User's Manual

Safety
2-20 Vscan Extend – User Manual
5721203-100
Rev. 13
Application selection
Selecting the application appropriate to a particular ultrasound
examination automatically provides acoustic output limits within
FDA guidances for that application. Other parameters which
optimize performance for the selected application are also set
automatically, and should assist in reducing the patient
exposure time.
Changing imaging modes
Acoustic output depends on the imaging mode selected. This
greatly affects the energy absorbed by the tissue (see ‘Acoustic
Output Reporting Tables’ on page 7-3 for TI and MI values in
black and white or color imaging).
ALARA
Ultrasound procedures should be performed using output levels
and exposure times As Low Reasonably Achievable (ALARA)
while acquiring clinical information.
During a diagnostic ultrasound examination, high frequency
sound penetrates and interacts with tissue in and around the
area of anatomy to be imaged. Only a small portion of the sound
energy is reflected back to the probe for use in constructing the
image while the remainder is dissipated within the tissue. The
interaction of sound energy with tissue at sufficiently high levels
can produce biological effects (aka bioeffects) of either a
mechanical or thermal nature. Bioeffect is generally undesired in
diagnostic application and may be harmful in some conditions.
ALARA training is provided in the Medical Ultrasound Safety
booklet, published by AIUM (American Institute of Ultrasound in
Medicine) provided on the Documentation CD. The ALARA
education program for the clinical end-user covers basic
ultrasound principles, possible biological effects, the derivation
and meaning of the indices, ALARA principles, and examples of
specific applications of the ALARA principle.