Automatic reconstruction of catheters in CT based bracytherapy treatment planning

The aim of this study was to develop an automatic reconstruction of brachytherapy catheters using CT data. Previously no such automatic facility has existed in any treatment planning software. To achieve this aim the authors have developed algorithms for the automatic reconstruction (which the authors term autoreconstruction) of plastic and metallic catheters. The authors´ algorithms overcome a number of difficulties which arise when a large number of catheters are present. These include situations with intersecting catheters and with loop techniques. Modern brachytherapy treatment planning is image based and frequently used imaging modality is CT scanning. CT based reconstruction accuracy depends on the CT imaging parameters such as the slice thickness, interslice distance and image resolution. In addition, accuracy also depends on observational ability of the user. Image based treatment planning methods can significantly reduce the time required for the treatment planning process, to the use of projectional reconstruction methods using radiographs. Even so, a significant part of the treatment planning time is still spent in the reconstruction of catheters. From the analysis the authors made on 30 clinical implants the manual catheter reconstruction procedure took an average of 43.4% of the total treatment planning time: range of 22.6% to 71%. These times does not include those for image processing and contouring. The reconstruction time per catheter was an average of 151.2 s: range of 42.9 s to 312 s