[ RadSafe ] Very Small Dosimeter

[Chris van den Bergen]

http://velocity.ansto.gov.au/velocity/ans0021/article1.asp


As Richard Branson gears up to commercialise flights into space, a team 
of Australian scientists are pushing new frontiers that could not only 
make air and space travel safer but also help in the fight against cancer.

In a world first, Australian scientists have designed and developed a 
miniature radiation detector the size of a human cell nucleus. The 
revolutionary device called a micro-dosimeter can accurately measure how 
much energy is deposited by radiation in the cell nucleus which greatly 
assists in the understanding of the effect of the radiation on the cell.

The technology was developed in collaboration between the University of 
Wollongong, ANSTO and the University of New South Wales based on an 
original concept from Professor Anatoly Rozenfeld of the University of 
Wollongong.

"This is a significant breakthrough in our ability to successfully 
measure different kinds of radiation and accurately predict the cancer 
risk of radiation exposure," said Anatoly.

Anatoly explained that conventional detectors are not sophisticated 
enough to give accurate readings as they are only designed to measure 
radiation in large volumes and only for specific types of radiation, 
namely gamma and neutron.

To build a micro-dosimeter, the volume of a cell nucleus, unique 
nanofabrication techniques were employed at the Nanotechnology 
Fabrication Facility at the University of New South Wales.

"This new technology has significant potential on two important fronts - 
for air and space travel where the radiation field is complex, 
(containing many different particle types) and for better understanding 
the radiation dose people receive during cancer treatments, like proton 
therapy," he said.

While proton therapy is still not available in Australia, it is an 
emerging cancer treatment that is more accurate in dose delivery, and 
hence reduces side effects. Proton interaction is more complex than 
conventional radiotherapy. The new micro-dosimeter is helping to 
understand the differences in these types of radiation.

While developmental testing of the technology was conducted at ANSTO 
making use of the organisation's heavy-ion particle accelerator, the 
work of the collaborative team has caught the attention of various 
international research scientists.

Dr Mark Reinhard, who is a research leader at ANSTO, explained the 
micro-dosimeter was tested in the Massachusetts Hospital, USA. They 
placed the micro-chips in a 'human phantom' - and measured the energy 
deposited in regions the size of a human cell nucleus.

"These findings will enable radiation oncologists to more accurately 
deliver proton treatments to fight cancer cells," Mark said.

The micro-dosimeter is also being investigated by the NASA space program 
as one of the major barriers for space travel is cosmic radiation. This 
type of radiation is so varied and intense that astronauts can suffer 
serious problems from exposure during space missions.

With funding from the US-based National Space Biomedical Research 
Institute (NSBRI) the micro-dosimeter was launched on board a US Naval 
Academy satellite in March 2007 to investigate how it could play a part 
in protecting astronauts from space radiation. The University of 
Wollongong and the ANSTO research team are expected to conduct further 
tests with NSBRI in the near future.

While space travel for most people might seem like light years away, air 
travel is very real. Most commercial flights travel at about 30,000 feet 
and radiation is variable with a mixture of gamma, neutron and heavy 
ion. Having this type of sophisticated monitoring equipment is important 
to further ensure travel safety - especially as we go into the future 
where people like Richard Branson will be taking people into space where 
ionising radiation levels can vary widely and cancer risk needs to be 
measured. Further testing of the micro-dosimeter to monitor modelled 
aviation radiation fields is due to commence shortly in CERN, the 
world's largest particle physics laboratory in Switzerland.

And for the future, the collaboration sees the micro-dosimeter getting 
even smaller! The team is now investigating new types of materials for 
fabricating devices that are the size of human DNA.

"We know that radiation can penetrate right through the human body and 
can break strands of DNA, the software of life that resides inside a 
cell nucleus. If we can model the effects of radiation on DNA level with 
the new radiation detectors then we are at the crest of countless 
possibilities," Mark concluded.



-- 
Chris van den Bergen
Assistant Radiation Protection Officer
Occupational Health and Safety
Building 11, Room S703
Monash University, Clayton, Vic 3800
Telephone: +61 3 9905 1101
Fax:       +61 3 9905 2580