B-K Medical Pro Focus 2202, Руководство пользователя

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30 Chapter 1
Some of the scanner functions can affect the acoustic output, as listed here.
(Instructions for using these functions are given in the relevant sections of this user
guide.)
•
Sizing functions such as ROI (region of interest) – in general, smaller size
results in higher acoustic intensity because the pulse repetition frequency (PRF)
is higher or the ultrasound beam is more strongly focused.
•
Focus – in general, strongly focusing the beam makes the acoustic intensity
higher.
•
Frame rate – higher frame rate results in higher acoustic intensity.
•
Range – increasing the Doppler range increases the acoustic intensity by
increasing the PRF.
•
CFM Resolution – higher resolution increases the acoustic output.
•
Color box size – narrowing the color box generally increases the acoustic output
within it.
The user can set a Thermal Index limit. This will provide an upper limit for acoustic
output.
Default Acoustic Output
After the scanner has been turned off, the transducers will start in the default setup
when the scanner is turned on again. The default setup may be factory-defined or
defined by the user.
The factory-defined default setup values of acoustic output for each transducer are
listed in the General Transducer Information (BB0555) manual.
These setups have been optimized to give the best compromise between low acoustic
output and enough power to obtain the image features as quickly as possible. This is
part of the ALARA principle. The factory default setup for all transducers is B-Mode
to ensure the lowest acoustic output when you start scanning.
To change the default setup to another that satisfies the ALARA principle, see
Chapter 13, “Setting Up and Customizing Your System”.
When you enter a new patient ID, the transducer setup will be reset to the default
setup. You can prevent this from happening – see “Keeping Image Settings” on
page 40.
Fetal
scanning
When you use transducers intended for fetal scanning, it is important to make sure
that the default settings are appropriate and to reset to the default setting before
scanning a new patient.
References
[1] EN 60529:1991+A1:2000. Specification for degrees of protection provided by enclosures
(IP code).