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Tissue is sliced very thin and light shone through it, through the lenses, to the eye.
Light waves can be large enough that they cannot fit between very small, close together features.
Shoots beams of electrons through very thinly sliced tissue ( which are picked up by a sensor? ).
Electron wave lengths are much smaller than light wavelengths and can fit between small, close together features so one can see definition between them.
Scanning electron microscope...
Tissue does not need to be thinly sliced. Carbon and gold dust are applied to the specimen. An electron beam is fired at the surface which causes the surface to emit electrons itself which are picked up by a detector and builds the information into a 3D image.
Electromagnetic "xrays" are projected at a body. Some of the radiation passes through to a film sheet behind body and some does not pass through by hitting bones and such on its way through body.
The film reveals dark areas where the xrays met little resistance and went straight to the film and white areas where the rays were blocked from reaching the film by bones.
CT or CAT ( computed axial tomography ). Consists of an Xray tube and recorder ( opposite of each other ) which rotate around the patient and sectional images of the patient.
Xenon is a gas that a patient will breath which is transported through the blood and which shows up on CT scans. This can be used to show where parts of the body are not getting good blood flow.
Digital Subtraction Angiography...
Used for taking xrays of blood vessels. An image of the vessel is taken, then contrast medium is put through the vessel, then another image is taken. The first image is removed revealing only the parts where the contrast medium is present.
Positron Emission Tomography PET scan...
Radioactive isotope is put into the bloodstream in the form of sugar or water. Cells take up the isotope. As the cells decay they emit positrons which cause gama rays to be emitted. Sensors in the scanner can detect the gama radiation and tell where the most active or least active cells are.
Ultrasonic sound waves are emitted through the end of a wand placed on a body, reflected off features inside the body, and picked up again by the wand, giving an image of what the sounds waves are being reflected off of.
Magnetic resonance imaging MRI...
Very, very strong magnetic field is produced around a patient. The nuclei of hydrogen atoms of water molecules line up with the magnetic field's alignment. Radio waves are pulsed at the patient and the aligned nuclei de-align and then realign. In the process they nuclei produce their own faint radio waves. These radio waves are picked up by sensors in the machine and are interpreted by a comuter to form an image.
This is good for looking at soft, squishy, water-rich organs.
FUnctional MRI detects blood oxygen and reveals how much oxygen is present in a part of the body. Low oxygen - low blood.