Comparative analysis of the absorbed dose in the heart and anterior descending branch of the left coronary artery (LAD) in patients with left-sided breast cancer who received radiotherapy using 3D-CRT, IMRT and VMAT techniques.

PURPOSE: The purpose of this study was to compare the absorbed dose distributions within the heart and lad in patients with left-sided breast cancer who underwent radiotherapy using 3D-CRT, IMRT and VMAT techniques. METHODS: The treatment plans of 11 patients with left-sided breast cancer were analyzed. All of the patients were irradiated in our facility with DIBH 3D-CRT. For all patients the plans in the IMRT (sliding window) and VMAT (Rapid Arc - Varian) techniques were prepared. Cumulative dose-volume histograms (DVH) were used to compare the dose distributions between the plans for each patient. Statistical analysis was carried out using the one-way ANOVA with repeated measurements and Tukey's post hoc test. RESULTS: The use of IMRT and VMAT techniques allowed for a better coverage of the PTV with 95% isodose and a more homogeneous dose distribution compared to the 3D-CRT technique. The use of dynamic technique (IMRT or VMAT) did not provide significant protection for OARs - only the dose absorbed in LAD was slightly lower. CONCLUSION: The use of 3D-CRT allows better protection of critical organs compared to other techniques, except for the dose in the lad artery which was the lowest in IMRT technique. exposure of large tissue volumes to so-called low radiation doses is undoubtedly a disadvantage of using dynamic techniques.

Visualization of dose distribution in intraoperative electron beam Radiotherapy based on ultrasound images.

PURPOSE: The purpose of this study was to develop a method for dose distribution visualization in the case of Electron Beam Intraoperative Radiotherapy based on the images obtained in the operating room. This cannot be relied on CT images obtained before surgery due to significant tissue deformation. METHODS: The ultrasound scanning is the only method to obtain 3-dimensional (3D) reconstruction of a patient's tissue under operating room conditions. We decided to apply this modality as a background to visualize 3D dose distribution in terms of intraoperative radiotherapy (IORT). Dose distribution was obtained on the basis of dosimetric measurements carried out in the water phantom (PDD curves, transversal profiles). RESULTS: The method which has been developed in our department helps optimize the treatment. The amount of information depends strongly on the quality of the ultrasound image. We have verified the method (spatial correctness of dose painting) using commercially available phantom typically used for performance and quality assurance in ultrasound imaging (CIRS) and we noticed good correlation between 3D dose distribution and ultrasound image. CONCLUSIONS: Using up-to-date ultrasound tissue images allows better treatment optimization compared to the previous method that uses pre-surgery scans (CT or MRI). It helps optimize the angle of the beam axis and choose the beam with adequate range (energy) and avoid the risk of inaccurate irradiation of the area of interest.