image production final

in many cases, digital fluoroscopy eleimates what

postprocedure “overhead” images

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

analog to digital converter

what is the smallest particles of an element that retains the characteristic of the element

atom

X-ray travels as bundles of energy called

photons

what is 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

AEC

when a predetermines 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 time possible?

falling load generator

what type of current in 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

octect 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- 186,000 per second

waves of radiation are called

sine waves

wavelength is defines as the distance from

peak to peak of the wave

frequency is defined as

the number of waves passing a point per unit

the speed of x-ray is based on

the fact that they are a form of electromagnetic radiation

wavelength and frequency are

inversely proportional to each other

the xray beam changes as it travels through the patient by a process called

attentuation

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 conversation of energy

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 field 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

220 pulses per second

high-frequency power

has almost no ripple

the primary advantage of three-phase power is that

voltage drops to zero only 6 times per second

a variable transformer that is used to select kVp for the xray circuit is the

autotransformer

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

step-down transformer

what is the transformer used to boost voltage to kilovoltage levels called

low-voltage transformer

voltage coming to the x-ray machine is kept constant through the use of an

autotransformer

a step-down transformer

steps down current

where does thermionic emission occur

step-down transformer

what device 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

step down transformer

what changes AC to DC

step down transformer

what is surrounded by a negatively charged focusing cup

step down transformer

what is composed of solid-state silicon based diodes

rectifier

what regulates the duration of x-ray production

timer

what is located in the xray circuit between the high-voltage transformer and the xray tube

rectifier

what measures tube current

mA meter

what device spins at 10,000-20,000 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 type of generator makes breathing techniques difficult to perform

falling load

what device is turned by a rotor

anode

what is located between the patient and the image receptor

ionization chamber

the filament is kept warm by

a standby current from the time the x-ray machine is turned on

activating the rotor

reduced tube life

when making an exposure, the radiographer should

activate the rotor and exposure switch in one continous motion

the process of thermoionic 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

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

characteristic

what percentage of energy in the xray tube is converted to xrays

1%

the xray beam is

heterogenous or polyenergetic

the xray emission spectrum consists of

discrete spectrum and continous spectrum

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

when a quality control test is performed to ensure that the penetrating ability of xray 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 rectificatin 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

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 the SID

at 100 kVp, the maximum energy of the beam must fall within

± 5 kVp of the control panel setting

exposure linearity must be accurate to within

10%

exposure reproducibility must be accurate to within

5%

fluorscopy exposure rate may not exceed

100 mGy, per minute

the feature that automatically adjusts kVp and mA during fluorscopy 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 10ms

resolution of the television system may be measured using what tool

resolution tool pattern

AECs may be tested using

phantoms

the mA used for analog fluoroscopy is

3 to 5

marks on the focal track of the anode resulting from bombardment of electrons is called

pitting

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

the joint commission

recpetor exposure may be defined as

dose area product

the radiographic image is formed by

exit rays striking the image receptor

the primary controlling factors of receptor exposure are

kVp and mAs

what kind of relationship do mAs and receptor exposure have

directly proportional

the number of electrons boiled off the cathode and consequently the number of x-rays produced are controlled by

mA