.3.2 DNA interstrand cross-links and Fanconi Anemia 10.4 Correcting DNA replication errors 10.4.1 Incorrect DNA base incorporation 10.4.2 Mismatch repair 10.4.3 Familial colorectal cancer and mismatch repair 10.5 Clustered DNA damage caused by radiation 10.5.1 DNA base damage caused by radiation 10.5.2 Radiation-specific
Recommended publications
  • Time, Dose and Fractionation in Radiotherapy
    2/25/2013 The introduction of Fractionation 2-13/13 Radiobiology lecture Time, Dose and Fractionation in Radiotherapy The Four Rs of Radiobiology Repair of Sublethal Damage • Cells exposed to sparse radiation experience • Efficacy of fractionation based on the 4 Rs: sublethal injury that can be repaired – Repair of sublethal damage • Cell killing requires a greater total dose when given –Repopulation in several fractions – Reassortment of cells within the cell cycle • Most tissue repair occurs in about 3 hours and up –Reoxygenation to 24 hours post radiation • Allows for repair of injured normal tissue and gives a potential therapeutic advantage over tumor cells Reoxygenation Redistribution • Oxygen stabilizes free radicals • Position in cell cycle at time of radiation • Hypoxic cells require more radiation to kill determines sensitivity •Hypoxic tumors • S phase is radioresistant – Temporary vessel constriction •G2 phase delay results in increased radiation – Outgrowth of blood supply and capillary collapse resistance • Tumor shrinkage reduces hypoxic areas • Fractionated RT redistributes cells • Reinforces fractionated dosing • Rapidly cycling cells like mucosa, skin are more sensitive • Slower cyclers like connective tissue, brain are spared 1 2/25/2013 Repopulation • Increased regeneration of surviving fraction Basics of Fractionation • Rapidly proliferating tumors regenerate faster • Determines the length and timing of therapy course • Dividing a dose into several fractions spares normal tissues • Accelerated Repopulation – Repair
    [Show full text]
  • 小型飛翔体/海外 [Format 2] Technical Catalog Category
    小型飛翔体/海外 [Format 2] Technical Catalog Category Airborne contamination sensor Title Depth Evaluation of Entrained Products (DEEP) Proposed by Create Technologies Ltd & Costain Group PLC 1.DEEP is a sensor analysis software for analysing contamination. DEEP can distinguish between surface contamination and internal / absorbed contamination. The software measures contamination depth by analysing distortions in the gamma spectrum. The method can be applied to data gathered using any spectrometer. Because DEEP provides a means of discriminating surface contamination from other radiation sources, DEEP can be used to provide an estimate of surface contamination without physical sampling. DEEP is a real-time method which enables the user to generate a large number of rapid contamination assessments- this data is complementary to physical samples, providing a sound basis for extrapolation from point samples. It also helps identify anomalies enabling targeted sampling startegies. DEEP is compatible with small airborne spectrometer/ processor combinations, such as that proposed by the ARM-U project – please refer to the ARM-U proposal for more details of the air vehicle. Figure 1: DEEP system core components are small, light, low power and can be integrated via USB, serial or Ethernet interfaces. 小型飛翔体/海外 Figure 2: DEEP prototype software 2.Past experience (plants in Japan, overseas plant, applications in other industries, etc) Create technologies is a specialist R&D firm with a focus on imaging and sensing in the nuclear industry. Createc has developed and delivered several novel nuclear technologies, including the N-Visage gamma camera system. Costainis a leading UK construction and civil engineering firm with almost 150 years of history.
