CH. 10 XRAY PRODUCTION

As kVp is increased, the production of brems photons ____.

increases

More than _____ % of an x-ray beam is made up of photons produced by the brems process.

90

Changing ___ will change the maximum energy of the photons in the x-ray emission spectrum.

kVp

A tech can control the quantity of the x-rays striking the patient by adjusting the ____.

mA

The process of removing low-energy photons from the x-ray beam is called:

filtration

shifts minimum energy of spectrum to the right

increased filtration

causes peaks (amplitude) of graph to decrease

decreased mA

amplitude, maximum and average energy all increased

increased kVp

characteristic radiation appears in new position

decreased target Z #

controls the projectile electron energy, the intensity, the maximum energy, and the average energy of the x-ray beam

kVp

controls the number of projectile electrons striking the anode and the intensity of the x-ray beam

mA

influences the intensity and average energy of the x-ray beam by eliminating low-energy photons

filtration

influences the intensity and the average energy of the x-ray beam by making the x-ray tube more efficient

circuit waveform

About ___% of the electron energy is converted to x-ray energy.

1

The energy of the photon is known as the:

keV

How does a projectile electron lose its energy in the Brems interaction?

by being slowed by the force of attraction

The shape and position of Brems x-ray emission spectrum ____ in amplitude with increasing number of projectile electrons.

increases

The efficiency of x-ray production increases as____ increases.

kVp

A soft x-ray beam has a low penetrability. This beam is also said to possess a ____ quality.

low

The efficiency of x-ray production is ___ the tube current.

not affected by

How would the characteristic spectrum change if operation were changed to 64kVp/200mA/20ms from operation at 80kVp/200mA/20ms?

it would disappear

The kVp sets the:

minimum wavelength and maximum energy

An increase in mAs would ____ the _____ of the emission spectrum.

increase; amplitude

True or False: x-ray quantity is inversely proportional to mAs.

false

True or False: changing from 84 to 94 kVp reduced the minimum wavelength

true

True or False: x-ray quantity is usually measured as exposure in rads.

false

True or False: the addition of 1 mm Al filtration to an x-ray machine operated at 84 kVp and 120 mAs will reduce the minimum wavelength slightly.

false

True or False: the minimum wavelength during chest radiography (125 kVp) is shorter than during mammography (28 kVp)

true

True or False: x-ray quality is measured by filtration

false

True or False: doubling the mAs and increasing the kVp will result in an increase in filtration

false

True or False: x-ray quantity is affected by both kVp and mAs

true

True or False: x-ray quantity is often measured in kVp

false

True or False: changing from large to small focal spot reduces the minimum wavelength

false

Brems x-rays are produced by ____ at the target.

slowing electrons

What factor has a significant effect on the energies produced during characteristic x-ray production process?

the atomic number of the material in the target of the x-ray tube

During an exposure, most of the ____ energy of the projectile electrons is converted to ____.

kinetic; heat

How does added filtration affect the emission spectrum?

reduced amplitude and a shift to the right

Projectile electrons travel from the ____ to the ____.

cathode; anode

The lowest energy in a beam of photons is determined by the ____.

filter

The quantity of brems radiation increases proportionately with increased ____.

mAs

The production of heat at the anode is directly proportional to the ______.

tube current

The efficiency of x-ray production can be calculated with the formula:

E = (k)(Z)(kVp)

Most of the heat generated at the target is due to:

outer shell excitation

For an x-ray emissions spectrum, the spectrum associated with the minimum wavelength is the energy corresponding to:

maximum energy

The useful characteristic x-rays from tungsten targets are ___ x-rays.

K shell

An increase in kVp would ____ the ____ of the emission spectrum.

increase amplitude and position

When a high speed stream of projectile electrons strikes the anode of an x-ray tube, the vast majority of the electrons’ kinetic energy is converted into:

infrared radiation

The ___ of an x-ray beam is higher when the peak of the emission spectrum is further to the ____.

quality; right

The amplitude of the emission spectrum is ___ with a ___ generator than/as with a 3 phase generator.

lower; single phase

An x-ray beam may be hardened by:

adding a filter

The amount of filtration and the kVp used with a heterogeneous beam are the 2 MAIN factors that will effect the:

penetrability and beam quality

In general, when changes are made that affect the x-ray emission spectrum and the spectrum shifts to the ____, a more penetrating beam is emitted.

right

The factor which determines the potential difference between the filament and the anode of an x-ray tube is the:

kVp

At 55 kVp, ___% of the useful x-rays produced are Brems.

100

The loss of energy by a projectile electron as it passes by a tungsten nucleus in the anode results in a photon being produced by an event termed:

brems radiation

Characteristic radiation emitted by an x-ray tube may also be called:

monoenergetic, discrete, homogeneous

Continuous radiation emitted by an x-ray tube may also be called:

brems, heterogeneous, white radiation

Brems radiation is produced whenever a:

charged particle is slowed down

Characteristic x-rays are produced by:

releasing binding energy

What 2 ways are x-rays produced?

brems and characterisitc

Which method of x-ray production requires the removal of an inner shell electron?

characteristic

Most of the x-ray beam is produced by which method?

brems

Name and describe 2 types of filtration.

added: piece of metal placed underneath the tube (2.0 mm Al equiv)

inherent: due to construction of tube (0.5 mm Al equiv)

total filtration = 2.5 mm Al equiv

What two things effect efficiency?

kVp and target material 

Efficiency is always less than ___%.

1

If kVp is less than ____, 100% of x-rays are brems.

69

______ = intensity

quantity

____ = penetrating power

quality

Quantity is controlled by ____.

mAs

Quality is controlled by ____.

kVp

Quantity is measured by ___.

mR

Quality is measured by ____.

HVL

Quantity is affected by ____. (4 things)

mAs, distance, filtration, kVp

Quality is affected by ___.

filtration

Minimum wavelength is determined by ____.

kVp

Maximum energy is determined by ____.

kVp

Maximum wavelength is determined by ____.

filtration

What is the formula for minimum wavelength?

12.4/kVp

Hard x-rays have _____ energy.

high

Hard x-rays have _____ frequency.

high

Hard x-rays have _____ wavelength.

short

Hard x-rays have _____penetrating power.

high

Hard x-rays have _____quality.

high

Hard x-rays have _____ skin absorption.

low

How do you harden an x-ray beam?

increase kVp, increase filtration, high Z # target

Soft x-rays have _____ energy.

low

Soft x-rays have _____ frequency.

low

Soft x-rays have _____ wavelength.

long

Soft x-rays have _____penetrating power.

low

Soft x-rays have _____quality.

low

Soft x-rays have _____skin absorption.

high

How do you soften an x-ray beam?

decrease kVp, decrease filtration, low Z # target

The kinetic energy of the projectile electron in an x-ray tube is about ____% efficient in the production of x-rays.

1

The shift of the characteristic x-ray spectrum to higher energy occurs because of an ____ in target atomic number.

increase

What is produced when the projectile electron excited an outer shell electron in the target?

heat

The energy of characteristic x-rays increases with increasing:

atomic number of target material

X-rays are produced when:

projectile electrons interact with target atoms

Characteristic x-rays are characteristic of:

target Z #

The efficiency of x-ray production is ____ of tube current.

independent

Brems radiation is produced by:

conversion of projectile electron kinetic energy into electromagnetic energy