Flashcards in Diagnostic and Imaging Technology/Terminology Deck (154)
How is an x-ray created?
radiation beam emitted is scattered or absorbed in diffedrent amounts by different tissues.
what are densities responsible for the shades of black, grey and white produced on the x-ray film?
fat, water, air, and bone.
how does computer radiography work?
Much like an x-ray but uses a laser and a computer to read and store the image of the plate.
how does digital radiography work?
a digital x-ray sensor are used to transmit the image immediately to a computer where it an be viewed on a monitor- no plate required. Its faster and emits a lower dose of radiation . - also allows technitian to manipulate the images stored in the computer
what is a down fall of x-ray imaging (regarding a patient health)
the images are only 2-D, thus multiple angle shots will sometimes be required. Each image creates a dose of radiation.
what is fluroscopy?
imaging tool that allows "real" time view of moving parts of the body. (can be used for dx and tx)
how does fluoroscopy work?
x-ray scanner produces images of the area of interrest that are projected onto a monitor by the use (most often) of contract agents. Great for invasive surgery.
how are contrast agents taken?
they are a substance taken orally or instilled into hollow organs that tolerate well and have low allergic reactions.
give three examples of contrast agents
Barium, iodine and gaolinium-based contrast agents are most common- other available.
what is a con of using contrast agents>
they can cause hypersensitivity reactions- most often cured by taking an antihestimine.
how are contrast agents eliminated from the body?
through waste or urine
what is nuclear medicine?
the use of small amounts of short-live radiative substances that is formulated to be absorbed by targeted tissues.
what are common radionuclides?
radioactive iodine, technetium, thallium, gallium, and indium, though other are available.
how are radionuclides imaged?
though a scanning device or gamma camera which records the distribution of the radioactive material in the target organ. They are then produced as a 3-D data displayed in 2-D.
How can a computer improve radionuclear imaging.
to quantify imaging, into this sliced images. Simmilar to CT scanning. They are useful to study bone, and thyroid and hepatobiliary function, and CAD
what is an ultrasonography?
uses high-frequency sound waves to image soft tissue and produce an image called Ultrasound.
what kind of waves are used to transmit the echos through the patient
sound waves, they are read through the transducer and trasmitting gel.
depending on the tissue how can the waves alter in an US?
they can be scattered, refracted or attenuated.
how are US projected?
the size of the organ is calculated by measuring the time it takes for the waves to travel from the transducer to the reflecting surface being studied and back to the transducer where they are amplified and displayed on a monitor.
explain how fat reflects sound waves.
fat is hyperechoic tissue- which reflects a large number of sound waves
explain how fluid reflects sound waves.
fluid is a hypoechoic (tissue that reflects only a few sound waves) or anechoic (refers to the total absence of reflected sound waves)
name 5 advantages of US over MRI and CT scanning imaging
1. differentiate between fluid and solid- filled structures
2. low cost
5. no exposure to ionizing agents.
what are 3 limitations to ultrasonography?
1. skill level of technician
2. image resolution that is not as good as other techniques
3. "noise" produced when US waves hit gas and bone.
name the 5 times of US techniques
A-mode, B-mode, M-mode, Gray-scale, real time, and Doppler.
what is the difference between doppler and (a-mode, b-mode, gray-sale and real time)
the group: provides info on size, motion or both. (can be rapid)
doppler: measures velocity and direction of blood flow within heart and Blood vessels by measuring changes in pitch.
what is a duplex scan?
combines both b-mode with doppler US.
CT and CAT are created how?
passing a rotating beam of x-rays into the individual and obtaining thousand of point images at specific depths. the data produces a cross-sectional, 2-D image or program it into 3-D.
what is an advantage of CT or CAT scans, as well as a disadvantage.
produces an image of a much higher resolution, but also exposes an individual to a significantly higher dose of ionizing radiation.
how are spiral or helical scanners better than scanners from before?
they are faster, can have multiple rows, of detectors provide thinner slices, minimize motion artifact and move continuously as the table moves.