Purpose

To report initial clinical experience of the Tulip Add-On hybrid intracavitary/interstitial (IC/IS) brachytherapy applicator in locally advanced carcinoma cervix, and to compare its dosimetric performance with conventional IC brachytherapy.

Material and methods

Eight patients with FIGO stage IIB-IIICr1 cervical cancer were treated between January 2021 and January 2022. All received external beam radiotherapy with concurrent chemotherapy, followed by CT-guided IC/IS brachytherapy using Henschke applicator with Tulip Add-On interstitial needles. Paired dosimetric plans (IC/IS vs. IC-only) were generated for each patient. Target coverage (D90, D98, D100, V90, and V100) and implant quality indices, including conformity index (CI), dose homogeneity index (DHI), dose non-uniformity ratio (DNR), and overdose volume index (ODI), were analyzed, along with organ at risk (OAR) doses.

Results

Median age was 58 years; median high-risk clinical target volume (HR-CTV) was 55.6 cc (range, 25.6-81 cc). Six patients required bilateral and two unilateral interstitial insertions. Compared with IC-only, IC/IS plans significantly improved HR-CTV coverage: D90 was 77.2 Gy vs. 69.5 Gy, and D100 was 63.8 Gy vs. 56.9 Gy. OAR doses were similar (rectum D2cc: 65.9 Gy vs. 65.5 Gy; bladder D2cc: 71.6 Gy vs. 74.0 Gy). Quality indices favored the hybrid approach, with higher CI (0.615 vs. 0.556) and DHI (0.45 vs. 0.40), and lower DNR and ODI values.

Conclusions

The Tulip Add-On applicator offers superior HR-CTV coverage without compromising OARs sparing. It is a practical, resource-adaptive technique that combines simplicity of intracavitary brachytherapy with dosimetric advantages of interstitial approaches, particularly valuable for patients with residual parametrial disease post-EBRT.