Κατεύθυνση Ιατρική Φυσική-Ακτινοφυσική
Library of the School of Health Sciences

2019-11-20

2019

Mpelitsou Maria Stavroula

Μαζωνάκης Μιχάλης, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, Πανεπιστήμιο Κρήτης
Μαρής Θωμάς, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, Πανεπιστήμιο Κρήτης
Περισυνάκης Κωνσταντίνος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, Πανεπιστήμιο Κρήτης

Σχεδιασμός πλάνων θεραπείας με τεχνικές 3D-CRT και VMAT και μελέτη επιβεβαίωσης των πλάνων με δυο ανεξάρτητες δοσιμετρικές μεθόδους

Greek

Designing of treatment plans with 3D-CRT and VMAT techniques and plans verification assessment via two independent dosimetric methods

The radical technological advancement has enabled the development of modern radiotherapy techniques. Due to the complexity of the techniques and software used in radiotherapy, it became imperative to confirm the three dimensional dose distribution with an independent metric system. In the current Master thesis, two independent metric systems were studied with the aim of providing dosimetric results for treatment plans for the anatomical area of the brain and head&neck. The metric systems used are a) the Delta4 diode array phantom (Scandidos, Uppsala, Sweden) and b) special 3D phantoms that simulate the anatomy of the head with a polymer gel solution (RTsafe, Athens, Greece).
The presentation of the current Master thesis follows such an escalation, so as to be of interest to the reader who has knowledge on the subject of radiotherapy and wants to delve deeper into the theory surrounding the verification of dose distribution. The thesis is divided into two parts. The first part contains the theoretical background of the knowledge needed to understand the subject of the work. Specifically, it focuses on radiotherapy, the design of treatment plans and the process of plans’ verification before being administered to the patient.
The second part discusses the experimental procedure followed and the results of this study. This process involves firstly planning the 3D-CRT and VMAT techniques through the treatment planning system (TPS) and then confirming the dose distribution of the plans via the metric systems previously mentioned. As for Delta4, it is a phantom with diode detectors and is used to verify dose distribution. On the other hand, polymer gel dosimeters are considered a promising method for 3D verification of dose distribution. Verification with simulation models injected with polymer gel was performed with the support of magnetic resonance imaging techniques.
Finally, the resulting distributions of the metric systems were compared to the ones derived from the treatment planning system. The Gamma-Index method was used to find the rate of agreement between the two distributions. With acceptance criteria of 3mm and 3%, percentage differences were found to be less than 7% for Delta4 while for the polymer gel dosimeters, with acceptance criteria of 2mm and 3%, percentage differences were found from 5% to 15%. The verification of the dose distribution of the polymer gel dosimeters was again performed via Delta4 and the Gamma Index percentages calculated at 100%. The main conclusion of this Master thesis is that both the Delta4 and the polymer gel dosimeters can be equally used as valuable tools for the verification of the dose distribution, regarding the anatomic region of brain.

Health Sciences

Radiotherapy, Verification of dose distribution, Polymer gel dosimeters, Delta 4

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https://pergamos.lib.uoa.gr/uoa/dl/object/2885917