    [Show full text]
  • G20070354/G20070331 Fact Sheet, Biological Effects of Radiation
    Fact Sheet 11 Ofice of Public Affairs Telephone: 301/415-8200 E-mail : opa @nrc.g ov I Biological Effects of Radiation Background Radiation is all around us. It is naturally present in our environment and has been since the birth of this planet. Consequently, life has evolved in an environment which has significant levels of ionizing radiation. It comes from outer space (cosmic), the ground (terrestrial), and even from within our own bodies. It is present in the air we breathe, the food we eat, the water we drink, and in the construction materials used to build our homes. Certain foods such as bananas and brazil nuts naturally contain higher levels of radiation than other foods. Brick and stone homes have higher natural radiation levels than homes made of other building materials such as wood. Our nation's Capitol, which is largely constructed of granite, contains higher levels of natural radiation than most homes. Levels of natural or background radiation can vary greatly from one location to the next. For example, people residing in Colorado are exposed to more natural radiation than residents of the east or west coast because Colorado has more cosmic radiation at a higher altitude and more terrestrial radiation from soils enriched in naturally occurring uranium. Furthermore, a lot of our natural exposure is due to radon, a gas from the earth's crust that is present in the air we breathe. The average annual radiation exposure from natural sources to an individual in the United States is about 300 millirem (3 millisieverts)*. Radon gas accounts for two-thirds of this exposure, while cosmic, terrestrial, and internal radiation account for the remainder.
    [Show full text]
  • Uranium Fact Sheet
    Fact Sheet Adopted: December 2018 Health Physics Society Specialists in Radiation Safety 1 Uranium What is uranium? Uranium is a naturally occurring metallic element that has been present in the Earth’s crust since formation of the planet. Like many other minerals, uranium was deposited on land by volcanic action, dissolved by rainfall, and in some places, carried into underground formations. In some cases, geochemical conditions resulted in its concentration into “ore bodies.” Uranium is a common element in Earth’s crust (soil, rock) and in seawater and groundwater. Uranium has 92 protons in its nucleus. The isotope2 238U has 146 neutrons, for a total atomic weight of approximately 238, making it the highest atomic weight of any naturally occurring element. It is not the most dense of elements, but its density is almost twice that of lead. Uranium is radioactive and in nature has three primary isotopes with different numbers of neutrons. Natural uranium, 238U, constitutes over 99% of the total mass or weight, with 0.72% 235U, and a very small amount of 234U. An unstable nucleus that emits some form of radiation is defined as radioactive. The emitted radiation is called radioactivity, which in this case is ionizing radiation—meaning it can interact with other atoms to create charged atoms known as ions. Uranium emits alpha particles, which are ejected from the nucleus of the unstable uranium atom. When an atom emits radiation such as alpha or beta particles or photons such as x rays or gamma rays, the material is said to be undergoing radioactive decay (also called radioactive transformation).
    [Show full text]
  • Radiobiology Is a Young Science and Is Solely Concerned with the Study Of
    The Rockefeller Foundation and its support of Radiobiology up to the 1970s By Sinclair Wynchank Senior Lecturer University of Cape Town Rondebosch, South Africa [email protected] © 2011 by Sinclair Wynchank Radiation biology, or radiobiology, is a very young science, solely concerned with the study of the interactions between ionizing radiation and living matter. This science slowly became a recognized field of study after the discovery of ionizing radiation (i.e., X rays) in 1895. A broadly varied and evolving terminology has been applied to aspects of radiobiology and therefore, archival searches concerning it are complex. This report is a work in progress, which mainly recounts support given by the Rockefeller Foundation (RF) to radiobiology. The RF was a most important player in the early history of radiobiology and a crucial influence in ensuring that the science steadily matured during its first six decades. Time constraints prevented all relevant items from being accessed, but a clear idea of the RF‟s strong influence on radiobiology‟s early history has resulted. Examples of RF activities to verify this assertion are given below, in by and large chronological order. After a brief analysis of RF aid, there is a short account of why its support so strongly benefitted the young science. To my knowledge there is very little written about the history of radiobiology and nothing about the role that the RF or other philanthropic bodies played in this history. Inevitably, for an extensive time, individual radiobiologists first studied other fields of science before radiobiology. Even in 2011 there are only five universities in the U.S.
