[P223] Treatment planing in brachytherapy HDR based on three-demensional images

Purpose Treatment planning in High Dose Rate (HDR) brachytherapy based on three-dimensional (3D) imaging allows for prearranging and realization optimal treatment process. This process consists of procedure planning, the choice of applicators, adjusting the appropriate implantation technique, and planning of three-dimensional distribution of dose in computerized treatment planning system. 3D images used in treatment planning in HDR brachytherapy allows for choosing the most appropriate application technique. This in turn allows for the best area coverage by reference dose with simultaneous protection of critical organs. Treatment planning on 3D images assures individual planning of dose dispersion in target area. Methods Several techniques will be presented based on 3D imaging in location such as lung, skin cancer, breast, and prostate cancer. For each location, relative cases will be provided where different applicators and techniques were applied. These examples are going to present images from before and after performed application along with the pictures from computer treatment planning system. In each of described locations, relative advice and rules of conducting accurate application will be provided. Results Differences between Monaco TPS and Dolphin in SRS/SRT plans, PTV1: 5.1%, PTVaverage: 8.1% and PTV99: 9.2%. Differences between Compass and Dolphin in SRS/SRT plans, PTV1: 2.9%, PTVaverage: 4.8% and PTV99: 6.5%. Differences between Monaco TPS and Dolphin in lung SBRT plans, PTV1: 3.5%, PTVaverage: 2.2% and PTV99: 2.6%. Differences between Compass and Dolphin in Lung SBRT plans, PTV1: 2.7%, PTVaverage: 2% and PTV99: 2.6%. Differences between Monaco TPS and Dolphin in spine SBRT plans, PTV1: −1.9%, PTVaverage: −5.8% and PTV99: −6.8%. Differences between Compass and Dolphin in spine SBRT plans, PTV1: 3.3%, PTVaverage: −0.47% and PTV99: −1.1%. When average gamma values are examined in the regions formed with 1, 2, 3, 4 cm margins in SRS/SRT/SBRT plans: 3–3 mm 0.34–0.6, 2%–2 mm 0.51–0.83, 1%–1 mm 0.92–1.15, 3%–1 mm 0.36–0.86. In 2D gamma analysis, SRS/SRT was 96%, lung SBRT was 88% and spine SBRT was 84.1% according to the criteria of 2–2 mm. SRS/SRT was 93%, lung SBRT was 83% and spine SBRT was 72.4% according to the criteria of 3–1 mm. Conclusions Computer tomography allows for establishing individual treatment solutions that provide optimal approach to every patient as in skin cancer. With more and easier access to threedimensional imaging, new ways of applying HDR brachytherapy open in new location as well as in form of radical treatment. With the use of imaging, we are now able to introduce catheters precisely into the tumor area with putting the patient at risk of posttreatment complications. It allows the treatment of people that no more qualify for other forms of treatment (radiotherapy). Because of the high gradient dose in HDR brachytherapy and patients with internal intracranial implants, i.e., pacemaker or cardioverter-defibrillator, we know exactly the dose the device will receive, so we can perform the procedures without exposing the patient to additional risk. Thanks to different optimization forms based on 3D images, HDR brachytherapy is applied not only in palliative treatment but also in new ways of radical treatment, i.e., in case of APBI.