Radiation Safety
What charge does an alpha particle contain?
+2 (positive two) charge
What charge does a beta particle contain?
-1 (negative one) charge
How much of the parent isotope remains after two half-lives of decay?
.25 or 1/4
The Becquerel (Bq) named in honor of French scientist and Nobel prize winner, Henri Becquerel. The becquerel is a very small unit.
1 Bq = 1 dps
The Gray (Gy) named in honor of British biologist, Louis H Gray. One gray is a large absorbed dose.
1 Gy = 100 RAD
The Sievert (Sv) named in honor of Swedish health physics pioneer, Rolf Sievert. One sievert is a large dose equivalent unit.
1 Sv = 100 REM
For those isotopes that emit weak beta particles, we must use liquid scintillator counters in order to detect ionizing radiation.
1.Gas scintillators 2.Liquid scintillators
Millicurie (mCI) = 37,000,000 dps Microcuri (µCi) = 37,000 dps Nanocurie (nCI) = 37 dps
10 -3 10 -6 10 -9
One RAD = ?
100 ergs of energy per gram of absorbing material
megaelectron volts (MeV) 1 Mev =
1000000 electron volts 1000000 ev
Given that protons are red and neutrons are blue, which two of the four graphics pictured are isotopes of the same element?
2 and 3 are isotopes
What is the atomic mass of this lithium atom?
6
Kiloelectron Volts (keV) 1 keV =
= 1000 electron volts 1000 eV
Battery
A battery applies a continuous voltage potential to both the anode and the detector wall.
Gamma & X-ray probe
A detector constructed of solid metal is designed to detect and measure gamma or X-ray radiation.It cannot detect alpha or beta radiation because the particles cannot penetrate the walls of the detector unit.
Which of these is a characteristic of an atom?
A single central nucleus
Wire Anode
A wire anode is mounted inside the detector and is electrically insulated from the detector walls.
Now that we've talked about cell composition and mortality, let's talk about the types of exposure those cells can receive. There are two types of exposure: acute, and chronic.
Acute Chronic
What does the roentgen measure the ionization of?
Air by gamma rays or X-rays
Why are alpha particles, beta particles, and gamma rays considered forms of nuclear radiation?
All three originate in the nucleus.
Alpha probe
Alpha probes are designed to measure alpha radiation. They have a window which is a section of the probe wall that is constructed of a different type of material to allow alpha particles into the detection chamber. Because alpha particles have a short range, the probe needs to be positioned very close to the alpha source (less than one quarter of an inch from the source; an eighth of an inch is ideal). Alpha probes are suited to monitor smooth, flat surfaces such as floors and table tops. They do not perform well on uneven surfaces where sources can go undetected inlow spots.
Alpha scintillation probes and gamma and X-ray scintillation probes are two examples of solid crystal scintillators.
Alpha scintillation probes gamma and X-ray scintillation probes
How is nuclear (radioactive) decay defined?
An unstable nucleus releasing energy
Given that protons are red, neutrons are blue, and electrons are gold, which atom is an ion?
B
A liquid scintillation counter is used to detect and measure which type of ionizing radiation?
Beta
Beta probe
Beta probes are designed to detect or measure beta radiation. They also have a window. If a beta shield is closed, only X-rays or gamma rays can penetrate to ionize the gas inside the detector. If a beta shield is open, both gamma and beta radiation can pass through the window.
Biological - Chemical - Thermal - Ionization - Scintillation -
Biological - changes in a living organism or system Chemical - breakdown and formation of chemical bonds Thermal - temperature increases from absorbed energy Ionization - collection and measurement of ion pairs Scintillation - measurement of light energy
Which type of exposure is received over an extended period of time?
Chronic
Chronic
Chronic exposure occurs over an extended period of time and usually refers to a lower level of exposure.
Which of the following is a substance composed of different elements bound in fixed proportions?
Compound
Gama Rays
Created inside the nucleus Form of nuclear radiation
X-Rays
Created outside the nucleus Form of non-nuclear radiation
What is the special unit for activity called?
