Background and purpose: A bolus is required when treating scalp lesions with photon radiation therapy. Traditional bolus materials face several issues, including air gaps and setup difficulty due to irregular, convex scalp geometry. A 3D-milled bolus is custom-formed to match individual patient anatomy, allowing improved dose coverage and homogeneity. Here, we describe the creation process of a 3D-milled bolus and report the outcomes for patients with scalp malignancies treated with Volumetric Modulated Arc Therapy (VMAT) utilizing a 3D-milled bolus. Materials and methods: Twenty-two patients treated from 2016 to 2022 using a 3D-milled bolus and VMAT were included. Histologies included squamous cell carcinoma (n= 14, 64%) and angiosarcoma (n= 8, 36%). A total of 7 (32%) patients were treated in the intact and 15 (68%) in the postoperative setting. The median prescription dose was 66.0 Gy (range: 60.0–69.96). Results: The target included the entire scalp for 8 (36%) patients; in the remaining 14 (64%), the median ratio of planning target volume to scalp volume was 35% (range: 25–90%). The median dose homogeneity index was 1.07 (range: 1.03–1.15). Six (27%) patients experienced acute grade 3 dermatitis and one (5%) patient experienced late grade 3 skin ulceration. With a median follow-up of 21.4 months (range: 4.0–75.4), the 18-month rates of locoregional control and overall survival were 75% and 79%, respectively. Conclusions: To our knowledge, this is the first study to report the clinical outcomes for patients with scalp malignancies treated with the combination of VMAT and a 3D-milled bolus. This technique resulted in favorable clinical outcomes and an acceptable toxicity profile in comparison with historic controls and warrants further investigation in a larger prospective study.
背景与目的：采用光子放射治疗头皮病灶时需使用组织补偿物。传统补偿材料因头皮不规则凸面几何结构易产生气隙且摆位困难。三维铣削补偿物可根据患者个体解剖结构定制，从而改善剂量覆盖与均匀性。本研究阐述三维铣削补偿物的制作流程，并报告采用该补偿物结合容积旋转调强放疗（VMAT）治疗头皮恶性肿瘤的临床结果。材料与方法：纳入2016年至2022年间接受三维铣削补偿物联合VMAT治疗的22例患者。病理类型包括鳞状细胞癌（14例，64%）和血管肉瘤（8例，36%）。其中7例（32%）为根治性放疗，15例（68%）为术后放疗。处方剂量中位数为66.0 Gy（范围：60.0–69.96 Gy）。结果：8例（36%）患者靶区覆盖全头皮，其余14例（64%）患者的计划靶区与头皮体积比值中位数为35%（范围：25–90%）。剂量均匀性指数中位数为1.07（范围：1.03–1.15）。6例（27%）患者出现3级急性皮炎，1例（5%）患者出现3级晚期皮肤溃疡。中位随访时间21.4个月（范围：4.0–75.4个月），18个月局部区域控制率与总生存率分别为75%和79%。结论：据我们所知，这是首项报道VMAT联合三维铣削补偿物治疗头皮恶性肿瘤临床结局的研究。该技术相较于历史对照展现出良好的临床疗效与可接受的毒性特征，值得在更大规模的前瞻性研究中进一步验证。
Scalp Irradiation with 3D-Milled Bolus: Initial Dosimetric and Clinical Experience
肿瘤(癌症)患者之家