EX1; Podcast - Principles of X-Ray Production

Question 1

When is an X-ray produced

Answer 1

when highly accelerates electron are suddenly brought to a stop by hitting a stationary object

Question 2

What specifically is converted into X-rays via the high speed electrons

Answer 2

kinetic energy

Question 3

This mechanism for production involves electron to nucleus interaction

Answer 3

bremsstrahlung

“braking radiation”

Question 4

What are the three requirements for x-ray production

Answer 4

electrons
high velocity (electrons)
high Z-number absorbing material/target (i.e Tungsten 74W)

Question 5

The higher the what, the greater the kinetic energy of the electron

Answer 5

velocity

KE = 1/2mV^2

Question 6

True or False

All the electrons move at the same velocity

Answer 6

False; some move at high velocity than others

Question 7

What occurs when some electrons striking the nucleus suddenly stop and give off all their KE

Answer 7

a single high energy x-ray photon is produced

Question 8

Most electrons pass close to the nucleus, decelerate and give up some of their KE and produce this

Answer 8

x-ray photons with various energies

Question 9

This mechanism for production involves electron to electron interaction

Answer 9

characteristic radiation (K-radiation)

Question 10

How does characteristic radiation cause ionization

Answer 10

incident electrons interact with K (or L) shell electrons of target (tungsten) atoms

Question 11

What is the result from characteristic radiation

Answer 11

heterogenous x-ray beam but much narrower energy spectrum than Bremsstrahlung

Question 12

What is the target/focal spot made of

Answer 12

tungsten embedded within the copper anode

Question 13

What are the actual dimensions of the target/focal sport

Answer 13

1x3mm

Question 14

What are the effective focal spot dimensions; it is angulated (20º) to produce a beam from a smaller area

Answer 14

1x1mm

Question 15

Why is tungsten used as a target

Answer 15

high melting point and heat stability
high ductility
produces predictable and optimal energy x-rays
high atomic numbers
high thermal conductivity
low vapor pressure (don’t want vapor in vacuum)

Question 16

What percentage of diagnostic x-ray beam is characteristic radiation

Answer 16

30%

Question 17

This is a significant byproduct of X-ray production (over 99%)

Answer 17

heat

Question 18

What is used to reduce overheating of the target

Answer 18

copper stem of anode and oil immersion

Question 19

The heterogenous x-ray beam produced at the anode is net out of a lined tube through what

Answer 19

the portal; a channel for the passage of X-rays

Question 20

This absorbs less penetrating (long wavelengths) x-rays which are harmful

Answer 20

the filter; made of aluminum

Question 21

X-rays with longer wavelengths are mostly absorbed by what and do not reach the target tissues

Answer 21

skin

Question 22

What is the half valve of the filter

Answer 22

the thickness of it; reducing number of X-rays passing

Question 23

This is “shaping of the beam”

Answer 23

collimation

Question 24

What does x-ray beam collimation greatly reduces what

Answer 24

unnecessary exposure to patients

Question 25

Most x-ray tubes have which type of collimation

Answer 25

round (7cm)

Question 26

This type of collimation is slightly larger than the size of the image receptor

Answer 26

rectangular

Question 27

This shaped diaphragm limits the size of divergent beam

Answer 27

doughnut

Question 28

This farther reduces the beam size providing mean of aiming the beam

Answer 28

external collimator

Question 29

What are the necessary conditions for x-ray production involving electrons

Answer 29

separation of electrons concentration of electrons imparting high speed to the electrons sudden stopping of the electrons stream to produce x-rays

Question 30

The purpose of this is to supply electrons through a heated filament cathode is the negate electrode

Answer 30

cathode

Question 31

The cathode filament is recessed into what to help contain and direct electrode

Answer 31

molybdeum focusing cup

Question 32

The purpose of this is to stop the high energy electrons and to convert their kinetic energy into x-rays and the positive electrode

Answer 32

anode

Question 33

This is low-voltage circuit, filament made of tungsten, molybdenum focusing cup, and electron cloud

Answer 33

cathode

Question 34

This is high-voltage circuit, angled tungsten target/focal spot, heat absorber/radiator (copper)

Answer 34

anode

Question 35

The production and separation is much like this

Answer 35

like a light bulb | "thermionic emission"

Question 36

The electron cloud is produced at what

Answer 36

the filament

Question 37

The electrons become more active by what

Answer 37

random collisions producing more free electrons

Question 38

Theis located at the cathode serves to concentrate the electrons

Answer 38

molybdenum collar (focusing cup)

Question 39

When the high voltage circuit (at the anode) is activated, these concentrated electrons form a beam that does what

Answer 39

hits the focal spot located on the face of the copper anode

Question 40

What activates the high voltage circuit at the anode

Answer 40

high potential difference created between the filament cathode and target anode

Question 41

These parts of the control panel influence radiographic imaging

Answer 41

millamperage (number of electrons) exposure time (between cathode/anode) kilovoltage

Question 42

These are factors influencing radiographic image

Answer 42

density, contrast, resolution distortion filtration and collimation

Question 43

True or False | The distance from source to receptor and the distance from object to receptor can play a roll in radiographic image

Answer 43

True

Question 44

Object attenuation (absorption) depends on what

Answer 44

density (of bone and such) atomic number thickness

Question 45

The permeability of x-rays depends on what

Answer 45

photon energy thickness of object density of the object being radiographed

Question 46

This is the complete absorption of the beam of object (like amalgam)

Answer 46

photoelectric absorption

Question 47

This is almost complete absorption (like cortical bone)

Answer 47

coherent/thompson scattering

Question 48

True or False | There is no such thing a complete penetration to receptor

Answer 48

False; there is in air filled spaces like the maxillary sinus

Question 49

This is scatter-partial/tangential exposure of receptor; undesirable but always occurs

Answer 49

compton scattering