Mammography Exam Questions with correct
Answers
Two screening mammography views
Craniocaudal and Mediolateral
When is ultrasound often used for mammography?
To differentiate cysts from solid masses and also for biopsy needle guidance
When is MRI often used for mammography?
Can differentiate from benign and malignant tumors. Used for diagnosis, staging, biopsy
guidance, and in some cases screenings.
When is mammoscintigraphy using Tc-99m sestamibi used?
In the evaluation of suspected breast cancer in patients for whom mammography is
nondiagnostic, equivocal, or difficult to interpret (eg scar tissue, dense breast tissue,
implants, or sever dysplastic disease). Also used to assist in identifying multicentric and
multifocal carcinomas in patients with tissue diagnosis of breast cancer.
Why are very low kVs used in mammography?
The contrast differences between cancerous and normal tissue are very small but more
noticeable at 10-15 keV.
Typical mammography focal spot sizes
0.3 mm (lg) and 0.1 mm (sm)
mA limits for mammography tubes
,100 mA for lg fs, 25 mA for sm fs. Or, for W anode, 200 mA for lg and 50 mA for sm
Why are Mo and Rh good target materials for anodes?
Mo produces characteristic x-rays of 17.5 and 19.6 keV, Rh of 20.2 and 22.7 keV
Why is W being used as an anode material in modern mammography units?
Increased, x-ray production efficiency (higher Z), better heat loading (higher melting point).
In addition, digital detectors have extended exposure latitude and because post-acquisition
image processing can enhance contrast, characteristic radiation from Mo or Rh is not as
important in digital mammography. Reduces dose (~65% of Mo?)
Specs on mammography anodes
Angles from 0-16 degrees (effective anode angle at least 22 degrees for a 24x30 cm field),
SID of about 65 cm.
How is the heel effect used in mammography?
The cathode (greatest intensity) is positioned over the chest wall and the anode over the
anterior to achieve uniform coverage to the detector
What is another reason the x-ray tube is oriented front-back in mammography?
It decreases the equipment bulk near the patient's head. The anode is kept at ground and
the cathode is set to highest negative voltage to reduce off-focal radiation.
"Half-field" x-ray beam geometry
Used to avoid exposure of patients' torsos and maximize breast tissue near chest wall
imaged. Achieved by fixed collimation at the x-ray tube head. The central axis of the x-ray
beam is directed at the chest wall edge of the receptor and perpendicular to the plane of
, the image receptor. The nominal focal spot size is measured at the reference axis, which
bisects the ex-ray field along the chest-wall-anterior direction of the field.
Projected mammography focal spot diagram
As a consequences of effective focal spot size variation in the field (the line focus
principle), there is greater spatial resolution on the (anterior/chest wall) side
anterior
Tube focal spot length at the reference axis formula
Where is the line pair phantom placed in a QC survey?
For contact mammo, 4.5 cm above breast support surface near the chest wall. For
magnification, 4.5 cm above magnification platform
Effective resolution
Reflects effects of focal spot dimensions, acquisition geometry, and detector sampling
characteristics
What limits the resolution in mammography?
In magnification, focal spot size. In contact, the detector element size or patient motion
Mammography spectrum illustration
Typical mammography filter thickness
0.03 mm Mo, 0.025 mm Mo/Rh, 0.05 W/Rh or W/Ag, 0.07 W/Al
Typical mammo target/filter combinations
Mo/Mo, Mo/Rh, Rh/Rh, W/Rh, W/Ag, W/Al
Answers
Two screening mammography views
Craniocaudal and Mediolateral
When is ultrasound often used for mammography?
To differentiate cysts from solid masses and also for biopsy needle guidance
When is MRI often used for mammography?
Can differentiate from benign and malignant tumors. Used for diagnosis, staging, biopsy
guidance, and in some cases screenings.
When is mammoscintigraphy using Tc-99m sestamibi used?
In the evaluation of suspected breast cancer in patients for whom mammography is
nondiagnostic, equivocal, or difficult to interpret (eg scar tissue, dense breast tissue,
implants, or sever dysplastic disease). Also used to assist in identifying multicentric and
multifocal carcinomas in patients with tissue diagnosis of breast cancer.
Why are very low kVs used in mammography?
The contrast differences between cancerous and normal tissue are very small but more
noticeable at 10-15 keV.
Typical mammography focal spot sizes
0.3 mm (lg) and 0.1 mm (sm)
mA limits for mammography tubes
,100 mA for lg fs, 25 mA for sm fs. Or, for W anode, 200 mA for lg and 50 mA for sm
Why are Mo and Rh good target materials for anodes?
Mo produces characteristic x-rays of 17.5 and 19.6 keV, Rh of 20.2 and 22.7 keV
Why is W being used as an anode material in modern mammography units?
Increased, x-ray production efficiency (higher Z), better heat loading (higher melting point).
In addition, digital detectors have extended exposure latitude and because post-acquisition
image processing can enhance contrast, characteristic radiation from Mo or Rh is not as
important in digital mammography. Reduces dose (~65% of Mo?)
Specs on mammography anodes
Angles from 0-16 degrees (effective anode angle at least 22 degrees for a 24x30 cm field),
SID of about 65 cm.
How is the heel effect used in mammography?
The cathode (greatest intensity) is positioned over the chest wall and the anode over the
anterior to achieve uniform coverage to the detector
What is another reason the x-ray tube is oriented front-back in mammography?
It decreases the equipment bulk near the patient's head. The anode is kept at ground and
the cathode is set to highest negative voltage to reduce off-focal radiation.
"Half-field" x-ray beam geometry
Used to avoid exposure of patients' torsos and maximize breast tissue near chest wall
imaged. Achieved by fixed collimation at the x-ray tube head. The central axis of the x-ray
beam is directed at the chest wall edge of the receptor and perpendicular to the plane of
, the image receptor. The nominal focal spot size is measured at the reference axis, which
bisects the ex-ray field along the chest-wall-anterior direction of the field.
Projected mammography focal spot diagram
As a consequences of effective focal spot size variation in the field (the line focus
principle), there is greater spatial resolution on the (anterior/chest wall) side
anterior
Tube focal spot length at the reference axis formula
Where is the line pair phantom placed in a QC survey?
For contact mammo, 4.5 cm above breast support surface near the chest wall. For
magnification, 4.5 cm above magnification platform
Effective resolution
Reflects effects of focal spot dimensions, acquisition geometry, and detector sampling
characteristics
What limits the resolution in mammography?
In magnification, focal spot size. In contact, the detector element size or patient motion
Mammography spectrum illustration
Typical mammography filter thickness
0.03 mm Mo, 0.025 mm Mo/Rh, 0.05 W/Rh or W/Ag, 0.07 W/Al
Typical mammo target/filter combinations
Mo/Mo, Mo/Rh, Rh/Rh, W/Rh, W/Ag, W/Al
