Publication date: Nov 03, 2025
Background/Objectives: The anatomical complexity of the auricular region poses a unique challenge for contact interventional radiotherapy (IRT, modern brachytherapy), especially in maintaining close conformity between the applicator and skin surface. Air gaps can arise due to the irregular shape of the ear, potentially compromising dose coverage. This study evaluates the dosimetric impact of air gaps in HDR IRT for non-melanoma skin cancer (NMSC) of the ear. Methods: Ten patients treated with contact IRT using alginate as supporting material were retrospectively analyzed. Treatment plans were recalculated using both the TG-43 and the TG-186 formalism. CTV coverage and organ-at-risk dose parameters were evaluated within the two formalisms. Results: CTV coverage was comparable between algorithms (mean V95% 96. 2% vs. 94. 4%, V100% 89. 6% vs. 86. 7%, and V150% 2. 6% vs. 2. 5% for TG-43 vs. TG-186; p > 0. 05), while the ipsilateral eye D2cc decreased from 4. 0% (TG-43) to 3. 2% (TG-186). In silico simulations showed that increasing air gaps reduced skin dose progressively (up to ~15% at 5 mm), whereas alginate thickness produced only a mild dose increase (
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| Concepts | Keywords |
|---|---|
| Compromising | non-melanoma skin cancer |
| Ctv | TG-186 |
| Organ | TG-43 |
| Radiotherapy | |
| V150 |
Semantics
| Type | Source | Name |
|---|---|---|
| drug | DRUGBANK | Medical air |
| disease | MESH | Melanoma |
| pathway | KEGG | Melanoma |
| disease | MESH | HDR |
| disease | MESH | skin cancer |
| drug | DRUGBANK | Pentaerythritol tetranitrate |
| drug | DRUGBANK | Alginic acid |