DOCSLIB.ORG

1 Practical Time-Dose Evaluations, Or How to Stop Worrying and Learn to Love Linear Quadratics Jack F

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
1 Practical Time-Dose Evaluations, Or How to Stop Worrying and Learn to Love Linear Quadratics Jack F Practical Time-Dose Evaluations, or How to Stop Worrying and Learn to Love Linear Quadratics 3 1 Practical Time-Dose Evaluations, or How to Stop Worrying and Learn to Love Linear Quadratics Jack F. Fowler CONTENTS 1.5.8 Conclusions Re Head-and-Neck Schedules 21 1.5.9 Concurrent Chemotherapy 22 Glossary 3 1.6 Hypofractionation for Prostate Tumors 22 1.1 Introduction 6 1.7 Summary 23 1.2 The Simplest Modeling 7 1.8 Appendix: Is This a Mistaken Dose 1.2.1 The Seven Steps to LQ Heaven – Brief Summary 7 Prescription? 24 1.3 The Seven Steps to LQ Heaven – The Details 8 1.8.1 For Equal “Late Complications” 25 1.3.1 Development of the Simple LQ Formula E = nd 1.8.2 For Equal Tumor Effect 25 (1+d/D/E) 9 1.8.3 Acute Mucosal Effects 26 1.3.2 Biologically Effective Dose 10 1.9 Line-by-Line Worked Examples: 1.3.3 Relative Effectiveness 11 Details of Calculations of the Schedules 1.3.4 Overall Treatment Time 12 Discussed in This Appendix 27 1.3.5 Acute Mucosal Tolerance 13 References 29 1.3.6 To Convert from BED to NTD or EQD2 Gy 14 1.3.7 One Example 14 1.3.8 What is the Standard of Precision of These This chapter is written mainly for those who say “I Estimates of BED or NTD? Gamma Slopes 15 don’t understand this DE business – I can’t be both- 1.4 Rejoining Point for Those Who Skipped: How to ered with Linear Quadratic and that sort of stuff.” Evaluate a New Schedule – Brief Summary 15 Well, it might seem boring – depending on your per- 1.5 Now Let Us Study Some of the Best-Known Schedules for Head-And-Neck Tumor Radiotherapy 16 sonality – but it is easy, and it makes so many things in 1.5.1 Standard Fractionation 16 radiation therapy wonderfully and delightfully clear. 1.5.2 Hyperfractionation 17 Experienced readers can turn straight to Section 1.4. 1.5.3 Radiation Therapy Oncology Group Four-Arm Fractionation Trial (RTOG 90-03) 17 1.5.4 Head-and-Neck Schedules That Were Initially “Too Hot” in Table 1.2 18 1.5.5 Shortening the Wang 2-Fraction-a-Day Schedule J. F. Fowler, DSc, PhD Using BED to Adjust Individual Doses 19 Emeritus Professor of Human Oncology and Medical Physics, 1.5.6 General Considerations of Medical School of University of Wisconsin, Madison, Wiscon- Head-and-Neck Radiotherapy 19 sin, USA; Former Director of the Gray Laboratory, Northwood, 1.5.7 A Theoretical Calculation of “Close to Optimum” London, UK Head & Neck Schedules: 3 Weeks at Five Fractions Present address: per Week 20 150 Lambeth Road, London, SE1 7DF, UK Glossary D, alpha Intrinsic radiosensitivity. Loge of the number of cells sterilized non-repairably per gray of dose of ionizing radiation. E, beta Repair capacity. Loge of the number of cells sterilized in a repairable way per gray squared. DE, alpha/beta ratio the ratio of “intrinsic radiosensitivity” to “repair capability” of a specified tissue. This ratio is large (>8 Gy) for rapidly proliferating tissues and most tumors. It is small (<6 Gy) for slowly proliferating tissues, including late normal-tissue complica- tions. This difference is vital for the success of radiotherapy. When beta (E) is large, both mis-repair and good-repair are high. It is the mis-repair that causes the cell survival curve to bend downward. 