BACKGROUND: Radiation is integral to the treatment of glioblastoma (GBM). However, radiation-induced scalp toxicity can negatively impact patients' quality of life. Volumetric modulated arc therapy (VMAT) optimizes the dose to organs at risk (OARs). We hypothesize that a scalp-sparing VMAT (SSV) approach can significantly reduce undesirable doses to the scalp without compromising the target dose.
METHODS: This is a retrospective cross-sectional study of GBM patients who originally received radiation with non-SSV. We contoured the scalp as a 5 mm rind-like structure beneath the skin above the level of the foramen magnum. We replanned our patients using SSV techniques. We compared dosimetric data for the scalp, planning target volume (PTV), and select critical normal structures between non-SSV and SSV plans.
RESULTS: Nineteen patients with newly diagnosed GBMs were included in our study. All patients received 60 Gy in 30 fractions. 9 patients received it in a single course. The rest received 46 Gy in 23 fractions to an initial volume followed by 14 Gy in 7 fractions to a cone-down volume (split course). New VMAT plans were generated after adding the scalp as an OAR. The median scalp volume was 416 cm3 (363-468 cm3). The median reductions in scalp Dmin, Dmax, and Dmean were 43.5% (-100% to 0%), 2.8% (+13.4% to -24.9%), and 15.7% (+2.1% to -39.9%) respectively. Median reductions in scalp D20cc and D30 cc were 19.5% (-2.7% to -54.5%), and 19.0% (-5.3% to -39.5%) respectively. The median volumes of the scalp receiving 30 Gy, 40 Gy, and 50 Gy were reduced by 42.3% (-70.6% to -12.5%), 72% (-100% to -2.3%), and 92.4% (-100% to +5.4%) respectively. There were no significant differences in the doses delivered to the PTV, brainstem, optic nerves, and optic chiasm between SSV and non-SSV plans.
CONCLUSIONS: SSV can significantly reduce scalp radiation dose without compromising target coverage or critical normal structure doses. This may translate into reduced acute and late radiation toxicity to the scalp. A prospective trial evaluating the clinical benefits of SSV is ongoing (NCT03251027).
Niazi, Muneeb Khan; Russial, Olga; Cappelli, Louis; Miller, Ryan; Chen, Yingxuan; Vakhnenko, Yelena; Lui, Haisong; and Shi, Wenyin, "Efficacy of Scalp-Sparing Volumetric-Modulated Arc Therapy Approach in Reducing Scalp Radiation Dose for Patients with Glioblastoma: A Cross-Sectional Study" (2023). Department of Radiation Oncology Faculty Papers. Paper 180.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.