RADT 101: Chapter 9 TEST 3

Air Kerma

Key Terms:

SI quantity used to measure energy transferred from radiation to matter, which may be at the surface of a patient’s or radiologic and imaging sciences professional’s body

ALARA

Key Terms:

Mnemonic meaning to keep all radiation exposure as low as reasonably achievable

Becquerel (Bq)

Key Terms:

Unit of radioactivity in the International System of Units, equal to one disintegration per second

Classic Coherent Scattering

Key Terms:

Interaction with matter in which a low-energy photon (below 10 kiloelectron volts) is absorbed and released with its same energy, frequency, and wavelength but with a change of direction

Compton Scattering

Key Terms:

Interaction with matter in which a higher energy photon strikes a loosely bound outer electron, removing it from its shell, and the remaining energy is released as a scattered photon

Curie (Ci)

Key Terms:

Unit of radioactivity defined as the quantity of any radioactive nuclide in which the number of disintegrations per second is 3.7 ×1010

Exposure (X)

Key Terms

The amount of radiation delivered to a point. Measured in coulomb per kilogram.

Key Terms

Cells of an organism whose function is to reproduce the organism (e.g., ovum, spermatozoa)

Gray (Gy)

Key Terms:

Unit in the International System used to measure the amount of energy absorbed in any medium; 1 Gy=100 radiation absorbed doses

Internation System (SI) of Units

Key Terms:

System of units based on metric measurement developed in 1948 and having units used to measure radiation

Kiloelectron Volts (keV)

Key Terms:

Units of energy equal to 1000 electron volts

Photoelectric Interaction

Key Terms:

Interaction with matter in which a photon strikes an inner shell electron, causing its ejection from orbit with the complete absorption of the photon’s energy

Radiation

Key Terms:

Forms of energy emitted and transferred through matter

Sievert (Sv)

Key Terms:

Unit in the International System used to measure the dose equivalence, or biologic effectiveness, of differing radiations;

• 1 Sv=100 rem

Somatic Cells

Key Terms:

All of the body’s cells except germ cells

X-Rays

Key terms:

Form of electromagnetic radiation traveling at the speed of light, possessing the ability to penetrate matter

Ionizing Radiation

______ _______ is energy capable of penetrating matter and possesses sufficient energy to eject orbital electrons along its path, thus ionizing atoms.

radiation exposure

Ionizing Radiation:

The radiologic and imaging sciences professional must act

to protect all persons from unnecessary ______ _______, including

themselves, the patient, and others within the clinical environment.

Human-made, natural

Sources of Ionizing Radiation:

• Two sources of ionizing radiation exposure:

  • _______ (artificial) radiation

  • ________ (background) radiation

Natural

Sources of Ionizing Radiation:

• _______ (background) radiation occurs spontaneously in nature and are not affected by human activity

• ex) cosmic radiation from the sun and other planetary bodies

• ex) naturally occurring radioactive substances present on earth (such as uranium and radium)

human-made

Sources of Ionizing Radiation:

• _____ ______ radiation include the nuclear industry, radionuclides, medical and dental exposures, and some consumer products.

nuclear industry

Sources of Ionizing Radiation:

• ______ ____ has contributed fallout from aboveground weapons testing, from accidents in nuclear power stations, and from the disposal of by-products from the plants.

radionuclides

Sources of Ionizing Radiation:

• Exposure to _________ results from products containing radioactive elements, such as smoke detectors, and radiopharmaceuticals used in the diagnosis and treatment of disease.

