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powered by Research progress on phase-contrast technology for enhanced X-ray images – using existing equipment

Scientists from the Paul Scherrer Institute in
Switzerland together with researchers from Philips, have developed a new
way of significantly enhancing contrast in X-ray images using existing
(low-brilliance) X-ray source equipment at standard patient radiation
doses. The technology has the potential to visualize structures in, for
example, breast tissue, which are difficult to see in standard
mammography images. Conventional X-ray imaging produces clear images of
certain materials, such as bone tissue, which strongly absorbs the
X-rays. However, it is less effective in generating contrasts of
different types of soft tissue. Although it is possible to improve the
quality of images by using higher doses of X-rays, such high doses are
of course potentially more harmful for the patient. As well as being
absorbed (which is the basis of standard X-ray images), X-rays are also
deflected by tiny amounts (known a refraction) as they pass through the
body. The amount of deflection depends on the type of tissue they pass
through. In addition X-rays are ‘scattered’ as they pass through the
body. The new technique measures the deflection and scattering of the
X-rays as they pass through the body. Using advanced imaging processing
techniques, this information can be merged with the standard absorption
image to create an enhanced, sharper image. By adding three gratings to a
standard X-ray imaging device, it is possible to detect X-ray
refraction and scattering as well as absorption (which is used in
standard X-ray imaging). The first grating, placed near the X-ray
source, ensures that the X-rays are aligned. This alignment is lost due
to refraction and scattering as the X-rays pass through the body. The
second grating and third gratings, placed in front of the X-ray
detector, create a so-called ‘interference pattern’ which enables the
loss of alignment of the X-rays to be measured, and the refraction and
scattering to be derived. Preliminary investigations on five mastectomy
samples using the new phase contrast imaging technology have shown an
enhancement of general image quality in terms of richness of detail.
Contrast and detail in soft tissue, which is typically low in absorption
X-ray seemed to be improved. Furthermore, increased visibility of fine
image structures was possible. Such structures include
‘micro-calcifications’, early signs of breast cancer, and spiculae, i.e.
fine extensions of certain breast tumors spreading into healthy tissue.
The new technology is expected to be highly cost-effective, because of
its compatibility with conventional X-ray sources, and detection
equipment. The technique is currently undergoing laboratory testing on
human tissue. More concretely, human mastectomy breasts samples from
over 30 patients in Switzerland are being scanned using conventional
mammography and phasecontrast mammography. They are then submitted to an
international team of radiologists for evaluation. Preliminary results
look promising for both screening and diagnostic mammography. If further
investigations support the initial findings, steps towards developing a
human mammographic prototype scanner may be considered. In combination
with Philips’ MicroDose spectral photon-counting mammography solution,
the technology has the potential to set the standard for image quality
in future digital mammography systems

PHILIPS HEALTHCARE