BTL Ultrasond 4000 User manual
BTL-4000
Ultrasound Therapy
USER'S GUIDE
ULTRASOUND THERAPY | PAGE 1 OF 19
110DA29/02/2008EN
CONTENTS
1 ULTRASOUND THERAPY ................................................................................................................................. 3
1.1 Mechanism of Action ..................................................................................................................................... 3
1.2 Methods of Application .................................................................................................................................. 5
1.2.1 According to Application Area and Movement of the Emitter Head.......................................................... 5
1.2.2 According to Application Area .................................................................................................................. 5
1.2.3 According to Contact Between Emitter Head and Body Surface.............................................................. 5
1.3 Ultrasound Frequency ................................................................................................................................... 6
1.4 Modes of Operation ....................................................................................................................................... 6
1.5 Emitter Head Size.......................................................................................................................................... 6
1.6 Application Time ............................................................................................................................................ 6
1.7 Intensity ......................................................................................................................................................... 7
1.8 Frequency of Treatments............................................................................................................................... 7
1.9 Combined Therapy ........................................................................................................................................ 7
1.9.1 Ultrasound + Low-frequency Currents ..................................................................................................... 7
1.9.2 Ultrasound + Amplitude Modulated Mid-frequency Currents (2-pole Interference) .................................. 8
1.9.3 Ultrasound + TENS (Transcutaneous Electrical Nerve Stimulation) ........................................................ 9
1.10 Specific Contraindications for Ultrasound Therapy ...................................................................................... 10
1.10.1 Absolute ................................................................................................................................................. 10
1.10.2 Relative .................................................................................................................................................. 10
1.11 Therapy Prescription.................................................................................................................................... 12
1.12 Instructions for the Patient ........................................................................................................................... 12
1.13 Treatment Procedure................................................................................................................................... 13
2 SETUP OF ULTRASOUND GENERATOR ...................................................................................................... 14
2.1 Setup and Control of Ultrasound Therapy ................................................................................................... 14
2.1.1 Ultrasound.............................................................................................................................................. 14
2.1.2 Ultrasound Sequence............................................................................................................................. 15
2.2 Specific Settings .......................................................................................................................................... 16
2.2.1 Ultrasound Head Calibration .................................................................................................................. 16
3 TECHNICAL PARAMETERS ........................................................................................................................... 17
3.1 Parameters of Ultrasound Generator........................................................................................................... 17
3.2 Step in Setting the Adjustable Values.......................................................................................................... 17
3.3 Parameters of Ultrasound Heads ................................................................................................................ 18
4 ACCESSORIES ................................................................................................................................................ 19
PAGE 2 OF 19
1 ULTRASOUND THERAPY
Continuing education is a very important aspect of healthcare delivery. Many excellent resources are available
today to expand a user's knowledge about many aspects of ultrasound therapy. BTL recommends a thorough
review of this guide prior to operating the equipment.
1.1 MECHANISM OF ACTION
Mechanical waves of frequency higher than 20 000 Hz are called ultrasound. Application of ultrasound does not
generate any electric current in tissues, and thus it is classified as mechanotherapy. The frequency usually used
in physiotherapy is 0.8 – 3 MHz.
When the air gap between the emitter head and the body surface is eliminated, the emitter head vibrations are
transmitted into the tissue and propagate to depth in the form of longitudinal waves. All cells in the path of the
ultrasonic beam begin to oscillate. This causes micro-massage followed by transformation of gel into sol (jelly
structures become liquid), transformation of mechanical energy into thermal, and deep warming of tissues.
The amount of generated heat depends on the amount of absorbed energy. Other effects of ultrasound
(degassing of solutions, formation of cavities in liquids, and local alkalization) are negligible with the ultrasound
doses and intensities used in physical therapy.
In order to avoid side effects, it is important to realize that molecular oscillation occurs not only in the path of the
ultrasonic beam, but also in places that are distant from the area of application as a result of transmission by body
fluids. This may lead to restoration of former epistaxis or acceleration of menstruation.
The features of the ultrasound beam and its distance from the emitter head determine the ultrasound field as
being either close or distant.
Close ultrasound field is characterized by low beam divergence and large intensity variations due to
interferential effects. The length of the close field is directly proportional to the effective radiation area (ERA – see
below) of the emitter head and inversely proportional to frequency. For example, the length of a close field with 4
2
cm
ERA emitter head and 1 MHz frequency is approximately 10 cm, and for an emitter head with 1 cm2 ERA and
1 MHz frequency it is approximately 2 cm.
Distant ultrasonic field is characterized by increasing beam divergence, gradual decrease in intensity, and
almost no interferential effects.
Therapeutic effects take place mainly in the close field. The ultrasonic beam in the close field has significant
interferential effects (interference of applied and reflected waves) - both constructive and destructive. It results in
a non-homogenous ultrasonic beam where peak levels of intensity (local increase in intensity caused by
constructive interference) may be many times higher than the pre-set value.
