Challenge Test 1

Attenuation:

a. Is radiation that emerges from the patient

b. Describes changes in the x-ray beam as it travels through the patient

c. Produces only scatter radiation

d. Occurs only at doses used in radiation therapy

B. These changes may include absorption and scatter radiation. Radiation that emerges from the patient is called exit radiation.

Which photon-tissue interaction makes radiography

possible because of its creation of contrast?

a. Compton

b. Coherent

c. Photoelectric

d. Pair production

C. Photoelectric interaction produces contrast as a result of the differential absorption of the incoming x-ray photons in the body's tissues. X-rays are completely absorbed in some areas of the patient. Choices A and B are types of scattering. Pair production does not occur in radiography.

Which photon-tissue interaction produces radiation that may expose others in the room during fluoroscopy?

a. Compton

b. Coherent

c. Photoelectric

d. Pair production

A. Compton interaction produces scattered photons that emerge from the patient in divergent paths and may expose the radiographer or radiologist. The photoelectric effect is responsible for total absorption of the incoming x-ray photon during attenuation. Coherent scattering and pair production occur when x-ray energies are beyond the moderate range used in radiography.

The unit of radiation absorbed in air is the:

a. Sievert

b. Gray(a)

c. Becquerel

d. Gray(t)

B. This stands for Gray in-air.

The unit of radioactivity is the:

a. Becquerel

b. Gray(t)

c. Sievert

d. Gray(a)

A.

The unit of effective dose is the:

a. Becquerel

b. Grayt

c. Sievert

d. Graya

C.

Linear energy transfer:

a. Is the same for all types of radiation

b. Is the same for wave and particulate radiations used

in diagnosis and treatment

c. Occurs only during x-ray procedures

d. Varies for different types of radiation

D. LET varies because of different levels of ionization.

It occurs with high-ionization radiations, such as neuTrons and alpha particles, and during x-ray and gamma-ray procedures.

The unit of Bq would be used in what imaging modality?

a. Radiography

b. CT

c. MRI

d. Nuclear medicine

D. The becquerel measures the quantity of radioactive material.

Medical x-rays are an example of:

a. Natural background radiation

b. Artificially produced radiation

c. Nonionizing radiation

d. Ionizing, natural background radiation

C. This describes a dose-response curve, such as linear-nonthreshold.

Graphs that show the relationship between radiation received and the organism's responses are called:

a. Response curves

b. Exposure curves

c. Dose-response curves

d. Radiation-threshold curves

B. Medical x-rays are an artificial source of ionizing radiation; diagnostic procedures account for the largest source of artificial radiation exposure to humans. Natural background radiation is that contained in the environment.

Cataractogenesis does not occur at low levels of radiation exposure; it is best expressed by which of the following dose-response relationships?

a. Threshold

b. Nonthreshold

c. Low dose

d. Occupational dose

A. There is a definite safe, or threshold, dose below which cataractogenesis does not occur. Choice C does not make logical sense because the question states that cataractogenesis does not occur at low levels of radiation exposure. Occupational dose is the amount of radiation to which radiographers are exposed. Study tip: When there are opposite choices (e.g., threshold and nonthreshold), one of them is usually the correct answer.

"Increased dose equals increased probability of effects" best describes which of the following?

a. Stochastic effects

b. Deterministic effects

c. Direct effect

d. Indirect effect

A. Be sure to review stochastic and deterministic (tissue reactions). The severity, not the probability, of deterministic effects increases with increased dose. Direct effect and indirect effect differentiate whether the initial ionizing event occurs on the most radiosensitive molecule (direct effect) or on another molecule (indirect effect).

The cumulative occupational exposure for a 22-year-old radiographer is:

a. 220 mSv

b. 22 mSv

c. 11 mSv

d. 110 mSv

A. Occupational cumulative exposure is determined by multiplying years of age times 10mSv. Study tip: Be sure to read each choice carefully and entirely before choosing an answer.

The annual effective dose limit for the general public, assuming frequent exposure, is:

a. 0.5 mSv

b. 500 mSv

c. 0.05 mSv

d. 1.0 mSv

D. This limit is important to keep in mind when considering ALARA.

The secondary protective barrier used in room shielding must be at least how thick?

a. {1⁄32}-inch Al equivalent

b. {1⁄16}-inch Al equivalent

c. {1⁄16}-inch Pb equivalent

d. {1⁄32}-inch Pb equivalent

D. Lead, not aluminum, equivalent will absorb most of the scatter radiation energy. Because the secondary barrier is located where only scatter or leakage occur, 1/32-inch lead equivalent is sufficient. Primary barriers require 1/16-inch lead equivalent.