Medical, dental

Sources of Ionizing Radiation:

• _______ and ______ exposures constitute the greatest source of human-made radiation.

x-rays

Human Made Radiation:

• Human-made ionizing radiation, or ____ as they are more commonly called, is a form of electromagnetic radiation that travels at the speed of light.

energy

Human Made Radiation:

• x-rays are bundles of ______ moving as waves in space, depositing

  their energy randomly.

electrons, accelerate, stop

Human Made Radiation:

• For x-rays to be produced, three things must be present:

(1) a source of ________

(2) a means to rapidly _______ the

electrons

(3) something to rapidly ____ this movement.

negative, positive

Human Made Radiation:

• The x-ray tube meets all the conditions to make x-rays

  • cathode: _______ terminal

  • anode: _______ terminal

  • a heat resistant and vacuum environment

electrons

Human Made Radiation:

• The filament in the cathode assembly is composed of thoriated tungsten, which provides the source of _______.

cathode, thermionic emission, anode

Human Made Radiation:

• When milliamperage (electric current) is applied to the ______ filament, it responds by boiling off electrons through a process known as _______ _______.

• Once kilovoltage (high voltage) is applied to the tube terminals, the electrons resulting from thermionic emission instantaneously accelerate toward the _____ end of the tube.

x-rays and heat

Human Made Radiation

• X-rays are produced when the electrons strike the anode , undergoing

  an energy conversion that produces both _____ and _____.

kiloelectron volts

Human Made Radiation

• The resultant x-ray beam is heterogeneous—that is, it has many energies, measured in _______ ____ (keV).

absorbed, scatter, pass

Human Made Radiation

• Once the x-rays strike matter, three possibilities exist:

(1) they can be _______,

(2) they can transfer some energy and then ______,

(3) they can _____ through unaffected.

compton scattering, photoelectric interaction

Interactions of X-Rays With Matter:

• X-rays interact with matter in five ways:

(1) classic coherent scattering,

(2) photoelectric interaction,

(3) Compton scattering,

(4) pair production

(5) photodisintegration.

_____ _____ and _______ directly influence patientand occupational worker exposure.

Classic Coherent Scattering, same

Classic Coherent Scattering steps:

1) _____ ______ ______ occurs when

an incoming x-ray photon strikes an atom and is absorbed, causing the atom

to become excited.

2) The atom then releases the excess energy in the form of another x-ray photon possessing the _____ energy as the original photon, but proceeding in a different direction.

scattered

Classic Coherent Scattering:

• Most of these _________ photons travel in a forward direction,

  stopping when they strike anything in their path. More

energy

Classic Coherent Scattering:

• results in no ______ transfer to the patient.

Photoelectric Absorption, inner, electron, outer

Photoelectric Absorption steps:

1) ________ _______ occurs when an incoming x-ray photon strikes an ____ shell electron and ejects it from its orbit around the nucleus of the atom, creating an ion pair.

2) photoelectron (the released _______) , continues to travel until it combines with other matter.

3) As ______ shell electrons transition to fill vacancies in inner shells,

they release excess energy in the form of x-rays.

photon

Photoelectric Absorption:

• All the energy from the _____ (that struck the electron) is completely consumed in this interaction; it is said that the energy is absorbed by the atom.

characteristic radiation

Photoelectric absorption

• X-rays originating within the body as a result of the photoelectric effect are collectively known as ________ ______ and are the source of secondary radiation.

Compton Scattering, outer, different

Compton Scattering Steps:

1) ______ ________ occurs when an incoming x-ray photon strikes a target atom and uses a portion of its energy to eject an ____ shell electron.

2) The remainder of the photon’s energy proceeds in a direction ______ from that of the incoming photon.

Compton Scattering

_____ _______is responsible for a majority of occupational workers exposure to

radiation.

Photoelectric Absorption

___________ ___________ is the greatest hazard to patients in diagnostic radiography.

metric

Units of Measure

• In 1948, the International Committee for Weights and Measures developed a system of units based on _____ measurement.

International System

Units of Measure

• The SI units system (Système International d’Unitès) or ______ ______ [SI] of Units) was officially adopted in 1985.