4 J. F. Fowler Accelerated fractionated schedules with shorter overall times than the conventional 7 (or 6) fractionation weeks. BED Biologically effective dose, proportional to log cell kill and therefore more conceptu- ally useful as a measure of biological damage than physical dose, the effects of which vary with fraction size and dose rate. Formally, “the radiation dose equivalent to an infinite number of infinitely small fractions or a very low dose-rate”. Corresponds to the intrinsic radiosensitivity (D) of the target cells when all repairable radia- tion damage (E) has been given time to be repaired. In linear quadratic modeling, BED=total dose×relative effectiveness (RE), where RE=(1+dDE), with d=dose per fraction, D=intrinsic radiosensitivity, and E=repair capacity of target cells. bNED Biochemically no evidence of disease. No progressive increase of prostate specific antigen (PSA) level in patients treated for prostate cancer. CI Confidence interval (usually ±95%). CTV Clinical tumor volume. The volume into which malignant cells are estimated to have spread at the time of treatment, larger than the gross tumor volume (GTV) by at least several millimeters, depending on site, stage, and location. See also GTV and plan- ning treatment volume (PTV). 't Time interval between fractions, recommended to be not less than 6 h. EBR External beam radiation. EGFR Epithelial growth factor receptor, one of the main intracellular biochemical path- ways controlling rate of cell proliferation. EQD Biologically equivalent total dose, usually in 2-Gy dose fractions. The total dose of a schedule using, for example, 2 Gy per fraction that gives the same log cell kill as the schedule in question. If so, should be designated by the subscript EQD2 Gy. EUD Equivalent uniform dose. A construct from the DVH of a non-uniformly irradiated volume of tissue or tumor that estimates the surviving proportion of cells for each volume element (voxel), sums them, and calculates that dose which, if given as a uniform dose to the same volume, would give the same total cell survival as the given non-uniform dose. Local fraction size is taken into account by assuming an DE ratio for the tissue concerned. Gamma, J-50, J-37 Slope of a graph of probability, usually tumor control probability (TCP), versus total fractionated dose (NTD or EQD), as percentage absolute increase of probability per 1% increase in dose. The steepest part of the curve is at 50% for logistic-type curves and at 37% for Poisson-type curves. Tumor TCP is usually between a gamma-50 (or -37) of 1.0 and 2.5. The difference between J-50 and J-37 is rarely clinically significant. Gy, gray The international unit of radiation dose: one joule per kilogram of matter. Com- monly used radiotherapy doses are approximately 2 Gy on each of 5 days a week. Gy10, Gy3, Gy1.5 Biologically effective dose (BED), with the subscript representing the value of that tissue’s DE ratio=10 Gy for early radiation effects, 3 Gy for late radiation effects and 1.5 Gy for prostate tumors. The subscript confirms that this is a BED, proportional to log cell kill, and not a real physical dose. GTV Gross tumor volume. The best estimate of tumor volume visualized by radiologi- cal, computed tomography (CT) scan, magnetic resonance, ultrasound imaging, or positron emission tomography. HDR High dose rate. When the dose fraction is delivered in less than five or ten minutes; that is, much shorter than any half-time of repair of radiation damage. Hyperfractionation More (and smaller) dose fractions than 1.8 Gy or 2 Gy. Hypofractionation Fewer (and larger) dose fractions than 1.8 Gy or 2 Gy. Isoeffect Equal effect. Practical Time-Dose Evaluations, or How to Stop Worrying and Learn to Love Linear Quadratics 5 LC Local control (of tumors). LDR Low dose rate. Officially (ICRU), less than 2 Gy/h; but this is deceptive because any dose rate greater than 