mosby's: STUDY MODE/SAFETY

Attenuation may be defined as:

Changes in the Xray beam as it travels through the patient

Which photon tissue interaction may expose radiographers during fluoroscopy?

Compton

The unit of absorbed dose is the:

Gray

The unit of radioactivity is the:

Becquerel

What is the unit of air kerma?

GrayA

Which of the following is attributed to linear energy transfer?

It varies for different types of radiation

What imaging modality uses the unit of measurement known as the becquerel?

Nuclear medicine

What graph illustrates the relationship between radiation and the organism’s response to it?

Dose response curves

Medical and dental x-rays are examples of:

Human produced radiation

What dose response curve best illustrates cataractogenesis, which does not occur at low levels of radiation exposure?

Nonthreshold

Which of the following effects describes the following: Increased dose equals increased probability of effects?

Stochastic effects

What is the cumulative effective dose limit for a 31 year old radiographer?

310 mSv

What is the annual effective absorbed does equivalent limit for the general public (frequent exposure)?

1 mSv

How thick is the secondary protective barrier used in room shielding to be?

1/32 inch lead equivalent

The intensity of the scattered beam is 1/1000th the intensity of the primary beam at what angle from the patient?

90 degree

If the air kerma 4 feet from the xray table is 2 Gya, what is the dose at a distance of 8 feet?

0.5 Gya (use inverse square law)

What is the minimum source to skin distance for fixed fluoroscopes?

15 inches

How much may female gonadal dose be reduced by using proper shielding?

Up to 50%

What describes oxygenated cells radioactivity?

Oxygen enhancement ratio

The blood count is depressed following a whole body dose equivalent of at least how many sievert?

0.25

What are highly reactive ions with unpaired outer shell electrons called?

Free radicals

What is the cell’s master molecule?

DNA

What is the process of somatic cell division called?

Mitosis

What is the most frequent cellular response to ionizing radiation?

Nothing

Where does most radiation induced damage to cells occur?

At doses of radiation much higher than that used in radiography

Radiation monitors that use lithium fluoride crystals to record dose are called:

Thermoluminescent dosimeters

What tissues or cells are relatively insensitive to radiation?

Nerve tissue

Which of these describes somatic effects of radiation?

They are caused when a large dose of high LET radiation is received by a large area of the body

What is the best way to keep radiation dose to the patient low?

Avoidance of repeat exposures

What do we call the process of removing electrons from the atoms of the body by Xray interactions?

Ionization

What are possible results of ionization?

1. unstable atoms

2. production of low energy x-rays

3. formation of new molecules to the cell

1,2, and 3

How may cell damage be manifested?

1. Loss of function

2. nothing occurs

3. abnormal function

1 and 3

How is damage to the cell being irradiated described?

Somatic

What are the radiation effects that manifest themselves in the next generation called?

Genetic

What is the radiation that is contained in the environment called?

Natural background

According to NCRP Report #160, what percentage of human exposure is natural background radiation?

50%

According to NCRP Report #160, what is the annual effective dose equivalent per person from natural background radiation?

3.11 mSv

What is the single largest source of natural background radiation?

Radon

Humans are partially protected from cosmic rays by:

Earth’s atmosphere

Artificial radiation accounts for what percentage of human exposure?

50%

The greatest source of human made radiation exposure is from:

diagnostic imaging procedures

The photon tissue interaction that may produce a photoelectron is:

Photoelectric

The photon tissue interaction that occurs when an incident photon strikes a k shell electron is:

Photoelectric

The photon tissue interaction that results in absorption of all of the energy of the incident photon is:

Photoelectric

Differential absorption is a result of which photon tissue interaction?

Photoelectric

The photon tissue interaction that produces scatter that exits the patient is:

Compton

The photon tissue interaction that occurs when an outer shell electron is struck by an incident photon is:

Compton

The photon tissue interaction that produces a recoil electron is:

Compton

How does the energy of a scattered photon compare with that of the incident photon?

