Chapter 3. Fundamentals of Dosimetry
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Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
Neutron Interactions and Dosimetry Outline Introduction Tissue
Outline • Neutron dosimetry Neutron Interactions and – Thermal neutrons Dosimetry – Intermediate-energy neutrons – Fast neutrons Chapter 16 • Sources of neutrons • Mixed field dosimetry, paired dosimeters F.A. Attix, Introduction to Radiological • Rem meters Physics and Radiation Dosimetry Introduction Tissue composition • Consider neutron interactions with the majority tissue elements H, O, C, and N, and the resulting absorbed dose • Because of the short ranges of the secondary charged particles that are produced in such interactions, CPE is usually well approximated • Since no bremsstrahlung x-rays are generated, the • The ICRU composition for muscle has been assumed in absorbed dose can be assumed to be equal to the most cases for neutron-dose calculations, lumping the kerma at any point in neutron fields at least up to 1.1% of “other” minor elements together with oxygen to an energy E ~ 20 MeV make a simple four-element (H, O, C, N) composition Neutron kinetic energy Neutron kinetic energy • Neutron fields are divided into three • Thermal neutrons, by definition, have the most probable categories based on their kinetic energy: kinetic energy E=kT=0.025eV at T=20C – Thermal (E<0.5 eV) • Neutrons up to 0.5eV are considered “thermal” due to simplicity of experimental test after they emerge from – Intermediate-energy (0.5 eV<E<10 keV) moderator material – Fast (E>10 keV) • Cadmium ratio test: • Differ by their primary interactions in tissue – Gold foil can be activated through 197Au(n,)198Au interaction and resulting biological effects -
Decays of the Tau Lepton*
SLAC - 292 UC - 34D (E) DECAYS OF THE TAU LEPTON* Patricia R. Burchat Stanford Linear Accelerator Center Stanford University Stanford, California 94305 February 1986 Prepared for the Department of Energy under contract number DE-AC03-76SF00515 Printed in the United States of America. Available from the National Techni- cal Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. Price: Printed Copy A07, Microfiche AOl. JC Ph.D. Dissertation. Abstract Previous measurements of the branching fractions of the tau lepton result in a discrepancy between the inclusive branching fraction and the sum of the exclusive branching fractions to final states containing one charged particle. The sum of the exclusive branching fractions is significantly smaller than the inclusive branching fraction. In this analysis, the branching fractions for all the major decay modes are measured simultaneously with the sum of the branching fractions constrained to be one. The branching fractions are measured using an unbiased sample of tau decays, with little background, selected from 207 pb-l of data accumulated with the Mark II detector at the PEP e+e- storage ring. The sample is selected using the decay products of one member of the r+~- pair produced in e+e- annihilation to identify the event and then including the opposite member of the pair in the sample. The sample is divided into subgroups according to charged and neutral particle multiplicity, and charged particle identification. The branching fractions are simultaneously measured using an unfold technique and a maximum likelihood fit. The results of this analysis indicate that the discrepancy found in previous experiments is possibly due to two sources. -
7. Gamma and X-Ray Interactions in Matter
Photon interactions in matter Gamma- and X-Ray • Compton effect • Photoelectric effect Interactions in Matter • Pair production • Rayleigh (coherent) scattering Chapter 7 • Photonuclear interactions F.A. Attix, Introduction to Radiological Kinematics Physics and Radiation Dosimetry Interaction cross sections Energy-transfer cross sections Mass attenuation coefficients 1 2 Compton interaction A.H. Compton • Inelastic photon scattering by an electron • Arthur Holly Compton (September 10, 1892 – March 15, 1962) • Main assumption: the electron struck by the • Received Nobel prize in physics 1927 for incoming photon is unbound and stationary his discovery of the Compton effect – The largest contribution from binding is under • Was a key figure in the Manhattan Project, condition of high Z, low energy and creation of first nuclear reactor, which went critical in December 1942 – Under these conditions photoelectric effect is dominant Born and buried in • Consider two aspects: kinematics and cross Wooster, OH http://en.wikipedia.org/wiki/Arthur_Compton sections http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=22551 3 4 Compton interaction: Kinematics Compton interaction: Kinematics • An earlier theory of -ray scattering by Thomson, based on observations only at low energies, predicted that the scattered photon should always have the same energy as the incident one, regardless of h or • The failure of the Thomson theory to describe high-energy photon scattering necessitated the • Inelastic collision • After the collision the electron departs -
