Flashcards in Imaging of cancer Deck (20):
What structure in the body are barium contrasts primarily used to show?
How do contrasts, such as barium sulphate, appear on a radiograph?
(unless inversed image)
Although they're rarely used, what are barium enema's used to study?
What are the types of cross-sectional imaging methods?
In what plane do CT, MRI and PET scanners take images?
What are Hounsfield's units?
Attenuation values for x-rays, of different substances
Relative to that of water
Air has a Hounsfield unit of:
b ( -1000 )
If it's easy to pass through, it's negative
If it is denser/better at absorbing - positive
What natural substance in the body has the highest Hounsfield unit?
+700 to +3000
What is the difference between a pixel and a voxel, and what are voxels used for?
Voxel is in the 3D plane, pixel is 2D
Used in 3D constructions of images taken from CT scans etc
Describe the oral contrast that is used in CT scanning.
Dilute iodine based contrast
Outline gastrointestinal tract
Not used much nowadays - scanners more effective
What contrast agent is used intravenously in CT scanning?
Describe it's effectiveness
Iodine based contrast
Shows blood vessels and vascularity of different tissues
What risk is associated with the IV contrasts in CT's?
Risk of allergic/anaphylactic reaction
What is the difference between a T1 and a T4 tumour?
(Dont really need to know this in much detail)
T1 is small and hasn't really invaded/spread to much tissue
T4 has spread to adjacent tissues
Different sites of malignancy can be imaged using different techniques, for a variety of reasons.
What two sites of malignancy can only be imaged using MRI scanners, and not CT?
Lymphomas of the CNS/MSK (not a 'site' but you get the point)
Aside from diagnosis, how is CT imaging used (in relation to cancers)?
Response to treatment
Checking for relapse
Checking progression of disease
What does ALARA stand for, and what is the ALARA principle used for?
'As Low As Reasonably Possible'
CT = fuck ton of x-rays = bad
To minimise risk of causing more harm (cancer) to the patient - examination should only be when:
- More information essential for appropriate protocol
Repeat examinations should be avoided
In MRI imaging, protons (H+) have their poles lined up with a strong magnetic field.
When they relax from this fixed alignment (and release energy), different molecules take a different amount of time to 'relax'.
What is the trend in the time taken to relax, and the molecular 'size'?
Heavier molecules - quick to relax
Lighter molecules - take longer
(Fat people are quicker to relax than fit, lighter people)
Describe the positives of MRI scanning?
Show bone and soft tissue in great detail
Show blood vessels
Imaging of the brain, spine, muscoloskeletal, abdomen, pelvis and cardiac
What is the main contrast used in MRI imaging?