DOCSLIB.ORG

General Chapter <821> Radioactivity

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
General Chapter <821> Radioactivity BRIEFING 821 Radioactivity, USP 38 page 616. This chapter was introduced in its current form in 1975 and has not undergone any major revision since its first publication. Currently, ⟨the chapter⟩ contains definitions, special considerations, and procedures with respect to the monographs for radiopharmaceuticals (radioactive drugs). The majority of this chapter is informational. USP has launched an initiative to minimize nonprocedural information in general chapters with numbers below 1000. The USP Council of Experts believes that 821 should be revised as part of this initiative. To achieve this objective, several members of the USP Council of Experts jointly published a Stimuli article in PF 38(4) [July–Aug.⟨ 2012],⟩ Revision of General Chapter Radioactivity 821 . The objectives of this Stimuli article were threefold: (1) provide background information about the need for the proposed revision, (2) initiate discussion about this topic, and⟨ (3)⟩ solicit public comments for review and discussion by the relevant Expert Committee and Expert Panel members and USP staff. The current chapter is divided into two major sections, General Considerations and Identification and Assay of Radionuclides, both of which contain several subsections with information about aspects of radioactivity. Because of the nature of the information presented in these subsections, these can be moved to the proposed Radioactivity— Theory and Practice 1821 . The Terms and Definitions section is now listed as Glossary and has been revised to reflect current practices. The revised chapter will contain procedures and⟨ information⟩ about instrumentation used in the identification and assay of the radionuclides, along with appropriate information about calibration and maintenance of instrumentation. To make the chapter more useful, we propose to include quantitative requirements such as minimum resolution for the detector, allowed variation for instrument performance, and appropriate interval for performance checks, as well as other useful parameters that can ensure the suitability of the equipment for its intended use. Interested parties are invited to submit their comments to the proposed revisions of the chapter. Additionally, minor editorial changes have been made to update the chapter to current USP style. (GCPA: R. Ravichandran.) Correspondence Number—C152699 821 RADIOACTIVITY Change to read: Radioactive pharmaceuticals require specialized techniques in their handling and testing in order that correct⟨ results⟩ may be obtained and hazards to personnel be minimized. All operations should be carried out or supervised by personnel having had expert training in handling radioactive materials. The facilities for the production, use, and storage of radioactive pharmaceuticals are generally subject to licensing by the federal Nuclear Regulatory Commission, although in certain cases this authority has been delegated to state agencies. The federal Department of Transportation regulates the conditions of shipment of radioactive materials. State and local agencies often have additional special regulations. Each producer or user must be thoroughly cognizant of the applicable regulations of the federal Food, Drug, and Cosmetic Act, and any additional requirements of the U. S. Public Health Service and of state and local agencies pertaining to the articles concerned. Definitions, special considerations, and procedures with respect to the Pharmacopeial monographs on radioactive drugs are set forth in this chapter. GENERAL CONSIDERATIONS Fundamental Decay Law The decay of a radioactive source is described by the equation: −λt Nt = Noe in which Nt is the number of atoms of a radioactive substance at elapsed time t, No is the number of those atoms when t = 0, and λ is the transformation or decay constant, which has a characteristic value for each radionuclide. The half-life, T1/2, is the time interval required for a given activity of a radionuclide to decay to one-half of its initial value, and is related to the decay constant by the equation: T1/2 = 0.69315/λ The activity of a radioactive source (A) is related to the number of radioactive atoms present by the equation: A = λN from which the number of radioactive atoms at time t can be computed, and hence the mass of the radioactive material can be determined. The activity of a pure radioactive substance as a function of time can be obtained from the exponential equation or from decay tables, or by graphical means based on the half- life (see Normalized Decay Chart, Figure 1). The linked image cannot be displayed. The file may have been moved, renamed, or deleted. Verify that the link points to the correct file and location. Fig. 1. Normalized Decay Chart. The activity of a radioactive material is expressed as the number of nuclear transformations per unit time. The fundamental unit of radioactivity, the curie (Ci), is defined as 3.700 × 1010 nuclear transformations per second. The millicurie (mCi) and microcurie (µCi) are commonly used subunits. The “number of nuclear transformations per unit time” is the sum of rates of decay from all competing modes of disintegration of the parent nuclide. Before the activity of any given radionuclide in a measured specimen can be expressed in curies, it is often necessary to know the abundance(s) of the emitted radiation(s) measured. Geometry The validity of relative calibration and measurement of radionuclides is dependent upon the reproducibility of the relationship of the source to the detector and its surroundings. Appropriate allowance must be made for source