TUTORIAL on NEUTRON PHYSICS in DOSIMETRY S. Pomp1
TUTORIAL ON NEUTRON PHYSICS IN DOSIMETRY S. Pomp1,* 1 Department of physics and astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden. *Corresponding author. E‐mail address: [email protected] (S.Pomp) Abstract: Almost since the time of the discovery of the neutron more than 70 years ago, efforts have been made to understand the effects of neutron radiation on tissue and, eventually, to use neutrons for cancer treatment. In contrast to charged particle or photon radiations which directly lead to release of electrons, neutrons interact with the nucleus and induce emission of several different types of charged particles such as protons, alpha particles or heavier ions. Therefore, a fundamental understanding of the neutron‐nucleus interaction is necessary for dose calculations and treatment planning with the needed accuracy. We will discuss the concepts of dose and kerma, neutron‐nucleus interactions and have a brief look at nuclear data needs and experimental facilities and set‐ups where such data are measured. Keywords: Neutron physics; nuclear reactions; kerma coefficients; neutron beams; Introduction Dosimetry is concerned with the ability to determine the absorbed dose in matter and tissue resulting from exposure to directly and indirectly ionizing radiation. The absorbed dose is a measure of the energy deposited per unit mass in the medium by ionizing radiation and is measured in Gray, Gy, where 1 Gy = 1 J/kg. Radiobiology then uses information about dose to assess the risks and gains. A risk is increased probability to develop cancer due to exposure to a certain dose. A gain is exposure of a cancer tumour to a certain dose in order to cure it. -
Charged Particle Radiotherapy
Corporate Medical Policy Charged Particle Radiotherapy File Name: charged_particle_radiotherapy Origination: 3/12/96 Last CAP Review: 5/2021 Next CAP Review: 5/2022 Last Review: 5/2021 Description of Procedure or Service Cha rged-particle beams consisting of protons or helium ions or carbon ions are a type of particulate ra dia tion therapy (RT). They contrast with conventional electromagnetic (i.e., photon) ra diation therapy due to several unique properties including minimal scatter as particulate beams pass through tissue, and deposition of ionizing energy at precise depths (i.e., the Bragg peak). Thus, radiation exposure of surrounding normal tissues is minimized. The theoretical advantages of protons and other charged-particle beams may improve outcomes when the following conditions a pply: • Conventional treatment modalities do not provide adequate local tumor control; • Evidence shows that local tumor response depends on the dose of radiation delivered; and • Delivery of adequate radiation doses to the tumor is limited by the proximity of vital ra diosensitive tissues or structures. The use of proton or helium ion radiation therapy has been investigated in two general categories of tumors/abnormalities. However, advances in photon-based radiation therapy (RT) such as 3-D conformal RT, intensity-modulated RT (IMRT), a nd stereotactic body ra diotherapy (SBRT) a llow improved targeting of conventional therapy. 1. Tumors located near vital structures, such as intracranial lesions or lesions a long the a xial skeleton, such that complete surgical excision or adequate doses of conventional radiation therapy are impossible. These tumors/lesions include uveal melanomas, chordomas, and chondrosarcomas at the base of the skull and a long the axial skeleton. -
Meeting the Joint Commission's Fluoroscopy Training Requirements
