Room: Exhibit Hall
Purpose: In the rare cases of recurrent endometrial carcinoma (â‰¤5% at 5 year), salvage radiation therapy (external beam radiation(EBRT) + brachytherapy(BT)), is the typical management choice. However, potential excessive cumulative dose to rectum and subsequent toxicity is a major concern. For our pilot patient, we used a polyethylene glycol hydrogel (TraceITâ„¢) as a spacer between the rectum and tumor, which effectively reduced the rectal dose. TraceITâ„¢ is radiopaque and is injected as-is without further polymerization. This report details the stability of TraceITâ„¢ in terms of volume, radiopacity, and geometry throughout the treatment course.
Methods: Under CT guidance the interventional radiologist injected a total of 18 cc of TraceITâ„¢ in 2cc-packets into the anterior perirectal space using 19-gauge needles (Day 0). Two planning CT image sets were available: CT-EBRT (Day 8) and CT-BT (Day 70), along with 25 CBCTs obtained during EBRT. TraceITâ„¢ was contoured on all image sets with the total volume and mean Hounsfield Unit(HU) recorded along with the distance of its center of mass(COM) from a nearby fiducial marker.
Results: The average volume of TraceITâ„¢ contoured on CBCT was 16 Â±0.4 cc (1SD) throughout the 2-month long EBRT treatment. The average HU of TraceITâ„¢ from CT-EBRT to CT-BT declined ~50% (195 to 97) in two months. This decrease in HU was confirmed by the CBCT findings. The relative location (COM) varies from the CT-EBRT by 2.5 Â±1 mm.
Conclusion: TraceITâ„¢ has the potential of becoming a valuable tool for the management of recurrent endometrial carcinoma. It maintains a consistent volume and anatomic location for the time frame pertinent to this study. However, the gradual decrease of the HU could limit the interval between injection and the end of treatment to approximately 4 months if the observed trend is constant, which is consistent with vendor recommendations.