configuration. Background Cosmic rays, radioactivity present in the detector and shielding materials, and radiation from nearby radioactive sources not properly shielded from the measuring equipment, all contribute to the background count rate. All radioactivity measurements must be corrected by subtracting the background count rate from the gross count rate in the test specimen. Statistics of Counting Since the process of radioactive decay is a random phenomenon, the events being counted form a random sequence in time. Therefore, counting for any finite time can yield only an estimate of the true counting rate. The precision of this estimate, being subject to statistical fluctuations, is dependent upon the number of counts accumulated in a given measurement and can be expressed in terms of the standard deviation σ. An estimate for σ is √n where n is the number of counts accumulated in a given measurement. The probability of a single measurement falling within ±100/√n% of the mean of a great many measurements is 0.68. That is, if many measurements of n counts each were to be made, approximately two-thirds of the observations would lie within ±100/√n% of the mean, and the remainder outside. Because of the statistical nature of radioactive decay, repeated counting of an undisturbed source in a counting assembly will yield count-rate values in accordance with the frequency of a normal distribution. Deviations in these values from the normal distribution conform to the χ2 test. For this reason, the χ2 test is frequently applied to determine the performance and correct operation of a counting assembly. In the selection of instruments and conditions for assay of radioactive sources, the figure of merit ε2/B should be maximized (where ε = counter efficiency = observed count rate/sample disintegration rate, and B = background count rate). Counting Losses The minimum time interval that is required for the counter to resolve two consecutive signal pulses is known as the dead time. The dead time varies typically from the order of microseconds for proportional and scintillation counters, to hundreds of microseconds for Geiger-Müller counters. Nuclear events occurring within the dead time of the counter will not be registered. To obtain the corrected count rate, R, from the observed count rate, r, it is necessary to use the formula: R = r/(1 − rτ) in which τ is the dead time. The foregoing correction formula assumes a nonextendable dead time. Thus, for general validity, the value of rτ should not exceed 0.1. The observed count rate, r, refers to the gross specimen count rate and is not to be corrected for background before use in the foregoing equation. Calibration Standards Perform all radioactivity assays using measurement systems calibrated with appropriately certified radioactivity standards. Such calibration standards may be purchased either direct from the National Institute of Standards and Technology or from other sources that have established traceability to the National Institute of Standards and Technology through participation in a program of inter-comparative measurements. Where such calibration standards are unavailable, the Pharmacopeia provides the nuclear decay data required for calibration. These data, as well as half-life values, are obtained from the Evaluated Nuclear Structure Data File of the Oak Ridge Nuclear Data Project, and reflect the most recent values at the time of publication. Carrier The total mass of radioactive atoms or molecules in any given radioactive source is directly proportional to the activity of the radionuclide for a given half-life, and the amount present in radiopharmaceuticals is usually too small to be measured by ordinary chemical or physical methods. For example, the mass of 131I having an activity of 100 mCi is 8 × 10−7 g. Since such small amounts of material behave chemically in an anomalous manner, carriers in the form of nonradioactive isotopes of the same radionuclide may be added
Load more

Recommended publications
  • Chapter 1.2: Transformation Kinetics
    Chapter 1: Radioactivity Chapter 1.2: Transformation Kinetics 200 NPRE 441, Principles of Radiation Protection Chapter 1: Radioactivity http://www.world‐nuclear.org/info/inf30.html 201 NPRE 441, Principles of Radiation Protection Chapter 1: Radioactivity Serial Transformation In many situations, the parent nuclides produce one or more radioactive offsprings in a chain. In such cases, it is important to consider the radioactivity from both the parent and the daughter nuclides as a function of time. • Due to their short half lives, 90Kr and 90Rb will be completely transformed, results in a rapid building up of 90Sr. • 90Y has a much shorter half‐life compared to 90Sr. After a certain period of time, the instantaneous amount of 90Sr transformed per unit time will be equal to that of 90Y. •Inthiscase,90Y is said to be in a secular equilibrium. 202 NPRE 441, Principles of Radiation Protection Chapter 1: Radioactivity Exponential DecayTransformation Kinetics • Different isotopes are characterized by their different rate of transformation (decay). • The activity of a pure radionuclide decreases exponentially with time. For a given sample, the number of decays within a unit time window around a given time t is a Poisson random variable, whose expectation is given by t Q Q0e •Thedecayconstant is the probability of a nucleus of the isotope undergoing a decay within a unit period of time. 203 NPRE 441, Principles of Radiation Protection Chapter 1: Radioactivity Why Exponential Decay? The decay rate, A, is given by Separate variables in above equation, we have The decay constant is the probability of a nucleus of the isotope undergoing a decay within a unit period of time.
