Intro To Radtech. X-ray Production Flashcards Preview

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Flashcards in Intro To Radtech. X-ray Production Deck (73)
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1
Q

What are x-rays?

A

A group or rays belonging to the electromagnetic spectrum

2
Q

Electromagnetic spectrum measures in…

A

Wavelengths and light

3
Q

What is radioactivity?

A

Radioactivity is the process of decay.

Everything around us is radioactive

4
Q

Sine waves travel at what speed

A

The speed of light

5
Q

What is the speed of light?

A

186,000 miles per second

3x10^8 meters per second

3x10^10 centimeters per second

C=constant

6
Q

EM wavelengths are measured in

A

The distance between two successive crests in a wave

Lamda

7
Q

EM Frequency is measure in

A

The time between each crest

Nu

8
Q

Wavelength and frequency of Em waves are

A

Inversely proportional

Speed of light = wavelength x frequency

9
Q

What is the crest of a wave?

A

The highest point in the wave

10
Q

What is the trough of a wave

A

The lowest point

11
Q

The wavelength of a wave

A

Crest to crest or trough to trough or center to center.

Distance between

12
Q

What is the wave height?

A

Distance between the crest and its neighboring trough

13
Q

What is amplitude?

A

The amount that the wave has been displaced from its median position.

Half of the wave height

14
Q

What is the undisturbed surface of a wave

A

The middle line of the wavelength

15
Q

What is frequency?

A

The number of crests or troughs that pass through during a specific time interval.

Inverse of period

16
Q

What is period?

A

.the length of time it takes to complete one cycle

17
Q

X-Ray beams are

A

Heterogenous

Meaning different energies

Average- very short wavelength

Useful range is 0.1A through 0.5A

18
Q

What are the two theories on properties of x-rays?

A

Wave concept

Particle concept

19
Q

What is the wave concept on properties of x-rays

A

It explains how they move through space. And yet travel in a vacuum

20
Q

What is the particle concept on properties of x-rays?

A

Explains how they can interact with matter as though they were particles.

21
Q

Define mathematical constant

A
  • constant: a non-varying value
  • variable: changing value
  • constant, in a formula, usually denoted by a letter, such as c for the speed of light
  • or planck’s constant: the letter h
22
Q

Is there a relationship between photon energy and frequency?

A
  • energy = plancks constant x frequency
  • plancks constant = 6.63x10^-34 joule-seconds

Symbol is h

As frequency increases, photon energy increases

23
Q

Who discovered x-rays?

A

Wilhelm Conrad Roentgen

November 8, 1895

Discovered by accident

Observed by 12 other scientists previously

Roentgen identified all of the properties of x-rays less than a month after his discovery

Part of university of wurzburg

24
Q

What is the first known medical radiograph?

A

A wrist x-ray performed on February 3, 1896 at Dartmouth college

25
Q

What conditions are needed for x-ray production?

A
  • separation of electrons
  • high-speed electrons
  • sudden stopping of electrons
  • concentration(focusing) of electrons
26
Q

Separation of electrons

A

Thermionic emission

Heating of the tungsten filament

Creates electron cloud aka space charge

27
Q

All x-Ray tubes are…

A

Dual focus

Two filaments used one at a time

One wired with high voltage and one with low

28
Q

Space charge

A

“Electron cloud”

29
Q

Space charge effect

A

Limits the number of electrons present in the space charge

Due to the negative charge on the focusing cup, forcing the electrons together

In spite of the electrostatic repulsion the electrons have for each other

30
Q

How fast do electron move?

A

Half of the speed of light

Speed of light = 186,000 mi/sec

31
Q

What is the focal spot?

A

The actual area on the anode that is struck by electrons

The smaller the focal spot, the greater the spatial resolution on the resulting images

32
Q

What is the line-focus principle?

A

Actual focal spot size is larger than the effective focal spot

33
Q

Bremsstrahlung Radiation

A

Means braking radiation
Also known as general radiation

Brems makes up 100% of the primary beam
If under 70 kVp and ~85% if over 70 kVp is used

Caused by deceleration of “cathode rays” when they are near the nucleus of a tungsten atom of the target

34
Q

What moves electrons?

A

Kinetic energy

35
Q

What is characteristic radiation?

A

Up to 15% of the primary beam (if over 70 kVp)

A direct hit between cathode rays and tungsten atoms

Energy of radiation is characteristic of the energy shell of the tungsten atom it interacted with

36
Q

Cathode

A

The negative electrode

Made of two parts

  • tungsten filaments
  • nickel focusing cup (or molybdenum)

Filament is heated by a separate low-voltage circuit

37
Q

Anode

A

Positive electrode

Made of a tungsten-rhenium alloy (some have layers of molybdenum and graphite)

Circular, it rotates to dissipate heat
- 3600 to 10,000 RPM

38
Q

What are the properties of x-rays?

