|
Lithotripsy - How it Works
|
|
 |
The first lithotripsy unit set up in Queensland was in Brisbane in October 1990 and was the first machine used to treat kidney stones in the state treating patients from Townsville, Rockhampton, Gold coast, Toowoomba…… Urologists would fly down with their patients to do a list regularly.
The original machine from the early 1980’s was called the HM1 Or Human model 1 and comprised a huge water bath, the Dornier MFL 5000 replaced the need for using a water bath and used a large spark plug and water cushion, this was then replaced a few years ago by the Dornier Lithotripter S and Dornier compact delta (mobile) which uses an electromagnetic coil.
|
Then followed the Dornier Epos Ultra designed specifically for use on orthopaedic conditions with a much shorter focal length to the kidney machine to enable exact focusing on very small tendons.
Lithotripsy works using acoustic waves of high pressure amplitudes with high rise times of a few nanoseconds and a frequency spectrum ranging from the audible to the far ultrasonic level.
Shockwaves result from intense changes in pressure such as explosion, supersonic aircraft, or lightning. These intense changes in pressure produce strong waves of compression and tensile forces that can travel through any elastic medium such as water, or certain solid substances. |
|
Using an electromagnetic coil to generate the shockwave, a convex lens focuses the shockwave into the therapeutic focal point. The electromagnetic therapy head (EMSE) is isocentrically integrated within the xray c-arm system which moves as a single unit in 3 axis x ,y, and z around the patient. When the localisation system is in focus with the stone, the shockwave focus is also in focus.
The therapy head is coupled to the patients body via a water cushion and shockwaves are released through the water and emitted from 60-240 shocks /minute. Shockwaves can be produced over a broad energy range from low to high energy so you can tailor your treatment to different tendon problems.
The EMSE works on a similar principal to a loud speaker. A capacitor is charged to high voltage of several kilovolts. After charging this energy is available for a high-energy discharge of short duration.
|
 |
The unit also consists of a coil opposite a highly conductive metallic layer. The two will be magnetically repulsed due to the current pulse through the system, produced after discharge. The metallic layer deflects towards the wave propagating medium (water) causing a shockwave in the water. The intensity of which is proportional to the current pulse and is propagated with the speed of sound. At a distance at the end of its path in the water a plane shock wave results. This is then focused using a convex acoustic lens to produce great and steep pressure amplitudes over a limited volume to the area of inflammation.
|
|
|
|
 |