    [Show full text]
  • Experimental Γ Ray Spectroscopy and Investigations of Environmental Radioactivity
    Experimental γ Ray Spectroscopy and Investigations of Environmental Radioactivity BY RANDOLPH S. PETERSON 216 α Po 84 10.64h. 212 Pb 1- 415 82 0- 239 β- 01- 0 60.6m 212 1+ 1630 Bi 2+ 1513 83 α β- 2+ 787 304ns 0+ 0 212 α Po 84 Experimental γ Ray Spectroscopy and Investigations of Environmental Radioactivity Randolph S. Peterson Physics Department The University of the South Sewanee, Tennessee Published by Spectrum Techniques All Rights Reserved Copyright 1996 TABLE OF CONTENTS Page Introduction ....................................................................................................................4 Basic Gamma Spectroscopy 1. Energy Calibration ................................................................................................... 7 2. Gamma Spectra from Common Commercial Sources ........................................ 10 3. Detector Energy Resolution .................................................................................. 12 Interaction of Radiation with Matter 4. Compton Scattering............................................................................................... 14 5. Pair Production and Annihilation ........................................................................ 17 6. Absorption of Gammas by Materials ..................................................................... 19 7. X Rays ..................................................................................................................... 21 Radioactive Decay 8. Multichannel Scaling and Half-life .....................................................................
    [Show full text]
  • Nuclide Safety Data Sheet Iron-59
    59 Nuclide Safety Data Sheet 59 Iron-59 Fe www.nchps.org Fe I. PHYSICAL DATA 1 Gammas/X-rays: 192 keV (3% abundance); 1099 keV (56%), 1292 keV (44%) Radiation: 1 Betas: 131 keV (1%), 273 keV (46%), 466 keV (53%) 2 Gamma Constant: 0.703 mR/hr per mCi @ 1.0 meter [1.789E-4 mSv/hr per MBq @ 1.0 meter] 1 Half-Life [T½] : Physical T½: 44.5 day 3 Biological T½: ~1.7 days (ingestion) ; much longer for small fraction Effective T½: ~1.7 days (varies; also small fraction retained much longer) Specific Activity: 4.97E5 Ci/g [1.84E15 Bq/g] max.1 II. RADIOLOGICAL DATA Radiotoxicity4: 1.8E-9 Sv/Bq (67 mrem/uCi) of 59Fe ingested [CEDE] 4.0E-9 Sv/Bq (150 mrem/uCi) of 59Fe inhaled [CEDE] Critical Organ: Spleen1, [blood] Intake Routes: Ingestion, inhalation, puncture, wound, skin contamination (absorption); Radiological Hazard: Internal Exposure; Contamination III. SHIELDING Half Value Layer [HVL] Tenth Value Layer [TVL] Lead [Pb] 15 mm (0.59 inches) 45 mm (1.8 inches) Steel 35 mm (1.4 inches) 91 mm (3.6 inches) The accessible dose rate should be background but must be < 2 mR/hr IV. DOSIMETRY MONITORING - Always wear radiation dosimetry monitoring badges [body & ring] whenever handling 59Fe V. DETECTION & MEASUREMENT Portable Survey Meters: Geiger-Mueller [e.g. PGM] to assess shielding effectiveness & contamination Wipe Test: Liquid Scintillation Counter, Gamma Counter VI. SPECIAL PRECAUTIONS • Avoid skin contamination [absorption], ingestion, inhalation, & injection [all routes of intake] • Use shielding (lead) to minimize exposure while handling of 59Fe • Use tools (e.g.
