Image-guided focal therapies for breast cancer

Breast cancer is the most common in women, affecting one in ten women, by geographic area. Accelerated Partial Breast Irradiation (APBI) is a new concept of postoperative irradiation after breast conserving surgery for cancer at low risk of local recurrence. In the first chapter of this thesis, we present the rational use of the APBI method as an alternative to the whole breast irradiation and then we discuss the principles, the benefits, and the drawbacks of the different techniques used. One of these techniques is the multi catheters high dose rate (HDR) interstitial brachytherapy. Multi catheter interstitial brachytherapy was the originally employed APBI technique and as a consequence has generated clinical experience with the longest follow-up duration, and with encouraging results. The accuracy of treatment planning system (TPS) in the source location and the dose calculation is absolutely necessary to ensure the planned dose. Sievert Integral and TG43 formalism provide quick and easy methods to check and to verify the dose calculated by the TPS. In the second chapter, we discuss a dose calculation and optimization tool for the APBI method using HDR sources. This tool simulates the dose from the parameters defined by the physicist. Often, the radiotherapist performs during the procedure a mental re-adjustment of catheters positions simulated on the CT images. This operation could lead to errors due to differences in breast form and catheters positions on the intra-operative ultrasound images compared to the planed one on CT images. In chapter three of this thesis, we propose a registration method between data from planning and the one from intra-operative ultrasound images as a solution that will allow to the radiotherapist to report planning data automatically on the brachytherapy template to visualize all data on the computer monitor. The APBI technique is considered an invasive and expensive method due to radiation protection reasons. Laser Interstitial Thermo-therapy (LITT) is minimally invasive ablative technique, and under evaluation. The LITT produces a coagulation necrosis area where the target volume is controlled while minimizing effects on surrounding tissues. In chapter four, we present the preliminary results of simulation of heat and damage distribution from applying the LITT method for focal laser ablation of breast cancer. (author)