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