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Medical Imaging Brief Overview

Terms

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Simple X-Rays
-Single high intensity burst of x-rays passed through body and recorded on film.
-single 2-d high resolution image on film
-best for bone tissue
-Disadvantages are high dose of x-rays which can potentially cause mutations; not good for soft tissue views


Mammography
-Single low-intensity x-rays passed through the breast and recorded on film or sensing plate for digital images
-single 2-d image on film or digital
-Good for soft tissue of breast to identify dense tumors
-low dose of x-rays but can still potentially cause mutations


Barium Contrast X-Ray
X-ray opaque barium compound coats digestive tract. X-rays used to visualize
-Individual 2-d image on film or digital.real time images if flouroscopy is used
-Abnormalities in digestive tract can be revealed including tumors, polyps, obstructions, etc.
-Prep consists of cleaning out the digestive tract. Not pleasant... x-ray mutation


IV Urogram
-X-Ray opaque contrast medium injected. medium is filtered by the kidneys and coats the urinary tract.
-Individual 2-d image on film or digital. Real time fluoroscopy.
-Abnormalities in urinary tract can be revealed including stones, tumors, obstructions.
-x-ray mutations possible


Angiogram
-X-ray opaque contrast medium injected by catheter at the entrance of coronary circulation, brain circulation, or aorta. x-ray used to see
-Individual 2-d image film or digital or fluoroscopy
-Abnormalities in circulation can be revealed, such as aneurysms or obstructions
-x-ray mutations possible


Bone Densitometry
-Prolonged but low intensity x-rays used to evaluate x-ray absorption by calcium
-2-d images film or digital
-determines extent of osteoporosis
-overall high dose of x-rays due to length of exposure to low doses
-x-ray mutations possible



Fluoroscopy
-Contrast medium is followed through digestive tract, urinary tract, or circulation by evaluating constant x-ray irradiation through the body and projected/recorded on a screen
-real time images of internal structures
-actual live visualization of flow of blood, food, or urine.
-Also used for insertion of needles in the spine and brain
-overall very high dose of x-rays due to typically longer length of tests or procedures that use fluoro



CT Scan

-Body irradiated with x-rays every few millimeters one plane at a time from all directions.
x-ray detectors record absorptions and a computer determines the density of each point in the plane and reconstructs an image of that plane.
-series of 2-d images of each plane scanned. Contrast medium sometimes used to improve visualization of certain structures or organs.
-soft tissue can be visualized very well since low intensity rays used.
-overall decent dose of rays but typically spread out over more area than other scans



PET Scan
Substance like glucose is tagged with positron emitting radioisotope and then injected into patient. More active cells pick up more of the tagged substance and emit more positrons which collide with electrons in the cells emitting gamma rays which are picked up by surrounding detectors. Computers then recreate the image with the high gamma areas glowing more then others
-low res images.Images can be of entire body i.e. looking for cancer when blood results indicate it but unknown where in body pt. has cancer.
-huge benefit is small cancer tumors can be found before they show up on ct or mri scans
-brain activity or lack there0of can be determined this way as well since a working brain needs much more resources than a dead brain.
impaired blood flow to an area can also be found
-low res pictures and gamma rays can potentially cause mutations




Radioneuclide Scan
Similar to PET Scan except the radioisotope itself is a gamma ray emitter
-Low res images like PET scan
-Used for bone scans to reveal bone tumors; coronary circulation analysis, and brain activity
-low res and gamma ray mutations


Ultrasound/Sonogram
High frequency soundwaves directed into the body and their echoes are analyzed by computer and it recreates the image
-low res typical except on newer 3-d machines
-best used in areas with plenty of fluid i.e. abdominopelvic cavity and to visualize fetus



Endoscopy/Arthroscopy
Lighted instrument inserted into body cavity and video recording can be made and projected onto a monitor. Upper GI endoscopy examins esophagus, stomach, and duodenum. Colonoscopy examines colon. Other endoscopy can check bronchi. Laproscopy checks abdominopelvic cavity, Arthroscopy examines a joint
-real-time video
used to diagnose problems or can be used during surgeries
-somewhatg invasive laproscopies and arthroscopies requires puncturing through tissue


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