    [Show full text]
  • Industrial Radiography
    RADIATION PROTECTION OF WORKERS Industrial Radiography RADIATION AND RADIOGRAPHS RADIOACTIVE SOURCES PROCEDURES RADIOGRAPHERS DO follow the procedures. Ionizing radiation can pen- Materials of higher den Sealed sources are small þ Safe storage Precautions þ DO use the appropriate equipment, including collimators. in size and contain material etrate objects and create sity absorb more radiation. þ DO confi rm that there are no other people working in the images on photographic The metal components are which emits penetrating area of radiography. fi lm. The technique is revealed inside this tele radiation continuously. Radioactive sources should be kept in a secure, fi re þ DO use clear working signs and signals. called radiography and phone because they have Special containers made þ DO set up the controlled area and the necessary barriers. the processed fi lms are absorbed more radiation of dense metal shielding resistant and adequately shielded storage location þ DO confi rm the location of the source, or that X rays are called radiographs. than the surrounding plastic. are necessary to store, not being generated, by use of a survey meter. when not in use, and should move and manipulate these þ DO secure and store the source or X ray machine when sources. Due to their small be kept separate from other not in use. materials. The storage loca- size and manoeuvrability, Portable and mobile radiographic þ DO wear your personal dosimeter. sealed sources can be containers. ~ tion for X ray machines that used in confined spaces. are not in use is not required to be shielded. OTHER WORKERS Iridium-192 is a common radioactive source used þ DO observe the access restrictions, however remote it may in gamma radiography.
    [Show full text]
  • Radiation Basics
    Environmental Impact Statement for Remediation of Area IV \'- f Susana Field Laboratory .A . &at is radiation? Ra - -.. - -. - - . known as ionizing radiatios bScause it can produce charged.. particles (ions)..- in matter. .-- . 'I" . .. .. .. .- . - .- . -- . .-- - .. What is radioactivity? Radioactivity is produced by the process of radioactive atmi trying to become stable. Radiation is emitted in the process. In the United State! Radioactive radioactivity is measured in units of curies. Smaller fractions of the curie are the millicurie (111,000 curie), the microcurie (111,000,000 curie), and the picocurie (1/1,000,000 microcurie). Particle What is radioactive material? Radioactive material is any material containing unstable atoms that emit radiation. What are the four basic types of ionizing radiation? Aluminum Leadl Paper foil Concrete Adphaparticles-Alpha particles consist of two protons and two neutrons. They can travel only a few centimeters in air and can be stopped easily by a sheet of paper or by the skin's surface. Betaparticles-Beta articles are smaller and lighter than alpha particles and have the mass of a single electron. A high-energy beta particle can travel a few meters in the air. Beta particles can pass through a sheet of paper, but may be stopped by a thin sheet of aluminum foil or glass. Gamma rays-Gamma rays (and x-rays), unlike alpha or beta particles, are waves of pure energy. Gamma radiation is very penetrating and can travel several hundred feet in air. Gamma radiation requires a thick wall of concrete, lead, or steel to stop it. Neutrons-A neutron is an atomic particle that has about one-quarter the weight of an alpha particle.
    [Show full text]
  • General Guidelines for the Estimation of Committed Effective Dose from Incorporation Monitoring Data
    Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaftt Wissenschaftliche Berichte FZKA 7243 General Guidelines for the Estimation of Committed Effective Dose from Incorporation Monitoring Data (Project IDEAS – EU Contract No. FIKR-CT2001-00160) H. Doerfel, A. Andrasi, M. Bailey, V. Berkovski, E. Blanchardon, C.-M. Castellani, C. Hurtgen, B. LeGuen, I. Malatova, J. Marsh, J. Stather Hauptabteilung Sicherheit August 2006 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Wissenschaftliche Berichte FZKA 7243 GENERAL GUIDELINES FOR THE ESTIMATION OF COMMITTED EFFECTIVE DOSE FROM INCORPORATION MONITORING DATA (Project IDEAS – EU Contract No. FIKR-CT2001-00160) H. Doerfel, A. Andrasi 1, M. Bailey 2, V. Berkovski 3, E. Blanchardon 6, C.-M. Castellani 4, C. Hurtgen 5, B. LeGuen 7, I. Malatova 8, J. Marsh 2, J. Stather 2 Hauptabteilung Sicherheit 1 KFKI Atomic Energy Research Institute, Budapest, Hungary 2 Health Protection Agency, Radiation Protection Division, (formerly National Radiological Protection Board), Chilton, Didcot, United Kingdom 3 Radiation Protection Institute, Kiev, Ukraine 4 ENEA Institute for Radiation Protection, Bologna, Italy 5 Belgian Nuclear Research Centre, Mol, Belgium 7 Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France 8 Electricité de France (EDF), Saint-Denis, France 9 National Radiation Protection Institute, Praha, Czech Republic Forschungszentrum Karlsruhe GmbH, Karlsruhe 2006 Für diesen Bericht behalten wir uns alle Rechte vor Forschungszentrum Karlsruhe GmbH Postfach 3640, 76021 Karlsruhe Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF) ISSN 0947-8620 urn:nbn:de:0005-072434 IDEAS General Guidelines – June 2006 Abstract Doses from intakes of radionuclides cannot be measured but must be assessed from monitoring, such as whole body counting or urinary excretion measurements.
