Mammography Physics

Question 1

Mammography which identify cancer in asymptomatic patients

Answer 1

Screening mammography

Question 2

Assess palpable lesions or evaluate suspicious lesions

Answer 2

Diagnostic mammography

Question 3

To differentiate cysts from solid lesions

Answer 3

Ultrasound

Question 4

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

Answer 4

MRI

Question 5

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

Answer 5

Mammoscintigraphy

Question 6

Mammohraphy has DUAL FILAMENTS

Answer 6

0. 3 mm

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

Question 7

Operating voltage of mammography

Answer 7

Below 40 kV

Question 8

Most common anode target material used in mammography

Answer 8

Molybdenum

Question 9

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

Used in DIGITAL mammography

Answer 9

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

Question 10

Source to image receptor distance in mammography

Answer 10

65cm

Question 11

Effective anode angle (adequate field coverage)

Answer 11

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

Question 12

Positioning of patient

Answer 12

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

Question 13

Focal spot nominal sizes

Answer 13

Contact mammography: 0.3 to 0.4mm

Magnification imaging: 0.1 to 0.15

Question 14

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

Answer 14

Half field

Question 15

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

Answer 15

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

Question 16

Tube port window in mammography

Answer 16

Beryllium (z=4)

Question 17

Elements that have K-shell binding energies

Answer 17

Mo, Rh and Ag

Question 18

Half value layer of a mammography xray beam

Answer 18

0.3 to 0.7 mm Al for the kV range

Question 19

HVL for breast tissues

Answer 19

1 to 3 cm

Question 20

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

Answer 20

Too much filtration
Pited anode
Aged tube

Question 21

Tube output

Answer 21

Measure of the intensity of the xray beam

Question 22

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

Answer 22

Fixed size metal apertures or adjustable shutters

Question 23

Used for optimizing the oblique projections for subjects with smaller breasts

Answer 23

Field Shift

Question 24

Automatic Exposure Control (AEC) employs

Answer 24

Radiation sensor
Charge amplifier
Voltage comparator

Question 25

For cassette based image receptors where is the phototimer located

Answer 25

Underneath

Question 26

Modifies the AEC response to permit adjustments for unusual imaging circumstances

Answer 26

Exposure adjustment selector (generator control panel)

Question 27

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

Answer 27

Back up timer

Question 28

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

Answer 28

Technique charts

Question 29

Firm compression

Answer 29

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

Question 30

Compression force

Answer 30

111 to 200 newtons (25 to 44lbs)

Question 31

Carries information regarding the attenuation characteristics of the breast

Answer 31

Primary radiation

Question 32

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

Answer 32

Scattered radiation

Question 33

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

Answer 33

Bucky Factor ( 2 to 3 in mammography)

Question 34

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

Answer 34

Geometric magnification

Question 35

Screen film mammogram comprises

Answer 35

Cassette Intensifying screen Light sensitive film

Question 36

Most commonly used screen phosphor (mammo)

Answer 36

Terbium activated gadolinium oxysulfide

Question 37

Degree of the obstruction of light transmission and optical density

Answer 37

Film opacity

Question 38

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

Answer 38

H and D curve (Film characteristic curve)

Question 39

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

Answer 39

Gradient Graph

Question 40

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

Answer 40

Sensitometer

Question 41

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

Answer 41

Densitometer

Question 42

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

Answer 42

Indirect conversion

Question 43

Four technologies for mammography based systems

Answer 43

Indirect conversion Direct conversion Stimulated luminescence Slot

Question 44

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

Answer 44

Computer aided detection (CADe)

Question 45

Include software that provides information BEYOND identifying suspicious findings

Answer 45

Computer assisted diagnosis (CADx)

Question 46

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

Answer 46

Stereotactic breast biopsy