Safety Biological Safety
44 Lumify Ultrasound System
Philips Healthcare 4535 618 58571_A/795 * MAY 2016
The conservative assumptions of the output estimation algorithms of linear propagation, at all
depths, through a 0.3 dB/cm‑MHz attenuative medium is not considered in the accuracy
estimate for the display. Neither linear propagation, nor uniform attenuation at the 0.3 dB/
cm‑MHz rate, occur in water tank measurements or in most tissue paths in the body. In the
body, different tissues and organs have dissimilar attenuation characteristics. In water, there is
almost no attenuation. In the body, and in particular, in water tank measurements, nonlinear
propagation and saturation losses occur as pulser voltages increase.
Therefore, the display accuracy estimates are based on the variability range of transducers and
systems, inherent acoustic output modeling errors, and measurement variability. Display
accuracy estimates are not based on errors in, or caused by measuring according to, the AIUM
measurement standards, or the effects of nonlinear loss on the measured values.
Control Effects
Controls Affecting the Indices
As various system controls are adjusted, the TI and MI values may change. This will be most
apparent as the output power control is adjusted; but other system controls affect the
on‑screen output values.
Power
The output power control affects the system acoustic output. Two real‑time output values are
on the display: TI and MI. They change as the system responds to power-control adjustments.
In combined modes, such as simultaneous Color and 2D, the individual modes each add to the
total TI. One mode will be the dominant contributor to this total. The displayed MI will be from
the mode with the largest MI value.
2D Controls
• Focus: Changing the focal depth will change MI. Generally, higher MI values will occur when
the focal depth is near the natural focus of the transducer.
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