Introduction/Background Despite modern techniques in external beam radiotherapy (EBRT), intensity modulated radiation therapy (IMRT) and stereotactic radiotherapy (SRT), brachytherapy (BT) remains one of the most important modalities for the treatment of advanced gynaecological cancer. In some special cases commercially available applicators for MRI-guided intracavitary/interstitial (IC/IS) BT do not offer proper target coverage. With the help of additive technologies, 3D-printed applicators can be tailored to the patient‘s tumour and anatomy.
Methodology In this report two cases of gynaecological cancer, one vaginal and one recurrent endometrial cancer are presented. The design of the applicator was based on MRI images of the patient with the standard Varian vaginal cylinder inserted. Parallel and oblique needles were virtually added to the planning system to get the best possible coverage of the tumour while respecting the dose constraints to the organs at risk (OARs). Individual applicators were made from biocompatible polyamide PA 12 with selective laser sintering (SLS) technology (figure 1). The next BT was performed with an individual applicator in situ. Rectal ultrasound was used for needle guidance. The dose-volume histogram (DVH) parameters for each patient were compared according to the planning aims. The planning aim for D90 high-risk clinical target volume (CTV-THR) was to reach physical dose > 20.5 Gy per one BT fraction delivered in 24 pulses of pulsed dose rate (PDR) BT.
Results The DVH parameters for both cases per one BT fraction are presented in table 1. The procedure and the implantation of the needles was performed without complications in regional anaesthesia. The applicator was well tolerated, no adverse effect was reported during the treatment or removal of the applicator.
Conclusion The advantages of using an individually-designed multi-channel vaginal applicator are:
better target coverage in advanced tumours extended in the vagina
can be used in a narrow vagina
implantation guidance of several oblique and parallel needles can be performed with minimized trauma to the surrounding tissue
allows for the treatment of several tumour locations in the same BT fraction
Disclosures Helena Barbara Zobec Logar, Robert Hudej and Manja Kobav have nothing to disclose.
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