Curie
What are the two major factors that determine how an instrument that uses the ionization principle will perform?Select all that apply.
Detector design Chamber design
What is the special unit for the energy level of ionizing radiation called?
Electron volt
which of the following is a pure substance that cannot be broken down into simpler substances by chemical means?
Element
Which types of ionizing radiation are primarily an external hazard?
Embryological
What is the RAD a measure of?
Energy absorbed by any target from any source
Most isotopes emit radiation strong enough to penetrate a detector containing a reactive medium, so we can use solid crystal scintillators to detect and measure.
For those isotopes that emit weak beta particles, we must use liquid scintillator counters in order to detect ionizing radiation.
What indicates the energy levels for gamma rays and X-rays?
Frequency
Which of the following has no charge?
Gamma Ray
Which types of ionizing radiation are primarily an external hazard?
Gamma Rays X-Rays
Which is the fastest moving?
Gamma ray
Geiger counters
Geiger counters also utilize gas amplification, but the secondary ionizations in a Geiger type detector are tremendous and completely disproportional to the number of original ion pairs created. Thismakes Geiger counters ideal for quickly detecting small quantitiesof ionizing radiation.
A half-life is the time it takes a radioactive isotope to transform 50 percent of its atoms by radioactive decay.
H-3 = Tritium has a half-life of 12.3 years. AM-241 = Americium-241 has a half-life of 458 years. U-238 = Uranium-238 has a half-life of 4.5 billion years. I-131 = Iodine-131 has a half-life of 8 days. Ni-63 = Nickel-63 has a half-life of 92 years.
z=1 proton z=6 protons z=26 protons also known as atomic number (z)
Hydrogen Carbon Iron
Ion Chambers
In ion chambers, ionizing radiation passes through a gas. The collisions with the gas molecules produce ion pairs and free electrons. If an electric field is present, ions will move apart and travel in opposite directions along the electric field until they encounter the conductors producing the electric field.
RADIAC instruments that operate on the ionization principle can be broken down into which three main categories?Select all that apply.
Ion chambers Geiger counters Proportional Counters
What is the process of a neutral atom acquiring either a positive or negative charge?
Ionization
Which statement best describes a daughter product of nuclear decay?
It can be stable or unstable but will always have less energy than its parent.
Liquid scintillators
Liquid scintillators are special laboratory instruments used to measure low energy beta emitters.
What are the three basic components of most modern RADIAC instruments?
Meter Cable Detector
"µCi" is the abbreviation for which unit of measure?
Microcurie
Sub-units of the roentgen (R):
Milliroentgen (mR) = one-thousandth of a roentgen Microroentgen (µR) = one-millionth of a roentgen Milliroentgen/hour (mR/hr) = milliroentgens after one hourof exposure
The smallest unit of a compound that still retains the unique physical and chemical characteristics of the compound is a?
Molecule
Which of the following is the smallest unit of a compound still retaining its unique physical and chemical characteristics?
Molecule
Solid crystal scintillators
Most solid crystal scintillators are specifically designed to measure alpha or low energy gamma and X-ray radiation.
What charge does a gamma ray contain?
No charge at all
In which type of gas amplification will a single original ionization generate just as many electrons as a much larger number of original ionizations?
Non-proportional
Acute
Now that we've talked about cell composition and mortality, let's talk about the types of exposure those cells can receive. There are two types of exposure: acute, and chronic.
Alpha scintillation probes
On alpha scintillation probes, the alpha window is located on the underside of the probe and is covered by a thin sheet of Mylar. A thin layer of zinc sulfide crystal is mounted inside the alpha window. The other major components include a prism apparatus and aphotomultiplier tube.
Gamma and X-ray scintillation probes
On gamma and X-ray scintillation probes, sodium iodide crystal is used to increase the chances of an interaction in order to detect and measure gamma and X-rays. The bottom of the probe is covered with aluminum to prevent alpha and beta particles from striking the crystal. When a gamma ray or X-ray interacts with the crystal, it gives off a pulse of light. This light is then converted into a stream of electrons, amplified and sent to the meter.
