Background and Purpose:
With the MapCHECK2 a relatively new QA tool is available to implement in the streamline of patient QA (validation of treatment plans). In order to achieve this, its properties and potentials need to be examined. This study is focussed on this characterisation and implementation of MapCHECK2 at the radiotherapy department of UZ Brussel, especially for the TomoTherapy treatment system. Tomotherapy is a system with unique characteristics opposed to conventional treatment machines and therefore needs an adapted implementation. The main goal is to obtain a representative patient QA technique that can be implemented for every planned treatment.
Materials and Methods
In order to examine its properties, MapCHECK2 will be used with its kVCT, MVCT and corrected CT images to find the ideal configuration for measurements. Along with this the angular dependence induced by the MapCHECK2's geometry will be reviewed to find the critical angles that can cause difficulties during rotational delivery. After this the first patient plans will be evaluated. Finally the challenge when using tools like this is to determine if the results are correct. Measurements can be cross-checked with other dosimetric tools but due to geometric diversities this cannot be the only option used. Therefore also the detection capability of intentional errors induced by the user is examined.
The results show that working with an adapted CT image where the MapCHECK2's geometry is replaced/masked by two theoretical known densities (MC2DENS) is the best reviewed option for patient QA measurements. MapCHECK2 also shows a high angular dependence in the ranges from 60° to 120° and 240° to 300° but the Tomotherapy system is able to deal with this using the inverse planning technique that takes the densities into account. Composite measurements compensate for the angular dependence. The cover up potential measurements show that the MapCHECK2's detection possibility is above expectations. This is an important result for QA measurements in IMRT.
With these promising results the MapCHECK2 is integrated in the streamline of the patient QA for Tomotherapy at UZ Brussel using the MC2DENS phantom created by masking the obtained HU (Hounsfield Units) with theoretical found HU values. Continued measurements still produce positive results.
If you want to cite this thesis in your own thesis, paper, or report, use this format (APA):
HEEREN, D. (2012). Clinical implementation of mapcheck 2 diode array for daily patient quality assurance.
Unpublished thesis, Xios, TIW.