Development and assessment of 3D-printed individual applicators in gynecological MRI-guided brachytherapy

Abstract

Purpose: To evaluate the clinical use of 3D printing technology for the modelling of individual applicators for advanced gynecological tumors in magnetic resonance imaging (MRI)-based brachytherapy (BT). Material and methods: We tested individually designed 3D-printed applicators in nine patients with advanced gynecological cancer. Before BT was performed, all patients were treated with external beam radiotherapy (EBRT). The most common indication for individualized BT was advanced gynecological tumors where the use of standard BT applicators was not feasible. Other indications were suboptimal dose-volume histogram (DVH) parameters for high-risk clinical target volume (CTV-T HR) at the first BT (V 100 ≤ 90% of CTV-T HR volume and D 98 ≤ 80%, D 90 ≤ 100%, and D 100 ≤ 60% of dose aim). The EQD 2 dose aim to the target volume D 90 CTV-T HR per one BT fraction was 20 Gy for cervical or recurrent endometrial cancer and 16 Gy for vaginal cancer patient. The first BT with the standard applicator in situ was used as the virtual plan for designing a 3D-printed applicator. The next BT was performed with a 3D-printed applicator in situ. The primary endpoint was to improve CTV-T HR DVH parameters without exceeding the dose to the organs at risk (OARs). Results: All DVH parameters for CTV-T HR were significantly higher with the use of an individually designed applicator. Mean D 90 CTV-T HR improved from 14.1 ±5.4 Gy to 22.0 ±2.5 Gy and from 7.1 Gy to 16.2 Gy for cervical/recurrent endometrial and vaginal cancer, respectively (p < 0.001). The mean D 2cm 3 bladder, rectum, sigmoid, and bowel dose was within institutional dose constraints, and increased from 13.0 ±1.5 Gy to 13.6 ±1.5 Gy (p = 0.045), 10.8 ±1.2 Gy to 11.7 ±1.3 Gy (p = 0.004), 8.9 ±3.2 Gy to 10.3 ±3.3 Gy (p = 0.008), and 8.7 ±3.8 Gy to 9.2 ±3.1 Gy (p = 0.2). Conclusions: With the use of individual 3D-printed applicators, all DVH parameters for CTV-T HR significantly improved without compromising the dose constraints for the OARs.

Comparing multichannel cylinder and 3D-printed applicators for vaginal cuff brachytherapy with preliminary exploration of post-hysterectomy vaginal morphology

“…The thickness of lesions treated in this study was limited to 10 mm. For patients with tumor sizes > 10 mm [ 18 ], paravaginal extension or pararectal space involvement [ 16 ], and insufficient target coverage [ 20 ], combined intracavitary/interstitial techniques should be used. Novel 3D-printed intracavitary applicators based on intensity-modulated techniques has been shown to be clinically feasible for treating vaginal tumors thicker than 10 mm [ 35 ].…”

“…Wiebe et al found that a 3D-printed applicator could offer favorable dose distribution at the vaginal apex for a 'dog ear' vaginal configuration, with sufficient and effective dwell positions [15]. However, previous studies investigating the use of this individual applicator in vaginal brachytherapy have focused on interstitial brachytherapy [16][17][18][19][20][21][22], whereas reports on vaginal intracavitary brachytherapy are scarce [15,23]. As such, whether 3D-printed applicators are superior to MCCs in clinical practice remains unknown.…”

A single-institution review of image-guided brachytherapy for vaginal malignancies using customized molded applicators and interstitial needles

“…Nilsson et al used a two-part putty [55]. However, further work is warranted investigating the use of 3D printing in the treatment of vaginal malignancies [56,57].…”

Preliminary results of modified interstitial MIAMI brachytherapy applicator for treatment of upper and apical vaginal tumors

“…These 3D-printed applicators are customized to patient's anatomy and have a protective shell around the needles, with needles extending directly into the vaginal apex to treat apically located lesions. These 3D-printed applicators, however, rely on the availability of a 3D printer and time for customization, are typically not reusable, and there is limited research for the various materials used to design 3D-printed applicators and their resulting dose distributions [36,37].…”