Ultrasound transducer

1. A catheter for medical therapy comprising:

a distal end; and

a proximal end adapted to be inserted into the body, comprising:

an ultrasound transducer positionable within a blood vessel;

a separation element configured to distance said ultrasound transducer at least a minimal distance away from a wall of said blood vessel, said minimal distance sufficient to allow blood to flow between said transducer and said wall;

said ultrasound transducer comprising:

an acoustic element for delivering ultrasound energy at an intensity sufficient for medical therapy; and

a temperature sensor mounted on said transducer and positioned adjacent said acoustic element, said temperature sensor positioned to contact blood flowing over a surface of said acoustic element to provide an indication of a temperature of said blood when said transducer and said temperature sensor that is mounted on it are distanced away from a wall of said blood vessel by said separation element;

wherein said catheter is connected to circuitry configured to apply electrical power to said transducer; said circuitry further configured to modify said applied electrical power according to said indication obtained from said temperature sensor.

2. A catheter according to claim 1 , wherein said temperature sensor is positioned downstream from said acoustic element.

3. A catheter according to claim 2 , wherein said circuitry is configured for estimating a temperature of said acoustic element using said indication of temperature of said blood.

4. A catheter according to claim 1 , wherein said circuitry is configured to maintain a temperature of said acoustic element under about 50 degrees Celsius while said transducer is used for medical therapy.

5. A catheter according to claim 1 , wherein said catheter further comprises a cooler operative to reduce a temperature of said acoustic element when said transducer is positioned within a blood vessel.

6. A catheter according to claim 5 , wherein said cooler comprises cold fluid that is aimed at said acoustic element to reduce a temperature of said acoustic element.

7. A catheter according to claim 6 , wherein said cold fluid is blood cooled by said cooler.

8. A catheter according to claim 6 , wherein said cold fluid is one of saline and dye.

9. A catheter according to claim 1 , wherein said temperature sensor is connected via a twisted pair of wires to at least one of a board onto which the acoustic element is mounted and a housing of said element.

10. A catheter according to claim 1 , wherein said sensor is a thermocouple.

11. A catheter according to claim 1 , comprising a plurality of temperature sensors.

12. A catheter according to claim 1 , wherein said minimal distance is at least 1 mm.

13. The catheter according to claim 1 , wherein said transducer is coated at least in part by a thin coating.

14. The catheter according to claim 1 , wherein said separation element extends radially away from a shaft of said catheter.

15. A method for removing excess heat from an acoustic element of a catheter for medical therapy, comprising

positioning said catheter in a blood vessel such that said acoustic element is distanced away from a wall of said blood vessel, such that blood is allowed to flow between said acoustic element and said wall;

estimating a temperature of said acoustic element by measuring, via a temperature sensor positioned adjacent said acoustic element, a temperature of said blood after blood flows passed said surface; and

controlling activation of said acoustic element according to said blood temperature.

16. The method according to claim 15 , further comprising delivering a liquid to flow over said acoustic element.

17. A method according to claim 16 , wherein said liquid is one of saline and dye.

18. A method according to claim 16 , wherein said liquid is colder than blood.