M Stock*, Y Vinogradskiy, R Taleei, Thomas Jefferson University, Philadelphia, PA

• 
  M Stock

SU-H400-IePD-F7-1 (Sunday, 7/10/2022) 4:00 PM - 4:30 PM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 7

Purpose: A mobile CT scanner has been developed to enable real-time imaging of HDR procedures. The purpose of this study is to report on the feasibility of utilizing this mobile CT scanner for the commissioning and quality assurance (QA) of brachytherapy applicators.

Methods: The dwell position accuracy within a gynecological lunar ovoid applicator (Venezia, Elekta AB, Stockholm, Sweden) was verified using three methods. The first was the traditional film-based approach which involved comparing an autoradiograph of the applicator acquired using the Ir-192 source to a planar radiograph of the applicator with marker cables inserted. For the second method the applicator was positioned within the bore of a mobile CT scanner (ImagingRing, Elekta AB, Stockholm, Sweden) and digital radiographs of the two configurations were acquired, applicator with the Ir-192 source dwelling at its furthest position and applicator with the marker cables inserted. For the third method, a cone-beam CT (CBCT) was taken of the applicator with marker cables inserted and another of the applicator and Ir-192 source. The dwell position accuracy was verified in each method by comparing the location of the HDR source to its expected location using the maker cables.

Results: For the traditional approach, film darkening from the autoradiograph made it difficult to distinguish the marker cable to verify dwell position accuracy. With the mobile CT scanner the marker cables and Ir-192 source could be clearly visualized on radiographs and CBCT. In each case, the position of the Ir-192 source was within 1mm from the location of the marker cable.

Conclusion: The novel methodology presented in this study can be utilized to verify dwell position accuracy with less uncertainty than the traditional approach using film. Based on our results it is feasible to use the mobile CT scanner for the purpose of brachytherapy applicator commissioning and QA.

Keywords

Brachytherapy, Commissioning, HDR

Taxonomy

TH- Brachytherapy: Imaging for brachytherapy: development and applications

Contact Email