0.5 Gy/h will give an increased biological effect compared with the traditional 0.42 Gy/h (1000 cGy per day). For example at 2 Gy/h, the biological effects will be similar to daily fractions of 3.3 Gy and 2.8 Gy on late complications and on tumors respectively. Linear effect Directly proportional to dose. Ln loge Natural logarithm, to base e. One log10 is equal to 2.303 loge. Log10 Common logarithm, to base 10. “Ten logs of cell kill” are 23.03 loge of cell kill. LQ Linear quadratic formula: loge cells killed=Dudose+Eudose-squared. Logistic curve A symmetrical sigmoid or S-shaped graph relating the statistically probable incidence of “events”, including complications, or tumors controlled, at a specified time after treatment, to total dose (NTD). This curve is steepest at the probability of 50%. LRC Loco-regional tumor control. LC would be local control. NTCP Normal tissue complication probability. NTD Normalized total dose of any schedule. The total dose of a schedule using 2 Gy per fraction that gives the same log cell kill as the schedule in question. The NTD will be very different for late effects (with DE=3 Gy and no overall treatment time factor) than for tumor effect (with DE=10 Gy and an appropriate time factor). Poisson curve A near-sigmoid graph of probability of occurrence of “events”, such as tumor control at X years, versus total dose or NTD. Based on random chance of successes among a population of tumors or patients, the probability of curve P=exp (–n), where an average of n cells survive per tumor after the schedule, but 0 cells must survive to achieve 100% cure. If an average of 1 cell survives per tumor, P=37%. If 2 cells sur- vive, P=14%. If 0.1 cells survive on average, P=90%. This curve is steepest at the probability of 37%. PTV Planning treatment volume – larger than CTV to allow for set-up and treatment- planning errors. PSA Prostate-specific antigen: can be measured in a blood specimen as a measure of activ- ity of the prostate gland. Often taken as a measure of activity of prostate cancer.
Load more

Recommended publications
  • Nuclear Radiation 1. an Atom Contains Electrons, Protons and Neutrons
    Nuclear Radiation 1. An atom contains electrons, protons and neutrons. Which of these particles a) are outside the nucleus b) are uncharged c) have a negative charge d) are nucleons e) are much lighter than the others? 2. Complete the table below. Name Symbol Charge What is it? Alpha particle β -1 Gamma ray An electromagnetic wave 3. How is an ionised material different from a material that is not ionised? National 5 Physics: Waves & Radiation 1 Absorption of Radiation 1. The figure below shows a Geiger tube used to detect radiation from a radioactive source. thick lead plate 0 4 2 5 start counter stop ON OFF reset Geiger tube radioactive source The following measurements were made using the apparatus above. Counts in 300 seconds Readings Average 1 No source present 102 94 110 2 Source present at fixed distance from tube a) No lead plate present 3466 3420 3410 b) Thick lead plate present 105 109 89 c) Aluminium sheet in place of the 1834 1787 1818 thick lead sheet a) Complete the table by calculating the average readings. b) Why are the readings on each line not the same? c) What can you say from the table about the effect on the radiation of: i. The lead plate? ii. The aluminium plate? d) Why is it possible to say from the readings that: i. gamma radiation is emitted by the source? ii. alpha and beta radiation might be emitted by the source? e) What further tests could you make using this arrangement to find out whether or not the source emits alpha radiation? National 5 Physics: Waves & Radiation 2 2.
