Introduction to Radiologic and Imaging Sciences and Patient Care: Radiographic Imaging Flashcards


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1

Intercepts the x-ray photons that are able to exit the patient (remnant radiation). Converts the energy of x-rays into an image.

Image receptor (IR)

2

Classes of Diagnostic Radiographic Imaging.

Film-screen Computed Radiography (CR) Digital Radiography (DR) Fluoroscopic imaging (NOTE: there are also cassette-based and cassette-less systems)

3

Requirements for x-ray production.

1. Vacuum inside x-ray tube 2. Source of electrons 3. Method to accelerate electrons to great speed 4. Method to stop electrons

4

Source of electrons.

1. Cathode 2. Filament (Within the cathode)

5

Method to accelerate electrons to great speed

Voltage (kVp)

6

Method to stop electrons

Target(Anode)

7

Classes of Radiation

Primary radiation Scatter radiation Absorbed radiation Remnant radiation

8

Primary radiation

The radiation (beam of photons) before it interacts with a patient's body. (Leaves the tube)

9

Scatter radiation

Type of radiation that provides little diagnostic information to image. Detracts from image quality with the creation of 'fog'.

10

Absorbed radiation

Radiation that does not exit the patient.

11

Remnant radiation

Radiation that exits the patient and creates an image in the IR. Creates chemical changes within the receptor that are invisible.

12

What is the reason an x-ray tube must have a vacuum?

The vacuum removes all of the air so gas molecules will not interfere with the production of x-rays

13

Attenuation

Loss of radiation energy as a result of passing through an absorbing material (body).

14

High attenuation

Degree of attenuation that occurs in radiopaque matter. (X-rays cannot pass through.)

15

Low attenuation

Degree of attenuation that occurs in radiolucent matter.

16

Differential absorption

Different materials absorb radiation energy differently based primarily upon density and atomic number.

17

Latent image

Invisible image created after exposure but before processing. (It must be processed to convert it to a visible image)

18

Considered an analog type of imaging

Film-screen systems

19

photostimulable phosphor (PSP) technology or storage phosphor technology

Computed radiography (CR)

20

Two methods of digital image capture. Can be indirect or direct?

Digital radiography (DR)

21

Digital radiography key features.

Uses no cassettes Image is displayed in seconds Detectors can be direct or indirect Uses thin-film transistors (TFT) Image brightness is not the same as radiographic density and is not related to exposure

22

Direct

Type capture that x-ray photons are immediately converted into an electrical signal.

23

Indirect

Type capture that x-ray photons are converted to light and then converted into an electronic signal.

24

Determines image quality in digital cassette-less systems. The more _________ the better the image.

Pixels

25

How do Film-screen systems work?

Intensifying screens convert the X-ray energy to light, and light energy creates chemical changes in film.

26

Exposed X-ray film is chemically processed in a ________ _____________ automatic processor.

wet chemistry

27

Exposure Index (EI)

A numeric representation of total x-ray exposure to the receptor. It is not an indicator of the patient's absorbed dose.

28

Prime technical exposure factors that a radiographer has direct control over.

Milliampere-second (mAs) Kilovoltage peak (kVp) Source-to-image distance (SID)

29

A proper balance between _____________ and __________ qualities is required for optimum image quality.

photographic and geometric

30

Photographic qualities

affecting the visibility of the image

31

The two primary image photographic quality factors:

IR exposure/Density Contrast

32

Geometric qualities

Contribute to image quality by affecting image resolution, size, and shape. Affect sharpness and accuracy of the image. Also known as recorded detail, sharpness of detail, and definition.

33

radiographic density

The overall darkness or blackness of an image as demonstrated on a polyester-based film media

34

What aspects primarily affects Image Receptor Exposure?

milliamperage (mA), exposure time (S), source-to-image distance (SID), kVp

35

mAs

Determines how many x-rays are produced by the x-ray tube. (It directly controls the quantity of x-ray photons produced)

36

quantity of x-ray production

mA

37

What is the relationship between mAs and density?

Directly proportional If the mAs is doubled the density is doubled. If the mAs is halved the density is halved

38

_____________ is the electrical current passing through the xray tube

mA

39

_____ is the duration of the exposure

S Can be expressed in decimals, fractions or milliseconds

40

mAs reciprocity law

Regardless of the mA and time combinations, the same mAs value will yield the same exposure

41

kVp

Measure of the electrical pressure forcing the current through the tube. It controls penetrating ability of the beam. (It affects the quality and quantity of x-ray photons produced)

42

X-ray beam is ______________ or _______________________.

poly-energetic or heterogeneous.

