Image Production-Mosby

In many cases, digital fluoroscopy eliminates which of the following?

Postprocedure "overhead" images

What is the smallest particle of an element that retains the characteristics of the element?

Atom

In digital fluoroscopy, the image must be turned into digital form by what device?

Analog-to-digital converter

X-rays travel as bundles of energy called:

Photons

What is the atomic mass?

The number of protons plus the number of neutrons

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

Automatic exposure control

When a predetermined level of ionization is reached in the ionization chamber, what does the machine do?

The exposure is terminated

What type of x-ray machine uses a continually decreasing mA for the shortest times possible?

Falling load generator

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

Direct

The law stating that the outer shell of an atom can contain no more than eight electrons is called

Octet rule

Examples of particulate radiation are

Helium nuclei and beta particles

Electromagnetic radiation travels

In waves along a straight path

The latest digital fluoroscopic units use

flat panel plates similar to DR

At what speed do x-rays travel?

The speed of light-186,00 miles per second

Waves of radiation are called?

Sine waves

Wavelength is defined as the distance from

Peak to peak of the wave

Frequency is defined as

The number of waves passing a point per unit time

The speed of x-rays is based on

The fact that they are a form of electromagnetic radiation

Wavelength and frequency are

Inversely proportional to each other

The x-ray beam changes as it travels through the patient by a process called

Attenuation

The intensity of radiation is inversely proportional to the square of the distance between the source of radiation and the person receiving it. This describes the

Inverse square law

As radiation strikes matter

The energy is transferred to the atoms according to the law of conservation of energy

Choose all of the following statements that are accurate regarding electrostatic charges:

A) Electrostatics is the study of electric charges at rest

B) The movement of electrons from one object to another is called ionization

C) Like charges attract, and unlike charges repel

D) Electrostatic charges concentrate on a conductor in the area of greatest curvature

E) Friction, contact, and induction are methods of ionization

A & D

Choose all of the following that are accurate:

A) A magnetic field always surrounds an electrical charge in motion

B) Current flows back and forth in AC

C) Current flows in one direction in DC

D) The volt is the unit of electrical current

E) A conductor allows the flow of electrons

F) The ampere is the unit of electromotive force

G) The volt is the unit of potential difference

H) The path of electrical current is called the circuit

A, B, C, E, G, & H

Electromagnetic induction is the process of causing an electrical current to flow in a conductor:

When it is placed in the magnetic field of another conductor

The two types of electromagnetic induction are

Self-induction and mutual induction

Self-induction is used in the operation of what device?

Autotransformer

The strength of the magnetic fields in a transformer is increased by

Coiling the wires and letting their magnetic fields overlap

Electricity is supplied to the imaging department by a

Generator

The electricity provided to the radiology department is

60 Hz AC

The electricity provided to the radiology department operates at

120 pulses per second

High-frequency power

Has almost no ripple

The primary advantage of three-phase power is that

Voltage never drops to zero

A variable transformer that is used to select kVp for the x-ray circuit is the

Autotransformer

A transformer that has more turns in the secondary coil than in the primary coil is called a

Step-up transformer

What is the transformer used to boost voltage to kilo-voltage levels called?

Step-up transformer

Voltage coming to the x-ray machine is kept constant through the use of a(n)

Line voltage compensator

A step-down transformer

Steps down voltage

Where does thermionic emission occur?

Cathode

Which of the following devices is prereading?

kVp meter

Which device reduces voltage and provides current to produce an electron cloud or space charge at the filament?

Step-down transformer

Which device is electronic, with a setting as low as 0.001?

Timer

What changes AC to DC?

Rectifier

Which of the following is surrounded by a negatively charged focusing cup?

Filament

Which of the following is composed of solid-state silicon-based diodes?

Rectifier

What regulates the duration of x-ray production?

Timer

What is located in the x-ray circuit between the high-voltage transformer and the x-ray tube?

Rectifier

Which of the following measures tube current?

mA meter

What device spins at 10,000-12,000 rpm?

Anode

What device uses maximum heat storage ability of the tube to deliver mAs?

Falling load generator

What is the source of bremsstrahlung and characteristic rays?

Anode

What device increases voltage approximately 500 times?

Step-up transformer

What is the most commonly used AEC?