RADIAC instruments that operate on the ionization principle are broken down into three main categories based on what?
Operating voltages
Proportional Counters
Proportional counters utilize gas amplification to create secondary ionizations which are in direct proportion to the number of original ionizations. This enables them to detect and measure lower levels of ionizing radiation.
Which atom is an ion?
Protium
What is the special unit used to measure absorbed dose?
RAD
What is the special unit for dose equivalent called?
REM
Refer to the Periodic Table of Elements to identify an element with an atomic number of eighty-eight (88).
Ra
what is the special unit used to measure exposure level?
Roentgen
What are the two most common operating principles for modern RADIAC instruments? Select all that apply.
Scintillation Ionization
RADIAC instruments that operate on the scintillation principle can be broken down into two categories:
Solid Crystal scintillator Liquid scintillators
One roentgen of exposure produces 2.08 billion ion pairs per cubic centimeter of dry air.
The Roentgen (R) = 2.58 X 10-4 coulombs/kilograms of air
How does the applied voltage in the chamber of the RADIAC instrument impact its performance?
The amount of applied voltage is directly related to the number of atoms ionized.
What is the REM a measure of?
The biological damage or risk from radiation energy
What is the REM a measure of? Select and submit your response.
The biological damage or risk from radiation energy
Cable
The cable carries the signal to the meter.
Detector
The detector converts ionizing radiation into an electrical signal. Some instruments have the detector and cabling permanently mounted inside the meter housing. Detectors that are not internally mounted are referred to as probes and come in a variety of shapes and sizes.
Inert Gas
The interior of the chamber is filled with an inert gas to enhance collection properties.
Meter Section
The meter section contains electronic components capable of measuring any electrical current flowing through the detector circuit. Each time an ion pair is created, the negatively charged electron is attracted to the anode and the ionized atom is attracted to the wall of the chamber. This generates a tiny electrical current which is converted into a reading on the face of the meter.
What is ionization?
The process of a neutral atom acquiring either a positive or negative charge
What is ionization? Select and submit your response.
The process of a neutral atom acquiring either a positive or negative charge
What is gas amplification?
The ratio of the charge collected to the charge liberated by the initial ionizing event in a radiation-counter tube
What configuration defines an isotope?
The same number of protons but a different number of neutrons
What is the atomic mass number?
The sum of protons and neutrons in an atom
What is the half-life of an unstable isotope?
The time required for half of its atoms to decay
How do RADIAC instruments that utilize the operating principle of ionization detect ionizing radiation?
They collect and measure the ion pairs created when radiation interacts with matter.
Which statement is true about beta particles?
They have the same mass as an electron.
Which statement is true about alpha particles?
They have two neutrons.
How do RADIAC instruments that use the operating principle of scintillation detect ionizing radiation? Select and submit your response.
They measure light energy released when a special phosphorescent material is struck by ionizing radiation.
Which statement is true about gamma rays?
They move at the speed of light.
Meter
This is usually as a form of a needle on a gauge, an LCD type of display, or an audio signal.
What is RADIAC equipment used for?
To detect or measure ionizing radiation
Which isotope of hydrogen is unstable?
Tritium | H-3
An ion will always carry either a positive charge or a negative charge.
True
Ions behave the same as their neutral forms.
True
Which of the following is equal to 1,000 electron volts?
keV
How are X-rays and gamma rays alike?Select all that apply.
o They are ionizing forms of radiation. x They have the same properties of range, ionization, and penetration.
How do RADIAC instruments that utilize the operating principle of ionization detect ionizing radiation? Select and submit your response.
o light energy is released x not gas is pumped into the chamber
What are the two major factors that determine how an instrument that uses the ionization principle will perform? Select and submit your responses.
x chamber design x detector design o gas amplification o applied voltage