What is Radiation The transfer of energy in

What is Radiation? The transfer of energy in the form of particles or waves from one object to another though a medium. Module #2

Types of Radiation Particulate Alpha Particle vs Beta Particle Neutron Module #2 Electromagnetic Photon

Electromagnetic Radiation v Oscillating electric and magnetic fields that transfer energy to matter via photon or wave interactions Ionizing Non-ionizing Visible Light X-Rays & Gamma Rays 10 -12 10 -10 10 -8 Ultra Violet 10 -6 Infrared 10 -4 10 -2 Micro waves 100 Wavelength (cm) Module #2 102 Electric waves Radio waves 104 106 108 1010

Types of Radiation Charged vs. Uncharged Alpha Particle Photon Beta Particle Neutron Module #2

Types of Radiation Ionizing vs. Has enough energy to completely remove an electron from an atom Non-Ionizing Not enough energy to completely remove an electron from an atom Module #2

Pair Production • A photon of at least 1. 022 Me. V energy may spontaneously form a positronelectron pair • The positron and electron interact with matter as energetic charged particles • The positron will eventually combine with an electron and produce two 511 ke. V photons Module #2

Exposure • The sum of the charges of one sign produced by photons in given mass of air • The SI unit of exposure in the coulomb/kilogram (C/kg) • The traditional unit is the roentgen ® • 1 R = 2. 58 x 10 -4 C/kg • This unit is only defined for photons of less than 3 Me. V energy in air • Symbol is X Module #2

Absorbed Dose • The energy deposited in (absorbed) by an object per unit mass • The SI unit of absorbed dose is the Gray (Gy) • The traditional units is the rad • 100 rad = 1 Gy = 1 J/kg • Applies to all radiations at all energies in all absorbers. • Symbol is D Module #2

Dose Equivalent • The energy deposited is an object per unit mass multiplied by a “quality factor” that accounts for the different biological effectiveness of different types of radiation • Symbol is H • H=D*Q • The SI unit of dose equivalent is the sievert (Sv) • The traditional unit is the rem • 100 rem = 1 Sv Module #2

Recommended Quality Factors RADIATION TYPE X- and Gamma Beta (except H-3) H-3 Thermal Neutrons Fast Neutrons Unknown Neutrons Alpha NRC 1 1 1 * * 10 20 * See 10 CFR Table 1004(b). 2 Module #2

Conversions • For purpose of radiation protection it is often assumed that 1 R = 1 rad = 1 rem – For photons, since R is only defined for photons and the quality factor is 1 for photons; 1 R is actually less than 1 rad so this is a conservative assumption ―The actual “conversion” factor is dependent on the absorber (1 R = 0. 96 rad for tissue) Module #2

Other Dose Equivalents • Deep Dose Equivalent (Hd) – The dose equivalent at a tissue depth of 1 cm due to external radiation • Eye Dose Equivalent (Heye) – The dose equivalent at a tissue depth of 0. 3 cm due to external radiation • Shallow Dose Equivalent (H 5) – The dose equivalent at a tissue depth of 0. 007 cm due to external radiation Module #2

Other Dose Equivalents * • Committed Dose Equivalent (HT 50) – The dose equivalent received by a tissue (T) over the next 50 years due to an intake of radioactive material • Committed Effective Dose Equivalent (CEDE or HE 50) – The sum of the products of the committed dose equivalent to a tissue and a weighting factor for that tissue [HE 50 = Sw T HT 50]] Module #2

Other Dose Equivalents* • Effective Dose Equivalent (HE) – The sum of the products of the dose equivalent to a tissue and a weighting factor (w. T) for that tissue [HE = Sw. THT] • Total Effective Dose Equivalent (TEDE) – the sum of the deep dose equivalent and the CEDE [TEDE = Hd + HE 50] Module #2