Supervisors info:
Ευάγγελος Παντελής, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παναγιώτης Παπαγιάννης, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παντελής Καραΐσκος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Summary:
Our aim was to study the nanoDot (Landauer Inc, IL, USA) optically stimulated luminescent dosimeters (OSLDs) and to check if they can be used for accurate dosimetry calculations in radiation therapy.
The work is divided into three parts: theoretical, computational and experimental.
In the theoretical part, we describe the optically stimulated luminescent dosimetry (OSLD) and the characteristics of nanoDot dosimeters. We analyze their principle of operation, the factors that affect their response, as well as how we measure their signal.
The nanoDot dosimeters are very small in size, measuring 10.0 mm × 10.0 mm × 2.0 mm, including their plastic case. The active OSL element of nanoDot is an aluminum oxide disk, with a diameter of 5.0 mm and a thickness of only 0.2 mm.
Thus, an important feature that needs study is the angular dependence of their response. According to the trading company's manual, as well as the relevant published works, this angular dependence is negligible in the photon energies used in radiation therapy.
In the computing part, then, we study the angular dependence of the nanoDot response, with Monte Carlo simulations, using the EGSnrc code and the C ++ application egs_chamber.
In the experimental part, we analyze the calibration process of the dosimeters and the experiment we performed.
The dosimeters’ calibration was performed in terms of dose to water, using a 6 MV photon beam, produced by a CyberKnife linear accelerator (Accuray Inc, CA, USA), for doses up to 300 cGy.
Finally, the experiment we performed included the dosimetric verification of the accuracy of the Precision system, for two TomoHelical treatment plans, using TomoTherapy (Accuray Inc, CA, USA), with dynamic jaws.
