Calculations and measurements of neutron fluence in the treatment room and along the maze of an 18 MV medical linear accelerator

Postgraduate Thesis uoadl:2768798 410 Read counter

Unit:
Διατμηματικό ΠΜΣ Ιατρική Φυσική-Ακτινοφυσική
Library of the School of Health Sciences
Deposit date:
2018-06-12
Year:
2018
Author:
Siltzovalis Georgios
Supervisors info:
Τζων Καλέφ-Εζρά, Καθηγητής, Ιατρική Πανεπιστημίου Ιωαννίνων
Ίων Σταματελάτος, Ερευνητής Α', Ε.Κ.Ε.Φ.Ε. «Δημόκριτος»
Ελευθερία Καρίνου, ΕΛΕ Α', Ελληνική Επιτροπή Ατομικής Ενέργειας
Original Title:
Προσομοιώσεις και μετρήσεις της ροής νετρονίων στο θάλαμο θεραπείας και κατά μήκος του λαβυρίνθου ιατρικού γραμμικού επιταχυντή 18 MV
Languages:
Greek
Translated title:
Calculations and measurements of neutron fluence in the treatment room and along the maze of an 18 MV medical linear accelerator
Summary:
High-energy linear accelerators (>10 MV), produce neutrons via nuclear reactions (γ, n), with the materials on the linac head. These neutrons must be considered in the treatment room shielding designing. Scope of the present study is the estimation of neutron fluence in the treatment room and along the maze of an 18 MV medical linear accelerator. Simulations were performed using Monte Carlo code MCNP in two stages. In the first stage the linac head and treatment room were modeled. The linac head was simulated using two simplified geometries from the bibliography, either as a spherical cell source composed of tungsten, 10 cm in thickness (Carinou, et al. 1999) or as a point source in the center of a spherical cell composed of tungsten (Vega-Carrillo, et al. 2012). The neutron energy spectrum at the source was taken from the analytical expression given by (Tosi, et al. 1991). In the second simulation stage, the neutron fluence calculated in stage 1 was used to evaluate the response of In and Au activation foil detectors positioned within Plexiglas moderators. The results of the calculations were verified against measurements performed using activation foils and against empirical methods to determine the neutron fluence in the treatment room and the door of the maze and a very a good agreement was observed. The results of the study enabled the development of a simple and computational time effective methodology for the calculation of neutron dose in the treatment room and maze of high energy medical accelerators and therefore contribute to the effort to reduce radiation dose to the personnel and patients in radiation therapy.
Main subject category:
Health Sciences
Keywords:
Neutrons, Accelerator, Maze, Fluence, Foils
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
34
Number of pages:
80
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