43

Higher kVp values _________ skin exposure to patients.

reduce

44

Increasing kVp ?% will double image receptor exposure

15

45

To maintain exposure, if increasing kVp by 15%, must ________ mAs

half

46

Grid

Used to reduce scatter. It intercepts a portion of the remnant radiation and improves image quality. Requires higher exposure technique when used.

47

SID

Distance between point of x-ray emission in the x-ray tube (focal spot) and the IR. (It affects intensity of radiation that reaches the IR as well as the geometric properties of the image)

48

What law deals with distance and intensity?

Inverse Square Law

49

What is the formula for the Inverse Square Law?

I1/I2= D2²/D1²

50

What law deals with distance and mAs?

Direct Square Law

51

What is the formula for the Direct Square Law?

mAs1/mAs2 = D1²/D2²

52

Can improve image quality and reduce dose as well as control scatter

Beam modification

53

Two types of primary beam modification:

-Filtration -Beam limitation (collimation)

54

Beam modification that involves use of attenuating material (aluminum) and removes low energy x-ray photons to decrease patient exposure. The more __________ used, the less intense the beam.

Filtration

55

Beam modification that decreases patient dose as well as improving image quality.

Beam limitation (collimation)

56

Factors affecting recorded detail

Motion Object unsharpness Focal spot size SID OID Material unsharpness Distortion

57

Most common cause of image unsharpness.

Motion distortion (Caused by voluntary and involuntary patient motion)

58

Object unsharpness

Loss in resolution caused by the inherent shape of the patient's anatomic structures relative to the divergence of the x-ray beam.

59

Optimum use of __________, __________, and __________ can lessen object unsharpness.

Focal point size OID SID (Increased SID makes image sharper)

60

The smaller the focal spot size, the __________ the detail.

Greater

61

Distortion

Any misrepresentation of the true size or shape of the patient's anatomy.

62

Two types of distortion.

Size Shape

63

Size distortion is minimized by using _________ and __________.

Longer SIDs Minimum OIDs

64

Shape distortion

Distortion controlled by alignment of central ray, patient's anatomy, and IR. It is also called 'true distortion'.

65

Deliberate distortion

Accomplished by angling or rotating the patient relative to the central ray. Helps overcome superimposition of anatomic structures.

66

Image density

Overall darkness or blackness of an image. It is directly related to x-ray exposure hitting the IR.

67

Half-Value layer

Term used for the amount of absorbing material that will reduce the intensity of the x-ray beam to half its original value. It is a way to express x-ray beam quality.

68

_________________ is most popular filtration material.

Aluminum

69

_________ detect the remnant radiation from the patient and convert it into chemical or electrical changes that make up the latent image

IRs

70

Three types of image receptors

Film/screen systems -Close to obsolescence Storage phosphor technology (CR) Flat-panel detectors using thin-film-transistor (TFT) technology

71

CR Technology

Exposed IP in cassette is placed in a reader for electronic processing of the latent image into a manifest image displayed on a monitor. Ultimately creates a digital image through computer software

72

Exposure to plate is stored in ___________ _________ ________ that create electron "traps."

barium fluorohalide crystals

73

Underexposure will produce an image that is "grainy" or noisy due to _____________.

quantum mottle

74

How does CR work?

-Cassette with IP placed in CR reader -Reader scans the IP with laser energy and recovers the energy from the electron traps -Energy converts into manifest image

75

__________ detector uses cesium iodide as a scintillator with amorphous silicon.

Indirect

76

Digital Cassetteless Systems use ____________ arranged in a matrix

Detector elements(DEL)

77

How does Indirect Detector Technology work?

-Uses a scintillator material bonded to amorphous silicon -Scintillator receives the X-ray energy and converts it to light energy. -Light energy is captured by amorphous silicon and converted to electrons. -Electrons are collected by TFT and sent to computer.

78

uses amorphous silicon (aSi)

Indirect DR

79

Digital detectors possess ___________ exposure latitude than conventional film-screen systems.

greater

80

DR systems can be operated at varying system sensitivities, known as ___________ _________.

system speed

81

How does Direct Detector Technology work?

.-Uses amorphous selenium as the active detector material -Uses TFT to capture electrons from X-ray interactions -TFT collects and amplifies the electron signal. -Electron signals are converted to computer data and displayed as an image.

82

uses amorphous selenium (aSe)

Direct DR

83

controls image brightness.

window level

84

controls contrast.

Window width (WW)

85

During __________, x-ray exposures are much less than radiographic exposures. Use of x-rays to create real-time images of patient anatomy and function Images taken are digital images and can be played back for review or sent to an archival system for long term storage (PACs)

Fluoroscopy