TY  - JOUR
A1  - Scherf, Christian
A1  - Licher, Jörg
A1  - Mletzko, Christina
A1  - Trommel, Martin
A1  - Tselis, Nikolaos
A1  - Chatzikonstantinou, Georgios
A1  - Diefenhardt, Markus
A1  - Rödel, Claus
A1  - Köhn, Janett
A1  - Ramm, Ulla
T1  - Individualized mould-based high-dose-rate brachytherapy for perinasal skin tumors: technique evaluation from a dosimetric point of view
T2  - Journal of contemporary brachytherapy
N2  - Purpose: Dosimetric treatment planning evaluations concerning patient-adapted moulds for iridium-192 highdose-rate brachytherapy are presented in this report.
Material and methods: Six patients with perinasal skin tumors were treated with individual moulds made of biocompatible epithetic materials with embedded plastic applicators. Treatment plans were optimized with regard to clinical requirements, and dose was calculated using standard water-based TG-43 formalism. In addition, retrospective material-dependent collapsed cone calculations according to TG-186 protocol were evaluated to quantify the limitations of TG-43 protocol for this superficial brachytherapy technique.
Results: The dose-volume parameters D90, V100, and V150 of the planning target volumes (PTVs) for TG-43 dose calculations yielded 92.2% to 102.5%, 75.1% to 93.1%, and 7.4% to 41.7% of the prescribed dose, respectively. The maximum overall dose to the ipsilateral eyeball as the most affected organ at risk (OAR) varied between 8.9 and 36.4 Gy. TG-186 calculations with Hounsfield unit-based density allocation resulted in down by –6.4%, –16.7%, and –30.0% lower average D90, V100, and V150 of the PTVs, with respect to the TG-43 data. The corresponding calculated OAR doses were also lower. The model-based TG-186 dose calculations have considered reduced backscattering due to environmental air as well as the dose-to-medium influenced by the mould materials and tissue composition. The median PTV dose was robust within 0.5% for simulated variations of mould material densities in the range of 1.0 g/cm³ to 1.26 g/cm³ up to 7 mm total mould thickness.
Conclusions: HDR contact BT with individual moulds is a safe modality for routine treatment of perinasal skin tumors. The technique provides good target coverage and OARs’ protection, while being robust against small variances in mould material density. Model-based dose calculations (TG-186) should complement TG-43 dose calculations for verification purpose and quality improvement.
KW  - brachytherapy
KW  - perinasal skin cancer
KW  - individual moulds
KW  - TG-43
KW  - TG-186
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/62941
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-629418
SN  - 2081-2841
VL  - 13
IS  - 2
SP  - 179
EP  - 187
PB  - Termedia
CY  - Poznań
ER  -