Spectral x-ray CT of bee

Medipix based detector heroes in NRC’s science article

Last week, Dorine Schenk from renowned Dutch newspaper NRC handelsblad wrote an article in the Scientific weekend special on the Timepix/Medipix based radiation detector that we have developed over the last few years in collaboration with Nikhef, and CERN. As the full article is originally published in Dutch, we’ve written a short piece on it in English:

Spectral x-ray CT of beeIn the article, Schenk, accompanied by Nikhef PHD Martin Fransen, investigates the use and benefits of our LynX 120 detector in real-life and real-time situations. Their journey starts in the Amsterdam Metro, where they measure the amount of cosmic particles that have penetrated the atmosphere, more than five meters of sand and two meters of concrete. Amazed by the amount of radiation still available in the subway, Fransen explains that Cosmic radiation consists of particles, especially atomic nuclei that fly from stars at high speed in the direction of the earth. They usually arise in powerful processes, such as when a star explodes at the end of its life.

Most of the particles in the subway tunnel come from the particle flow that occurs when an alien atomic nucleus arrives in the atmosphere and collides with molecules in the air. Here, charged particles such as electrons and their heavier counterparts create the muons, which then also collide with molecules in the air, creating an avalanche of particles. We measure that radiation on earth as an ever-present background radiation.

Originally, the measurement technique was not developed to measure cosmic radiation in the air, but for the LHC, the large particle accelerator at CERN in Geneva. There, protons (hydrogen cores) are shot at each other at a speed approaching the speed of light. This creates a large amount of particles in a fraction of a second. These are then measured with detectors using the Timepix and Medipix technology. By analyzing exactly which particles arise during the collisions, physicists hope to learn more about the world around us.

Practical application often results from this pure scientific research. Schenk already mentions the applications in medical research because it can measure X-rays quickly and with great accuracy, but our detectors have also proven to be highly effective in an array of other applications such as electron microscopy and mass spectrometry.

The next part of the article focuses on measurements done at Nikhef of a variety of dead insects. Although you can clearly see the density of the different bodyparts, in the medical world, only a few substances can be clearly distinguished; for example, calcium in your bones or a contrast fluid, such as iodine, that is inserted for research. The detector is therefore  ideal for various application in Industry, i.e. to determine the quality of a steel sheet. By looking at the different wavelengths of the radiation, errors and contaminations can be detected.

Els Koffeman, professor of instrumentation in particle physics, explains that she dreams of a scanner that makes a detailed picture, for example of your teeth. That information is sent to a 3D printer. He then manufactures a perfectly fitting crown or implant that can enter your mouth. Or you can put your broken arm in the hospital in a machine that makes a scan and a perfectly tailored splint for your print. The same should also be possible for objects: if something breaks, scan it and print a new part.

The current CT scanners only measure how many X-rays fall on the detector. The Medipix detector can also measure the energy of that radiation to bring more details to light. Moreover, the Medipix works a lot faster, so that you can zoom in during the scan. A doctor can then immediately see if she sees a tear somewhere, or that it is just a vein.

ASI and researchers at the Nikhef are working on a new CT scanner that makes better photos thanks to the smart Medipix detector with less X-rays, so that patients are exposed to less radiation. For this they work together with the FleX-ray Lab at Centrum Wiskunde & Informatica (CWI) in Amsterdam. In a recent article on our news page you can read more about the official opening of the FleX-ray Lab. The researchers at the FleX-ray lab develop algorithms to process the data as quickly as possible with brute calculation. For this they use graphics cards that can calculate much more in parallel than other processors. Koffeman says: “Every light particle does its own thing and has its own pixel. Because they are not interdependent, you can count on them in parallel. That is the power of the Medipix: fast, smart pixels.”

Originally Medipix was developed for experiments in high-energy physics, such as in the particle accelerator LHC in Geneva. But now the detector has found its own niche outside of experimental physics. The technique has been further developed for use in CT scanners and other practical purposes as you can read here. Over the past few years, ASI has successfully sold a number of these detectors known as LynX – 1800 for X-ray and Chee-tah 1800 for electron microscopy.

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