Science
Compare
Shock Wave Physics
| Shock Wave Physics |
|
Extracorporeal Shock Wave Technology (ESWT) is a technological breakthrough in non-invasive surgical alternatives. ESWT offers patients and physicians benefits which traditional surgery cannot match, and the clinical outcomes prove that ESWT is just as, if not more, effective when compared to traditional open surgery.
Electrohydraulic Shock Wave Generation (Spark Gap Method)True shock waves generated for medical purposes consist of a dominant pressure pulse which climbs steeply to some tenths or even hundreds of Mega-Pascals (MPa; 1 MPa = 10 bar) within several nanoseconds (nanosecond = 1/billionth of a second) and then falls again within several microseconds (microsecond = 1/millionth of a second); this wave is followed by a weaker tensile wave portion lasting for several microseconds.
The electrohydraulic source used by PulseVet's® VersaTron®, VersaTron® 4Paws, and EquiTron creates the most effective shock waves for medical purposes. These shock waves have the largest target volume and the steepest leading edge. The spark gap method, whereby a spark is generated between two electrodes, is a very effective and reproducible technique for producing shock waves of this kind. Owing to the extremely high rise in pressure at the wave front, there is a high concentration of mechanical energy in the direction of wave propagation.
This technique, which is the benchmark of all shock wave generation methods, is based on the following principle: a capacitor which has been charged to a high voltage discharges electrical energy abruptly at the 1st focal point over two electrode tips located in water (underwater spark discharge). The shock wave created by the explosive evaporation of water is focused by an ellipsoid and finally releases its maximum energy at the 2nd focal point. The shock wave is conveyed into the body via a water cushion. The electrohydraulic shock wave generation method is the only method that generates a true shock wave at all energy settings.
Other Types of Shock Wave Generation Electromagnetic Shock Wave Generation (EMSG)With this method, shock waves are generated on the basis of a principle similar to that used in loudspeakers. An electrical impulse is sent through an inductance coil, generating a magnetic field which repulses a metallic membrane. The acoustic impulse created by this repulsion is focused by an acoustic lens to form a shock wave. The electromagnetic method of shock wave generation requires an extensive water-based cooling system.
Piezoelectronic Shock Wave Generation Shock waves created on the basis of the piezoelectronic principle are generated by about a thousand piezoelectronic crystals arranged on the inside of a conical segment. The intermittent application of a high voltage to the crystals cause them to alternately contract and expand. Owing to the particular arrangement of the crystals on the conical segment, the acoustic impulses are bundled into a shock wave at the focal point.
*Piezoelectronic shock wave generation has not been approved by the FDA.
**Both electromagnetic and piezoelectric shock wave generation are popular for lithotripsy due to their small focal area, allowing most of the generated acoustic energy to be targeted at a very small object such as a kidney stone. A small focal area is not optimal, however, for treating a larger target area, as would be necessary in most orthopedic or chronic wound indications. At low-amplitude settings these technologies do not produce a true shock wave. Radial or Ballistic Pressure Wave Generation
(not a shock wave, but has been marketed as a shock wave)
Ballistic (Radial): This type of device has an oscillating pneumatically driven head that is applied directly to the tissue surface and mechanically impulses over the target tissue. Maximum penetration effect of this type of device is approximately 5mm. In a published study, it was found that one ballistic device investigated which was labeled as a "focused shock wave" device was neither focused nor a shock wave.
|