CT and MRI Study Guide

Question 1

What does Tomo and graphic stand for?

Answer 1

Tomo means slice. Graphia means describing

Question 2

Who is consider the father of CT and what year did you began his research?

Answer 2

Hounsfield began his research in 1969.

Question 3

Name the person that created the first 1st whole body scanner?

Answer 3

Ledley

Question 4

Which generation of CT had translate/rotate functions?

Answer 4

Both first and second generations.

First gen. had a pencil beam while the second gen. had fan beam.

Question 5

Which generation started the rotate/rotate function.

Answer 5

Third generation

Question 6

What is the mA range?

Answer 6

10 to 500 mA

Question 7

What do we call a single square, or picture element, within the matrix?

Answer 7

A pixel.

Question 8

What does HU stand for? What are they used for?

Answer 8

HU stands for Hounsfield unit. A scale use to determine the density of a tissue compared to water.

Question 9

Where does water stand on the HU scale?

Answer 9

0

Question 10

Can you name the four basic functions of CT computer?

Answer 10

Data acquisition (DAS), Reconstruction, Storage of image data, and Image display.

Question 11

What are DAS functions?

Answer 11

It turns detectors on and off at appropriate times, transfer data, and monitor the system operation.

Question 12

What does the Gantry house?

Answer 12

X-ray tube, DAS, detectors, slip ring, high voltate generator.

Question 13

Which generation is used for cardiac studies?

Answer 13

5th Generation

Question 14

What is the average tilt of a gentry?

Answer 14

30 degrees. The aperture is about 28 inches.

Question 15

How much heat can a CT x-ray tube can handle?

Answer 15

4-5 MHU. Standard x-ray tubes can go up to 2.1 MHU.

Question 16

Name the two types of detectors?

Answer 16

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

Question 17

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.

Answer 17

Slip ring

Question 18

What is the power range for a CT scanner?

Answer 18

20-100 KW

Question 19

Filters are positioned between the ____ and ____ to shape the beam and provide more uniformity at the detectors.

Answer 19

x-ray tube and patient

Question 20

What type of wavelength does filtration remove?

Answer 20

long-wavelength x-ray photons

also shapes the energy distribution

Question 21

What does the pre-collimator do?

Answer 21

Ensure constant beam width. Reduce PT radiation doses. Station between the x-tube and before the patient.

Question 22

Where is the DAS located?

Answer 22

Between the detectors array and the computer.

Question 23

What is another name for patient table?

Answer 23

Couch. Weight limit can range from 300 to 600 lb.

Question 24

What does the post-patient collimator do?

Answer 24

Refines the x-ray beam. Reduce scatter radiation and noise. Improves thickness of the slice.

Question 25

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.

Answer 25

Conventional (slice-by-slice) Scanning

Question 26

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.

Answer 26

Volume (spiral/helical) Scanning

Question 27

Radiation Dose: Average dose resulting from scans over an interval length on the patient.

Answer 27

MSAD (Multiple Scan Average Dose)

Question 28

Radiation Dose: Used for volume scanning.

Answer 28

CTDI (Computed Tomography Dose Index)

Question 29

Radiation Dose: The method used to report dose.

Answer 29

DLP (Dose Length Product)

Question 30

The tissue density can be distinguished in less than .05% and can see the see the small differences in density.

Answer 30

Contrast Resolution

Question 31

This image quality is affected by the degree of blur and the ability to see the difference between two objects close together.

Answer 31

Spatial Resolution

Question 32

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.

Answer 32

Temporal Resolution

Question 33

How much barium is in oral contrast?

Answer 33

2% barium sulfate | *intravenous - never exceed over 200 cc*

Question 34

What is the Kvp?

Answer 34

80 to 140 KVp.

Question 35

What affects the brightness of image?

Answer 35

window level/center

Question 36

What affects the contrast of the image?

Answer 36

window width

Question 37

Difference between Scan and Display FOV?

Answer 37

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.

Question 38

Who was the person that produced the 1st MRI image of the human being?

Answer 38

Damadian

Question 39

The antennas that MRI system that broadcast the ___ signal to the patient or receives the return signal

Answer 39

RF (Radiofrequencey) coils

Question 40

Who was the first to produce the 1st MRI image of an object?

Answer 40

Lauterbur

Question 41

In MRI, the most abundant element in the body?

Answer 41

Hydrogen | *Hydrogen has the strongest nuclear magnet*

Question 42

Name the three types of magnets.

Answer 42

``` Resistive magnets (limited field strength) Superconductive magnets (uses liquid helium for cooling) Permanent magnets (does not require electricity) ```

Question 43

How much does 1 Tesla equal to?

Answer 43

10,000 G

Question 44

Low-field magnets range between?

Answer 44

0.2 T -- 1.0 T

Question 45

In MRI, if wanted to look for pathology, which image setting would I use?

Answer 45

T2 weighted image | *For anatomy use T1*

Question 46

What is gadolinium?

Answer 46

Paramagnetic substance used in T1 agents.

Question 47

The force of the projectiles are pulled towards magnetic field is proportional to:

Answer 47

Strength of the magnet distance of the magnet mass of the object material that the object is made from

Question 48

MRI can produce noises up to ___

Answer 48

130 dB

Question 49

Thermal injuries can arise from...

Answer 49

Cables from the coil, metals, wires, medications skin patches with foil

Question 50

Thermal injuries can arise from...

Answer 50

Cables from the coil | Metals, wires, medications skin patches with foil

Question 51

Which generation rotate/stationary model.

Answer 51

4th generation. | *Has a ring of detectors*