RADI 143 - Exam 3

The main circuit of an x-ray machine is composed of what

controle counsole, x-ray tube, low voltage & high voltage

the purpose of the tube circuit is to

supply the x-ray tube with potential difference

which is not part of the control console circuit?

line monitor

rheostat

ma selector

kvp selector

all

when setting the ma station you adjust what flowing through the filament circuit?

amps

all the controls that a radiographer control are located on the

low voltage side of the main circuit

- most be about 5 mm and radiolucent

- the x-rays ionize the gas in the chamber and liberate the electrons which cause a current

- when the predetermined amount of current is produced, the exposure is terminated

ionization chamber (AEC)

the filament circuit, the incoming voltage is

stepped down

which device is not typically found in the high-voltage section of the x-ray machine

rheostat

the milliamperage in the x-ray circuit is controlled by what device

rheostat

in the x-ray console the exposure switch is placed

between the auto transformer and timer circuit

the autotransformer in the x-ray circuit controls which technical factor?

kvp

on a 3 phase, 12 pulse generator, the photon energy is increased by how much compared to a single phase generator

40%

the incoming voltage of filament circuit is stepped down by how many volts

6-12

US public law 90-602 states that generators must terminate the exposure at ___ mas for exposures above 50 kvp and ___ mas for exposure below 50 kvp

600, 2000

as the wavelength of x-rays increases, the frequency ___

decreases

when an electron is ejected from the inner orbits of the target atoms, x-rays result. this interaction is called

characteristic

when an electron is attracted towards the nucleus and is deflected from its original direction, the electron is slowed down. the kinetic energy lost is emitted in the form of radiation interaction is called

bremsstrahlung

the filament circuit produces amperage. the can be adjusted by a

line monitor & rheostat

the term used to describe the characteristic interaction of an electron from an outer shell dropping into a "hole" of a vacant shell is called

cascade effect

how much more average photon energy does a 3 phase, 12 pulse generator produce when compared to a 3 phase, 6 pulse

5%

- they are non-uniform in energy and wavelength

- a single electron can cause numerous brems interactions

- the amount of energy lost is determined by how close the electron comes to the nucleus

bremsstrahlung interactions

the purpose of the low voltage circuit in the x-ray machine is to

heat up the filament

conditions necessary for x-ray production

- high speed electron undergoes rapid deceleration

- an outer shell electron drops into the inner shell of an electron

- the electron goes from a higher energy state to a lower energy state

what kvp will produce a tube efficiency of .5% (tungsten z = 74)

68

what is the efficiency of an x-ray tube when using a tungsten target at 60 kvp that is converted into heat?

99.56%

what % of characteristic x-rays are produced at 65 kvp

0%

the minimum reaction time for an ionization chamber is

.001 seconds

the purpose of the rectification bridge is to

change AC to DC

which component of the x-ray tube causes the ther moons to jump the gap at very high speeds?

potential difference

what is the efficiency of an x-ray tube using a bismuth target (z=83) at 80 kvp

66%

for a radiograph produced a 90 KVP, what percent of x-rays produced will be from a bremsstrahlung interaction

90%

what does the 90-30 table mean

The table tilts 90° in an upright position and 30° in the opposite direction

the fixed height for most radiographic tables is

30-40"

the detent lock is placed at what location in the room

40" and 72"

The type of x-ray equipment that may be stationary or mobile and has fluoroscopic capability is called

c-arm

a radiographic table too may be

stationary, floating, motor-driven, radiolucent

the most common cause of tube failure is

arcing

The physical area of the focal spot that is projected out of the table towards the patient is called the

effective focal spot

parts of the cathode assembly include

filament, focusing cup, associated wiring, filament circuit

The thickness of most filament wires is

.1 to .2 mm

an anode has an angle of 40°. How will the effective focal spot up here compared to the effective focal spot of an anode with only an angle of 15°?

larger