Application value of individualized 3D-printed vaginal template for cervical cancer brachytherapy

Objective To introduce the workflow of individualized 3D-printed intracavitary/interstitial vaginal template design. Dosimetric parameters and operation safety were investigated to evaluate the performance of 3D-printed template and freehand implantation. Methods Forty patients previously treated with intracavitary/interstitial Ir-192 HDR brachytherapy were enrolled in this study. All patients were randomly divided into the treatment (n=20) and control groups (n=20). In the treatment group, twenty patients were treated with individualized 3D-printed template. CT-based preplan was carried out to determine the needle implantation cannels. Template with customized shape and implantation cannels was then produced by a 3D printer. Finally, the template was inserted under CT guidance. In the control group, twenty patients received freehand implantation. Needle insertion was decided empirically without the preplan process. Results The difference of D90 for high risk CTV was found to be minor, while the D2cm3 in the rectum, bladder and sigmoid was significantly improved in the treatment group. Meanwhile, the high dose region and conformal index were also improved in the treatment group. A total of 273 needles were inserted and one (0.3%) not-used needle was found. No normal tissues were penetrated during needle insertion in the treatment group. In the control group, a total of 203 needles were inserted and 4(2.0%) not-used needles were observed, and normal tissue penetration occurred in 3(1.5%) needle insertion. Conclusions The individualized 3D-printed template implantation approach has advantages in terms of dosimetry and safety compared with freehand implantation. The actual treatment can achieve the dosimetric design requirements of the preplan. Key words: 3D printing; Cervical neoplamsm/brachytherapy; Dosimetry