Optimized radiation for prostate cancer therapy
23 October 2008
The determination of the precise anatomical location of a tumour is
the prerequisite for setting optimal parameters for radiation treatment
of prostate cancer. This approach guarantees that the ionizing radiation
only destroys tumorous cells and does not affect other organs in the
vicinity of the prostate.
In a cooperative study with Innsbruck Medical University and the
East-Vienna Center of Social Medicine, two physicists of Vienna
University of Technology (TU), evaluated the mean deviation of radiation
parameters for prostate cancers and compared various sources of
Movement inaccuracies of up to two centimetres may occur in prostate
radiation. “During the radiation treatment, patients have to lie on a
table for some 20 minutes without moving. Over time, the muscles relax
and the pelvis drops. As a consequence, the radiation may focus on the
bladder or other organs. In our calculations, we concentrated on the
precision of localizing the prostate and on improvement potentials in
treatment,” explained Karin Poljanc, Assistant Professor at the Atomic
Institute of Austrian Universities.
In a study conducted in cooperation with SMZ Ost (East-Vienna Center
of Social Medicine, Danube Hospital), Poljanc and her research
associates, Tanja Futschek and Leila Teymournia, used a number of
ultrasound examinations that allowed for a precise localization of the
patients’ organs from the outside.
In the next step, the scientists analyzed the positioning of 60
patients, and evaluated the deviation of radiation in various spatial
directions, such as to the right or left, and upward or downward (using
420 radiation plans for thirty patients).
While it takes more time, an ultrasound system makes the shifts in
position visible and traceable. If the deviation exceeds 0.8 cm, the
radiology technicians are responsible for returning the patient to the
correct position to ensure that the radiation only targets the specified
In the subsequent study phase, Poljanc and her group calculated
normal tissue compensation rates and the probability of tumour control.
“This provides us with an overview of the probability that the tumour is
targeted directly and the probability of side effects for individual
patients,” notes Poljanc.
These approaches serve as forecasts and provide clues for the
likelihood of healing. After a study period of some 2.5 years, with
generous sponsorship of the Anniversary Fund of the Austrian National
Bank, the scientists were able to implement the calculated average
positioning inaccuracies in a radiation planning system.
Sums up Leila Teymournia: “Depending on the calculation model used,
the normal tissue compensation rate can vary widely in the results.
While the use of Model A may yield a negligible complication rate, the
same process calculated with Model B shows a deviation of up to 40
Due to the absence of biological parameters, major discrepancies may
result with different models. Nevertheless, the results of calculations
can provide physicians with data for improving patient positioning
accuracy and therefore, and improvement of treatment success.
As part of their study of different radiation sources, Karin Poljanc,
Tanja Futschek, and Leila Teymournia found that localization aids, such
as ultrasound systems, are indispensable for accurate proton therapy of
prostate carcinomas. In most cases, this combination leads to therapy
results with a high level of tissue preservation.
The future establishment of the cancer research and therapy centre
“Med-AUSTRON” in Wiener Neustadt will implement such a treatment method
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