Submitted by Pooja Pandey on Fri, 30/06/2023 - 09:18
Scientists have created a new recipe, just like a cake recipe, that can be used to make a phantom.
Having this new phantom material is very exciting as we can now test the performance of photoacoustic imaging systems as we undertake clinical trials. In our ongoing clinical trials, we will use this phantom material to test for any technical errors in the system so that we can focus our research purely on the biological differences we are looking for between humans. Sarah Bohndiek
No, these are not ghosts and ghouls, but are solid objects that are used to test medical imaging technologies such as X-ray or ultrasound. They look just like a human being to the imaging system. They absorb light just like we do. They scatter light just like we do. They even sound like us. But instead of being made of organs, they are made of simpler materials that are durable and contain simple shapes for us to find deep inside.
Medical imaging technologies allows us to make measurements in people that can detect the earliest signs of diseases such as cancer. To test these technologies, scientists use imaging phantoms.
The researchers based at the Cavendish Laboratory (and at other places) are working with a brand-new imaging technology called photoacoustic imaging, that uses light to make sound waves in our bodies. This technology can be used to measure changes in our blood. However, the problem with this brand-new imaging technology is that we can’t just buy a phantom to test it.
In this research project, published in JoVE Journal, scientists have set out to create phantoms that look and sound to the imaging system just like a human would. They have created a recipe, just like a recipe for making a cake, that can be used to make the new phantom. “Unlike making a cake, this recipe is special because it is customisable,” said Lina Hacker, who carried out the research at the Cavendish Laboratory and is now based in the Department of Oncology at the University of Oxford. “We can easily change the ingredients to have different proportions, which changes how the phantom looks and sounds.”
Phantom materials are used widely in medicine; however, they do not interact with visible light and sound in the same way human tissues do. The new phantom material overcomes the inherent disadvantage of not interacting with visible light and sound in the same way human tissues do and therefore can be used to test new imaging systems that use light and/or sound.
“It was exciting to see that not only the phantom is low cost but is also stable for a long time. So, unlike a cake, it will not degrade over weeks, months or even years,” said Hacker. “Even we could not have predicted that phantoms could sit on the shelf for years and still have the same properties.”
Image: Three simple test phantoms| ©Lina Hacker
There are many great technologies – such as photoacoustic imaging systems - out there that are either based on light and/or sound, but cannot be reliably used yet, as they are not properly validated. As the new phantom material can mimic human tissues interaction with light and sound, scientists can use it to check that those new imaging machines are working accurately, and that their output can be compared across different devices.
This breakthrough will help scientists to create more accurate research results, and doctors to better diagnose patients.
“Having this new phantom material is very exciting as we can now test the performance of photoacoustic imaging systems as we undertake clinical trials. In our ongoing clinical trials, we will use this phantom material to test for any technical errors in the system so that we can focus our research purely on the biological differences we are looking for between humans,” says Prof. Sarah Bohndiek, from Cavendish Laboratory and Cancer Research UK Cambridge Institute.
Currently the researchers are doing a large-scale study with different photoacoustic research and industry centres across the world to test the reproducibility of the phantom recipe. If successful, the material may be adopted more broadly in research and clinical settings, supporting the development of medical imaging systems and making their testing better and more reliable. Having a means to test their performance will help to speed up their development, safety and efficacy, thereby bringing them to hospitals more quickly.
Reference:
Hacker, L., Ivory, A. M., Joseph, J., Gröhl, J., Zeqiri, B., Rajagopal, S., Bohndiek, S. E., 'A Stable Phantom Material for Optical and Acoustic Imaging', J. Vis. Exp. (196), e65475, (2023), DOI:10.3791/65475
Image:
An image of a mouse ear taken with one of the photoacoustic imaging systems (where the individual blood vessels can be seen.) The grey half of the image has been changed digitally to mimic a phantom. Credit: Lina Hacker