    [Show full text]
  • Copyright by Arthur Bryan Crawford 2004
    Copyright by Arthur Bryan Crawford 2004 The Dissertation Committee for Arthur Bryan Crawford Certifies that this is the approved version of the following dissertation: Evaluation of the Impact of Non -Uniform Neutron Radiation Fields on the Do se Received by Glove Box Radiation Workers Committee: Steven Biegalski, Supervisor Sheldon Landsberger John Howell Ofodike Ezekoye Sukesh Aghara Evaluation of the Impact of Non -Uniform Neutron Radiation Fields on the Dose Received by Glove Box Radiation Workers by Arthur Bryan Crawford, B.S., M.S. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin December, 2004 Dedication I was born to goodly parents Harvey E. Crawford and Johnnie Lee Young Crawford Acknowledgements I would like to express my gratitude to Dr. Sheldon Landsberger for his vision in starting a distance learning program at the University of Texas at Austin and for his support and encouragement on this quest. I would like to thank my advisor, Dr. Steven Biegalski, for his support and encouragement even though the topic area was new to him. I would like to thank the members of my dissertation committee for finding the time to review this dissertation. To the staff of the Nuclear Engineering Teaching Laboratory I say thank you for your kindness and support during those brief times that I was on cam pus. A special thanks to my past and present group leaders, David Seidel, Eric McNamara, and Bill Eisele and my Division Leader, Lee McAtee, at Los Alamos National Laboratory, for their support in being allowed to use time and material resources at the Lab oratory and for financial support in the form of tuition reimbursement and travel expenses.
    [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]
  • Overview and Basis of Design for NCRP Report
    This Report was prepared through a joint effort of NCRP Scientific Committee 46-13 on Design of Facilities for Medical Radiation Overview & Basis of Design for NCRP Therapy and AAPM Task Group 57. Report 151 James A. Deye, Chairman James E. Rodgers, Vice Chair Raymond K. Wu, Vice Chair Structural Shielding Design and Evaluation for Peter J. Biggs Patton H. McGinley Megavoltage x- and Gamma-ray Radiotherapy Facilities Richard C. McCall Liaisons Kenneth R. Kase Marc Edwards Raymond K. Wu, PhD Consultants OhioHealth Hospitals Robert O. Gorson Jeffrey H. Kleck Nisy E. Ipe Columbus, OH Secretariat Marvin Rosenstein Eric E. Kearsley Learn • Calculation methods • W, U, T, IDR, TADR, RW, Rh, • Dose at maze door • Neutron, capture gamma at door • Laminated primary barrier This Report addresses the structural shielding design New Issues since NCRP # 49 and evaluation for medical use of megavoltage x- and gamma-rays for radiotherapy and supersedes related – New types of equipment, material in NCRP Report No. 49, Structural Shielding – Some with energies above 10 MV, Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies Up to 10 MeV, which was – Many new uses for radiotherapy equipment, issued in September 1976. – Dual energy machines, The descriptive information in NCRP Report No. 49 unique to x-ray therapy installations of less than 500 – Room designs without mazes, kV (Section 6.2) and brachytherapy is not included in – Varied shielding materials including composites, this Report and that information in NCRP Report No. 49 for those categories is still applicable. – More published data on empirical methods.
    [Show full text]
  • Radiological Emissions-I
    Radiological Emissions-I Ghulam Rasul Athar Applied Systems Analysis Group, Pakistan Atomic Energy Commission, P.O. Box 1114, Islamabad, Pakistan [email protected] IAEA Workshop on the ‘Use of the SimPacts Model for Estimating Human Health and Environmental Damages from Electricity Generation’ Trieste, Italy, May 12-23, 2003. Overview of the Presentation • Explanation of some terms used in radiation protection • Nuclear fuel cycle • NukPacts Becquerel (Bq) Becquerel is the basic unit of radioactivity. One Becquerel is equal to one disintegration per second. 1 Bq=2.7E-11 Ci One Ci = 3.7E+10 Bq Absorbed Dose When ionizing radiation interacts with the human body, it gives its energy to the body tissues. The amount of energy absorbed per unit weight of the organ or tissue is called absorbed dose. Absorbed dose is expressed in units of gray (Gy). One gray dose is equivalent to one joule radiation energy absorbed per kilogram of organ or tissue weight. Rad is the old and still used unit of absorbed dose. One gray is equivalent to 100 rads. (1 Gy = 100 rads) Equivalent Dose • Equal doses of all types of ionizing radiation are not equally harmful. • Alpha particles produce greater harm than do beta particles, gamma rays and x rays for a given absorbed dose. • To account for this difference, radiation dose is expressed as equivalent dose. • Equivqlent Dose is equal to "absorbed dose" multiplied by a "radiation weighting factor" (WR). • Equivalent Dose is measured in Sievert (Sv). • The dose in Sv (Equivalent Dose) = Dose x WR. • Prior to 1990, this weighting factor was referred to as Quality Factor (QF).
