CT and MRI Study Guide Flashcards
What does Tomo and graphic stand for?
Tomo means slice. Graphia means describing
Who is consider the father of CT and what year did you began his research?
Hounsfield began his research in 1969.
Name the person that created the first 1st whole body scanner?
Ledley
Which generation of CT had translate/rotate functions?
Both first and second generations.
First gen. had a pencil beam while the second gen. had fan beam.
Which generation started the rotate/rotate function.
Third generation
What is the mA range?
10 to 500 mA
What do we call a single square, or picture element, within the matrix?
A pixel.
What does HU stand for? What are they used for?
HU stands for Hounsfield unit. A scale use to determine the density of a tissue compared to water.
Where does water stand on the HU scale?
0
Can you name the four basic functions of CT computer?
Data acquisition (DAS), Reconstruction, Storage of image data, and Image display.
What are DAS functions?
It turns detectors on and off at appropriate times, transfer data, and monitor the system operation.
What does the Gantry house?
X-ray tube, DAS, detectors, slip ring, high voltate generator.
Which generation is used for cardiac studies?
5th Generation
What is the average tilt of a gentry?
30 degrees. The aperture is about 28 inches.
How much heat can a CT x-ray tube can handle?
4-5 MHU. Standard x-ray tubes can go up to 2.1 MHU.
Name the two types of detectors?
Scintillation (solid state) beam strikes crystal and emits light which is converted to a electrical signal.
Ionization (gas) beam strikes gas chamber were it disturbs and beam converts to electrical energy. Uses xenon gas
This device allows for continuous rotation of an x-ray tube/detector assembly. It also provides electrical power to operate x-ray tube and transfer signals from detectors to computer.
Slip ring
What is the power range for a CT scanner?
20-100 KW
Filters are positioned between the ____ and ____ to shape the beam and provide more uniformity at the detectors.
x-ray tube and patient
What type of wavelength does filtration remove?
long-wavelength x-ray photons
also shapes the energy distribution
What does the pre-collimator do?
Ensure constant beam width. Reduce PT radiation doses. Station between the x-tube and before the patient.
Where is the DAS located?
Between the detectors array and the computer.
What is another name for patient table?
Couch. Weight limit can range from 300 to 600 lb.
What does the post-patient collimator do?
Refines the x-ray beam. Reduce scatter radiation and noise. Improves thickness of the slice.
Name the type of scan that involves a x-ray tube rotating around the patient and collects data, stops to allow the patient to move, and repeats the process.
Conventional (slice-by-slice) Scanning
A type of scanning that involves the x-ray tube to continuously rotate around the patient and trace a spiral/helical path under a single breath-hold.
Volume (spiral/helical) Scanning
Radiation Dose: Average dose resulting from scans over an interval length on the patient.
MSAD (Multiple Scan Average Dose)
Radiation Dose: Used for volume scanning.
CTDI (Computed Tomography Dose Index)
Radiation Dose: The method used to report dose.
DLP (Dose Length Product)
The tissue density can be distinguished in less than .05% and can see the see the small differences in density.
Contrast Resolution
This image quality is affected by the degree of blur and the ability to see the difference between two objects close together.
Spatial Resolution
This image quality has the shortest amount of time needed to complete a scan and has the ability to freeze any motion of a scanned object.
Temporal Resolution
How much barium is in oral contrast?
2% barium sulfate
intravenous - never exceed over 200 cc
What is the Kvp?
80 to 140 KVp.
What affects the brightness of image?
window level/center
What affects the contrast of the image?
window width
Difference between Scan and Display FOV?
Scan FOV measures a circular region of a scanned region.
Display FOV displays what was scanned but setting must be equal to or less than the scan FOV.
Who was the person that produced the 1st MRI image of the human being?
Damadian
The antennas that MRI system that broadcast the ___ signal to the patient or receives the return signal
RF (Radiofrequencey) coils
Who was the first to produce the 1st MRI image of an object?
Lauterbur
In MRI, the most abundant element in the body?
Hydrogen
Hydrogen has the strongest nuclear magnet
Name the three types of magnets.
Resistive magnets (limited field strength) Superconductive magnets (uses liquid helium for cooling) Permanent magnets (does not require electricity)
How much does 1 Tesla equal to?
10,000 G
Low-field magnets range between?
0.2 T – 1.0 T
In MRI, if wanted to look for pathology, which image setting would I use?
T2 weighted image
For anatomy use T1
What is gadolinium?
Paramagnetic substance used in T1 agents.
The force of the projectiles are pulled towards magnetic field is proportional to:
Strength of the magnet
distance of the magnet
mass of the object
material that the object is made from
MRI can produce noises up to ___
130 dB
Thermal injuries can arise from…
Cables from the coil, metals, wires, medications skin patches with foil
Thermal injuries can arise from…
Cables from the coil
Metals, wires, medications skin patches with foil
Which generation rotate/stationary model.
4th generation.
Has a ring of detectors
