Proton density
after laser impact on a spherical solid density target: irradiated by an
ultra-short, high
intensity laser
(not in picture) the intense electro-magnetic field rips electrons apart from
their ions and
creates a plasma.
By varying the target geometry and laser properties, scientists could find
optimal
regimes to
accelerate high quality, directed ion beams that are currently studied in
accompanying
experiments. Image
Credits: Axel Huebl, HZDR, David Pugmire, ORNL).
(January 26, 2016) German
team makes large computational gains in laser-driven radiation therapy of
cancer
Since lasers were first produced in the early 1960s,
researchers have worked to apply laser technology from welding metal to
surgeries, with laser technology advancing quickly through the last 50 years.
Surgery, chemotherapy, and radiation therapy all play
important roles in cancer treatment, and sometimes the best successes come from
combining all three approaches.
Doctors usually do the most common form of radiation therapy
with x-rays, which can penetrate tissue, killing the cancerous cells in
deep-seated tumors. Unfortunately, these same x-rays can also damage healthy
tissue surrounding the tumor.
Thus, in recent years, the use of beams of heavy particles,
such as protons or ions, has come into focus. These beams can deposit most of
their energy inside the tumor, while at the same time leaving the healthy
tissue unharmed. Unfortunately, these beams come from bulky particle
accelerators, which make the treatment cost prohibitive for many patients.
At the German research laboratory Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), researchers are looking into replacing particle
accelerators with high-powered lasers. The electromagnetic fields of the laser
can accelerate ions in a very short time, thus effectively reducing the
distance needed to accelerate the ions to therapeutic energies from several
meters to a few micrometers.
As a scientist experienced in accelerator research and laser
physics, HZDR researcher Michael Bussmann aims for understanding and
controlling this new method of particle acceleration to make it available for
patient treatment. “I’m coming from accelerator research and laser physics, and
what my team and I have been looking at is how we make best use of the
high-power lasers so they can replace accelerators for applications like
treating cancerous tumors,” Bussmann said.
“This is fundamental physics on the one hand, as the laser
pulse rips apart all the matter found in a target, usually a very thin metal
foil or a tiny sphere, separating the building blocks of atoms—negatively
charged electrons and positively charged atomic nuclei, ions—from each other.
This state of matter is called a plasma,” Bussmann explained. “On the other
hand, it has real applications as well. Simulations play a role that is unique,
as experiments are still not very reproducible and we can’t really diagnose
what’s happening in a few femtoseconds.”