In vivo dosimetry with the use of Optically Luminescence Dosimeters (OSLs) in breast radiotherapy treatments

Postgraduate Thesis uoadl:2905193 385 Read counter

Unit:
Κατεύθυνση Ιατρική Φυσική-Ακτινοφυσική
Library of the School of Health Sciences
Deposit date:
2020-05-15
Year:
2020
Author:
Valianti Anna
Supervisors info:
Σιούντας Αναστάσιος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΑΠΘ, Επιβλέπων
Καραΐσκος Παντελής, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παπαναστασίου Εμμανουήλ, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΑΠΘ
Original Title:
In Vivo δοσιμετρία με χρήση δοσιμέτρων φωτοφωταύγειας (OSLs) σε εφαρμογές ακτινοθεραπείας καρκίνου μαστού
Languages:
Greek
Translated title:
In vivo dosimetry with the use of Optically Luminescence Dosimeters (OSLs) in breast radiotherapy treatments
Summary:
Purpose: Optically stimulated luminescent detectors (OSLDs) are recently used as passive dosimeters for a variety of applications in medicine including radiotherapy. The aim of this study is to investigate the suitability of using OSLDs in measuring surface dose during breast radiotherapy and to compare results with LiF Thermoluminescence Dosimeters (TLDs)
Materials and Method: Commercially available OSLDs (Nanodot dosimeters - Al2O3:C, Landauer, Inc., Glenwood, IL), which are thin discs of 4mm in diameter and 0.3 mm thickness 0.3mm enclosed in a plastic cassette measuring 10 × 10 × 2 mm as well as Lif TLD 1x1 mm microcubes were used. Both detectors were calibrated using a 6 MV linear accelerator and used for surface dose measurements in a solid water phantom as well as in 15 patient treatments with breast cancer, irradiated with tangential fields. For phantom measurements OSLDs were irradiated with gantry 0o with the central axis of the incident beam perpendicular to the plane of the dosimeter. For in-vivo patient measurements at least four dosimeters (two OSLDs and two TLDs) were placed as close as possible to each other during irradiation with their planes in contact with the surface of the patient.

Results: In phantom measurements where the plane of the OSLDs was perpendicular to the beam and the thickness of the detector parallel to the beam axis of the order to 0.3 mm and lower than the corresponding thickness of the TLD detector (1mm), OSLD measurements were found ~4% lower compared to the corresponding TLD measurements due to the fact that the effective point of measurement in both detectors was positioned in the build-up region and for the OSLDs corresponded to a lower distance from the surface. In vi-vo patient measurements where the plane of the OSLDs (4mm in diameter within a plastic disk of 10mm in diameter) was parallel to the beam axis and the effective point of measurement corresponded to a larger distance from the surface compared to the TLD (1mm thickness) and still in the build-up region, the nanoDot measurements were found 11% on average higher from the corresponding TLD measurements.

Conclusions: Optically stimulated luminescent detectors (OSLDs) can be useful for in-vivo measurements of surface dose in breast radiotherapy treatments. The effective point of measurement and the detector response, however, depend on the orientation of the detector disk relative to the beam axis and this has to be taken into account in such measurements.
Main subject category:
Health Sciences
Keywords:
OSLDs, TLDs, Surface dose, Breast radiotherapy
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
56
Number of pages:
77
File:
File access is restricted only to the intranet of UoA.

MSc-Thesis_ Valianti Anna.pdf
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