    [Show full text]
  • Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion
    United States Office of EPA-520/1-88-020 Environmental Protection Radiation Program September 1988 Agency Washington, DC 20460 Radiation EPA Limiting Values of Radionuclide Intake And Air Concentration and Dose Conversion Factors For Inhalation, Submersion, And Ingestion Federal Guidance Report No.11 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 makes any warranty express or implied, or assumes any legal liability of responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency I thereof. This report was prepared by the OFFICE OF RADIATION PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY Washington, DC 20460 and by the OAK RIDGE NATIONAL LABORATORY Oak Ridge. Tennessee 37831 operated by MARTIN MARIE-I-I-A ENERGY SYSTEMS, INC. for the U.S. DEPARTMENT OF ENERGY Contract No. DE-ACO5-84OR21400 FEDERAL GUIDANCE REPORT NO. 11 LIMITING VALUES OF RADIONUCLIDE INTAKE AND AIR CONCENTRATION AND DOSE CONVERSION FACTORS FOR INHALATION, SUBMERSION, AND INGESTION Derived Guides for Control of Occupational Exposure and Exposure-to-Dose Conversion Factors for General Application, Based on the 1987 Federal Radiation Protection Guidance Keith F.
    [Show full text]
  • Polonium-210
    Health Physics Society Fact Sheet Adopted: May 2010 Revised: June 2020 Health Physics Society Specialists in Radiation Safety Polonium-210 General In 1898, Marie and Pierre Curie discovered their first radioactive* element. It was later named polonium in honor of Marie Sklodowska Curie’s native Poland. Polonium, a naturally occurring element that can be found throughout our environment, results from the radioactive decay of radon-222 gas—a part of the uranium-238 decay chain. There are over 30 known isotopes of polonium, and all are radioactive, but the one occurring most in nature—and the one most widely used—is polonium-210 (210Po). With a half-life of 138 days, it decays to stable lead-206 by the emission of an alpha particle (an alpha particle has two protons and two neutrons). Radioactive materials are quantified by activity, or the number of disintegrations that occur over a period of time. A terabecquerel (TBq), for instance, is equal to 1 x 1012 disintegrations per second. Polonium-210 has a very high specific activity—activity per unit mass—of about 166 TBq per gram (4,490 curies, Ci, per gram). In other words, it doesn’t take a large physical amount to be very radioactive. Because of the high specific activity and the large associated thermal cross section, according to a human health fact sheet for 210Po produced by Argonne National Laboratory, a capsule containing about 0.5 grams (83 TBq) of 210Po can reach temperatures exceeding 500o C (ANL 2005). When it is purified, polonium melts at a low temperature and can be quite volatile.
    [Show full text]
  • Tritium (Hydrogen-3)
    Human Health Fact Sheet ANL, October 2001 Tritium (Hydrogen-3) What Is It? Tritium is the only radioactive isotope of hydrogen. (An Symbol: H (H-3) isotope is a different form of an element that has the same number of protons in the nucleus but a different number of neutrons.) The nucleus Atomic Number: 1 of a tritium atom consists of a proton and two neutrons. This contrasts (protons in nucleus) with the nucleus of an ordinary hydrogen atom (which consists solely of a Atomic Weight: 1 proton) and a deuterium atom (which consists of one proton and one (naturally occurring H) neutron). Ordinary hydrogen comprises over 99.9% of all naturally occurring hydrogen. Deuterium comprises about 0.02%, and tritium comprises about a billionth of a billionth (10-18) percent. The most common Radioactive Properties of Tritium forms of tritium are tritium gas Half- Natural Specific Radiation Energy (MeV) Decay (HT) and tritium Isotope Life Abundance Activity Mode Alpha Beta Gamma oxide, also called (yr) (%) (Ci/g) (α) (β) (γ) “tritiated water.” H-3 12 a trillionth 9,800 β - 0.0057 - In tritiated water, a tritium atom Ci = curie, g = gram, and MeV = million electron volts; a dash means the entry is not applicable. (See the companion fact sheet on Radioactive Properties, Internal replaces one of the Distribution, and Risk Coefficients for an explanation of terms and interpretation of hydrogen atoms so radiation energies.) Values are given to two significant figures. the chemical form is HTO rather than H2O. The chemical properties of tritium are essentially the same as those of ordinary hydrogen.
