30
Chapter 2
January 2015
bk3000 User Guide
(16-01249-EN-01)
•
Image patients only when clinical reasons make it necessary.
•
Keep exposure time as short as possible.
•
Be careful to prepare the patient correctly so that you get the best possible
image.
•
Start imaging at a low acoustic output level (see “Thermal and Mechanical
Indices” on page 30) and increase the level only as much as necessary to obtain
a satisfactory image.
•
If you switch from an application requiring high acoustic output levels (see
“Functions Affecting Acoustic Output” on page 32), to one that requires lower
levels (fetal imaging, for example), be sure to reset the levels before you image.
(For example, start in B-mode.)
•
Take into account all the types of tissue that may be affected. For example, when
imaging a breast, it may be appropriate to monitor the TI in bone rather than in
soft tissue because the ribs will be subjected to ultrasound.
Acoustic output data for transducers used with the system are given in the Technical
Data (BZ2100) that accompanies this user guide. The uncertainty level for each
parameter is also listed. For definitions of the parameters, refer to the Food and Drug
Administration (FDA) Guide as well as EN 60601-2-37
(Particular requirements for
the safety of ultrasonic medical diagnostic and monitoring equipment)
and
AIUM/NEMA standards.
The routes (or tracks) available for clearance by the FDA are well-defined. Track 3
is for diagnostic ultrasound systems that follow the Output Display Standard. Under
Track 3, acoustic output will not be evaluated on an application-specific basis, but
the maximum derated Spatial Peak–Temporal Average Intensity (I
SPTA
) must be
720mW/cm
2
, the maximum Mechanical Index (MI) must be
1.9, and the
maximum Thermal Index (TI) must be
6. All BK Medical transducers for use with
the 2300 Ultrasound System are Track 3.
Monitor Display
The Mechanical Index (MI) and Thermal Index (TI) can be viewed in all imaging
modes.
Thermal and Mechanical Indices
The MI and TI indices are intended to allow users to implement the ALARA (As
Low As Reasonably Achievable) principle using an indicator related to a potential
bioeffect.
The full details of the indices are given in references EN60601-2-37 and
AIUM/NEMA standard, but the formulas are given below.
Appropriate
transducer
WARNING
AO-w2
To avoid tissue damage, always use the transducer best suited to the examination.
