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BY-NC-ND 4.0 license Open Access Published by De Gruyter September 7, 2017

Gynecological brachytherapy with Elekta microSelectron V3 afterloading system

A method for determination of actual dwell positions in CT/MR ring applicators

  • Christine Kornhuber EMAIL logo , Nico Homonnay , Frithjof Lange , Reinhard Gerlach and Dirk Vordermark


Objective: For commissioning of source path mo-dels for ring tubes of Nucletron (now Elekta) CT/MR ring applicators, a method was established using a source position simulator (SPS) and a CT scanner. Methods: An acrylic glass support for ring tubes was constructed serving as defined coordinate system. With SPS, 40 positions were set in the ring in steps of 2.5mm from proximal to distal direction. In each position a CT-series was taken with ring plane inside scan plane using a GE Optima 580 scanner (slice width 0.625mm). Evaluation was done in multiplanar recon-struction mode under display settings revealing dummy source shape. With a 3D-cursor dwell position coordinate (center of Ir-192 core) was determined. Measurements were validated by film autoradiography in selected positions. Four rings were investigated: 60° Φ26, 45° Φ26, 60° Φ30, and 45° Φ30 with figures denoting angle between ring plane and stem and ring diameter in mm. Results: The method is feasible to reconstruct source dwell positions with an overall accuracy of ±0.3mm. Detected coordinates are consistent and in excel-lent agreement with those obtained by autoradiography. Comparison with Elekta’s source path models, however, re-vealed mean deviations of up to 3.5mm. Discussion: It is advisable to measure individual source paths and have them added to the data base of the treatment planning system.

Published Online: 2017-09-07

©2017 Christine Kornhuber et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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