    [Show full text]
  • National 5 Physics Unit 2 Waves & Radiation Section 2 Nuclear Radiation Problem Booklet
    North Berwick High School Department of Physics National 5 Physics Unit 2 Waves & Radiation Section 2 Nuclear Radiation Problem Booklet Author: S Belford 2 Contents Topic Page Properties of Radiation 4 - 5 Activity 6 - 7 Half Life 8 - 9 Absorbed Dose 10 Equivalent Dose 11 - 13 Nuclear Fission and Fusion 14 Author: S Belford 3 Properties of Radiation 1. Describe the internal structure of the atom. 2. Describe what the following radiations are made up of. Include symbols. (a) Alpha (b) Beta (c) Gamma 3. What is the meaning of the term ‘ionisation’? 4. Copy and complete this table to show the absorption of radiation as they travel through different materials. Absorbing material Piece of 3 cm of 3 cm of Radiation 3 cm of Air Paper Aluminium Lead Alpha Beta Gamma Put a if the radiation will pass through the material. Put a x if the radiation will be absorbed by the material. 5. Give three safety precautions that should be followed when working with radioactive materials. 6. What is background radiation? Author: S Belford 4 7. What are the main sources of background radiation? 8. Is background radiation mostly naturally occurring or man-made? 9. What effect does radiation have on living cells? 10. Smoke alarms are made with an alpha source (Americium-241). Describe how a smoke alarm uses ionisation to warn people of a possible fire. 11. A radioactive tracer is a gamma emitting chemical compound that can be injected in to a patient in hospital. Describe how this can be useful in diagnosis of medical problems.
    [Show full text]
  • Quantities and Units for External Dose Assessment
    XA0053408 QUANTITIES AND UNITS FOR EXTERNAL DOSE ASSESSMENT R.V. GRIFFITH International Atomic Energy Agency, Vienna Abstract Three sets of quantities are relevant for occupational radiation protection purposes - physical quantities, protection quantities and operational quantities. While the protection quantities have been defined by the International Commission on Radiological Protection and recommended by the IAEA for dose limitation purposes, they are not measurable. Measurable operational quantities have been defined by the International Commission on Radiation Units and Measurements and recommended by the IAEA for practical demonstration of compliance with the dose limits. A Joint ICRP/ICRU Task Group has prepared a report, published by each Commission, which reviews the relationship of these quantities in detail. The report includes detailed sets of dose conversion coefficients which are recommended for use in calibration and interpretation of dosimeters and instruments. Additional dose conversion coefficients for reference radiation fields specified by the International Organization for Standardization has been calculated and are recommended for use in dosimeter and instrument calibration. The result of the work of these international organizations - IAEA, ICRP, ICRU and ISO - is a coherent, harmonized and comprehensive set of data that is recommended for use in occupational radiation protection. 1. INTRODUCTION Monitoring of workers potentially exposed to external radiation constitutes an integral part of any radiation protection
    [Show full text]
  • A Two-Dimensional Point-Kernel Model for Dose Calculations in a Glovebox Array
    A Two-Dimensional Point-Kernel Model for Dose Calculations in a Glovebox Array ~- D. E. Kornreich and D. E. Dooley Los Alamos National Laboratory I. Background An associated paper’ details a model of a room containing gloveboxes using the industry standard dose equivalent (dose) estimation tool MCNP.2 Such tools provide an excellent means for obtaining relatively reliable estimates of radiation transport in a complicated geometric structure. However, creating the input deck that models the complicated geometry is equally complicated. Therefore, an alternative tool is desirable that provides reasonably accurate dose estimates in complicated geometries for use in engineering-scale dose analyses. In the past, several tools that use the point-kernel model for estimating doses equivalent have been constructed (those referenced are only a small sample of similar This new tool, the Photon And Neutron Dose Equivalent Model Of Nuclear materials Integrated with an Uncomplicated geometry Model (PANDEMONIUM), combines point-kernel and diffusion theory calculation routines with a simple geometry construction tool. PANDEMONIUM uses VisioTM5to draw a glovebox array in the room, including hydrogenous shields, sources and detectors. This simplification in geometric rendering limits the tool to two-dimensional geometries (and one-dimensional particle “transport” calculations). DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liabili- ty or responsibility for the accuracy, completeness, or usefulness of any information, appa- ratus, product, or process disclosed, or repments that L use would not infringe privately owned rights.
