MIDTERM PT. 2 Flashcards
Equipment parts: (mammogram)
- x-ray tube
- tube port
- filter
- .collimator
- compression paddle
- grid
- x-ray detector
- phototimer detector
Components of : (mammogram)
- c-arm x-ray tube stand
- mammography tube
- beam restricting device
- grid
- casette holder
- others
Patient support includes:
- lead apron
- holding support
- seating table
- patient gown
mammography tube consists of: (2)
anode +
cathode -
cathode has a ___ and ___
focusing cup
filament
The mammography x-ray tube is configured with dual-filaments in the
focusing cup to produce 0.3mm and 0.1mm focal spot size(fss)
cathode
dual-filaments in the focusing cup to produces ____and____ focal spot size (fss)
0.3mm
0.1mm
Anode Target Materials:
1.Molybdenum
2. Rhodium
3. Tungsten
most common anode target material used in mammography x-ray tube (soft tissue imaging)
molybdenum
“Dual Targets are also used ____”
Mo/Rh
what type of x-ray tube:
-glass envelope
-tungsten anode
-anode angle 7 degrees to 16 degrees
-axis of rotation- horizontal
-Al filter for dose reduction
Conventional x-ray tube
what type of x-ray tube:
-metal tube housing
-grounded Mo, Rh anode
-anode angle is o degree- tube tilt 16 degrees-
-axis of rotation- vertical
-Mo and Rh filters for special shaping
Mammography x-ray tube
used for special shaping
Mo and Rh
Made up of Beryllium (Beryllium Window / Be Window)
exit window
____ proximal collimator for the reduction of extra focal radiation
focus
used as it has a low atomic number of 4
Beryllium
Beryllium has a low atomic number of ____ and lower absorption of less than ____.
4
5kVp
___ of Be is equivalent to ____ Al material (inherent filtration)
1mm
0.1mm
Mo target with 0.03 mm Mo filter (atomic no. _____)
42
Rh target with 0.02mm Rh filter (atomic no. _____)
45
___ Target with ____ Rh filter
W
0.05mm
Target filter recommendations are for:
- fatty breast up to ~4 cm thick
- glandular breast~ 5 to 7 cm
- breast thickness > 7 cm
target-filter reco.:
-Mo target and 30 micron Mo filter
-24-26 kVp
fatty breast up to ~4 cm thick
target-filter reco.:
-Mo target and 25 micron Rh filter
-27-31 kVp
glandular breast~ 5 to 7 cm
target-filter reco.:
-Rh target and 25 micron Rh filter
breast thickness > 7 cm
The source-to- image plane- distance (SID) typical ____
60-65 cm
focal spot size (fss) are:
-0.3 to 0.4mm
-0.1 mm
FSS: for contact mammography (breast compressed against the grid and image receptor)
0.3 to 0.4mm
FSS: for magnification mammography, it reduces geometric blurring so that microcalcifications can be resolved.
0.1 mm
One fortunate consequence of the line focus principle
Anode heel effect
Radiation Intensity on the cathode side of the x-ray tube is ____ that the anode side
higher
the _____ the anode; the _____ the anode heel effect
smaller
greater
Cathode Side
Chest wall
Anode Side
nipple
-must be a moving grid.
-Focused grid, with a grid ratio 3:1 or 5:1
anti-scatter grids
Focused grid, with a grid ratio ____
3:1 or 5:1
types of screen film casettes:
- conventional screen film
- computed radiography
Flat surface plate used for uniform compression.
compression device
compression plate : anterior portion of the breast is not compressed properly
conventional compression plate
compression plate: are better for equal compression to all areas of the breast
Newer slanted paddles
Uruguanian radiologist who first uses breast compression
Raul Leborgne, MD
what year: first breast compression used
1949
what year: compression devices common on dedicated mammography units
1970’s
What are the functions of breast compression:
- reduces breast thickness
- reduces motion and geometric unsharpness
- reduces x-ray scatter and beam hardening, thus improving contrast
-lowers radiation
-spreads breast tissue apart
-produces a more uniform thickness
-allow use of narrow latitude, high contrast film
reduces breast thickness
a 22.5 degrees angled paddle, followed by progressive angle reduction
Breast biphasic compression
Advantages of Breast biphasic compression:
- Provides immobilization of the part during exposure
- Produces radiograph of uniform density
- Improves contrast
- Reduces tissue overlap and improves resolution
Disadvantage of Breast biphasic compression:
patient discomfort
It is used to magnify small area of the breast for better visualization
spot compression
uniform density across the image
-clear polycarbonate paddle
-~0.3 cm thick
full compression paddle
better compression over small area
spot compression
compression:
- ___decreases tissue thickness
-low superimposition of tissues
SPOT COMPRESSION
spot paddle
compression:
-clear polycarbonate paddle
-~0.3 cm thick
-flat, parallel geometry deflection < 1cm
AREA COMPRESSION
full compression paddle
amount of compression is between ___ and ___ pounds of pressure
25
40
uncompressed scatter to primary ratio is ___
0.8-1.0
compressed scatter to primary ratio is ___
0.4 - 0.5
2 types of compression:
- Area compression
- spot compression