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48 Cards in this Set
- Front
- Back
FEATURES OF MAMMOGRAPHIC UNIT:
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Adequate contrast
Fine details Easy positioning of breast with firm compression Low radiation dose to breast tissues Consistency of exposure factors |
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What are the benefits of the high frequency generator?
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Allows precise control of kVp, mA, and
exposure times; Excellent linearity & reproducibility of X-ray exposures; More efficient x-ray production; Do not require an autotransformer or line compensation circuit – compact |
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What is the range of kVp used in mammography?
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KVp selections range from 22 to 40 KVp
- commonly used in clinical practice varies between 25 & 32 KVp (Breast tissue has low inherent subject contrast) |
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What is the exposure time, ma and mAs?
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mA varies from 2 to 180
Short exposure times to reduce motion Exposure times : 0.4 to 2 sec (standard projections) 2 to 4 sec ( magnification technique) - low mA & small focus |
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What is the AUTOMATIC EXPOSURE CONTROL used for?
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To provide consistent film density for the various
thickness & density compositions of breast tissues Radiation-sensitive detectors |
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where is the optimal placement of the photocell/detector?
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beneath the most dense area of the breast.
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a fatty breast/area would produce ____ image.
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- Less dense
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a glandular breast/area would produce _____ image.
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– Dense (Increased in density)
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study the parts of the mammographic unit
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study!
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Study the parts of the mammographic unit x-ray tube
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- Helical shaped tungsten filament
- Focal spot sizes 0.3 & 0.1 mm |
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When using conventional X-ray tube, will have missed tissue
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study!
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Make sure no missed tissue, use mammo unit where anode at the side
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study
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X-ray tube
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Anode - Solid Mo disk
doped with 3% vanadium |
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what is the range of the rahodium Rh target?
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s x-rays with a higher
energy range of about 20.2 and 22.8 keV |
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For very dense breasts, what target is the best option?
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Rhodium
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What are the type of filters that are most commonly used?
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Molybdenum & Rhodium
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What is an advantage of using different type of combinations of target and filter material?
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allows improvement
in penetration and reduction in the mean glandular dose in dense breasts. |
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What is the main goal of mammograpy imaging?
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The goal is to obtain the highest possible image quality while using the lowest
radiation dose. |
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the choice of target and filter combination will affect ________ (3 things)
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-High contrast
-Low dose -Compromise between dose and contrast |
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what are the advantages of using Molybdenum?
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- Increased number of low-energy
photons - High radiographic contrast |
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What are the disadvantages of using Mo?
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Less X-ray photons output
Increased mAs required Increased dose |
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what is the energy if the Mo filter?
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20 keV K-edge energy
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If Mo has an energy of 20 keV K-edge, radiation above ____keV will be removed.
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20
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what is the thickness of an Mo filter?
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0.03mm
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Using Mo filter, ________ will be removed.
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high end bremsstrahlung/X-rays
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What is a good combination for fatty breast tissues / breast with 1:1 fatty and glandular tissues?
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Molybdenum target and Molybdenum filter. (Mo/Mo)
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What is the energy of a Rhodium filter?
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Rhodium has a 23 KeV K-edge energy, so it allows
slightly higher energy x-rays to pass through. |
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When is a Mo/Rh selected?
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when imaging denser breasts
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What is the thickness of Rh filter?
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0.025 mm
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Study the Moly/Rhodium spectrum
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Moly target
Rh 0.025mm filter |
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Study the Moly/Moly spectrum
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mo target
mo 0.03mm filter |
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What combination combines higher energy x-rays with higher energy filter?
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Rh/Rh
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Rh/Rh provides more
penetration than the Molybdenum/Rhodium combination. True/false?` |
True
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What type of breasts is Rh/Rh good for?
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This works best for very thick breasts or very dense breasts.
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Name another kind of filter that's ;es commonly used.
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Aluminum Filter
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what is a typical range of kVp for mo target?
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24 to 30 KVp
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what is a typical range of kVp for rh target?
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26 to 32 KVp.
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give advantages for magnified views
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Increased resolution
- due to small focal spot & reduced quantum mottle. Reduction in scatter radiation reaching the film due to air-gap. Improved visibility of detail due to the larger field of view. |
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what is the functionof a grid?
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To reduce scatter radiation reaching the film
and maintain high contrast in the image. |
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grid specification (mammo unit)
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Grid ratio: 4 : 1 or 5 : 1
30 - 50 lines per cm Moving grid |
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What is A?
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X-ray tube
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What is B?
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Berrylium window
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C?
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Filter
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D?
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Extension cone
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What is E?
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Compression
paddle |
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F?
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grid
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G?
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AEC
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What is the focal spot sizes of tungsten filament in mammo unit X-ray tube?
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0.3& 0.1 mm
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