Ionization chamber

What device always delivers the shortest exposure time possible?

Falling load generator

What device is turned by a rotor?

Anode

Which of the following is located between the patient and the image receptor?

Ionization chamber

The filament is kept warm by

A standby current form the time the x-ray machine is turned on

Activating the rotor

Reduces tube life

When making an exposure, the radiographer should

Activate the rotor and exposure switch in one continuous motion

The process of thermionic emission causes

Electrons to boil off the filament

The force with which the electron stream passes from cathode to anode is a result of___ passing through the x-ray tube.

Kilovoltage

Heat is produced in the x-ray tube as

Electrons interact with the target material

Most of the energy conversion in the x-ray tube produces

Heat

X-rays are produced as incident electrons are slowed going past the nuclei of target atoms by a process called

Bremsstrahlung

X-rays are produced as incident electrons collide with inner shell electrons in target atoms by a process called

Characteristic

What percentage of energy in the x-ray tube is converted to x-rays?

1%

Choose all that are properties of x-rays

-Affect film emulsion

-Scatter and produce secondary radiation

-Invisible to the human eye

-Travel in bundles of energy called photons

-Can ionize matter and gases

-Cause phosphors to fluoresce

The x-ray beam is

Heterogeneous or polyenergetic-consisting of many different energies (wavelengths)

The x-ray emission spectrum consists of

Discrete spectrum (produced by characteristic rays) and continuous spectrum (produced by brems rays)

The primary purpose of filtration is

Radiation protection

The amount of material needed to reduce the intensity of the beam by 1/10 is called

Tenth-value layer

Which of the following statements regarding filtration is true?

Total filtration (not less than 2.5-mm aluminum equivalent) = inherent filtration (glass envelope, tube housing, oil) + added filtration (aluminum)

Calculating heat units for three-phase, 12-pulse equipment requires the use of ____ as a constant; calculating heat units for single-phase equipment requires the use of ___ as a constant; calculating heat units for three-phase, 6-pulse equipment requires the use of ___ as a constant.

1.41, 1.0, 1.35

When a quality control test is performed to ensure that the penetrating ability of the x-ray beam is accurate, the result must be within what amount of the control panel setting?

50%

The primary type of grid used in diagnostic imaging is

Focused

The portion of the image-intensifier tube that converts electron energy to visible light is the

Output phosphor

The portion of the image-intensifier tube that converts visible light to electrons is the

Photocathode

The input phosphor of the image-intensifier tube converts

X-ray energy to visible light

Total brightness gain achieved using an image intensifier equals

Flux gain times minification gain

Single-phase, full-wave rectification produces

Pulsating, direct current with 120 pulses per second and 100% ripple

Three phase, 6 pulse full wave rectification produces

Direct current with 13% ripple

Three phase, 12-pulse full-wave rectification produces

Direct current with 4% ripple

The increase in average photon energy when using three-phase, 6-pulse equipment compared with single-phase equipment is

35%

The increase in average photon energy when using three-phase, 12-pulse equipment compared with single-phase equipment is

41%

Programs that deal with the safe and reliable operation of equipment and programs that address all aspects of the delivery of radiology services are called, respectively

Quality control and quality assurance

An image intensifier's conversion factor is expressed as the ratio of

The luminance of the output phosphor to the exposure rate at the input phosphor

The collimator must be accurate to a level of

+/-2% of SID

kVp must be accurate to within

10% of the control panel setting

Exposure linearity must be accurate to within

10%

Exposure reproducibility must be accurate to within

5%

Fluoroscopy exposure rate may not exceed

100 mGya per minute

The feature that automatically adjusts kVp and mA during fluoroscopy is called

ABC

The test that measures the accuracy of adjacent mA stations is

Exposure linearity

The test that measures the accuracy of successive exposures is

Exposure reproducibility

The accuracy of the timer must be within

5% of the time chosen for exposures over 10 ms

Resolution of the television system may be measured using the following tool(s)

Resolution test pattern

AECs may be tested using

Phantoms

The number of mAs used for analog fluoroscopy is

3 to 5

Marks on the focal track of the anode resulting from bombardment of electrons are called

Pitting

Effective quality control and quality assurance programs are required for accreditation by

The Joint Commission