Detecting breast cancer earlier with 3D X-rays

In 2020, breast cancer was the most commonly diagnosed form of cancer worldwide, with over two million cases. In women, it accounts for about a quarter of all cancer cases and is responsible for 15.5 percent of cancer-related deaths. The earlier the diagnosis is confirmed, the sooner the appropriate therapy can begin and the higher the chances of survival. That’s why researchers around the world are working to improve early diagnosis.

And this has now been achieved by a team of researchers from the Paul Scherrer Institute PSI and ETH Zurich together with the Baden Cantonal Hospital (KSB) and the University Hospital Zurich (USZ). They have has succeeded in refining the technique used to detect tumours in their early stages, to produce considerably more reliable results and be less unpleasant for the patients.  With this, the researchers have enhanced conventional computed tomography (CT) in a way that significantly improves image resolution without increasing the radiation dose.

This means that small deposits of calcium known as microcalcifications, which indicate breast cancer, could potentially be detected earlier than before. This significantly increases the chances of recovery for affected women. According to the experts, this technique, which is based on X-ray phase contrast, could be swiftly put to use in clinical settings. “We still need a little time,” says Marco Stampanoni, head of the research group at PSI and Professor of X-ray Imaging at ETH Zurich, “but we’ve reached a milestone along the way with our work.”

How effective is mammography?

More accurate early detection of tumours is an important step in the fight against breast cancer. Currently, mammography screening programmes are are used as an early detection tool in many industrialised countries. However, the effectiveness of mammography screening is a controversial topic.

Control studies have found that only 46 percent of suspected cases detected in screening turned out to be actual cases of cancer. A false alarm can cause great distress to sufferers, as it can be two to three weeks before a biopsy result gives the all-clear. Moreover, studies suggest that mammography misses 22 percent of actual cases, lulling those affected into a false sense of security. This is even more serious, as it means valuable time is wasted before treatment can begin.

The weaknesses mentioned here are due to the difficulty that even experts have interpreting mammography images. Soft breast tissue offers only limited contrast on X-ray, while the complicated interior of the breast is often blurred in two-dimensional fluoroscopy. To take X-rays of the breast, it must be squeezed tightly to hold it still. Patients sometimes find this uncomfortable or even painful, which is why some women do not go for screening.

Three-dimensional X-rays bring advantages

In X-ray phase contrast, researchers extend the tumour diagnostics with additional physical information. In other words, the images they create draw on information that conventional X-ray imaging does not take into account: the signals generated when biological tissue refracts and scatters the radiation. When X-rays pass through structures of different densities, they are not only attenuated but also refracted and diffracted. This information can be used to improve both the contrast of the images and their resolution, making the smallest objects easier to identify.