Διατμηματικό ΠΜΣ Ιατρική Φυσική-Ακτινοφυσική
Library of the School of Health Sciences

2017-04-26

2017

Logothetis Andreas

Ευάγγελος Παντελής, Επίκουρος καθηγητής, Ιατρική Σχολή, Ε.Κ.Π.Α.
Παντελής Καραΐσκος, Καθηγητής, Ιατρική Σχολή, Ε.Κ.Π.Α.
Παναγιώτης Παπαγιάννης, Αναπληρωτής καθηγητής, Ιατρική Σχολή, Ε.Κ.Π.Α.

Ανάπτυξη εξειδικευμένου κώδικα χρήστη για υπολογιστική δοσιμετρία Monte Carlo προσομοίωσης με χρήση του EGSnrc

Greek

Due to the requirement for high accuracy in dose delivery in radiation therapy and specifically in stereotactic radiosurgery, the usage of Monte Carlo techniques in the calculation of dose in order to reduce its contribution on the total uncertainty of delivered dose seems ideal, since it is the most accurate method of dose calculation as it is done from first principles; however it is extremely demanding in computational power and time consuming, so it is not really suitable for clinical applications. In order to reduce the Monte Carlo simulation time, various techniques have been developed. One of these techniques which is used in linear accelerator simulations is the recording of the phase space after the accelerator head so as to be possible to reuse it without the need for the complete simulation, in which many particles do not contribute to the final beam.
The purpose of this thesis is the development of an EGSnrc C++ user code that will record phase space data in IAEAphsp format in various user-defined conditions, so as to investigate applicability, and the possible benefits in simulation time, in Gamma Knife simulations and especially simulations of the Gamma Knife Perfexion model, as it has been developed in EGSnrc by Pappas et al (2016).
A series of audits has been conducted in order to validate the developed user code. Then, phase space files where saved from a sector for each collimator aperture width of the Gamma Knife Perfexion and then the dose profiles in the three axes where scored in a spherical water phantom with 16 cm diameter for the cases of
(a) one active sector, and (b) all 8 sectors active. After the comparison with full simulation data and with data from calculations using the TMR10 algorithm, the results have shown that practically there is no difference between full simulation and simulation that uses phase space file, and that the benefits in efficiency are spectacular, with efficiency ratios up to 2560 for one Gamma Knife sector.

Health Sciences

Monte Carlo, EGSnrc, Gamma Knife, Phase space file, Stereotactic radiosurgery

No

0

Yes

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https://pergamos.lib.uoa.gr/uoa/dl/object/1502339