Nucletron – Radiological Needlework #SWI2006

Nucletron is a high-tech, international company, that specializes in equipment for
medical diagnostics.

Problem description
To treat prostate cancer with radiological techniques, the prostate is perforated with a
number of needles. Before the radiological treatment may start, the exact positions of
these needles must be known. To detect these positions, an ultra-sound sensor is used.
This sensor approaches the prostate via the rectum. Because of the geometry, the
sensor cannot move around the prostate. This implies that horizontal slices of the
prostate are scanned in only one direction.

The ultra sound waves (wave length about 0.5 mm) are scattered by the needles (of
radius about 1 mm) and this scattering blurs the measurements. For example, if the
position of one needle is in the ‘shadow’ of a neighbouring one, its exact position is
hard to detect.

Question: Develop a method to reconstruct the needle positions from the ultrasound

– The needles are a bit flexible and may bend.
– The part of a needle entering the prostate may vary from needle to needle.
– Also plastic needles are used. They give rise to less scattering, but the


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Nucletron – Radiological Needlework