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Renco manufactures ultrasonic instrumentation for the detection
of pregnancy in mammals and for the measurement of tissue thickness
in various animals.
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Contact us today!
Renco
Corporation
116 Third Ave. North
Minneapolis, MN 55401
Toll Free: 800-359-8181
Local: 612-338-6124
Fax: 612-333-9026
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Renco
Technical FAQ
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| Q. |
What
is ultrasound? |
| A. |
Ultrasound
is regular sound at very high frequency, far above the
range of human hearing. The frequencies used in our products
ranges from 1,000,000Hz to 5,000,000Hz. (The range of
sound heard by the human ear is 20Hz to 20,000Hz.) |
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| Q. |
What
is a "transducer" and how does it work? |
| A. |
The
transducer, which we call a probe, contains a treated
ceramic disk that flexes when a voltage pulse is applied
and which produces a voltage when it is mechanically flexed.
This is called the piezoelectric effect. This action produces
ultrasound in the same manner as a speaker produces normal
sound.
The
pulse of ultrasound emitted by the transducer moves
though skin and tissues, until it encounters a type
of tissue that it cannot penetrate because the tissue
has a high resistance to the particular sound frequency.
It is then reflected back towards its source. This reflection
is called an echo. The instrument alternately uses the
probe as a speaker to send the pulse, and then as a
microphone to receive the echo.
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| Q. |
What
is "A-mode"? |
| A. |
All
RENCO products use A-mode. A pulse of ultrasound
is sent out, the echo processed and a determination made
on the basis of the time it took to go and return. When
a visual display is used, the presentation is a series
of spikes rather than a picture. |
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| Q. |
How
do pregnancy detectors work that are based on the
"Doppler Effect" (also
called "Doppler shift")? |
| A. |
Doppler
instruments use ultrasound to provide an audible indication
of movement, such as a beating heart or pulsing
blood vessel. The classic example of Doppler shift is
a train whistle. As the whistle moves towards the listener,
a higher pitch is produced. As it moves away from the
listener, a lower pitch produced. |
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| Q. |
What
are the advantages and disadvantages of Doppler versus
RENCO A-mode pregnancy detectors? |
| A. |
Advantages:
Assuming a skilled operator, Doppler instruments give
fewer false negative readings at earlier times. Also,
though not of particular importance from a production
point of view, they permit the number of fetuses to be
counted. Disadvantages: Doppler instruments are considerably
more expensive and require considerably more time per
test, thus increasing cost and providing lower efficiency.
They also require a longer time for the operator to develop
the necessary skill to differentiate between a beating
heart and pulsing blood vessels, and also to be able to
mentally set aside high levels of background noise. |
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| Q. |
How
does ultrasound produce pregnancy, backfat, and loin
information? |
| A. |
For
pregnancy detection, the instruments determine if amniotic
fluid is present by detecting an echo from the interface
between the interior of the far side of the uterus and
amniotic fluid. Ultrasound does not pass through air,
so if there is no fluid, no echo is returned. The PREG-ALERT
displays echoes as "spikes" on a TV-like screen.
Travel time is displayed in equivalent units of
distance. The SONO-GRADER displays
the words "Pregnant" or "Not Pregnant"
along with the calibrated scale. The PREG-TONE
and PREG-TONE II PLUS, indicate the pregnancy
status by an audible tone. These instruments use an electronic
"window" to place upper and lower time limits
for accepting a returning echo as valid indication of
pregnancy.
For
backfat measurement, valid echoes are produced by interface
between fat and the tissue layer separating fat layers
and also the interface between the bottom layer and
loin muscle. The LEAN-MEATER®
can be set to measure either two or three fat layers.
It will look for either one or two echoes respectively
and accept the next echo as indicating the bottom of
the last layer. The PREG-ALERT and SONO-GRADER
visually display valid echoes.
The
SONO-GRADER has several options for making
loin muscle measurements at the 10th rib.
In all cases, the instrument subtracts the total fat
measured at P2. It should be noted that there are numerous
factors that can cause variations in readings from time
to time even when using the same method; there is no
unvarying "absolute". A "standard"
is only that which the user chooses to call a standard.
Therefore, provision is made for altering the speed
of sound factor individually for fat and loin tissues.
This permits the user to adjust the readings to track
those of any method the user chooses to use as a "standard".
The
PREG-ALERT displays all fat layer echoes
and the echo from the bottom of the loin along a scale
calibrated in mm. The operator does the subtraction.
(The LEAN-MEATER is not designed to make
loin muscle measurements.)
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