Meeting The Joint Commission’s Outline Fluoroscopy Training Requirements • Overview of TJC’s recent fluoroscopy requirements Part I: Image Gently, Image Wisely and Dose Optimization • Basics of radiation units, terminology and regulatory limits • Radiation risks in fluoroscopy, their prevalence and probabilities • Physical and operational aspects of fluoroscopes Satish Nair Ph.D, CHP, DABMP Certified Health Physicist • Best practices in fluoroscopy: for patients and operators Certified Medical Physicist F. X. Massé Associates, Inc. Health and Medical Physics Consultants Gloucester, MA fxmasse.com 20th Annual SRPE Educational Conference, Las Vegas, NV April 2019 1 January 2019 Terminology Convert to Equivalent dose (mrem, mSv) X-ray , Gamma, Beta = 1 Alpha = 20 Proton = 2 Head CT Neutron = 5 to 20 Cardiac Exposure Stress Test KUB Image Gently: ‘Pause and Pulse’ resources X Ray 1 January 2019 • Annual Medical Physics evaluation of fluoroscopes • Designated Radiation Safety Officer (RSO) Measure Exposure Extremity X Ray • Dose indices stored in retrievable format: CAK or KAP - if displayed Roentgen Compare to NB Convert to R, mR, mR/h If not displayed: cumulative fluoro time and # of digital spot images Calculate Radiation Effective Dose (Whole Body Dose) • Establish radiation exposure and skin dose thresholds for adverse effects Absorbed dose to organ • Perform evaluation if exceeded these thresholds are exceeded Roentgen equivalent man Roentgen absorbed dose rem, mrem, mrem/year rad, mrad 1 July 2018 Sievert: Sv, mSv • Use of shielding -
The Basic Interactions Between Photons and Charged Particles With
Outline Chapter 6 The Basic Interactions between • Photon interactions Photons and Charged Particles – Photoelectric effect – Compton scattering with Matter – Pair productions Radiation Dosimetry I – Coherent scattering • Charged particle interactions – Stopping power and range Text: H.E Johns and J.R. Cunningham, The – Bremsstrahlung interaction th physics of radiology, 4 ed. – Bragg peak http://www.utoledo.edu/med/depts/radther Photon interactions Photoelectric effect • Collision between a photon and an • With energy deposition atom results in ejection of a bound – Photoelectric effect electron – Compton scattering • The photon disappears and is replaced by an electron ejected from the atom • No energy deposition in classical Thomson treatment with kinetic energy KE = hν − Eb – Pair production (above the threshold of 1.02 MeV) • Highest probability if the photon – Photo-nuclear interactions for higher energies energy is just above the binding energy (above 10 MeV) of the electron (absorption edge) • Additional energy may be deposited • Without energy deposition locally by Auger electrons and/or – Coherent scattering Photoelectric mass attenuation coefficients fluorescence photons of lead and soft tissue as a function of photon energy. K and L-absorption edges are shown for lead Thomson scattering Photoelectric effect (classical treatment) • Electron tends to be ejected • Elastic scattering of photon (EM wave) on free electron o at 90 for low energy • Electron is accelerated by EM wave and radiates a wave photons, and approaching • No -
Charged Current Anti-Neutrino Interactions in the Nd280 Detector
CHARGED CURRENT ANTI-NEUTRINO INTERACTIONS IN THE ND280 DETECTOR BRYAN E. BARNHART HIGH ENERGY PHYSICS UNIVERSITY OF COLORADO AT BOULDER ADVISOR: ALYSIA MARINO Abstract. For the neutrino beamline oscillation experiment Tokai to Kamioka, the beam is clas- sified before oscillation by the near detector complex. The detector is used to measure the flux of different particles through the detector, and compare them to Monte Carlo Simulations. For this work, theν ¯µ background of the detector was isolated by examining the Monte Carlo simulation and determining cuts which removed unwanted particles. Then, a selection of the data from the near detector complex underwent the same cuts, and compared to the Monte Carlo to determine if the Monte Carlo represented the data distribution accurately. The data was found to be consistent with the Monte Carlo Simulation. Date: November 11, 2013. 1 Bryan E. Barnhart University of Colorado at Boulder Advisor: Alysia Marino Contents 1. The Standard Model and Neutrinos 4 1.1. Bosons 4 1.2. Fermions 5 1.3. Quarks and the Strong Force 5 1.4. Leptons and the Weak Force 6 1.5. Neutrino Oscillations 7 1.6. The Relative Neutrino Mass Scale 8 1.7. Neutrino Helicity and Anti-Neutrinos 9 2. The Tokai to Kamioka Experiment 9 2.1. Japan Proton Accelerator Research Complex 10 2.2. The Near Detector Complex 12 2.3. The Super-Kamiokande Detector 17 3. Isolation of the Anti-Neutrino Component of Neutrino Beam 19 3.1. Experiment details 19 3.2. Selection Cuts 20 4. Cut Descriptions 20 4.1. Beam Data Quality 20 4.2. -
Neutrino Physics
