The aim of this study was to demonstrate the utility of the dose-volume parameters of the target lesions and the radiation dose to the organ at risk (OAR) in two patients with primary cutaneous angiosarcoma of the scalp (CAS) treated with high-dose-rate brachytherapy (HDR-BT) using a surface mold applicator. In 2020, two men, aged 80 years and 60 years, respectively, were treated with HDR-BT with paclitaxel for CAS with no distant metastases and no surgical indication at our institution. The total irradiated dose was 57 Gy administered in daily fractions of 3 Gy four days per week. The method of HDR-BT involved the construction of a helmet that fitted over the patient's head, with parallel catheters fixed to the outside at 2.0 cm intervals to transport the iridium-192 HDR-BT source. In conclusion, HDR-BT may be superior when the dose to the target lesion plays a more important role than the OAR dose in selecting radiotherapy modalities for CAS.