    [Show full text]
  • Measuring Radioactivity
    Health Physics Society Public Education Committee Fact Sheet MEASURING RADIOACTIVITY Because ionizing radiation cannot be detected with our human senses, we use various types of instruments and radiation detectors to measure the amount of radiation present. We usually measure both the amount of radioactivity in a radioisotope source, and the ionizing radiation field density being emitted by the source. We define radioactivity as the number of atoms which decay (disintegrate) in a radioisotope sample in a given period of time. The base unit is the Becquerel (Bq) or one disintegration per second (dps). This number is very small and therefore, not very useful. For this reason we use the Curie (Ci) which is 37 billion Bq. Because we often use very large or very small numbers when discussing radioactivity, we use a series o f prefixes which express multiples of 1000. The following table shows some of these prefixes: milli (m) = 1/1,000 kilo (k) = times 1,000 micro (u) = 1/1,000,000 mega (M) = times 1,000,000 nano (n) 1/1,000,000,000 giga (G) times 1,000,000,000 Pico (P) 1/1,000,000,000,000 tera (T) times 1,000,000,000,000 Using the table, a mCi = 1/1000 of a Curie and a GBq 1,000,000,000 Becquerels. To put this in perspective, a normal home smoke detector contains a small sealed source of about 10 uCi (370,000 Bq) of radioactivity. Ionizing radiation fields are expressed in units of Roentgens (R) which is equivalent to the number of atoms of a gas which are ionized.
    [Show full text]
  • The International Commission on Radiological Protection: Historical Overview
    Topical report The International Commission on Radiological Protection: Historical overview The ICRP is revising its basic recommendations by Dr H. Smith Within a few weeks of Roentgen's discovery of gamma rays; 1.5 roentgen per working week for radia- X-rays, the potential of the technique for diagnosing tion, affecting only superficial tissues; and 0.03 roentgen fractures became apparent, but acute adverse effects per working week for neutrons. (such as hair loss, erythema, and dermatitis) made hospital personnel aware of the need to avoid over- Recommendations in the 1950s exposure. Similar undesirable acute effects were By then, it was accepted that the roentgen was reported shortly after the discovery of radium and its inappropriate as a measure of exposure. In 1953, the medical applications. Notwithstanding these observa- ICRU recommended that limits of exposure should be tions, protection of staff exposed to X-rays and gamma based on consideration of the energy absorbed in tissues rays from radium was poorly co-ordinated. and introduced the rad (radiation absorbed dose) as a The British X-ray and Radium Protection Committee unit of absorbed dose (that is, energy imparted by radia- and the American Roentgen Ray Society proposed tion to a unit mass of tissue). In 1954, the ICRP general radiation protection recommendations in the introduced the rem (roentgen equivalent man) as a unit early 1920s. In 1925, at the First International Congress of absorbed dose weighted for the way different types of of Radiology, the need for quantifying exposure was radiation distribute energy in tissue (called the dose recognized. As a result, in 1928 the roentgen was equivalent in 1966).
