I’ve been doing some work lately that has caused me to begin to question the wisdom of traditional Biomeds moving into imaging service. You see, when we were trained to repair the general biomed equipment (monitors, infusion pumps, incubators, etc.), we had simulators which created known and precise inputs. We then could measure the outputs, which had to be just as exact and precise (within specified tolerances). It is fairly simple for us to adjust the medical equipment to make the output match the input. You use a simulator to inject an 80 BPM ECG and make sure that the monitor reads 80 BPM. Simple. Easy. Foolproof.
Let’s now examine ultrasound. The image is fuzzy. It is not well defined. It is not often clear what the doctor is looking for. It is not obvious what is normal and what is not normal.
One of the most difficult things for a biomed to do when servicing an ultrasound is return the unit to an image that the sonographer finds acceptable. It seems that almost every sonographer has different preferences and thoughts about what is the “correct” setup and image.
So, if the sonographers can’t agree among themselves, how can we be expected to apply a uniform standard? I see only one way to do it. Use a phantom and have some pre-printed photos of how the screen should look when the particular phantom is used in such-and-such mode, with certain settings.
Those of us who are old will remember when we had to manually adjust the color on our color television set. We had a color and tint control. By adjusting these, we could vary the intensity and shading of the images. I was a TV repairman back in those days. In order to help us adjust the color accurately, and avoid the varied perceptions of each of our customers, we had a preprinted COLOR BAR CHART. One of our items of test equipment was a COLOR BAR GENERATOR. It created a matching color pattern on the TV screen. We then held the preprinted color chart up to the front of the TV, and adjusted the color and tint controls until the screen colors matched the color chart. Simple.
Why shouldn’t we do the same thing for ultrasound? Using a known phantom, with preset machine settings, print what the image on the screen should look like. When making a service call, using the phantom and the standard settings, if the screen matches the preprinted screenshot, then that is a pretty good indication that the entire image chain, from the transducer to the front end, to the signal processor, to the display, are all working properly.
I am sure that some people out there will fine holes in this straightforward plan. Please – let me know where I am missing the boat. It seems so simple to me.