Room: Exhibit Hall | Forum 4
Purpose: Interstitial high dose rate (HDR) brachytherapy has long been used in the management of locally advanced or recurrent gynecological tumors unsuitable for intracavitary applicator treatments. A pre-plan is always desirable to provide an optimal needle implant arrangement in order to obtain good target coverage. The purpose of this project is to develop a pre-planning system to automatically generate good needle implant geometry for interstitial HDR brachytherapy.
Methods: Diagnostic MRI images are usually acquired 3~5 days before needle implant in our institution. Clinical target volume (CTV) is then delineated on MRI images by our physician, and the location of the interstitial template on the MRI images is also estimated. Once the MRI images and contours are fed into our pre-planning system developed in Matlab, four steps will be conducted: 1) Upsample CTV contour due to the large slice thickness usually used in our MRI scan protocol; 2) Convert CTV contour into a solid volume structure; 3) Identifies the holes on the template whose needles will pass through the CTV or be close enough to CTV, and calculates the desired needle insertion depth; 4) Generate a report listing the needle indices and depths, and display the geometry of CTV, template and needles in a 3D view. Four different template orientations (0Â°,45Â°,90Â°,135Â°) are considered in our system, allowing users to choose the best orientation specifically for each case.
Results: We have preliminarily tested our pre-planning system on five patient cases treated with interstitial HDR brachytherapy in our institution, and achieved reasonable needle implant locations and depths.
Conclusion: We have developed a geometry-based pre-planning system for interstitial HDR brachytherapy and demonstrated its feasibility for clinical use. Systematic study will be performed in future to evaluate its potential clinical benefit in terms of facilitating routine brachytherapy workflow and improving plan quality and patient outcome.