If the air kerma measured 6 feet from the x-ray table is 5 Graya, what is the air kerma measured at a distance of 3 feet?

a. 20 Gray(a)

b. 10 Gray(a)

c. 1.25 Gray(a)

d. 2.5 Gray(a)

C. Photons lose considerable energy after scattering.

The intensity of the scattered beam is 1⁄1000 the intensity of the primary beam at a ________ angle 1 m from the patient.

a. 45-degree

b. 25-degree

c. 90-degree

d. 10-degree

A. The dose is determined by the inverse square law. The distance was halved; therefore, the dose went up 4

times (not 2 times).

The minimum source-to-skin distance for fixed fluoro scopes is:

a. 15 inches

b. 12 inches

c. 10 inches

d. 18 inches

A. The minimum source-to-skin distance for fixed fluoroscopes is 15 inches; for portable fluoroscopes, it is 12 inches (although 15 inches is preferred). Be sure to review these required distances.

When increased dose equals increased severity of tissue reactions, this is called:

a. probabilistic

b. stochastic

c. deterministic

d. mutagenic

C.

"Cells that are oxygenated are more susceptible to radiation damage"; this describes:

a. Target theory

b. Direct effect

c. Doubling dose

d. Oxygen enhancement ratio

D. Target theory states that for a cell to die after radiation exposure, its master, or target, molecule (DNA) must be inactivated. Direct effect occurs when radiation transfers its energy directly to the DNA. The doubling dose is the dose of radiation necessary to produce twice the frequency of genetic mutations as would have occurred in the absence of the radiation. Be sure to review these concepts.

The blood count is depressed after a whole-body dose equivalent of at least how many mSv?

a. 10 mSv

b. 0.25 mSv

c. 5mSv

d. 0.01 mSv

B. The dose equivalent at which blood count is depressed is much higher than diagnostic levels but may occur during radiation therapy or interventional procedures.

Highly reactive ions that have unpaired electrons in the outer shell are called:

a. Electrified

b. Radiolytic

c. Hydrogen peroxide

d. Free radicals

D. This is the definition of free radicals, which can cause biologic damage to the cell. Some free radicals may chemically combine to form hydrogen peroxide. Radiolysis results in an ion pair in the cell: a positively charged water molecule and a free electron.

The master molecule that directs cell activities is:

a. RNA

b. Hydrogen peroxide

c. A free radical

d. DNA

D. According to target theory, substantial research indicates that DNA, contained in the cellular nucleus, is the master molecule. Hydrogen peroxide is a poison that can cause damage to the cell. A free radical is a highly reactive ion with unpaired electrons in the outer shell. RNA transmits genetic instructions from the nucleus to the cytoplasm of the cell.

The process of somatic cell division is called:

a. Mitosis

b. Spermatogenesis

c. Organogenesis

d. Cytogenesis

A. Cytogenesis refers to the origin and development of cells. Spermatogenesis is the development of spermatozoa. Organogenesis refers to the formation and differentiation of organs during embryonic development. Germ cell division is called meiosis.

The most common effect from exposure to ionizing radiation is:

a. Mutations

b. Ionization of atoms in the cells

c. Cell death

d. Nothing

D. Although all of these effects may occur, the most common result of LET is no effect. Nevertheless, ALARA must still be practiced.

Most radiation-induced damage to cells occurs:

a. At diagnostic levels of radiation

b. During fluoroscopy

c. At doses of radiation much higher than doses used in radiography

d. From background radiation

C. Adult nerve tissue and even immature cells, which are very radiosensitive, require doses of radiation higher than those used in medical diagnostic procedures, although ALARA must still be practiced.

Radiation doses up to ________ are considered relatively low risk to the embryo and fetus.

a. 5 mSv

b. 10 mSv

c. 0.01 mSv

d. 0.20 mSv

A. Such doses still pose a risk to the embryo-fetus, so ALARA must still be practiced.

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:

a. LET

b. RBE

c. MPD

d. ALARA

D. As low as reasonably achievable is a concept used in radiography to protect both the patient and the radiographer.

Which of the following is (are) relatively insensitive to radiation?

a. Nerve tissue

b. Reproductive cells

c. Epithelial tissue

d. Immature sperm cells

A. Epithelial tissue and reproductive cells, including immature sperm cells, are highly radiosensitive. On the other hand, adult nerve tissue requires very high doses to cause damage; although ALARA must still be practiced because once cells are damaged, repair may not take place.

