Card Set Information
What are the four main image quality factors?
What is the most significant geometric factor for spatial resolution?
Detector aperture width
What factors affect spatial resolution?
Focal spot size
What factors affect contrast resolution?
X-ray beam energy
Patient size and detector sensitivity also have direct effect on contrast resolution
What scan parameters affect noise?
X-ray beam energy
Also patient size and scattered radiation contribute to noise
What is incrementation?
The distance the table moves between scans aka scan index
Define SSD. What would you use SSD for?
Shaded Surface Display. CT numbers above threshold selected for 3D.
Soft tissue trauma
Define MIP. What would you use MIP for?
Maximum Intensity Projection
: Very bright images. Excludes unwanted anatomy below a certain CT number.
Contrast filled structures
What can endoluminal imaging be used for?
Contrast enhanced blood vessels or bladder
Pitch is the ratio of the speed of table motion to slice thickness.
Define segmentation and what it is used for.
A procedure that removes unwanted structures from the image, where different structures have similar radiodensity.
What are the three considerations for IV contrast media injections?
Volume, rate, scan delay.
What direction are CT brain scans done?
What direction are thorax CT scans done?
What direction are abdomen/pelvis CT scans done?
Does spiral CT give more or less dose than single slice?
Depends on choice of factors. In practice, gives more.
List the factors that affect CT dose.
Rotation or exposure time
Section or slice thickness
Dose reduction techniques (mA modulation)
Distance from tube to isocentre
Attenuation (size of patient, pediatric vs adult)
What is the biggest risk factor in developing breast cancer?
Age. Over 75% of BC occur in women >50
9 out of 10 women who get breast cancer have a family history of breast cancer. T/F?
False. 9 out of 10 women who get breast cancer DO NOT have a family history of breast cancer.
List clinical indications of breast cancer.
Change in size or shape of breast
Lumps in armpit
What is the breast made up of?
Ducts (carries milk from lobules to nipple)
Lobules (milk-producing glands)
Stroma (fatty and connective tissue)
Where do most breast cancers begin?
In the cells lining the ducts
Name the two routes of spread for breast cancer.
Lymphatic system or vascular system.
What are the two standard views in mammography?
: Cranial Caudal
: Mediolateral Oblique
Why are two projections obtained in mammography?
Increases the detection rate of breast cancer by 24%. (Wald et al., 1995)
What two things determine the quality of mammograms?
Specificity and sensitivity.
Which quality of a mammogram decreases false positives?
Specificity: the higher the specificity, the fewer false positives.
Which quality of a mammogram decreases false negatives?
Sensititivy: the higher the sensitivity, the fewer false negatives.
What is the difference in purpose between screening and diagnostic mammography?
: reducing mortality rate of breast cancer
: diagnosis of breast pathologies
What are the two ways of considering the pathology of the breast?
: ductal or lobule
2. Pathological classification
: benign or malignant