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A Tool for Automatic Depth Prescription in Surface Skin Brachytherapy

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A Otal

A Otal1*, J Richart1 , S Rodriguez1 , M Santos1 , J Vijande2 , F Ballester2 , J Perez-Calatayud3 , (1) Hospital Clinica Benidorm, Benidorm, Alicante, (2) University of Valencia, Burjassot,(3) Hospital La Fe, Valencia,


SU-I-GPD-T-53 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Skin brachytherapy has undergone a very important development in the last years. For non-small lesions, individualized molds or specific applicators such as Flaps or HAM are used. In these cases, PTV is contoured in a CT image in which a thin wire is placed to delimit the area. A set of points in the periphery with which prescribing-optimization is performed are usually established on this PTV. The problem arises of the tedious operation of erasing all the points that do not correspond to PTV the distal limit of the PTV. The purpose of this work is show a solution for the direct establishment of a set of distal points.

Methods: In our TPS, in this case Oncentra Brachytherapy (v4.3.0, Elekta), we define the external contour and a set of points that conform the boundary of the treatment area. After export this data in dicom format, we import them in Jupyter (jupyter.org) and we obtain a set of points inside the treatment area. With the help of MeshLab (www.meshlab.net) and from the set of points obtained in python, we calculate the normals to the surface and with this information back in Jupyter, we move the points in the direction of normals the prescription depth. After a "copy-paste" process we take this information to Oncentra.

Results: After normalize our treatment to this set of points and because they have been obtained with information about the curvature of the skin, the isodose lines of 100 % of the prescribed dose is adapted the shape of the skin.

Conclusion: The set of points obtained is a very efficient solution to make the normalization for the brachytherapy treatment at the distal PTV edge. In a future improvement, we'd like to avoid the step in MeshLab to create an more integrate application.

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