| Abstract [eng] |
Cancer is one of the leading cause of morbidity and mortality in Lithuania and Europe. Radiation therapy uses high energy particles and photons to kill cancer cells. Due to the limited penetration electrons are used for the treatment of shallow tumours (head, neck, breast, skin). Bolus is a tissue equivalent material used in radiotherapy as a compensator for missing tissue, irregular tissue shape or as a dose distribution modifier. Usually, standard thick (1cm) and shape bolus are used. Conformal therapy is an advanced technique of radiotherapy for a better target coverage and better sparing of the surrounding tissues. Bolus electron conformal therapy is an application of individualized bolus for electron therapy to acquire dose distribution conformal to tumour shape. Three-dimensional printing is a modern additive technique that can be used for manufacturing of individualized bolus for electron therapy. In this work bolus modification algorithm was created in Matlab that uses dose distribution and patient structures from commercial treatment planning system (Eclispe) to create a structure of an individualized bolus. Contours of modified bolus can be used for bolus manufacturing by three-dimensional printer. Created bolus modification algorithm was tested for hypothetical plastic phantom and patient case. For hypothetical case an example of individualized bolus was printed from acrylonitrile butadiene styrene thermoplastic. The dosimetric evaluation of printed bolus was performed. Gamma comparison (3%/3mm/Th90) between dose distributions of theoretical and printed bolus showed an agreement of 98,4±0,6%, 93,6±4,5% and 97,6±1,4% in X, Y and Z directions, respectively. Dose measurements with Markus PTW parallel-plate chamber and scanning water phantom was performed. Measured dose distributions was in agreement with theoretical dose distribution. The implementation of bolus modification algorithm for patient case showed better target coverage using individualized bolus. Therefore it was demonstrated that created bolus modification algorithm is effective and can be implemented for electron conformal therapy using three-dimensional printed bolus. |
