Purpose
Breast cancer comprises the second deadliest type of cancer for the female population of the United States of America [1,
2].
Despite the recent increase in breast cancer incidence,
mortality associated with this type of cancer has declined,
because of the improvement of diagnostic and therapeutic techniques [1].
Radiation therapy comprises one of the most effective treatments for breast cancer. Reported experience has suggested that a local control rate of 90% to 95% can be achieved for early stage cancer patients [3].
The number of...
Methods and Materials
Construction of the medical linear accelerator model
The MCNP 5 Monte Carlo (MC) code was employed for the simulation of a 6 MV (Philips SL 75/5,
Philips/Elekta,
The Netherlands) medical LINAC.
The simulation incorporated all the main beam modifying components of the LINAC head.
In order to save computer time the simulation was performed in two steps [6].
Figure 1 shows the relative positions of the modeled components.
In the first step a 6 MeV electron beam impinged on a heavy metal target.
The generated...
Results
Verification of the simulated beam's dosimetric properties
The calculations performed for the verification of the beam's dosimetric properties agreed very well with the measured data on a water phantom.
Figure 1 shows PDD calculations for a 20 x 20 cm2 field superimposed to measurement data for the same field size.
Doses were normalized to d10.
Local differences did not exceed 2%.
Figure 2 demonstrates the comparison between the measured and the calculated lateral dose profile for the 20 x 20 cm2 field at d10.
Local...
Conclusion
The constructed MC model of a 6 MV therapeutic photon beam can be used for the direct organ dose calculation associated with radiotherapy of breast cancer.
The generated computerized model provided accurate dose estimations for all radiosensitive tissues partially included or excluded from the treatment field.
The size of the therapeutic fields used may affect organ doses considerably.
These organ dose calculations may be used by medical physicists and radiotherapitsts to estimate the magnitude of secondary cancer risk.
Accurate risk estimations may be of clinical...
References
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Personal Information
Theocharis Berris,
M.Sc.
Department of Medical Physics,
Faculty of medicine,
University of Crete.
P.O.
Box 2208,
71003 Iraklion,
Crete,
GREECE
E-mail:
[email protected]