Ch.1 Intro to DMS pt.2

What device converts energy from one form to another?

Transducer

Most transducers today are a combination of elements that form an..

array

Annular array

Has a large diameter with multiple rings of focus

Electronically scanned arrays may be ____ or ______

Curved, or linear

Phased/Sector Array

Has multiple small elements within the transducer face.

Type of transducer selected depends on several factors:

Type of examination, size of patient, amount of fatty or muscular tissue present.

This transducer is used for smaller structures like thyroid, scrotum, breast, etc.

High frequency linear array probes

Abdomen is usually scanned with..

A curved array and/or sector array.

Frequency for abdomen depends on

The size of the patient (lower frequency than linear)

Which transducer is used to scan between ribs in echocardiography?

Phased array

What probe is used for intercavity areas like the prostate?

Transvaginal (Intraluminal) probe.

Transesophageal studies are obtained with a..

Transesophageal probe to image the detailed anatomy of cardiac structures.

Obstetric and Gynecologic scans are usually performed with..

Curved array Transducer

What type of image can a linear-array transducer be steered to produce?

Trapezoidal image

What is the field of view range for a transvaginal probe?

90 to 120 degrees

Which transducer is typically used for abdominal scans?

Curved Array

What axes are used to reconstruct 3D ultrasound images?

x, y, z

3D reconstruction is useful for imaging the fetal face in the second and third trimesters.

True

Power output

Determines the strength of the pulse transmitted into the body

What should you do first if the image is too bright?

Turn down output power

Returning echoes are ____ when the transmitted pulse is _____. This means the image is _____

Stronger, Stronger, Brighter

Power output is displayed as

Decibles (DB) or as a percent of maximum

ALARA Principle

As Low As Reasonably Achievable Less Than 100% Output Power

Receiver Gain

Allows the sonographer to amplify or boost echo signals.

It’s done to compensate for the attenuation of sound in deeper tissues.

Acoustic exposure to the patient increases when receiver gain is increased.

False. Acoustic exposure to the patient remains unchanged when receiver gain is increased.

What happens if the gain setting is too high?

Artificial echo noise will be displayed throughout the image

Time Gain Compensation

TGC control allows the sonographer to amplify receiver gain gradually at specific depths.

Time Gain Compensation is also reffered to as

Depth Gain Compensation (DGC)

Focal Zone

Allows transducer to focus transmitted sound at different depths. Where the sound beam is the thinnest creating optimal image quality.

Where should the focal point be set for optimal image quality?

At or just below the region of interest

Region of Interest

The specific area or structure you want to examine.

What happens to the frame rate as multilevel focusing is used?

Frame rate decreases

Field of View (depth)

Allows the sonographer to adjust the depth and width of an image (how much of the body you can see on the ultrasound)

Depth is displayed in _____ on the side of the image

Centimeters

According to the 2-3 finger rule, where should the ROI be?

2-3 fingers from bottom of the image.

The sound beam is thinnest at the focal point.

True

Multiplanar imaging

Can “follow” the path of a tortuous vessel, moving cardiac structure, or fetus.

What technique allows evaluation of blood flow?

Doppler, allows qualitative and quantitative evaluation of blood flow.

How does the cost of ultrasound compare to other imaging systems?

Costs less

What are today's ultrasound contrast agents made of?

Gas microspheres injected intravenously

Contrast agents facilitate the detection or diagnosis of specific

pathologic conditions

How are curved-array transducer pulses typically scanned to produce their characteristic image format?

They produce a blunted sector field of view from curved scanning surface