Modern Brachytherapy for Gynaecological Cancer Therapy

Local control for cervical carcinoma and therefore the survival rate of affected women can be increased by using magnetic resonance imaging based brachytherapy. Optimized treatment planning as a form of targeted cancer therapy can on the same side decrease side effects. While image guided radiotherapy becomes standard for lung, head & neck and prostate, its application has not been used in clinical routine for cervix carcinoma. The Medical University of Vienna performed basic research and the clinical application of 3-dimensional image based radiotherapy for gynaecological (GYN) malignancies. The existing results and experiences have the potential to be integrated into widespread daily clinical routine in the western, but also developing world. The planned research activities include: Analysis of uncertainties in the 3D reconstruction of the implanted applicators will lead to quality assurance recommendations. Our worldwide largest database of clinically applied GYN treatment plans will be reviewed to obtain accepted standards, based on the known clinical outcome. Such standards are used for modern automatic treatment planning tools, but also within reduced infrastructure (e.g. departments with high patient load in Eastern Europe, Asia and South America). In order to guarantee dose delivery as initially planned, the changes of the anatomy and applicator geometry during time (4D imaging) are studied in detail, also including fusion algorithms for dose distributions. This project will improve the clinical outcome of brachytherapy for women with GYN cancer within modern and limited infrastructure. It gives the chance to maintain and extend our currently unique strategic position in one of the most promising fields of radiotherapy physics. It will transfer our experiences made within an academic infrastructure to widespread clinical use.

This project developed essential principles and technical methodologies for improvement of local control and reduction of side effects in gynaecological brachytherapy. Brachytherapy of cervix cancer, especially of locally advanced tumours, is an integral part of treatment. Even though the number of patients in Western Europe has been declining, brachytherapy treatment of cervix cancer needs sophisticated developments and improvements. While such technical development has been largely performed for prostate cancer brachytherapy, gynaecological techniques needed more investigations. Cervix cancer is still the most common cancer affecting the female population in many countries outside Europe. However especially centers in these countries, but also in Western Europe have only limited infrastructure, due to prevailing funding problems. Therefore new cost effective methods which increase the accuracy of radiation therapy under such conditions have to be developed. Gynaecological brachytherapy is usually fractionated - applied in many single fractions. Research in this project was focused on uncertainties caused by organ movement and anatomy changes between consecutive fractions. The biggest accuracy for each fraction has been achieved with Magnetic Resonance Imaging (MRI). This rather expensive method could be partly replaced with cheaper and more easily available Computer Tomography (CT) using a method for image fusion that was developed in this project. Another work that was performed under the project evaluated the use of ultrasound images as an alternative imaging modality for this treatment. The analysis of all the individual steps of brachytherapy, from diagnosis, target volume definition, application, dose planning, to dose application in the presence of anatomical variations, resulted in an estimation of uncertainties that may guide further technical development of each segment. Beside the uncertainties analysis, the analysis of dose distribution and dose optimization should result in increased tumour control and reduction of side effects by application of clinical applicable dosimetric concepts.Finally, the physics and technical methods together with results of clinical analysis performed in this project will lead to more accurate and optimized dose application for patients receiving gynaecological radiation therapy.