Efficacy and feasibility of 3D printed redesigned Venezia™ applicator for treating advanced cervix and recurrent endometrial cancer

Abstract

Purpose: Venezia™ is an interstitial brachytherapy applicator for treating advanced cervical and vaginal vault recurrent cancer. However, there are limitations that lead to suboptimal target coverage. 3D printing introduction allows the redesign of Venezia™ for bulky and irregular-shaped tumors.

Methods: This study first describes three new designs included: 1) add-on needles template allowed for an extra layer of straight and oblique needles, 2) redesigned vaginal cap so straight and oblique needles can be used together and 3) redesigned central tube allowed vaginal vault interstitial needle insertion. Drawbacks to original Venezia™ and rationale for using these new designs were discussed. Dosimetric analysis by comparing the original Venezia™ with new design for 10 cases in Oncentra treatment planning system v4.5 (Elekta, Stockholm, Sweden) to observe the dose differences in gross tumor volume (GTV), high risk clinical target volume (HRCTV), intermediate clinical target volume (IRCTV) and organs at risk.

Results: For the dosimetric comparison, there were statistically significantly increased median minimal dose to 98% (D_98%) of GTV, 90% (D_90%) of HRCTV, and IRCTV for the new design with p-value of 0.008, 0.005 and 0.0018, respectively. Comparing the physical dose of D_98% of GTV, D_90% of HRCTV, and IRCTV when using the new design, it averagely increased by 11.7%, 8.0%, 19.4%, respectively per fraction.

Conclusions: Dosimetric comparison revealed the new designs increased the dose to GTV, HRCTV and IRCTV and fulfilled the dose constraints of bladder, rectum and sigmoid. The 3D printed new design is biocompatible, inexpensive and can be patient specific.

Keywords: 3D printed applicator; Advanced cervix; Image guided brachytherapy; Interstitial and intracavitary brachytherapy; Recurrent endometrial cancer.