Coulombs per kilogram (C/kg)

Radiation Quantities and SI Units of Measurement

• Exposure (X)

Gray (Gy)

Radiation Quantities and SI Units of Measurement

• Air Kerma

Gray (Gy)

Radiation Quantities and SI Units of Measurement

• Absorbed Dose (D) (Efd)

Sievert (Sv)

Radiation Quantities and SI Units of Measurement

• Effective Dose (EfD)

Sievert (Sv)

Radiation Quantities and SI Units of Measurement

• Dose equivalent (EqD)

Becquerel (Bq)

Radiation Quantities and SI Units of Measurement

• Radioactivity

Exposure (Coulomb per kilogram).

Quantity

• _________ is the measure of ionization in air as a result of exposure to x-rays or gamma rays.

• does not indicate actual exposure to to individuals when absorbed.

Exposure

Quantity

______ is defined as quantity of x-radiation or gamma radiation that produces the quantity of 2.08 × 109 ion pairs per cubic centimeter (cc) of air for a total charge of 2.58 × 10−4 coulombs per kilogram (C/kg: coulomb is a quantity of electric charge).

Air kerma (Gray)

Quantity

• _______ is the kinetic energy transferred from a beam of radiation to air or tissue.

• total kinetic energy released in a unit mass (kilogram) of air and is measured in joules per kilogram (J/kg), where 1 J/kg is 1 Gray (Gya).

Absorbed Dose (D) (EfD)

Quantity

• ______ _____ is the radiation energy per unit mass and has units of J/kg or Gyt.

• The units Gya and Gyt refer to radiation dose in air and tissue, respectively.

air kerma

Absorbed Dose

• For a given ___ _____ (radiation exposure), the absorbed dose depends on the type of tissue being irradiated.

Effective dose

Quantity

• ____ _____ is used for occupational exposure and is measured in Sieverts (Sv)

  • The Sievert also expresses a patient dose that accounts for partial-body irradiation.

Dose equivalent

Quantity

• _____ _____ is the product of the average dose in a tissue or organ in the human body and its associated weighting factor, or quality factor.

• also measured in Sieverts (Sv)

• expressed as the product of the absorbed dose in Sievert and a quality factor.

radiation, degree

Dose equivalent

• Not all types of ______ produce the same response in living tissue.

  • Alpha particles, neutrons, and beta particles may produce a different ______ of biologic damage than x-rays and gamma rays.

Becquerel (Bq)

Quantity

• The __________is the unit of quantity of radioactive material, not the radiation emitted by that material

• ex) 1 d/s = 1 Bq

Activity

.The measure of the rate at which a radionuclide decays is referred to as ____

exposed, limits

Standards For Regulation of Exposure

• Because patients and radiologic technologists _______ to radiation are at risk for biologic effects, ______ must be set to ensure safe practice for both the patient and the radiologic technologist.

Center for Devices and Radiological Health

Standards For Regulation of Exposure:

The ____ ____ _____ _____ _____ ____ (CDRH), under the direction of the US Food and Drug Administration,

• sets and regulates the standards for radiation-producing equipment

• researchs possible ways of minimizing exposure to ionizing radiation

The National Council on Radiation Protection and Measurements

Standards For Regulation of Exposure:

The _____ ____ __ ______ _____ __ ______ (NCRP) is a

• not-for-profit organization

• formed by Congress in 1964 to collect and distribute information regarding

radiation awareness and safe practice to the public

• is considered an advisory group, because it does not have the authority to enforce the recommendations contained within its reports.

Nuclear Regulatory Commission

Standards For Regulation of Exposure:

The _______ _________ _________(NCRP)

• cooperates with other organizations to review the latest data on

  • radiation units

  • measurements

  • protection

maximum, ionizing radiation

Standards For Regulation of Exposure:

• The concept of a maximum permissible dose was traditionally used to describe the _______ dose of ______ ________that, if received by an individual, would carry a negligible risk for significant bodily or genetic damage.

Nonthreshold

Standards For Regulation of Exposure:

• ________ indicates that no dose exists below which the risk of damage does not exist.

