Patient-specific cylinder templates for hybrid interstitial vaginal brachytherapy: Feasibility of automated 3-D design, 3D printing, and dosimetric outlook

Michael Kudla; Francois Bachand; Jocelyn Moore; Deidre Batchelar

doi:10.1016/j.brachy.2023.03.002

Patient-specific cylinder templates for hybrid interstitial vaginal brachytherapy: Feasibility of automated 3-D design, 3D printing, and dosimetric outlook

Brachytherapy. 2023 Jul-Aug;22(4):468-476. doi: 10.1016/j.brachy.2023.03.002. Epub 2023 May 9.

Authors

Michael Kudla¹, Francois Bachand², Jocelyn Moore³, Deidre Batchelar⁴

Affiliations

¹ Department of Physics, The University of British Columbia - Okanagan, Kelowna, BC, Canada. Electronic address: michael.kudla@bccancer.bc.ca.
² Department of Radiation Oncology, BC Cancer - Kelowna, Kelowna, BC, Canada.
³ Department of Radiation Oncology, Saskatoon Cancer Center, Saskatoon, SK, Canada.
⁴ Department of Physics, The University of British Columbia - Okanagan, Kelowna, BC, Canada; Department of Medical Physics, BC Cancer - Kelowna, Kelowna, BC, Canada.

PMID: 37169607
DOI: 10.1016/j.brachy.2023.03.002

Abstract

Purpose: Delivering highly conformal treatment plans for high-dose rate vaginal brachytherapy using commercially available applicators can be challenging. A partially automated workflow is presented for the in-house modeling and 3D printing of patient-specific cylindrical templates (PSCTs), which facilitate placement of flexible intracavitary and interstitial needles. To demonstrate feasibility, we compare PSCT treatment plans to retrospective interstitial brachytherapy plans delivered at our center. PSCTs derived from these plans were 3D printed to test the validity of the auto-design process. To facilitate clinical implementation, we validated the steam sterilization compatibility of PSCTs printed using polyetheretherketone (PEEK).

Methods and materials: Plans for ten patients treated using a combination of vaginal cylinder and interstitial needles were compared to PSCT-based plans created for the same patient. DVH parameters for the HRCTV (V100, V150, V200, D90) and OARs (D2 cm³) were evaluated, as well as the number of needles used and the total interstitial length. Each planned PSCT was printed and compared to the intended needle geometry. 3D printed models were sterilization validated by an independent contractor for an autoclave protocol.

Results: PSCT plans demonstrated advantages over template based perineal BT in reducing the total interstitial needle length required while preserving or improving HRCTV and OAR dosimetry. All printed PSCTs matched planned geometry.

Conclusions: PSCTs stand to be an alternative to current HDR-BT templates/applicators for patients with vaginal and locally recurrent endometrial cancers. Clinically equivalent or improved treatment plans can be created and devices to deliver these plans can be accurately printed and sterilized.

Keywords: 3D printed applicators; 3D printing; Brachytherapy; Cancer; High-dose rate; Hybrid brachytherapy; Individualized; Interstitial; Intracavitary; Patient specific; Recurrent endometrial; Vaginal brachytherapy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brachytherapy* / methods
Feasibility Studies
Female
Humans
Neoplasm Recurrence, Local / etiology
Printing, Three-Dimensional
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods
Retrospective Studies