Somatic effects of radiation:

a. Are common

b. Are caused when a large dose of high-LET radiation is received by a large area of the body

c. Are caused after exposure to DNA

d. Include genetic mutations

B. In general, these take large doses to manifest themselves.

The best way to keep the radiation dose to the patient low is:

a. Distance

b. Shielding

c. Time

d. Avoidance of repeat exposures

D. Repeats double the dose to the patient for each exposure.

X-rays may remove electrons from atoms in the body by a process called:

a. Electrification

b. Exposure

c. Ionization

d. Radicalizing

C. This is what may cause harmful effects.

Ionization may cause:

a. Stable atoms

b. Production of high-energy x-rays

c. Formation of new molecules beneficial to the cell

d. Unstable atoms

D. Ionization is multifaceted. Study tip: Be sure to read all choices before choosing an answer. Choice A is true, but you must read all the choices to see that choice D is the correct answer.

Cell damage may be exhibited as:

a. Loss of function or abnormal function

b. Nothing

c. Enhanced function

A. Cell damage may be exhibited as loss of function or abnormal function.

Damage to the cell being irradiated is called:

a. Genetic

b. Exposed cell

c. Somatic

d. Molecular

C. Damage from somatic effects is evident in the organism being irradiated. Most of the time these effects are benign. Genetic damage is passed to the next generation.

Radiation effects that show up in the next generation are called:

a. Genetic

b. Exposed cell

c. Somatic

d. Molecular

A. Somatic effects are evident in the organism being irradiated.

Radiation that is contained in the environment is called:

a. Man-made

b. Artificial

c. Natural background

d. Artificial background

C. There is no control over natural background radiation, which has been present in the environment since the formation of the universe. Choices A, B, and D all refer to artificially produced radiation, that made by humans. Study tip: Choices A, B, and D are basically the same; they are too similar for one of them to be the correct answer. Choice C is the only unique answer.

Background radiation is the source of approximately what percent of human exposure?

a. 95%

b. 82%

c. 50%

d. 35%

C. Natural background radiation, which has been present since the formation of the universe, accounts for 50% of human exposure. The greatest single source is radon.

The annual effective dose per person from natural background radiation is approximately:

a. 1.0 mSv

b. 3.0 mSv

c. 50 mSv

d. 9.0 mSv

B. You can safely assume that natural background radiation would be less than the annual recommended limits of exposure from diagnostic imaging. Although all choices are less than this limit, choice B is correct. Background exposure is not high but is always present.

The greatest source of natural background radiation to humans is:

a. X-rays

b. Delta rays

c. Radon

d. Radium

C. Radon, which exists as a gas, accounts for 55% of human exposure to natural background radiation.

According to NCRP Report #160, the increase in total exposure is primarily attributed to increased use of:

a. MRI

b. Diagnostic medical ultrasound

c. Fluoroscopy and interventional procedures

d. CT

D. The huge increase in the use of CT since the 1980s

has primarily caused this increase.

What barrier must be at least 1⁄16-inch lead equivalent?

a. Lead apron

b. Primary protective barrier

c. Bucky slot cover

d. Secondary protective barrier

B. The primary protective barrier in the wall extends

from the floor to a height of 7 feet.

CT accounts for approximately what percent dose to the population (NCRP Report #160)?

a. 24%

b. 50%

c. 15%

d. 80%

A. This accounts for the largest increase in radiation

exposure since 1980.

Meiosis describes the process of division of what type of cells?

a. Somatic

b. Cancer

c. Muscle

d. Germ

D. Mitosis describes division of somatic cells.

What refers to the lifetime-accumulated occupational dose?

a. Annual accumulated effective dose

b. Cumulative effective dose

c. Common effective dose

d. Common medical effective dose

B.

Exposure times longer than ______ minutes can lead to skin effects.

a. 5

b. 10

c. 20

d. 30

D.

What provides an approximate skin dose where the x-ray beam is entering the patient?

a. Sievert

b. Becquerel

c. Air kerma

d. Effective dose

C. Air kerma is the x-ray energy being deposited in a specific location

The preferred term for radiation exposure is:

a. Coulombs per kilogram

b. Gray

c. Sievert

d. Air kerma

C. Coulombs per kilogram is used less frequently

Effective dose limits may be found in what published material?

a. Dose limit reports

b. NCRP reports

c. Environment Protection Agency reports

d. Health and Human Services reports

B.

