Mammography, which is an x-ray examination, is the standard technology used for screening. Dr. Thomas Mertelmeier, 55, is working with Siemens Healthcare in Erlangen on the evolution of digital 2D mammography to 3D tomosynthesis. “We need a method that provides more precise screening results,” says Mertelmeier. He is convinced that tomosynthesis will replace conventional mammography in just a few years.

According to Mertelmeier, tomosynthesis is able to detect tissue changes better than mammography, thus allowing for more precise diagnosis. Currently roughly five percent of all woman screened in Europe undergo a second examination because the results of the mammogram are unclear. Around 20 percent of the suspicious findings are confirmed in the followup exams involving additional mammograms, ultrasound or magnetic resonance tomograms. The doctors perform a biopsy on these women, which in 80 percent of the cases shows that it is not cancer. “Such a high number of followup examinations is not only very expensive, it is also very stressful for the affected women,” explains Mertelmeier.

Mammography often delivers unclear results because it can only portray the structures of the examined breast in two dimensions. Suspicious structures therefore cannot be unequivocally identified. Dense structures such as connective tissue or glandular tissue in the path of the x-ray beam may also hide a tumor behind these structures. “Whether a mammogram provides precise results is highly dependent on the tissue structure of the breast under examination,” says Mertelmeier. Over the last five years, the head of innovation of the Siemens Women's Health department has collaborated with his employees and clinical partners to build several prototypes for tomosynthesis, which are now undergoing clinical testing.  The results of this testing immediately flow back into product development. “We are now in the middle of the product rollout,” says Mertelmeier. The University Hospital in Malmö, Sweden, plans to be the first to use a tomosynthesis device developed by Siemens for screening.

In tomosynthesis, the x-ray tube moves at an approximately 50 degree angle from left to right above the breast lying on the detector and takes 25 images. A program then uses a mathematical image reconstruction process to compute sectional images of the breast. The fine structures such as milk ducts and glands can be displayed much better on these images than on conventional digital 2D mammograms. With tomosynthesis, the radiation dose is distributed over all 25 images and totals roughly the same dose received with conventional mammography.

Mertelmeier has been working on the mathematical reconstruction of the sectional images for many years. After studying physics in Erlangen, Mertelmeier joined Siemens and was assigned to a fundamental research department for mathematics and physics that developed simulation calculations for imaging methods. The inventor, who already holds 40 individual granted patents in 54 IPR families covering 78 inventions, many of which were discovered by a team, was working with tomosynthesis even then. “When I then switched to mammography, international circles of experts had just begun discussing tomosynthesis as a future alternative to mammography,” recalls Mertelmeier. He was also convinced early on of the advantages of the new method and advocated persistently for its further development. His work doesn’t leave the inventor a lot of time for hobbies. Like many of his innovative colleagues, he likes to relax outdoors with his wife while hiking, mountain biking or cross-country skiing.

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