Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How strongly does tissue decelerate the therapeutic heavy ion beam?

16.07.2014

PTB has developed a method for the more exact dosing of heavy ion irradiation in the case of cancer

Irradiation with heavy ions is suitable in particular for patients suffering from cancer with tumours which are difficult to access, for example in the brain.

These particles hardly damage the penetrated tissue, but can be used in such a way that they deliver their maximum energy only directly at the target: the tumour. Research in this relatively new therapy method is focussed again and again on the exact dosing: how must the radiation parameters be set in order to destroy the cancerous cells "on the spot" with as low a damage as possible to the surrounding tissue?

The answer depends decisively on the extent to which the ions can be decelerated by body tissue on their way to the tumour. Scientists of the Physikalisch-Technische Bundesanstalt (PTB) have established an experiment for the more exact determination of the stopping power of tissue for carbon ions in the therapeutically relevant area which is so far unique worldwide.

Although the measurement data so far available must still become more exact, the following can already be said: The method works and can, in future, contribute to clearly improving the dosing for cancer therapy with carbon ions. The first results have recently been published in the magazine "Physics in Medicine and Biology".

Human tissue mainly consists of water. It can, therefore, be simulated well in liquid water in which form accelerated ions can be stopped on their way and at which target they deliver their maximum energy quantity – at least theoretically, because up to now experimental data has existed only for water vapour. Scientists, however, assume: If the aggregate state is neglected, the data determined for the determination of the radiation dose become too imprecise.

Within the scope of the doctoral thesis of J. M. Rahm, PTB scientists have now succeeded for the first time in determining the stopping power of liquid water for carbon ions with kinetic energies in the range of the maximum energy dissipation by experiment. The first results actually indicate that carbon ions are less strongly stopped in liquid water, related per molecule, than in water vapour.

As soon as more exact data are available, the findings will be included in the calibration of ionization chambers which are used to determine the dose in therapy planning. At present, the Heidelberg Ion-Beam Therapy Center (HIT) is the only institution in Europe which irradiates patients with heavy ions.

The procedure applied by the researchers is based on a method which originates from nuclear physics: the Inverted Doppler Shift Attenuation Method. While the carbon ions excited by a nuclear reaction move through the water volume, they are stopped and fall back into their ground state.

The energy distribution of the gamma quanta emitted thereby is recorded with the aid of an ultra-pure germanium detector. The Doppler effect, which leads to the displacement of the gamma energy, and the exponential-decay law allow the development of the velocity of the carbon ions with time to be pursued and, thus, conclusions on the stopping process to be drawn.

Woon Yong Baek | Eurek Alert!
Further information:
http://www.ptb.de

Further reports about: Doppler Doppler effect HIT Nuclear Physics PTB damage gamma-ray energy ions kinetic physics therapy tumour

More articles from Physics and Astronomy:

nachricht CCNY physicists master unexplored electron property
26.07.2017 | City College of New York

nachricht Large, distant comets more common than previously thought
26.07.2017 | University of Maryland

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>