    [Show full text]
  • Laboratoire National Henri Becquerel Ccri(I)/01-05 Dimri/Lnhb/Bc/01-146 30/03/01
    BUREAU NATIONAL DE MÉTROLOGIE COMMISSARIAT À L'ÉNERGIE ATOMIQUE LABORATOIRE NATIONAL HENRI BECQUEREL CCRI(I)/01-05 DIMRI/LNHB/BC/01-146 30/03/01 BUREAU NATIONAL DE METROLOGIE Laboratoire National Henri Becqurel (BNM-LNHB) Laboratoire Central des Industries Electriques (BNM-LCIE) DOSIMETRY OF PHOTONS AND CHARGED PARTICLES Progress Report 2000-2001 B.Chauvenet Participation in the CCRI K4 key comparison on calibration factors of ionisation chambers in terms of absorbed dose to water for 60Co photons Comparison of standards of absorbed dose to water for high-energy photon beams with METAS A comparison was carried out with METAS in October 2000. This comparison dealt with air kerma and absorbed dose to water standards in 60Co beams, and absorbed dose to water standards for high-energy x rays from accelerators (6 MV, 12 MV and 20 MV). The comparison was carried out in BNM-LNHB beams (60Co and Saturne 43 accelerator), with transfer chambers from METAS. Results are under analysis. Comparison of standards of absorbed dose to water for high-energy photon beams with NRC This comparison was carried out in October 1998. The results were discussed and analysed, and will be presented in a paper which has been submitted to “Physics in Medicine and Biology”. EUROMET projects Participation in EUROMET Contact Persons meetings for the preparation of CMC tables. The laboratory will participate in the proposed project of METAS on quality factors for high-energy photon beams. Absorbed dose to graphite by calorimetry The realisation of a new graphite calorimeter is under study to replace the present one built in 1984.
    [Show full text]
  • Radiation and Cell Cycle
    High Yield Summary Reviews in Radiation Oncology Radiation and Cancer Biology Gayle E. Woloschak, PhD Tuesday, June 18, 2019 11:00 a.m. – 1:00 p.m. Eastern Daylight Time June 25, 2019 Gayle E. Woloschak PhD Professor of Radiation Oncology, Radiology, and Cell & Molecular Biology Associate Dean for Graduate Student and Postdoctoral Affairs Northwestern University Feinberg School of Medicine June 25, 2019 Definitions • Bq-2.7x10-11 Ci—equal to one disintegration per sec • Ci—3.7x1010 disintegrations per sec • Gy—absorbed radiation dose, the quantity which deposits 1 Joule of energy per kg—1Gy=100rad • Sievert—dose equivalence—multiply absorbed dose in Gy by the Quality Factor (Q)— 1Sv=100rem • LET—measure of the rate of energy transfer from an ionizing radiation to the target material—keV of energy lost/micron track length Unit Conversion Factors: SI and Conventional Units • 1 Bq = 2.7 × 10–11 Ci = 27 pCi • 1 Ci = 3.7 × 1010 Bq = 37 GBq • 1 Sv = 100 rem • 1 rem = 0.01 Sv • 1 Gy = 100 rad • 1 rad = 0.01 Gy • 1 Sv Bq–1 = 3.7 × 106 rem μCi–1 • 1 rem μCi–1 = 2.7 × 10–7 Sv Bq–1 • 1 Gy Bq–1 = 3,7 × 106 rad μCi–1 • 1 rad μCi–1 = 2,7 × 10–7 Gy Bq–1 Biomolecular Action of Ionizing Radiation; Editor:Shirley Lehnert, 2007 Units Used in Radiation Protection • Equivalent dose—average dose x radiation weighting factor—Sv • Effective dose—sum of equivalent doses to organs and tissues exposed, each multiplied by the appropriate tissue weighting factor—Sv • Committed equivalent dose—equivalent dose integrated over 50 years (relevant to incroporated radionuclides)—Sv
    [Show full text]