DIT: Fake tissue to aid training in ultrasound imaging
Innovation Profile Complex mimicking of a real breast is set to boost the efficiency of scanning and the skills of experts
Dr Jacinta Browne of DIT with co-researcher Prof Andrew Fagan of St James’s Hospital and Minister Sean Sherlock.
Ultrasound scanning is a very powerful diagnostic tool and plays a particularly important role in the detection of conditions such as breast cancer. However, as some recent cases in this country have demonstrated, the technology must be used properly if it is to be effective.
Researchers from the school of physics in DIT and the Centre for Advanced Medical Imaging in St James’s Hospital are addressing this issue through the development of a highly advanced tool for training radiologists and sonographers in the use of ultrasound scanners.
The problem to be addressed lies in the very nature of ultrasound scanning itself, according to Dr Jacinta Browne, who leads the Medical Ultrasound Physics and Technology Group at DIT. “Ultrasound scanning is very different from an X-ray, for example,” she explains. “With an X-ray, you put the patient into the required position and take an image at the required power setting. It’s quite straightforward and easy for the patient. The images can be viewed later and further images taken if needed.”
With ultrasound, there is no snapshot picture. Instead, the scanner operator uses a transducer pressed against the skin of the patient to send sound waves into the tissue and detect their reflections or echoes. These reflections are displayed on a screen in the grainy black -and-white images familiar to all who have experience of foetal ultrasound scans. But the image is built up as a combination of very small thin “slices” just a few millimetres wide and centimetres thick produced by the transducer.
“A radiologist has to be very skilled when using the equipment,” Browne notes. “They have to press the transducer against the skin of the patient with the right force and keep it at the right angle to get usable images and they have to do this while looking at the screen and adjusting various controls to adjust and enhance the image. It’s very difficult and requires a lot of skill.”
Deterioration of image
And the level of concentration and expertise required to pick up on lesions or other abnormalities which may be displayed on screen is also quite considerable. There is a 90 per cent loss of energy per centimetre of tissue which the sound waves pass through so the quality of the image deteriorates quite dramatically with the depth of the scan.
There are ways to boost the quality of the image by changing the frequency of the sound but higher frequencies do not penetrate as deeply as lower ones. There are also ways of amplifying the sounds that come back but this can result in other distortions.
The skill level required is evident but training is still very much on-the-job for radiologists.
“Currently, radiologists are trained in a live-patient environment, with all the associated problems this brings,” says Browne. “Prior to this, their training is typically limited to a simulation using stocks of preprepared images and lectures on the underlying physics. This offers no tactile feedback and does not help with co-ordination skills, nor does it afford trainees the opportunity to master the complex ultrasound scanning technology used for breast imaging.”