How much is the lifespan of an ultrasound transducer?

Just to clarify my prior post and Professor Watson's reply, I make a well at least 3/4 of an inch deep, or greater depending on the width of the tape I use to make the well. This allows me to pour a one to two ounces of water into the well and over the transducer head. I agree with Prof. Watson that just a few droplets of water can damage a transducer but with more water as I have described, we have never seen a decline in transducer function verified by calibration procedures.

Prof James. Many thanks for that suggestion. The drops of water on the transducer face - a commonly employed 'trick' looks great but potentially causes transducer damage. I like your idea - will go try it as it is not one that I have employed - and I can see the benefits as a demo and quick test without the risk of transducer damage. Thank you. I can feel a YouTube video coming on . . . . .!!!!!

Similar to Professor Watson's suggestion for a simple visual assessment of sound output, you can take some kind of tape, preferably 1" wide or more and apply it around the US head creating a well into which you can pour water. After you turn on the US device, I suggest initially testing with a 100% duty cycle and 1 W/cm2. If the transducer head is functioning, you will see a disturbance of the water surface in what appears to be concentric rings. As you decrease the duty cycle you will see the magnitude or severity of the water disturbance decrease with the decreasing duty cycle. In this manner you can at least determine if the transducer is still providing differing duty cycles. Another neat feature of this methods of assessing an US transducer is that you can get an idea of the effective radiating area (ERA) when looking down into the water well and seeing the diameter of the area where the water ripples originate in comparison to the size or diameter of the transducer head. Not a technical or specifications check, but a quick functional assessment and wonderful teaching lesson.

The first piece of equipment I bought when I went into private practice was an ultrasound machine. That was in 1980 and it is still going strong. I have a calibrated water balance and it still works to the original specs. We are also very careful with the heads and take care they are not knocked or dropped!

Thank you Tim for your contribution

KR Patrick

there used to be a very low cost water balance available (about 50 pounds GB) but I could not find it when I looked the other day. If I find anyone who still supplies it, I will post here.

I tried the thing with the water and it worked and was kinda fun to show it to a patient. Thanks for that and for the links. 225 pounds is not cheap price in Bulgaria though.

we use some equipment to test devices in the lab which is fairly expensive so would not be in routine use. There are some small and low cost ways to do a basic test using a 'water balance' indicator (I will paste example link below) but these will only give you and indication of approximate output - you will know if your device is working and in the right general power level but I would not count as accurate. Simplest way to test output - at zero cost - is to immerse ultrasound transducer in bowl of water, turn applicator face up towards the surface, put machine on continuous output, turn up to say 1.0 W cm^2 and if it is giving an output you will see water surface ripple/disturbed. Gives no indication of accuracy, but at least you will know whether something is happening and therefore whether some output. Examples of high cost water balance test kit: http://www.acoustics.co.uk/product/radiation-force-balance/ http://www.emsphysio.co.uk/product/precision-ultrasound-balance/

Low cost units such as: http://www.emsphysio.co.uk/product/budget-ultrasound-output-indicator/

Not sure which country you are based in - might make a difference

Well, I am not shure where I can test the machine in my country. Is there any easy way to do that without special equipment?

So long as they are looked after and (calibration) tested to be sure that they are functioning properly, they can last a lot longer. I was using a device manufactured in 1990 the other day and the transducer was delivering perfectly good ultrasound and was spot on when I checked the calibration. One of the things that seriously reduces life span is 'knocking' the transducer - so being careful does pay off. I am sure that some of the manufacturers might have a technical view - let's see if anybody comes up with anything