Beam Non-uniformity Ratio (BNR) states how many times the peaks of intensity exceed the pre-set values. This
value characterizes an ultrasound head with a given frequency. The BNR value of a good quality ultrasound head
is lower than 5. This means that if the pre-set intensity of the unit is 1 W/cm
ultrasonic beam is not higher than 5 W/cm
2
.
2
, the intensity in any part of the
The BNR of older ultrasound heads and some newer ones (some manufacturers do not mention the BNR
value) is often 20 or even more!
The Effective Radiating Area (ERA) is always smaller than the actual surface area of the emitter head (the ERA is
determined by the size of the piezoelectric crystal or ceramic tablet that generates ultrasound by oscillating).
The ultrasound dose (power emitted to a surface area) is, therefore, related to the ERA and not to the actual
surface area of the emitter head.
ULTRASOUND THERAPY | PAGE 3 OF 19
The phenomena of ultrasound refraction and reflection are caused by ultrasound wave transmission from one
tissue into another and by different transmission speeds in these tissues. When applying ultrasound, it is
necessary to eliminate the air gap between the emitter head and the skin. Therefore, modern ultrasound heads
have a built-in optical and/or acoustic check of insufficient contact, possibly with automatic termination of
application time countdown.
Due to interference in the close ultrasound field (it reaches the highest level at the site of the soft tissue/bone
boundary - up to 35%), ultrasonic beam power increases (constructive interference) or decreases (destructive
interference).
In order to avoid tissue lesions at peak levels of intensity, it is necessary to move the emitter head continuously.
As a result of reflection and constructive interference, local increase in intensity and temperature may occur,
particularly at the periosteum/bone boundary. This increase can lead to periosteum pain during ultrasound
application. If this occurs, the intensity must be immediately lowered.
Ultrasound is primarily absorbed in deeper tissues. Since these tissues usually do not include thermoreceptors, it
is impossible to perceive local rise in temperature. The patient feels pain only if the local temperature exceeds
o
45
C and nociceptive receptors are irritated. Most authors agree that a short-term rise in local temperature to
o
45
C is not dangerous.
In the area of classic inflammation (oedema, erythema, local rise in temperature, pain or dysfunction) additional
heat production is contraindicated, and thus only pulsed ultrasound (athermic) can be applied if necessary.
During the peracute phase of post-traumatic conditions (up to 24-36 hours) pulsed ultrasound application is
contraindicated (vibrations hinder capillary proliferation and may cause delayed bleeding).
Local rise in temperature and micro-massage have several physiological effects:
• Improvement of local circulation and thus also metabolism. Rise in temperature enhances
vasodilatation (more evident in continuous ultrasound).
• Increase in capillary permeability and increased resorption of extravasation fluid.
• Improvement of local circulation and decrease in orthosympathetic activity resulting in significant muscle
relaxation.
• Decrease in local ischaemia pain.
• Transformation of gel into sol (due to transformation of fibrinogen into fibrin, haematomas and oedemas
change into gel; ultrasound dissolves this gel and speeds up resorption). As the transformation of fibrinogen
into fibrin is the basis of the healing process (scar formation), it is not advisable to apply ultrasound in
peracute post-traumatic conditions.
• Improvement of tissue regeneration capabilities as a result of the above-mentioned effects.
Ultrasound also has several non-therapeutic effects that can have negative impacts, such as:
• Tissue lesion - Mechanical and/or thermic tissue lesion can occur when the intensity is too high.
Especially sensitive is the nervous system (peripheral nerve) situated right on the bone
(interference!) below the surface (close field!). Impulse transmission speed in the corresponding
nerve decelerates, then occurs total (reversible) impulse transmission blockage and finally
irreversible disintegration of the neuron (myelin coats are preserved). Therefore, be extremely
cautious when applying ultrasound e.g. on paravertebral muscles after laminectomy when nerve
structures lose their natural bone protection. Similarly, bone projections located just under the skin
(ankles, epicondyles, spondyle spines, etc.) are also sensitive.
• Leukocyte mobility impairment – this can be minimized by sufficient movement of the emitter head.
• Other effects (mainly caused by overdosage) are: decrease in glycaemia, increased fatigue, nervousness,
changes in appetite, constipation, increased tendency to catch colds.
ULTRASOUND THERAPY | PAGE 4 OF 19
1.2 METHODS OF APPLICATION
1.2.1 ACCORDING TO APPLICATION AREA AND MOVEMENT OF THE EMITTER HEAD
Static application - The head is fixed to the treated area by a special holder and it is not moved. Due to the
above-mentioned adverse effects, it is the least suitable form of application.
Semi-static application - is used when the application area corresponds to the ERA of the emitter head. The
therapist continuously moves the emitter head in a spiral along the perimeter of an imaginary circle.
Dynamic application - the application area is bigger than the ERA of the emitter head. The therapist moves the
emitter head in spirals in the treatment area. The application time is prolonged proportionally according to how
many times the application area is bigger than the ERA of the head.