    [Show full text]
  • Radiation Safety: New International Standards
    FEATURES Radiation safety: New international standards The forthcoming International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources are the product of unprecedented co-operation by Abel J. B*y the end of the 1980s, a vast amount of new This article highlights an important result of Gonzalez information had accumulated to prompt a new this work for the international harmonization of look at the standards governing protection radiation safety: specifically, it presents an over- against exposures to ionizing radiation and the view of the forthcoming International Basic safety of radiation sources. Safety Standards for Protection Against Ionizing First and foremost, a re-evaluation of the Radiation and for the Safety of Radiation Sour- radioepidemiological findings from Hiroshima ces — the so-called BSS. They have been jointly and Nagasaki suggested that exposure to low- developed by six organizations — the Food and level radiation was riskier than previously es- Agriculture Organization of the United Nations timated. (FAO), the International Atomic Energy Agency Other developments — notably the nuclear (IAEA), the International Labour Organization accidents at Three Mile Island in 1979 and at (ILO), the Nuclear Energy Agency of the Or- Chernobyl in 1986 with its unprecedented ganization for Economic Co-operation and transboundary contamination — had a great ef- Development (NEA/OECD), the Pan American fect on the public perception of the potential Health Organization (PAHO), and the World danger from radiation exposure. Accidents with Health Organization (WHO). radiation sources used in medicine and industry also have attracted widespread public attention: Cuidad Juarez (Mexico), Mohamadia (Moroc- The framework for harmonization co), Goiania (Brazil), San Salvador (El Sal- vador), and Zaragoza (Spain) are names that ap- In 1991, within the framework of the Inter- peared in the news after people were injured in agency Committee on Radiation Safety, the six radiation accidents.
    [Show full text]
  • Radiation Weighting Factors
    22.55 “Principles of Radiation Interactions” Radiological Protection For practical purposes of assessing and regulating the hazards of ionizing radiation to workers and the general population, weighting factors are used. A radiation weighting factor is an estimate of the effectiveness per unit dose of the given radiation relative a to low-LET standard. Gy (joule/kg) can be used for any type of radiation. Gy does not describe the biological effects of the different radiations. Weighting factors are dimensionless multiplicative factors used to convert physical dose (Gy) to equivalent dose (Sv) ; i.e., to place biological effects from exposure to different types of radiation on a common scale. A weighting factor is not an RBE. Weighting factors represent a conservative judgment of the envelope of experimental RBEs of practical relevance to low-level human exposure. Radiation Weighting factors Radiation Type and Energy Radiation Weighting Factor, WR Range X and γ rays, all energies 1 Electrons positrons and muons, all 1 energies Neutrons: < 10 keV 5 10 keV to 100 keV 10 > 100 keV to 2 MeV 20 > 2 MeV to 20 MeV 10 > 20 MeV 5 Protons, (other than recoil protons) and energy > 2 MeV, 2-5 α particles, fission fragments, heavy nuclei 20 [ICRU 60, 1991] Background Radiation Page 1 of 16 22.55 “Principles of Radiation Interactions” For radiation types and energies not listed in the Table above, the following relationships are used to calculate a weighting factor. [Image removed due to copyright considerations] [ICRP, 1991] Q = 1.0 L < 10 keV/µm Q =
