I designed an opthalmic ultrasound in the late '80s. The article describes "b-mode" ultrasound which actually creates an image (in some fraction of a circle li

I designed an opthalmic ultrasound in the late '80s. The article describes "b-mode" ultrasound which actually creates an image (in some fraction of a circle like you see when someone shows you their unborn child). Back then, the electronics to electrically steer the beam were very hard to create (20MHz was a fast clock back then) and so the b-mode transducers were often mechanically steered. there was one transducer that was moved in an arc by the steering motor and coupled to an acoustically transparent housing by some gel. Central Pennsylvania (from whence I'm writing tonight) played a key role in the creation of ultrasound systems - and Johnson and Johnson still manufacturers their transducers about 15 miles from where I'm sitting. The technology originally developed for SONAR came to the Pennsylvania State University where some of the engineers though of cool other ways to use transducers. Good thing the human body has so much water (or other components with a similar density and propagation speed. When you get a b-mode ultrasound, you see the interface between two types of tissue (or bones) due to reflection. If you look at an image, it takes some practice to even "see" what the picture is. So back to the cost issue - the biggest single expense in creating an ultrasound unit was getting through the FDA approval process. It was grueling - requiring a lot of testing by outside laboratories and a lot of internal engineering time for paperwork. Once you start to manufacture them, you're making (for a small company like ours) hundreds of units and even the large manufactures aren't making them like the Coca-Cola company spits out cans of soda. You're amortizing a lot more development costs into each unit. And then, once you start selling to hospitals and doctors offices, the mark-up is huge. They in turn pass a large chunk of the cost of the machine to the insurance companies. If you were charging $500 per scan 20 times a day, you'd pay for your $8000 machine pretty quickly).