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 Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>