Medical Imaging Techniques

Question 1

Types of imaging

Answer 1

Conventional radiology (x ray)
Computed tomography (CT)
Ultrasonography (US)
Magnetic Resonance imaging (MRI)
Nuclear medicine imaging

Question 2

What is a plain field study

Answer 2

Conventional radiology in which special techniques such as contrast media have not been used

Question 3

How does conventional radiology work

Answer 3

Highly penetrating dreams of x rays transilluminate the patient , showing tissues of different densities of mass as images of differening intensities (light and dark)on film monitor

X ray tube—>human—> detector behind human

Question 4

What appears dense (white) and less dense (dark) on conventional radiology (x ray)

Answer 4

Compact bone absorbs or reflects more then
Spongy bone
Organ-transparent in between

Question 5

Radiolucent

Answer 5

Less dense

Question 6

Radioopaque

Answer 6

Dense

Question 7

PA projection

Answer 7

X rays transvers from posterior to anterior (x ray tube is posterior and detector is anterior)

Question 8

AP projection

Answer 8

Opposite

Question 9

Conventional radiographs are all viewed for body, head trunk shoulder, arms and legs

Answer 9

Patient is facing you AP view

Patient left always your right

Question 10

How do you view radiographs for wrist, hands, feet

Answer 10

As if looking at own wrists hands or feet

Question 11

What do L and R mean on radiographs

Answer 11

Side placed closes to the film (detector) image is viewed from same direction beam was projected

Question 12

What does the introduction of contrast media(radioopaque fluids such as iodine or barium) to conventional radiography cause

Answer 12

Study of luminal or vascular organs and potential or actual spaces-such as digestive tract, blood vessels, kidneys, synovial cavities, and the subarachnoid space-that are not visible with plain films

Question 13

Why do we usually need two views at 90 degree angles

Answer 13

Each radiograph represents a 2d view of 3d structure
Structures that get beams overlap each other

Need 2 views to localize an abnormality

Question 14

What is seen in computed tomography

Answer 14

Radiographic images of body that resemble transverse anatomical sections

Question 15

How does CT work

Answer 15

X ray passes through the body as the x ray tube and detector rotate around the axis of the body. Multiple overlapping radial energy absorption’s are measured, recorded, and compared by a computer to determine the radio density of each volumetric pixel (vowel) of chosen body plane

Question 16

In CT the computer maps the vowels into a ___ __ that is displayed on a monitor or print out

Answer 16

Planar image (slice

Question 17

In a CT what is seen as light and dark

Answer 17

Light-bone treated absorption (transparent) white

Dark-little absorption

Question 18

How is an axial ct viewed

Answer 18

As if standing at patients feet -from inferior

Question 19

How are coronal ct images viewed

Answer 19

As if patient is facing you

Question 20

How are sagittal ct viewed

Answer 20

Standing at patients left side

Question 21

What is ultrasonography used for

Answer 21

Visualizesuperficial or deep structures in body by recording pulses of ultrasonic waves reflecting off the tissues

Question 22

Advantadge of ultrasonography

Answer 22

Cheap and transportable
Real time-can see things moving
Structures and flow in vessel

Question 23

How does ultrasonography work

Answer 23

Transducer in contact with skin generates high frequency sound waves that pass through the body and reflect off tissue interfaces between tissues of differing characteristics, such as soft tissue and bone . Echoes from the body reflect into the transducer and convert to electrical energy. The electrical signals are recorded and displayed on a monitor as a cross sectional image which can be viewed in real time and recorded as a single image or on videotape

Question 24

Doppler ultrasonography

Answer 24

Shifts in frequency between emitted ultrasonic waves and their echoes are used to measure the velocities of moving objects . Blood flow through vessels seen in color superimposed on a 2d cross sectional image

Question 25

What does scanning the pelvic viscera require for ultrasound

Answer 25

Fully distended bladder. The urine serves as an acoustical window, transmitting sound waves to and from the posteriorly placed pelvic viscera. Distended bladder also displaces gas filled intestinal loops out of the pelvis

Question 26

Why do transvaginal ultrasound

Answer 26

Permits positioning of transducer closer to the organ of interest and avoid fats and gas which absorb or reflect sound waves, whereas air conducts them poorly.

Question 27

Ultrasound used for lungs

Answer 27

No

Question 28

Does ultrasound use radiation

Answer 28

No

Question 29

MRI provides images of the body similar to those of CT scene but is better for ___ __ differentiation

Answer 29

Soft tissue

Question 30

How does MRI work

Answer 30

Person placed in scanner with a strong magnetic field, and the body is pulsed with radio waves. Signals subsequently emitted from the patients tissues are stored in a computer and reconstructed into various images of the body .

Question 31

For MRI, how can how can we control appearance of tissues to generate images

Answer 31

Controlling radio frequency pulses

Question 32

In MRI, free protons int he tissues that become aligned by the surrounding magnetic field are excited (flipped) with a radio wave pulse. As the proton lips back, minute but measurable energy signals are emitted. What emits stronger and weaker signals

Answer 32

More signals emitted by tissues that are high in proton density, such as fat and water Weaker0less protons

Question 33

What do moving fluids appear as what on T1

Answer 33

Black | Even through proton dense, after flip they move out of field

Question 34

T2

Answer 34

``` World was 2 Water looks white t2 Fat dark Blood flow dar Subacute blood bright Cyst bright Solid mass bright ```

Question 35

T1

Answer 35

``` Fat bright Acute and chronic blood gray Subacute blood bright Cyst dark Solid mass dark ```

Question 36

MRI see real time?

Answer 36

Yea with fast scanners

Question 37

Nuclear medicine imaging

Answer 37

Infor about distribution or concentration of trace amounts of radioactive substances introduced into the body. Shows images of specific organs after IV injection of a small dose of radioactive material

Question 38

A radionucleotide is attached to a compound that is selectively taken up by an organ such as ___ fr bone scanning

Answer 38

technetium-99m | Tc-MDP

Question 39

Positron emission tomography

Answer 39

Uses cyclotron produced isotopes of extremely short half life that emit positrons Examines the physiologic function of organs such as the brain on a dynamic basis Images viewed as whole organ or cross section

Question 40

SPECT

Answer 40

Similar to PET but longer lasting tracers | Less costly but more time and have lower resolution