Neutrino Physics Steve Boyd University of Warwick Course Map 1. History and properties of the neutrino, neutrino interactions, beams and detectors 2. Neutrino mass, direct mass measurements, double beta decay, flavour oscillations 3. Unravelling neutrino oscillations experimentally 4. Where we are and where we're going References K. Zuber, “Neutrino Physics”, IoP Publishing 2004 C. Giunti and C.W.Kim, “Fundamentals of Neutrino Physics and Astrophysics”, Oxford University Press, 2007. R. N. Mohaptara and P. B. Pal, “Massive Neutrinos in Physics and Astrophysics”, World Scientific (2nd Edition), 1998 H.V. Klapdor-Kleingrothaus & K. Zuber, “Particle Astrophysics”,IoP Publishing, 1997. Two Scientific American articles: “Detecting Massive Neutrinos”, E. Kearns, T. Kajita, Y. Totsuka, Scientific American, August 1999. “Solving the Solar Neutrino Problem”, A.B. McDonald, J.R. Klein, D.L. Wark, Scientific American, April 2003. Plus other Handouts Lecture 1 In which history is unravelled, desperation is answered, and the art of neutrino generation and detection explained Crisis It is 1914 – the new study of atomic physics is in trouble (Z+1,A) Spin 1/2 (Z,A) Spin 1/2 Spin 1/2 electron Spin ½ ≠ spin ½ + spin ½ E ≠ E +e Ra Bi “At the present stage of atomic “Desperate remedy.....” theory we have no arguments “I do not dare publish this idea....” for upholding the concept of “I admit my way out may look energy balance in the case of improbable....” b-ray disintegrations.” “Weigh it and pass sentence....” “You tell them. I'm off to a party” Detection of the Neutrino 1950 – Reines and Cowan set out to detect n 1951 1951 1951 I. -
Basic Radiation Interactions, Definition of Dosimetric Quantities, and Data Sources
Basic Radiation Interactions, Definition of Dosimetric Quantities, and Data Sources J.V. Siebers Virginia Commonwealth University Richmond, Virginia USA 2009 AAPM Summer School Learninggj Objectives 1. To review and describ e the bas ics of radiation interactions for understanding radiation dosimetry 2. To review definitions of quantities required for understanding radiation dosimetry ©JVS: 2009 AAPM SS Constants Units Conversions ©JVS: 2009 AAPM SS ©JVS: 2009 AAPM SS Scope Radiation Types Ionizing Interactions can remove atomic orbital electrons Non-Ionizing Particulate Electromagnetic -electron -positron -proton -neutron -alpha -etc. ©JVS: 2009 AAPM SS Types of ionizin g radiation Direc tltly ion iz ing radia tion Direct interactions via the Coulomb force along a particles track Charged particles electrons positrons protons heavy charged particles ©JVS: 2009 AAPM SS Direct Ionization Coulombic Interaction e- A charged particle exerts electromagnetic forces on atomic Energy transfer can electrons result in the ejection of an electron (ionization) ©JVS: 2009 AAPM SS Indirectlyyg Ionizing Radiation Uncharged particles that must first transfer energy to a charged particle which can then further ionize matter Two step process Examples Elec tromagne tic radia tions: x- or γ-rays Neutrons ©JVS: 2009 AAPM SS Indirectly Ionizing Radiation Pho toe lec tr ic Effec t e- Ejec te d h electrons further ionize matter ©JVS: 2009 AAPM SS Radiant Energy R R – Total energy, excluding rest mass, carried by particles Photons: E = hν = hc/λ -
Glossary Module 1 Electric Charge
Glossary Module 1 electric charge - is a basic property of elementary particles of matter. The protons in an atom, for example, have positive charge, the electrons have negative charge, and the neutrons have zero charge. electrostatic force - is one of the most powerful and fundamental forces in the universe. It is the force a charged object exerts on another charged object. permittivity – is the ability of a substance to store electrical energy in an electric field. It is a constant of proportionality that exists between electric displacement and electric field intensity in a given medium. vector - a quantity having direction as well as magnitude. Module 2 electric field - a region around a charged particle or object within which a force would be exerted on other charged particles or objects. electric flux - is the measure of flow of the electric field through a given area. Module 3 electric potential - the work done per unit charge in moving an infinitesimal point charge from a common reference point (for example: infinity) to the given point. electric potential energy - is a potential energy (measured in joules) that results from conservative Coulomb forces and is associated with the configuration of a particular set of point charges within a defined system. Module 4 Capacitance - is a measure of the capacity of storing electric charge for a given configuration of conductors. Capacitor - is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. Dielectric - a medium or substance that transmits electric force without conduction; an insulator. Module 5 electric current - is a flow of charged particles.