    [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]
  • 1 ,.,. the Origin Gamma Rays Doughs Re41i!J
    1 ,.,. The Origin of Gamma Rays Doughs Re41i!j 1.1 GAMMA RAYS AND THE EIECI’ROMAGNETIC sPEclmJM Gamma rays are high-energy electromagnetic radiation emitted in the deexcitation of the atomic nucleus. Electromagnetic radiation includes such diverse phenomena as radio, television, microwaves, infrared radation, light, ultraviolet radiation, x rays, and gamma rays. These ti]ations all propagate througli vacuum with the speed of light. They can be described as wave piienomena involving electric and magnetic field oscillations analogous to mechanical oscillations such as water waves or sound. They differ from each other only in the frequency of oscillation. Although given dWferent names, electromagnetic radiation actually forms a continuous spect~m, from low- frequency radio’ waves at a few cycles per second to gamma rays at 1018 Hz and above (see Figure 1.1). The parameters used to describe’ an electromagnetic wave— fre@ency, wavelength, and energy—are related and maybe used interchangeably. It is common practice to use frequency or wavelength for radio’waves, color or wavelength for light waves (including infrared and ultraviolet), and energy for x rays and gamma rays. Frequenty Wavelength Energy (Hz) (meters)(electronvolts) 1(i” Oamma Rays +-- 106 (1MeV) 1 i?’ x Rays id’ + 103 (1 keV) 10’8 ultraviolet 10-8 10’5 \\S Wsibb SSSSS 4-10° (1 eV) Inrrared 10-5 10’2 ehon mdlo waves 10-2 llf 10’ V \\\\\\\\\\\\\\~\\\\\\\ boadcasl emd t Mefmhertz lcf’ \\\\\\\\\\\\\\\\\\\\\\\\\\ 104 1 kit01wrt2 ltf LongRadio Waves 10’ lrf’ // Power Lines Fig. 1.1 The electromagnetic spectrum showing the relationship between gamma rays, x rays, light waves, and radio waves.
    [Show full text]
  • Radiation Dosimetry in Cases of Normal and Emergency Situations
    Radiation Dosimetry in Cases of Normal and Emergency Situations A Thesis Submitted to Department of Physics Faculty of Science, Al Azhar University for The Degree of PhD. in Physics by Tarek Mahmoud Morsi M.Sc. (Physics, 2003) Radiation Protection Department, Nuclear Research Center, Atomic Energy Authority Under Supervision Emeritus Prof. M. I. El Gohary Emeritus Prof. M. A. Gomaa Prof. of Biophysics Prof. of Radiation Physics Al Azhar University Atomic Energy Authority Emeritus Prof. Samia M. Rashad Emeritus Dr. Eid M. Ali Prof. of Radiation Emergencies Lecturer of Radiation Physics Atomic Energy Authority Atomic Energy Authority 2010 Approval Sheet for Submission Ti tle of the PhD. Thesis Radiation Dosimetry in Cases of Normal and Emergency Situations Name of the Candidate Tarek Mahmoud Morsi Atomic Energy Authority This thesis has been approved for submission by the supervisors : Emeritus Prof. M. I. El Gohary Emeritus Prof. M. A. Gomaa Prof. of Biophysics Prof. of Radiation Physics Al Azhar University Atomic Energy Authority Emeritus Prof. Samia M. Rashad Emeritus Dr. Eid M. Ali Prof. of Radiation Emergencies Lecturer of Radiation Physics Atomic Energy Authority Atomic Energy Authority Acknowledgement First and above all, all thanks to ALLAH the Merciful, the Compassionate without his help. I couldn't finish this work. I wish to express my sincere thanks and gratitude to Professor Dr. Mohamed I. EL-Gohary, Prof. of Biophysics, faculty of science, Al- Azhar University and Professor Dr. Mohamed A. Gomaa, Prof. of Radiation Physics, Atomic Energy Authority (A.E.A) for their kind supervision, continuous encouragement and helps during the course of this work.