Risk versus benefit

Standards For Regulation of Exposure:

• _____ ____ _____ governs the exposure of individuals when physicians ordered radiographic procedures.

• The benefit to the patient from performing those procedures must outweigh the risk of possible biologic damage.

50

Standards For Regulation of Exposure:

• The annual whole-body effective dose limit for the occupational worker is __ mSv.

• Currently the recommended maximum accumulated whole-body effective dose limit is (10 mSv)(age) in years (or 1 Sv×age in years).

5

Standards For Regulation of Exposure:

The whole-body dose-equivalent limit for the general population is one-tenth the occupational worker’s annual limit, or __ mSv (0.5 rem).

atomic structure

Biological Response to Ionizing Radiation

• Ionizing radiation, absorbed by matter, undergoes energy conversions that result in changes in _______ ______

• These changes, when considered in light of living tissue, can have major consequences on the life of any organism.

cell

Basic Cell Structure

• The ___ is the simplest unit of organic protoplasm capable of independent existence.

multicellular

Basic Cell Structure:

• Simple organisms are composed of one or two cells; complex organisms are __________—that is, made of many cells.

nucleus

Basic Cell Structure:

• The _______ is separated from the rest of the cell by a double-walled membrane called the nuclear envelope.

• contains chromosomes, which are made up of genes

membrane, pores

Basic Cell Structure:

The ________ of the nuclear envelope has openings, or _____, that permit other molecules to pass back and forth between the nucleus and the cytoplasm.

Genes

Basic Cell Structure:

• ______ are the units of hereditary information, composed of DNA, which is a double- stranded structure coiled around itself as a spiral staircase.

• It is one of the molecules at risk when a cell is exposed to ionizing radiation.

cytoplasm, metabolic

Basic Cell Structure:

• The _________ of the cell is separated from its environment by the cell membrane.

• It contains several organelles responsible for the _______ function of the cell.

• The cytoplasm itself is primarily water, which can undergo changes when struck by ionizing radiation.

Somatic cells, 46, 23, mitosis

Cell Types:

• _____ ____ perform all the body’s functions.

• possess two of every gene on two different chromosomes.

• chromosomes are paired, but each pair is different.

• Possess a total of chromosomes, or ___ pairs.

• They divide through the process of ______.

Germ cells, meiosis

Cell Types:

• ____ ____ are the reproductive cells of an organism;

• 23 chromosomes

• reproduce through the process of ______.

direct hit theory, ion pairs

Theories for Cellular Absorption of Ionizing Radiation:

• _____ ____ _____ proposes that any type of radiation transfers its energy directly to the key molecule it has struck,

  • resulting in the formation of ____ ____ or elevation to an increased, excited energy state.

phosphate bonds, genetic information

Theories for Cellular Absorption of Ionizing Radiation:

• Although any important structure can be hit by radiation, serious consequences arise when radiation interacts with DNA.

• Breaks in the bases or _______ ____ can result in rearrangement or loss of _____ _______, which can injure or kill the cell as it continues through its life cycle.

Indirect hit, ionized

Theories for Cellular Absorption of Ionizing Radiation:

• During ______ __(s) molecules are affected by radiation depositing its energy elsewhere in the cell.

• Because cells are approximately 80% water, this occurs when water molecules are _____.

• This action produces chemical changes within the cell that alter the internal environment, injuring the cell, which can result in eventual cell death.

indirect

Theories for Cellular Absorption of Ionizing Radiation:

• With x-radiation and gamma radiation, the vast majority of cellular damage is the result of ______ hits.

molecules, not. replacement

Target Theory of Absorption of Ionizing Radiation:

• Some ________ existing within a cell are key to the continued viability or life of that cell.

• Some of these molecules exist in great number; others in limited supply.

• If damage occurs to a molecule in abundant supply, the effect on the cell may ___ be as detrimental because others exist to maintain the function of the cell.