1.2.2 ACCORDING TO APPLICATION AREA
Local application - Ultrasound is applied to the affected area. It is the most common manner of application,
particularly suitable for local muscle spasms, chronic post-traumatic oedemas, etc.
Segmental application - Ultrasound is applied to the outflows of nerve radices of the affected area (e.g. Sudeck
syndrome, Morbus Reynaud, etc). The application is paravertebral and homolateral; in the area of C
pathologies of upper limbs and in the L3 - S1 area for lower limbs.
- Th1 for
5
Neural application - is based on the effect of decrease in impulse transmission speed in the peripheral nerve
where ultrasound is applied. As the dividing line between the lowering of conductivity and irreversible nerve
damage (asymptomatic) is very fine, this method of application is considered dangerous, and it is used only
exceptionally (e.g., phantom pain).
Radicular application - Ultrasound is applied subsequently to the corresponding spinal root and manifested
Head zone. For application above the spinal root, the same risks and limitations apply as for neural application.
1.2.3 ACCORDING TO CONTACT BETWEEN EMITTER HEAD AND BODY SURFACE
Direct contact - is provided by a contact medium (ultrasound gel). This is a common manner of ultrasound
application, and it is not necessary to mention it in ultrasound therapy prescription. For combined therapy
(ultrasound + electrotherapy) it is recommended to write "conductive gel" in the prescription because some gels
do not conduct electricity. The BTL ultrasound gel is conductive; if this gel is not available, you can use ECG gel
or another water-based gel instead. However, never use paraffin oil, because it is non-conductive and could
damage the head.
Subaqual application. This method has a range of advantages: It uses mainly the distant ultrasound field, where
interference does not occur. Furthermore, there is no need to press the emitter head against the skin in order to
maintain sufficient contact (this pressure is unpleasant or even painful for post-traumatic conditions). In addition,
this application is not limited by uneven surfaces, and ultrasound can be easily applied to these surfaces, such as
to interphalangeal joints.
Disadvantages of subaqual application include difficult handling of the special porcelain bath, limitation of
ultrasound application to acral body parts, and the risk of the therapist getting hand lesions if the hand is put in
water. (It is strictly prohibited due to reflection and interference of ultrasonic waves against the walls of the
porcelain bath!) Some emitter heads (even newer) are claimed to be water resistant, but if they do not have a
holder, they do not provide safe subaqual ultrasound application.
Ultrasound can also be applied via a thin-walled rubber bag (surgical gloves, condom) filled with boiled water.
However, when using this method, it is necessary to eliminate the air gap between the bag and skin (use gel) and
between the emitter head and the bag. This method is often perceived as very time-consuming.
ULTRASOUND THERAPY | PAGE 5 OF 19
1.3 ULTRASOUND FREQUENCY
Older ultrasound units employ a fixed frequency, usually 0.8 – 1 MHz. Newer ones are multi-frequency units, the
selected frequency being determined by the target tissue; 1 MHz frequency is used for deep tissues and 3 MHz
frequency for superficial tissues.
1.4 MODES OF OPERATION
a) continuous - is characterized by heat generated deeply in tissues. It is contraindicated in inflamed areas and
anywhere else where local warming is undesirable.
b) pulsed - together with shortening of pulse length there occurs decrease in the so-called Duty factor. As a
result, the thermic effect is suppressed and when the Duty factor is below 12.5% (1:8), an athermic effect can
be expected.
Duty factor (DF) can be set in pulsed mode of operation. Its value states for how many percent of the duration
the ultrasound signal is generated. When setting therapy parameters of BTL units, the ratio of ultrasound signal
duration to the period length is stated in brackets. This ratio is used in the parameters of recommended
ultrasound therapies of BTL units. In case of continuous setting of the parameter, only the percentage expression
is used.
Example:
Duty factor 25% (1:4) means that 25% (1/4) of the period is ultrasound and the rest of the period is pause.
The same example, more detailed:
With a pulse frequency of 100 Hz, the period is 10ms long. With DF set to 25% (1:4), pulse duration is 2.5 ms
and pause is 7.5 ms.
1.5 EMITTER HEAD SIZE
The size of the emitter head is determined by the Effective Radiating Area (ERA): 1 cm2 (small head) and 4 cm2
(medium head, or large head according to some manufacturers). The choice of the head depends on the size of
the application area. Ultrasound application to large areas using a small head is too time-consuming, difficult for
the therapist, and the dose is not applied homogeneously.
Small heads with ERA about 1 cm
an emitter head of standard size the ultrasound would have to be applied subaqually.
2
are used for trigger points, scars or for small and uneven surfaces where with
1.6 APPLICATION TIME
Application time varies and largely depends on the stage of the disease. For acute conditions, it is 3 minutes at
the beginning; for chronic conditions, it is usually 5 minutes at the beginning, and then it is prolonged using the
positive step method. Application time for most therapies does not exceed 10 minutes. If the application area is x-
times larger than the ERA of the head, application time has to be x-times prolonged and dynamic application is
used.
ULTRASOUND THERAPY | PAGE 6 OF 19
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