    [Show full text]
  • Radiation Doses to Hanford Workers from Natural Potassium-40
    PNNL-18240 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Radiation Doses to Hanford Workers from Natural Potassium-40 DJ Strom TP Lynch DR Weier February 2009 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 Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper.
    [Show full text]
  • Units of Radioactivity and Units of Radiation Absorbed Dose
    UNITS OF RADIOACTIVITY AND UNITS OF RADIATION ABSORBED DOSE After completing this tutorial, attendees will be able to • Understand the measurement of units of radioactivity. • Give the definition of activity and identify the number of disintegrations/sec in a Ci and a mCi • List all units from Ci to pCi • State the relationship between disintegrations/sec and Bq • Differentiate between a count and a disintegration • State the definition of and formula for Detection Efficiency • Define Specific Activity • Define Rad, Rem, Quality Factor, Gray and Sievert • Perform basic calculations of activity and radiation dose This tutorial will define how radioactivity is measured and give different formulas for measuring units of radiation. UNITS OF RADIOACTIVITY Definition: A Curie is the unit of absolute activity and is abbreviated Ci. It is expressed in terms of disintegrations per second (dps). A Curie is represented by a sample with a decay rate of 3.7 X 1010 dps or 2.22 X 1012 dpm. Unit # of Curie # of DPS # of DPM Megacurie (MCi) 106 Ci 3.7 x 1016dps 2.22 x 1018 dpm Kilocurie (kCi) 103 Ci 3.7 x 1013dps 2.22 x 1015 dpm Curie (Ci) 1 Ci 3.7 x 1010dps 2.22 x 1012 dpm Millicurie (mCi) 10-3 Ci 3.7 x 107 dps 2.22 x 10 9 dpm Microcurie (µCi) 10-6 Ci 3.7 x 104 dps 2.22 x 106 dpm Nanocurie (nCi) 10-9 Ci 3.7 x 101 dps 2.22 x 103 dpm Picocurie (pCi) 10-12 Ci 3.7 x 10-2 dps 2.22 dpm Femtocurie (MCi) 10-15 Ci 3.7 x 10-5 dps 2.22 x 10-3 dpm The bolded line represents the most commonly used Ci-related termsDefinition: In the SI System, the Basic Unit of Absolute Activity is a Bq (Becquerel).
    [Show full text]
  • 6 Equations of Radioactive Decay and Growth
    6 EQUATIONS OF RADIOACTIVE DECAY AND GROWTH The mathematical expressions presented in this chapter are generally applicable to all those processes in which the transition of the parent nucleus to a daughter nucleus , i.e. the process of radioactive decay, is governed by statistical chance. This chance of decay is equivalent to the degree of instability of the parent nucleus. Each radioactive nuclide has its specific degree of instability which, as we will see, is going to be expressed by the half-life assigned to this nuclide. The radioactivity of a sample is more complicated if it consists of two or more components, such as: (i) in the case of a mixture of independent activities, (ii) if one specific type of nuclide shows two modes of decay, so-called branching decay, and (iii) if we are dealing with a nuclear decay series in which also the daughter nuclides are radioactive. All these phenomena will be discussed separately. 6.1 LAW OF RADIOACTIVE DECAY The fundamental law of radioactive decay is based on the fact that the decay, i.e. the transition of a parent nucleus to a daughter nucleus is a purely statistical process. The disintegration (decay) probability is a fundamental property of an atomic nucleus and remains equal in time. Mathematically this law is expressed as: dN = Ndt (6.1) and dN / dt (6.2) N where N is the number of radioactive nuclei, -dN/dt the decrease (negative) of this number per unit of time and is thus the probability of decay per nucleus per unit of time.
    [Show full text]