• Injury to a molecule in limited supply, however, can be life threatening, because no immediate _________ is available.

target, nucleus, DNA

Target Theory of Absorption of Ionizing Radiation:

• The term ______ is used to describe any critical molecule,

• in this case the _____ of a cell, that has undergone some interaction with ionizing radiation, either directly or indirectly.

• The target whose damage has serious consequences to the life of the cell is _____.

division, structure

Radiosensitivity of Cells:

• Bergonie and Tribondeau

• Cells are the most sensitive to radiation during active ______, when they are primitive in structure and function.

  • ex) basal skin cells

  • ex) crypt cells of the small intestine

  • ex) germ cells

• Cells resistant to radiation, being more specialized in _______ and function, do not undergo repeated mitosis.

  • ex) nerve, muscle, and brain cells

Bergonie, Tribondeau

Radiosensitivity of Cells:

• a method of classification according to sensitivity was developed by _____ and ________ in 1906.

• These researchers determined that mitotic activity and specific characteristics of each cell affected how the cell exhibited radiation damage

Ancel, Vitemberger, external conditions

Radiosensitivity of Cells:

• _____ and _______, who modified this theory, stated that all cells possess the same sensitivity to radiation; the time of expression of injury is the factor that differs.

• This factor depends on mitosis and the _____ _____ in which the cell is placed.

• Therefore, rapidly dividing cells demonstrate the injury sooner and only appear as though they are more sensitive to radiation than those whose mitotic rate is slower.

Death, Delay, Repair

Response of Cells to Radiation:

• _____ before mitosis

• ____ entering mitosis

• fail to divide at a normal rate

• _____ damage (NOTE: incomplete repair can result in adverse biolig effects occurring after times has elapsed)

systems, sensitivity

Total Body Response to Irradiation:

• The total body response of any organism to radiation depends on the effect all the ________ of the body.

• Because every system is different in its ________ or resistance, the total body response at a particular dose is defined by the system most affected.

prodromal

Early Effects of Radiation Exposure

• The first is the _______ stage, commonly referred to as the nausea,

  vomiting, and diarrhea stage.

latent

Early Effects of Radiation Exposure

• The second stage is the ______ period, in which the organism feels well; however, during this time, the body is undergoing biologic changes

manifest

Early Effects of Radiation Exposure

• final period, the ______ stage: the organism feels the full effects of the exposure, leading to either recovery or death

hematopoietic, gastrointestinal, central nervous system

Early Effects of Radiation Exposure

Three radiation syndromes are:

(1) __________ syndrome (also known as bone marrow syndrome),

(2) ___________ (GI) syndrome

(3) _____ _____ _____ (CNS) syndrome.

hematopoietic

Early Effects of Radiation Exposure

• The __________ syndrome occurs at doses of 2 to 10 Gy.

• Total body exposure results in infection, hemorrhage, and anemia.

GI

Early Effects of Radiation Exposure

• ___ syndrome results from doses of 10 to 50 Gy.

• Individuals experience diarrhea, nausea, vomiting, and fever when subjected to these doses.

CNS

Early Effects of Radiation Exposure

• ____ syndrome occurs at doses above 50 Gy

• individual experiencing seizures, coma, and eventual death from increased intracranial pressure.

somatic, genetic

Late Effects of Radiation Exposure:

• can develop over a long period after exposure and are two groups:

(1) ______ effects, which develop in the individual exposed, and

(2) ______ effects, which occur in future generations as a result of damage to the germ cells.

somatic

Late Effects of Radiation Exposure:

• common ______ effects are

  • cataract formation

  • carcinogenesis

  • cancer

genetic

Late Effects of Radiation Exposure:

• _____ effects result from germ cells whose DNA has been altered by radiation exposure,

• mutations are recessive in future generations, become dominate when mutated cell is fertilized by other reproductive cell carrying the same mutation