Photoacoustic imaging promises breast cancer screening without ionizing radiation


May 10, 2012

The Twente Photoacustic Mammoscope (PAM) integrated into a bed so patients can be scanned laying down (Photo: Michelle Heijblom, University of Twente)

The Twente Photoacustic Mammoscope (PAM) integrated into a bed so patients can be scanned laying down (Photo: Michelle Heijblom, University of Twente)

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While breast cancer screening tests are accepted as safe – and we definitely wouldn’t want to scare anyone off from a potentially life-saving test – they do have some risks associated with them. The most obvious being the exposure to low doses of ionizing radiation, which in itself is a risk factor for breast cancer. X-ray mammography can also give false positive and negative results. In the quest for a safer, more accurate alternative, Dutch researchers have provided proof of concept that photoacoustic imaging can be used to detect and visualize breast tumors.

Photoacoustic imaging is a hybrid optical and acoustical imaging technique in which biological tissue is exposed to non-ionizing laser pulses. Because malignant tissue absorbs more light, it increases in temperature and expands when exposed to the laser pulses. This thermal expansion creates a pressure wave that can then be detected and converted into an image using ultrasound.

Using this approach, researchers from the University of Twente and Medisch Spectrum Twente Hospital in Oldenzaal created a specialized device called the Twente Photoacoustic Mammoscope (PAM) and built it into a hospital bed so the patient can lay prone while laser light at a wavelength of 1,064 nanometers scans her breast. An ultrasound detector placed on one side of the breast detects the photoacoustic signals, which are then processed by the PAM system and reconstructed into images. Areas of abnormally high intensity will indicate malignant tissue, while areas of low intensity will indicate benign tissue.

When they compared the performance of the system with conventional diagnostic X-rays, ultrasound imaging, MRI, and tissue exams, the researchers found that malignancies produced a distinct photoacoustic signal. Additionally, the photoacoustic contrast of the malignant tissue was found to be higher than the contrast provided by conventional X-ray mammographies.

"PAM needs some technical improvements before it is a really valuable clinical tool for diagnosis or treatment of breast cancer,” said Michelle Heijblom, a Ph.D. student at the University of Twente. “Our next step is to make those improvements and then evaluate less obvious potential tumors, benign lesions, and normal breasts with it."

The research team’s paper appears in the Optical Society’s open-access journal Optics Express.

Source: The Optical Society

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

I am starting to think that for the most part, X-Ray Machines are the lazy persons method of testing - sure it's fast, easy and cheap, but for the most part, that is all that it is.

Glad to see that better "NON ionising" equipment is coming on the market.

Mr Stiffy

Mr "Stiffy" there are many considerations when choosing a modality (biological imaging system). That is why we have so many different sorts. Of those that produce ionising radiation there are a wide variety of applications each is designed for. If what you are saying was true then we'd use ultrasound and MRI for everything. It is well accepted that ionising radiation has risk, but why do you think they still use them if they are so dangerous? It may be of interest for you to consider that you are exposed to ionising radiation every day without going near any xray/nuclear medicine equipment. Solar radiation is unavoidable, in fact it is particularly high in relative terms everytime you take a ride on an airplane - yet we don't warn pilots, air stewards or passengers of it or try to limit their "exposure".

Ionising radiation occurs from elements in the soil, in the bricks and concrete of our homes, the air we breathe and the food we eat. There is a whole swathe of physicists that have the profession of knowing the science of Xray radiation and it's risks and safeguards. These people work for governments, hospitals and medical imaging companies to name but a few. Within the medical world there is constant efforts to lower dose to the patient. The risks are well documented and researched. Technology like that in this story is welcomed and should be developed. But until it proves better detection rates than conventional mammography, the risk associated with the radiation can be regarded as negligable in light of possible cancer detection.

To call an X-Ray Machine a lazy person's method of testing shows little appreciation for the diagnostic powers of XRays, even a humble general XRay room can (and does) rapidly diagnose life-threatening diseases and fractures. Then we can speak of angiography. It would not be wise to call a Cardiologist lazy when he is using XRays to place a stent in one of your closed arteries in order to save your life. CT is the fastest and most reliable method to diagnose internal injuries to victims of trauma like motor vehicle accidents. There is simply no way they could use any imaging system that doesn't use XRays to obtain this quick diagnosis. In the emergency department, seconds and minutes often mean the difference between life and death.

I'm afraid I need to be careful I'm not being sarcastic because your comment really smacks of ignorance.

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