Investigation of a new method for the diagnosis of cancer in breast tissue

The aim of any mammography investigation is to detect tumours in the female breast as early as possible, so that treatment can start in good time. A good mammography procedure is therefore expected to recognise as many tissue changes as possible and to distinguish tumour tissue clearly from any other tissue. At the same time, the radiation dose administered during the investigation must be kept as low as possible.

Tests under realistic conditions

Researchers at the Paul Scherrer Institute have developed a procedure that should provide these benefits. Working with doctors from the Kantonsspital Baden (KSB), they have now succeeded for the first time in generating images of tissue that originated from breast surgery but had not been preserved. This approach produces an extremely close approximation to the situation in which an actual investigation is carried out on human beings. For example, we could use this new process to distinguish scars from tumour tissue and identify extremely small cancer nodules, of a size never yet identified by current investigation techniques, said Dr. Nik Hauser, director of the certified breast centre at the Kantonsspital, who led the project on the medical side. A clinical study is currently underway, and should prove the advantages of the new method using a larger group of patients. In particular, doctors who did not take part in the development of the method are required to make an independent assessment of the advantages of the new images in comparison with those obtained from conventional X-rays.

Method developed at the Paul Scherrer Institute

In this new procedure, X-rays pass through the breast in exactly the same way as in conventional mammography. However, a normal X-ray image can only determine how much of the beam has been retained by the tissue – basically, an X-ray image just shows the shadow cast by the object under investigation. However, X-rays also undergo another subtle change as they travel through an object. Physically, X-rays are electromagnetic waves and, as they pass through various tissue structures, the direction of the waves undergoes slight changes – a similar effect to that shown by water waves hitting a pier in a harbour. We at the Paul Scherrer Institute have spent years developing methods for investigating these changes and interpreting the information they contain, so that we can create the basis for new investigative methods to be used in medical and materials research, explained Marco Stampanoni, Professor at the Institute for Biomedical Engineering at the University and ETH Zurich and director of this project at PSI. One particular feature of the phase-contrast method used in this process is the three extremely fine gratings through which the X-rays have to pass – one in front of the object under investigation and the other two located behind it. The various components of the light waves interact with each other here in such a way as to provide the required information. The X-rays are generated in a tube that is essentially the same as an X-ray tube used in normal, everyday clinical practice.

The next goal: A prototype for use in practice

The long-term aim of this work is to develop a novel piece of equipment that can be used for regular routine breast examinations in clinical practice, and deliver improved images of breast tissue – at a significantly lower cost than techniques such as computer tomography or magnetic resonance imaging. Philips has been brought into the project as an experienced partner in the field of healthcare. The potential of this method is defined on the one hand by the innovative nature of the measured information, but on the other hand is also characterised by the use of conventional technologies that are widely applied in medical technology to generate and detect X-rays. Our declared goal is to use the example of mammography on humans beings to conclusively demonstrate the clinical benefits, explained Ewald Rössl, project manager for this research work at Philips.

Approved by the Institutional Review Board

This study used tissue obtained from people who had just undergone surgery. The individuals in question gave their written consent to the use of their tissue and the study was approved by the local Institutional Review Board at the Kantonsspital Baden.

About PSI

The Paul Scherrer Institute develops, builds and operates large-scale, complex research facilities and makes them available to the national and international research community. The organisation’s own research activities focus on solid state physics and materials sciences, elementary particle physics, biology and medicine, energy and the environment. It is Switzerland’s largest research institution, with a workforce of 1400 and an annual budget of approximately CHF 300 million.

About the KSB

The Kantonsspital Baden provides basic medical care for 150,000 local residents, together with more extensive and specialised care for about 300,000 inhabitants of the eastern part of Canton Aargau. It treated 18,000 in-patients and more than 65,000 out-patients in 2010. The KSB has a turnover of CHF 269 million, with a workforce of 1750 staff and 209 trainees.