TY  - GEN
AV  - public
ID  - heidok9657
TI  - Development of a Dose Calculation Model as a Supplemental Quality Assurance Tool for TomoTherapy
N2  - Helical TomoTherapy is a state-of-the-art delivery technique used in photon radiotherapy. This system relies on the superposition of many small fields to precisely administer the prescribed dose to the patient. This thesis presents a new model that predicts dose distributions delivered by TomoTherapy. The model may be used within a dose verification tool for quality assurance purposes. It is based on so-called "energy deposition kernels" and can accurately predict dose distributions in a homogeneous medium for a broad range of field sizes, down to 2 mm in diameter. The model takes into account the two main effects that influence the dose distribution in small fields: (i) the spatial extension of the radiation source and (ii) the loss of charged particle equilibrium (CPE) within the field. The shape of the source is determined by a combination of a "slit-method" reconstruction and a collimator factor fitting procedure, whereas the loss of CPE is taken into account by the use of a poly-energetic pencil beam kernel. The model was successfully validated for a 6 MV photon beam produced by a conventional linear accelerator. The dose verification tool was evaluated for simple beam configurations and used to study the influence of temporal beam parameter variations on the integral dose. The developed model allows to evaluate the performance of devices applying narrow photon beams in the treatment delivery. Furthermore, it can be used as an alternative to the conventional dosimetry of small fields.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/9657/
KW  - Tomotherapie 
KW  -  Qualitätssicherung 
KW  -  Dosisverifikation 
KW  -  Dosimetrie 
KW  -  kleinen FeldernTomotherapy 
KW  -  quality assurance 
KW  -  dose verification 
KW  -  dosimetry 
KW  -  small fields
Y1  - 2009///
A1  - Caprile, Paola
ER  -