Photon-cell interactions occur:

a. Predictably

b. By chance

c. Seldom

d. Only at high radiation doses

B.

The smallest particle of an element that retains the characteristics of the element is a(n):

a. Element

b. Atom

c. Molecule

d. Neutron

B.

Atomic mass refers to:

a. The number of protons plus the number of neutrons

b. The number of electrons

c. The number of electron shells

d. The number of protons

A.

X-rays travel as bundles of energy called:

a. Protons

b. Phasers

c. Particles

d. Photons

D.

The height of a sine wave is called the:

a. Wavelength

b. Altitude

c. Amplitude

d. Frequency

C.

The transformer that operates on the principle of self-induction is the:

a. Step-up transformer

b. Step-down transformer

c. Induction transformer

d. Autotransformer

D.

Electronic timers used in x-ray equipment allow for

exposure times as short as:

a. 1⁄100 second

b. 1⁄1000 second

c.1μs

d. There is no limit to how short the exposure can be

B. One millisecond

To ensure consistency of radiographic quality from one exposure to the next, what device may be used?

a. Electronic timer

b. Automatic collimation

c. Automatic exposure control

d. Falling load generator

C.

An x-ray machine that uses a continually decreasing mA for the shortest times possible uses a(n):

a. Ionization chamber

b. Phototimer

c. AEC

d. Falling load generator

D.

Devices in the x-ray circuit that operate on the principle of mutual induction are called:

a. Rectifiers

b. Generators

c. Timers

d. Transformers

D.

The high-voltage section of the x-ray circuit makes use of what type of transformer?

a. Step-up

b. Autotransformer

c. Step-down

d. Falling load

A.

The device in the x-ray circuit that changes AC to DC is the:

a. Autotransformer

b. Step-up transformer

c. Rectifier

d. Falling load generator

C.

What type of current is required for proper operation of the x-ray tube?

a. Direct

b. Falling load

c. Alternating

d. Fluctuating

A.

The result of thermionic emission is a(n):

a. Recoil electron

b. Electron cloud

c. Scattered photon

d. Characteristic photon

B.

The focusing cup is located at the:

a. Cathode

b. Anode

c. X-ray tube window

d. Control panel

A.

An interaction that produces x-rays at the anode as a result of outer shell electrons filling holes in the K-shell is called:

a. Characteristic

b. Photoelectric

c. Compton

d. Brems

A.

In digital fluoroscopy, the image should be viewed on what device to take advantage of the digital capabilities?

a. Digital viewbox

b. High-resolution monitor

c. High-definition TV

d. Plasma TV

B.

A primary advantage of digital fluoroscopy is:

a. Postprocessing manipulation of the image

b. No radiation dose to the patient

c. No fluoroscopist required

d. Lower cost

A.

In digital fluoroscopy and computed radiography, the energy must be changed to a digital form by a(n):

a. Digital-to-analog converter

b. Flux capacitor

c. Analog-to-digital converter

d. DVD-ROM

C.

An algorithm is:

a. A mathematical hypothesis used in imaging

b. A mathematical formula used to reconstruct the image in digital imaging

c. An advanced imaging procedure

d. The mathematical basis for film-screen imaging

B.

In computed radiography, each pixel corresponds to a shade of gray representing an area in the patient known as a(n):

a. Pathology

b. Density

c. Voxel

d. Artifact

C.

Lightness and darkness of the image in computed radiography may be adjusted by:

a. Doubling the kVp

b. Adjusting the window level

c. Adjusting the window width

d. Using digital fluoroscopy

B. Window width adjusts gray scale.

The window level in computed radiography is the:

a. Area of the patient being irradiated

b. Amount of radiation needed to obtain the image

c. Midpoint of densities

d. Top of the midpoint of densities

C.

Radiographic contrast in computed radiography may be adjusted by changing the:

a. Window level

b. Window width

c. Area of the patient being irradiated

d. Imaging plate

B. Window width adjusts contrast. Window level adjusts brightness.

The amount of receptor exposure is controlled primarily by:

a. kVp

b. Focal spot size

c. AEC

d. mAs

D.

The visible image may also be called the:

a. Manifest image

b. Image-in-waiting

c. Preprocessed image

d. Latent image

A.

The quantity of x-rays produced is directly controlled by:

a. kVp

b. OID

c. SID

d. mAs

D.