    [Show full text]
  • Thesis a Comparison of Mcnp Modeling Against Empirical
    THESIS A COMPARISON OF MCNP MODELING AGAINST EMPIRICAL DATA FOR THE MEASUREMENT OF GAMMA FIELDS DUE TO ACTINIDE OXIDES IN A GLOVEBOX Submitted by David Wright Adams Department of Environmental and Radiological Health Sciences In partial fulfillment of the requirements For the Degree of Master of Science Colorado State University Fort Collins, Colorado Fall 2012 Master’s Committee: Advisor: Alexander Brandl Thomas E. Johnson James E. Lindsay ABSTRACT A COMPARISON OF MCNP MODELING AGAINST EMPIRICAL DATA FOR THE MEASUREMENT OF GAMMA FIELDS DUE TO ACTINIDE OXIDES IN A GLOVEBOX Los Alamos National Laboratory (LANL) is a facility that conducts research in the fields of global security, astrophysics, nuclear energy, and materials science. At Technical Area 55 (TA-55) actinide oxides used for experimental nuclear fuel research are placed in gloveboxes to be manipulated by glovebox operators. The actinide oxides are radioactive and emit gamma rays which impact the glovebox operator. Although proper precautions protect workers from unnecessary dose, the measurement and characterization of the gamma fields are useful in deciding if multiple dosimetry may be necessary as per standards at the lab and national standards. Experimental measurements were made by radiation protection personnel of TA-55 at the glovebox containing different actinide oxides. Thermoluminescent dosimeters (TLDs) were utilized to determine the dose to workers at the glovebox. A lead apron covered some of the TLDs while others were left unshielded to simulate shielded and unshielded portions of the body. Monte Carlo N-Particle Code Version 5 (MCNP5) was used to model and simulate the experimental setup at TA-55 to determine the efficacy of the lead apron and to determine the spatiality of the dose distribution as required to determine whether multiple dosimetry is necessary or not.
    [Show full text]
  • John Harrison UK Task Group 79 : Use of Effective Dose As a Risk-Related Radiological Protection Quantity
    3rd International Symposium on the System of Radiological Protection Seoul, October 2015 John Harrison UK Task Group 79 : Use of Effective Dose as a Risk-related Radiological Protection Quantity John Harrison C2 Mikhail Balonov formerly C2 Colin Martin C3 Hans-Georg Menzel MC, formerly C2 Pedro Ortiz-Lopez C3 Rebecca Smith-Bindman Jane Simmonds formerly C4 Richard Wakeford C1 Equivalent dose and Effective dose, E E for children and fetus E as a measure of risk 3 Protection of workers and public primarily using constraints and reference levels applying to doses from a single source Constraints / reference levels Limits Enables the summation of all radiation exposures by risk adjustment using simplified weighting factors Applies to sex-averaged reference persons, and relates to nominal risk coefficients for uniform external low LET radiation exposure Applied without uncertainties, assumes LNT dose- response, chronic = acute, internal = external 5 ? Radiation Cancer Cancer Risk Radiation ~100 mGy Dose Cancer site Age at exposure, years Males Females 0-9 20-29 60-69 0-9 20-29 60-69 Breast --- 4.9 2.2 0.2 Colon 1.5 1.0 0.3 0.7 0.5 0.1 Liver 0.6 0.3 0.1 0.2 0.2 0.03 Lung 0.7 0.7 0.6 1.4 1.6 1.4 Thyroid 0.2 0.1 0 0.9 0.3 0.01 Leukaemia 1.1 0.8 0.5 0.5 0.5 0.3 All cancers 10 6.2 2.2 14 8.5 3.1 Publication 60 (1991) Cancer Hereditary Total Worker 4.8 0.8 5.6 Public 6.0 1.3 7.3 Publication 103 (2007) Worker 4.1 0.1 4.2 Public 5.5 0.2 5.7 1.
    [Show full text]