Room: Exhibit Hall
Purpose: To assess the improvement in brachytherapy dosimetry by using multi-channel applicators as in the case of Tandem-and-Ring with interstitial needles, Capri applicators, and Rotte Double-Tandems.
Methods: Plans from five patients treated with Tandem-and-Ring and interstitial needles, five patients treated with Capri multi-channel applicators, and five patients treated with the Rotte double-tandem applicator were used for this study. Each original plan was re-planned with extra components (needles or channels) removed to simulate simple Tandem-and-Ring, single-channel cylinder, and single-tandem (reconstructed by splitting the difference between the Rotte double-tandems) implants, and re-optimized with the IPSA algorithm (Oncentra TPS) and re-normalized to match the High Risk CTV (HR-CTV) coverage as the original. The doses to the OARs were compared using DVH analysis.
Results: For the similar coverage of HR-CTV, the double-tandem spared the 2 cmÂ³ bladder and sigmoid dose in all five patients, rectum doses up to 6% in three patients, and bowel doses as much as 34% in three patients. Similarly, in the cases of tandem-and-ring with interstitial needles, higher rectum, sigmoid, and bowel doses resulted for patient 1 from the original plans, and patients 2 and 5 had 2% higher bowel doses in the original plans but were spared bladder, rectum, and sigmoid doses. Patients 3 and 4 had better dosimetry with original plans. Last, the Capri applicator proved to be superior to single-channel cylinder in patients 1 through 4. Patient 5 had 2.7% higher bladder dose, but the rectum was spared by 17% less dose.
Conclusion: Multi-channel HDR brachytherapy treatments allow for better dose conformity to the target structure and manipulation of dose to the normal tissues. The advantages of using multi-channel devices vary depending on the size, shape, and irregularity of the target structure.