The rule or law that governs changing technique using kVp is the:

a. Inverse square law

b. Density maintenance law

c. Reciprocity law

d. 15% rule

D.

If SID is halved, what may be said about receptor exposure?

a. Receptor exposure doubles

b. Receptor exposure is reduced by half

c. Receptor exposure is reduced by one-half of the mAs

d. Receptor exposure is quadrupled

D. This is inverse square law.

Distortion that affects the size of the object as represented on the radiographic image is called:

a. Minification

b. Foreshortening

c. Elongation

d. Magnification

D.

Shape distortion may take the form of:

a. Magnification and minification

b. Size and shape distortion

c. Elongation and foreshortening

d. Magnification and elongation

C.

A longer than usual OID may cause:

a. Elongation

b. Foreshortening

c. Minification

d. Magnification

D.

CR cassettes should be erased at least:

a. Every 24 hours

b. Every 48 hours

c. Every 3 months

d. Weekly

A.

The equation H/D describes:

a. Grid radius

b. Contrast

c. Grid ratio

d. Reciprocity law

C.

If the exposure field is not accurately recognized, the histogram:

a. Narrows

b. Widens

c. Remains the same

B.

Noise increases with an increase in:

a. mAs

b. Speed class

c. SID

d. OID

B.

Edge enhancement provides:

a. Artificial increase in display contrast at an edge of the image

b. Artificial increase in display brightness at an edge of the image

c. Artificial increase in spatial resolution at an edge of the image

A.

Which of the following grid errors would result in an image that shows normal exposure in the middle but decreased exposure on the sides and may follow removal and replacement of the grid?

a. Upside down

b. Off-level

c. Lateral decentering

d. Grid-focus decentering

A.

Grid frequency is described as the:

a. Height of the lead strips divided by the distance between the lead strips

b. Distance between the lead strips divided by the height of the lead strips

c. Number of lead strips per inch or centimeter

d. SID at which the grid may be used

C. The total amount of lead in the grid

When working with CR and DR, one must be aware that their response to scatter radiation is:

a. Very sensitive

b. Minimally sensitive

c. Irrelevant

A.

The images on radiologists' monitors appear:

a. The same as on radiographers' monitors

b. In greater detail than on radiographers' monitors

c. In less detail than on radiographers' monitors

B.

A histogram analysis error may be caused by:

a. Excessive mAs

b. Pixel unresponsiveness

c. Inappropriate collimation

d. Excessive kVp

C.

Smoothing provides:

a. Higher spatial resolution

b. Equalization

c. Evenness in brightness

d. Higher contrast resolution

C.

Consistency of image appearance is achieved through the use of:

a. Higher speed class

b. Uniform processing codes

c. More effective postprocessing

d. Lower exposure index numbers

B.

Which of the following sets of exposure factors would produce an image with the poorest spatial resolution?

a. 60 mAs, 80 kVp, 40-inch SID, 4-inch OID

b. 30 mAs, 92 kVp, 40-inch SID, 4-inch OID

c. 120 mAs, 92 kVp, 20-inch SID, 4-inch OID

d. 15 mAs, 100 kVp, 40-inch SID, 4-inch OID

C. It has a short SID.

Which of the following sets of exposure factors would produce an image with the best spatial resolution?

a. 60 mAs, 80 kVp, 72-inch SID, 4-inch OID

b. 30 mAs, 92 kVp, 40-inch SID, 4-inch OID

c. 120 mAs, 92 kVp, 20-inch SID, 4-inch OID

d. 15 mAs, 100 kVp, 40-inch SID, 4-inch OID

A. It has a long SID.

Beam restriction has the following effect on contrast:

a. Decreases contrast

b. Longer scale of contrast

c. Shorter scale of contrast

d. No effect on contrast

C. Fewer Compton interactions are occurring.

As kVp increases, there is an increased production of:

a. Long wavelengths

b. Low-energy waves

c. Short wavelengths

d. Electrons

C.

TherelationshipbetweenkVpandreceptorexposureis:

a. Indirect

b. Directly proportional

c. Direct, although not proportional

d. Inverse

C.

Grids that have strips angled to coincide with divergence of the x-ray beam are called:

a. Parallel

b. Crosshatch

c. Focused

d. Rhombic

C.

In digital imaging, the radiographer must be aware that:

a. mAs is the primary controlling factor

b. The image is determined by the total exposure

c. Speed class is the primary controlling factor

d. kVp is the primary controlling factor

B.