A

A. Can penetrate matter of any kind
B. Electrically neutral ( not deflected by magnetic or electric field)
C. They occur in a wide range of wavelengths (0.04 A to 1000 A)
D. X-ray beams are heterogenous
E. x-rays travel in straight lines
F. Travel at the speed of light in a vacuum
G. Capable of ionizing gases
H. Cause fluorescence in certain crystals
I. Cannot be focused by a lens
J. Affect photographic film
K. Produce chemical and biological changes
L. Produce secondary and scattered radiation

39
Q

Exposure rate is altered by…

A

Milliamerage

Kilovoltage

Distance

Filtration

40
Q

Milliamperage (mA)

A

Determines quantity of radiation

Settings on panel go from 25 mA - 1500mA

Increases tube current, so increases number of x-rays produced

Exposure rate is directly proportional to the mA

41
Q

What is mAs?

A

Milliamperage x time(in seconds) = mAs

Milliampere-second

42
Q

Kilovoltage(kV)

A

Determines the quality of radiation

Quality is the penetrating ability of the beam. (Denotes energy of beam)

• kV increases speed of electrons from cathode to anode

43
Q

More kinetic energy of the electrons traveling from cathode to anode results in…

A

More x-ray energy when those electrons hot the anode

44
Q

The 15% rule

A

Increasing the kVp by 15% will have the same effect (on density/brightness) as reducing the mAs to 50%

Formula: kVp x 1.15; then mAs/2
KVp x 0.85; then mAs x 2

45
Q

Inverse square law

A

a law stating that the intensity of an effect such as illumination or gravitational force changes in inverse proportion to the square of the distance from the source.

46
Q

Beam quality

A

The penetrating ability of the beam

Longer wavelengths are low kV

47
Q

Crookes x-ray tubes (col cathode tubes) were used until

A

About 1920

48
Q

What year did eastman introduce radiographic film?

A

1918

49
Q

What year was the society of radiographers formed?

A

1920

50
Q

When did Siegbahn receive the nobel prize in physics for x-ray spectroscopy

A

1924

51
Q

What is an x-ray beam?

A

A group of rays belonging to the electromagnetic spectrum

52
Q

Wavelength is?

A

The distance between to successive crests

53
Q

Wave frequency is

A

The number of crests per second

54
Q

Speed of light =

A

Wavelength x frequency

55
Q

What is radiation

A

The transfer of energy in the form of particles or waves

Or

A relatively high-energy photon having a wavelength in the approximate range from 0.01 to 10 nanometers

56
Q

What is an angstrom

A

Measurement of wavelength

1A= .1 nanometer

1 electron

57
Q

What is a photon

A

The smallest amount of any type of electromagnetic radiation

Also considered a bundle of energy called a quantum

Travels at the speed of light, in waves in a straight path

58
Q

Types of photons

A
X-radiation
Gamma
Light
Radio
Etc
59
Q

Maximum E in a photon beam is expressed in

A

KVp

60
Q

The wave equation

A

Wavelength= velocity/frequency

61
Q

Characteristics of x-rays

A
  • are invisible
  • are electrically neutral
  • have no mass
  • travel at the speed of light in a vacuum
  • cannot be optically focused
  • form a polyenergetic or heterogeneous
  • can be produced in a range of energies
  • travel in straight lines
  • can cause some substances to fluoresce
  • causes chemical changes in radiographic and photographic film
  • can penetrate the human body
  • can be absorbed or scattered in the human body
  • can produce secondary radiation
  • can cause damage to living tissue
62
Q

In what year where x-rays discovered?

A. 1892
B. 1895
C. 1898
D. 1901

A

B. 1895

63
Q

In what year were some of the biologically damaging effects of x-rays discovered?

A. 1892
B. 1895
C. 1898
D. 1901

A

C. 1898

64
Q

X-rays were discovered in experiments dealing with electricity and___________?

A. Ionization
B. Magnetism
C. Atomic structure
D. Vacuum tubes

A

D. Vacuum tubes

65
Q

X-rays were discovered when they caused a barium platinocyanide-coated plate to ____________?

A. Fluoresce
B. Phosphoresce
C. Vibrate
D. Vacuum tubes

A

A. Fluoresce

66
Q

X-radiation is classified in which spectrum?

A. Radiation
B. Energy
C. Atomic
D. Electromagnetic

A

D. Electromagnetic

67
Q

X-rays have a duel nature, which means that they behave like both _________________

A. Atoms and molecules
B. Photons and quanta
C. Waves and particles
D. Charged and uncharged particles

A

C. Waves and particles

68
Q

The wavelength and frequency of x-rays are_______________related

A. Directly
B. Inversely
C. Partially
D. Not

A

B. Inversely

69
Q

X-rays have____________electrical charge

A. A positive
B. A negative
C. An alternately positive and negative
D. No

A

D. No

70
Q

X-rays have__________

A. No mass
B. The same mass as electrons
C. The same mass as protons
D. The same mass as neutrons

A

A. No mass

71
Q

The x-ray beam used in diagnostic radiography can be described as being________________

A. Homogenous
B. Monoenergetic
C. Polyenergetic
D. Scattered

A

C. Polyenergetic

72
Q

The unit that measures the transfer of radiation energy into tissue is known as the____________

A. Roentgen
B. REM
C. Gray
D. Sievert

A

C. Gray

73
Q

Which of the following will minimize radiation exposure to the patient?

A. Beam restriction
B. Gonadal shielding
C. Screening for pregnancy
D. All of the above

A

D. All of the above