Dosimetric considerations when utilizing Venezia, Capri, Rotte double tandem, and tandem and ring with interstitial needles for the treatment of gynecological cancers with high dose rate brachytherapy
This work evaluated the difference in dosimetry of high dose rate (HDR) brachytherapy treatments between plans using advanced multichannel applicators and simplified base versions. Eighteen HDR patients treated using Interstitial Ring CT/MR Applicator Set (Elekta Brachytherapy, Netherlands) (TRN) (21 plans), CapriTM Applicator Set (Varian Medical Systems, Inc., Palo Alto, CA) (CC) (19 plans), Rotte Endometrial Applicator Set (Elekta Brachytherapy, Netherlands) (RDT) (18 plans), and the Advanced Gynecological Applicator Venezia (Vz) (Elekta Brachytherapy, Netherlands) (6 plans) were retrospectively reviewed. For each plan, "advanced" channels including any interstitial channels, the 12 noncentral channels in the CC, and the lateral extending aspects of the RDT were removed and a new plan with the original inverse planning settings was optimized using only the remaining "simplified" applicator and compared to the original. The new plans were renormalized to match the original percent dose to 90% of the high-risk clinical target volume (HR-CTV). Critical structures included bladder, rectum, sigmoid colon, and small bowel. Comparisons were made utilizing dose volume histograms of HR-CTVs, conformation number (CN), and the equivalent total dose in 2 Gy fractions (EQD2) to 2 cm