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FEESICKS BUSHBIRD III > Chapter 7 - Radiography > Flashcards

Chapter 7 - Radiography Flashcards

1
Q

A procedure where X-ray shadows project the patient’s anatomy onto the detector

A

Projection radiography

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2
Q

An exposed film that has not been chemically developed which contains a pattern of invisible silver halide grains with latent image centers

A

Latent image

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3
Q

Slight differences in film density depending on the exposure rate

A

Reciprocity law failure

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4
Q

Aqueous chemical bath containing a reducing agent

A

Developer

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5
Q

Bath of an aqueous oxidizing solution

A

Fixer

  • dissolves the remaining (inactivated) silver halide from the emulsion layer areas that were not exposed (or were underexposed) to light.
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6
Q

Plot of the log of the relative exposure on the X axis and the optical density (OD) of the processed film on the y-axis

A

H and D curve (Hurter and Driffield)

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7
Q

Defined as the negative of the base-10 logarithm of the transmittance (T) of the film

A

Optical density

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8
Q

Refers to a photostimulable phosphor detector (PSP) systems

A

Computed radiography

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9
Q

PHOSTIMULABLE PHOSPHOR DETECTOR (PSP) screens

A

Storage phosphors

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10
Q

Activation procedure that creates defects in the BaFBr crystals that allow electrons to be trapped more efficiently

A

Doping

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11
Q

Defects in the crystalline lattice caused by the europium dopant

A

F-centers

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12
Q

Refers to the stage where the number of quanta is the lowest and therefore where the statistical integrity of the signal is worst

A

Quantum sink

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13
Q

The quantum sink should be at the stage where the X-ray photons are absorbed in the converter (scintillator or solid state detector)

A

X-Ray quantum limited detector

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14
Q

Detectors that make use of technology similar to that used inflation panel displays….

A

Flat panel thin-film-transistor(TFT) array detectors

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15
Q

Uses a scintillator to convert X-rays to light with optical coupling of the scintillator to the active matrix

A

Indirect X-Ray conversion TFT(thin-film-transistor) arrays

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16
Q

An electronic switch that is comprised of three connections: gate, source, and drain

A

Thin-Film-Transistor (TFT)

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17
Q

Refers to the percent of the area of each Dexel that is photosensitive

A

Fill factor

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18
Q

Use a semiconductor material that produces electron-hole pairs in proportion to the incident X-ray intensity

A

Direct X-ray conversion TFT arrays

19
Q

Lower kVs emphasize _______due to the photoelectric effect in the patient

***page 223

A

Contrast

20
Q

At the same kV and distance, the X-ray fluence is ______ proportional to the mAs– double the mAs and the X-ray fluence _____.

**page 223

A

Linearly; doubles

21
Q

Used to describe how well X-ray detectors captures the incident X-ray photon beam

A

Quantum detection efficiency

22
Q

Most X-ray detectors are?
A. Energy integrators
B. Photon counters

A

A. Energy integrators

23
Q

Include X-ray to light photon Energy transfer in scintillators, etc.

A

Conversion efficiency (CE)

24
Q

Increasing the speed of the detector by increasing the CONVERSION EFFICIENCY _______ image noise.

***page 226

A

Increases

25
Q

Increasing ABSORPTION EFFICIENCY can ____ dose but has ______ on quantum noise in the image

***page 226

A

Reduce; no detrimental effect

26
Q

A phenomenon where technologists tend to use unnecessarily high exposures(most likely occurs in exams such as portable radiography)

A

Dose creep

27
Q

Indicates the amount of radiation reaching the detector and is not an indicator of dose to the patient

A

Exposure index

28
Q

Feedback to the user on whether an appropriate exposure has been achieved is given by the_____.

A

Deviation index (DI)

DI=0 ; intended exposure to the detector is achieved
DI>0 ; overexposed
DI<0 ; underexposed

29
Q

Higher atomic number materials (i.e.bone,with effective Z = 13,or Iodine, with Z=53) have _______ photoelectric absorption levels than lower atomic materials such as soft tissue (effective Z=7.6)

A

HIGHER

30
Q

Characterizes the amount of scatter detected in an image

A

Scatter-to-primary ratio (SPR) OR the Scatter Fraction

31
Q

Most widely used technology for reducing scatter in radiography,fluoroscopy and mammography

A

Anti-scatter grid (aka scatter grid)

32
Q

The ratio of the height of the interspace material to its width; most fundamental descriptor of the grid’s construction

A

Grid ratio

33
Q

The number of grid septa per centimeter

A

Grid frequency

34
Q

Occurs if the X-ray tube is accidentally located at a different distance from the grid

A

Grid cut-off

35
Q

A grid that moves with a reciprocating motion during the X-ray exposure,causing the grid bars to be blurred by this motion and not visible in the image. The motion is PERPENDICULAR to the long axis of the linear septa in the grid

A

Bucky grid

36
Q

Essentially describes the radiation dose penalty of using the grid

A

Bucky factor

37
Q

Fraction of primary photons that are transmitted through the grid

A

Primary transmission factor

38
Q

Fraction of scattered radiation that penetrates the grid

A

Scatter transmission factor

39
Q

Refers to the reduction in contrast due to scattered radiation

A

Contrast Degradation Factor

40
Q

By moving the patient away from the detector, less of the scatter that is emitted from the patient will strike the detector; concept is similar to INVERSE SQUARE LAW (radiation intensity decreases as the square of the distance from the source)

A

Air gap principle

41
Q

Gold standard in scatter reduction methods

A

Scan-slot radiography

42
Q

Rare earth scintillator (3)

A

Gd2O2S, LaOBr and YTaO4

43
Q

Silver halide film composition…

A

95% AgBr and 15% AgI

44
Q

(Film) _____ introduces defects in the ionic crystal structures

A

AgS

FEESICKS BUSHBIRD III (13 decks)

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