Less

Scattered photons emerging from the patient travel in what kind of paths?

Divergent

The photon tissue interaction that results from very low energy x-rays is:

Coherent

The photon tissue interaction that may simply cause electrons to vibrate from the energy of the incident photons is:

Coherent

The photon tissue interaction that is also known as classical or thompson’s is:

Coherent

The photon tissue interaction that does not cause ionization is:

Coherent

The photon tissue interaction that does not occur in diagnostic imaging is:

Pair production

What is used to modify the absorbed dose amount to account for the greater damage inflicted by some forms of ionizing radiation?

Radiation weighting factor (WR)

Radiation weighting factor (WR) takes into account:

Linear energy transfer

Which of the following is true when radiations with higher LET are absorbed?

More radiation damage occurs

Which of the following is true when radiations with lower LET are absorbed?

Less radiation damage occurs

Examples of low LET radiations include:

x-rays

Examples of high LET radiations include:

• Alpha particles

• neutrons

The amount of energy deposited per unit length of tissue defines:

Linear energy transfer

The radiation weighting factor (WR) for x-ray is:

1

A concept of radiologic practice that encourages radiation users to adopt measures that keep the dose to the patient and themselves at minimum levels is called:

ALARA

The dose response relationship that states no level of radiation can be considered completely safe and that the degree of response is directly proportional to the amount of radiation received is:

Linear nonthreshold

This dose response curve demonstrates:

Linear nonthreshold

This dose response curve demonstrates:

Linear threshold

This dose response curve demonstrates:

Nonlinear threshold

This dose response curve demonstrates:

Nonlinear nonthreshold

The annual effective absorbed dose equivalent limit for occupational exposure is:

50 mSv

The annual effective absorbed dose equivalent limit for the general public, assuming infrequent exposure is:

5 mSv

The effective absorbed dose equivalent limit for the unborn per month of gestation is:

0.5 mSv

The effective absorbed dose equivalent limit for the unborn during gestation is:

5 mSv

The function of the cell membrane is to:

1. protect the cell

2. hold in water

3. allow water, nutrients, and waste to pass through

1,2, and 3

The cytoplasm consists primarily of:

Water

Smaller bodies within the cytoplasm are called:

Organelles

Which of the following is not an organelle?

Nucleus

DNA is contained where in the cell?

Nucleus

What does DNA control?

All cellular functions

What percentage of the cell is water?

80%

Prophase, metaphase, anaphase, and telophase are the four stages of:

Mitosis

Somatic cell division is called:

Mitosis

Germ cell division is called:

Meiosis

The number of chromosomes in the cell after mitosis is:

46

The number of chromosomes in the cell after meiosis is:

23

The ability of radiation to produce biologic damage is called:

Relative biologic effectiveness (RBE)

The WR used to calculate sievert is a measure of what aspect of the radiation being measured?

Relative biologic effectiveness

What occurs when radiation transfers its energy to the DNA or RNA?

Direct effect

The most common result of LET and the direct effect is:

Nothing

Considering probability, Xray photons will probably strike:

Water

What occurs when radiation transfers its energy to the cytoplasm?

Indirect effect

Xray photons depositing their energy in the water of cytoplasm may cause:

Radiolysis

Radiolysis creates ion pairs called:

Free radicals

Particles that may cause biologic damage by transferring their excess energy to surrounding molecules or by disrupting chemical reactions are called:

Free radicals

Free radicals may recombine to form:

Hydrogen peroxide

The result of hydrogen peroxide poisoning the cell is:

Indirect effect

Most damage from exposure to radiation occurs as a result of:

Indirect effect

Each cell has a master molecule that directs cell activities. If this master molecule is damaged by radiation and is inactivated, the cell will die. This summarizes:

Target theory

Cells are most sensitive to radiation when they are immature, undifferentiated, and rapidly dividing. This summarizes:

The law of bergonie and tribondeau

What are the most radiosensitive blood cells in the body?

Lymphocytes