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Brant And Helms > Mammography Physics > Flashcards

Mammography Physics Flashcards

1
Q

Mammography which identify cancer in asymptomatic patients

A

Screening mammography

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2
Q

Assess palpable lesions or evaluate suspicious lesions

A

Diagnostic mammography

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3
Q

To differentiate cysts from solid lesions

A

Ultrasound

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4
Q

Excellent tissue contrast sensitivity and with contrast enhancement. Can be used to diagnose, stage, biopsy guidance and sometimes for screening

A

MRI

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5
Q

Utilizes Tc - 99m sestamibi evaluation of suspected breast ca in patients whom mammography is non diagnostic

A

Mammoscintigraphy

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6
Q

Mammohraphy has DUAL FILAMENTS

A
  1. 3 mm

0. 1 mm - for magnification studies to reduce geometric blurring

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7
Q

Operating voltage of mammography

A

Below 40 kV

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8
Q

Most common anode target material used in mammography

A

Molybdenum

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9
Q

Increase use of tungsten (W) is due to its…

Used in DIGITAL mammography

A

Increased xray production efficiency (due to high atomic number)
Improved heat loading (higher melting point)

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10
Q

Source to image receptor distance in mammography

A

65cm

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11
Q

Effective anode angle (adequate field coverage)

A

At least 22 degrees
0 degree - tube tilt of 24 degrees
16 degree - tube tilt of 6 degress

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12
Q

Positioning of patient

A

Cathode (kept at highest negative voltage) over the Chest wall
Anode (kept at ground potential) over the anterior portion (nipple)

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13
Q

Focal spot nominal sizes

A

Contact mammography: 0.3 to 0.4mm

Magnification imaging: 0.1 to 0.15

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14
Q

In order to avoid exposure of the patient’s torsos and to maximize thr amount of breast tissue near the chest wall. Mammography utilize _____ which is achieved by fixed collimation at the xray tube head

A

Half field

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15
Q

Focal spot resolvability with or without magnification is measured by imaging a high resolution bar pattern with up to

A

20 line pairs/mm

Conventional breast imaging: 4.5 cm above the breast support surface near the chest wall

Magnification imaging: placed 4.5 cm above the magnification palform

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16
Q

Tube port window in mammography

A

Beryllium (z=4)

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17
Q

Elements that have K-shell binding energies

A

Mo, Rh and Ag

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18
Q

Half value layer of a mammography xray beam

A

0.3 to 0.7 mm Al for the kV range

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19
Q

HVL for breast tissues

A

1 to 3 cm

20
Q

X ray beam that is HARDER than optimal that results to a reduced output and poor image quality indicates

A

Too much filtration
Pited anode
Aged tube

21
Q

Tube output

A

Measure of the intensity of the xray beam

22
Q

Collimation of xray beam (mammography) is achieved by the use of

A

Fixed size metal apertures or adjustable shutters

23
Q

Used for optimizing the oblique projections for subjects with smaller breasts

A

Field Shift

24
Q

Automatic Exposure Control (AEC) employs

A

Radiation sensor
Charge amplifier
Voltage comparator

25
Q

For cassette based image receptors where is the phototimer located

A

Underneath

26
Q

Modifies the AEC response to permit adjustments for unusual imaging circumstances

A

Exposure adjustment selector (generator control panel)

27
Q

An xray exposure that is not stopped by the AEC circuit and exceeds a preset time is terminated by

A

Back up timer

28
Q

Useful guides to help determine the appropriate kV and target filter combinations for a specific tasks

A

Technique charts

29
Q

Firm compression

A

Reduces overlapping anatomy
Decreased breast tissue thickness
Reduces motion of the breast

30
Q

Compression force

A

111 to 200 newtons (25 to 44lbs)

31
Q

Carries information regarding the attenuation characteristics of the breast

A

Primary radiation

32
Q

Additive, gradually varying radiation distribution that degrades subject contrast and adds random noise

A

Scattered radiation

33
Q

The ratio of exposure with the grid compared to to the exposure without the grid to achieve the same film optical density

A

Bucky Factor ( 2 to 3 in mammography)

34
Q

Used to improve system resolution, typically for better visualization of microcalcidications

A

Geometric magnification

35
Q

Screen film mammogram comprises

A

Cassette
Intensifying screen
Light sensitive film

36
Q

Most commonly used screen phosphor (mammo)

A

Terbium activated gadolinium oxysulfide

37
Q

Degree of the obstruction of light transmission and optical density

A

Film opacity

38
Q

Represents the relationship between the incident xray exposure and the resulting OD in the processed film

A

H and D curve (Film characteristic curve)

39
Q

Graph of the change of OD per unit change in the incident exposure

A

Gradient Graph

40
Q

A device that emulates a range of incident radiation exposures by using a constant light source and calibrated optical attenuation steps to expose a mammographic film to known relative light intensities

A

Sensitometer

41
Q

Is a device that measures the light transmission through a small area of the film and calculates the OD

A

Densitometer

42
Q

Describes absorption of xrays in the CsI (structured cesium iodide)

A

Indirect conversion

43
Q

Four technologies for mammography based systems

A

Indirect conversion
Direct conversion
Stimulated luminescence
Slot

44
Q

Computer based set of algorithms that incorporates pattern recognition and uses sophisticated matching and similarity rules to flag possible findings on a digital mammographic image

A

Computer aided detection (CADe)

45
Q

Include software that provides information BEYOND identifying suspicious findings

A

Computer assisted diagnosis (CADx)

46
Q

Provide the capability to localize breast lesions in three dimensions and physicay sample them with a targeted biopsy instrument

A

Stereotactic breast biopsy

Brant And Helms (24 decks)

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