Use of a head-tilting baseplate during volumetric-modulated arc therapy (VMAT) to better protect organs at risk in hippocampal sparing whole brain radiotherapy (HS-WBRT)

• Published in: PloS one 2020-04, Vol.15 (4), p.e0232430-e0232430
• Main Authors: Oh, Se An, Yea, Ji Woon, Park, Jae Won, Park, Jaehyeon
• Format: Article
• Language: English
• Subjects: Biology and Life Sciences; Brain; Brain cancer; Cancer therapies; Computed tomography; Computer simulation; Conformity; Dosimetry; Drug dosages; Exocrine glands; Head; Hippocampus; Homogeneity; Lenses; Magnetic resonance imaging; Medicine and Health Sciences; Metastases; Metastasis; Neurotoxicity; Oncology; Organs; Parotid gland; Patients; Radiation therapy; Research and Analysis Methods; Salivary glands; Simulation; Supine position
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0232430

Coplanar arcs are used with limited arc range to prevent direct beam entrance through the lens, which is challenging for satisfactory planning of hippocampal sparing in whole brain radiotherapy (HS-WBRT) with VMAT. We evaluated the dosimetric impact of applying a head-tilting technique during VMAT, which allows unrestricted use of the arc range. Twenty patients with multiple brain metastases who had received two computed tomography (CT)-simulation sessions between January 2016 and December 2018 were included. One session was delivered in a traditional supine position; the other was delivered with a tilting acrylic supine baseplate (MedTec, USA) to elevate the patients' head by 40°. For each patient, a VMAT without (sVMAT) and with head-tilting (htVMAT) plan was generated. Conformity index (CI), homogeneity index (HI), and organ at risk (OAR) dose were evaluated. The Wilcoxon-signed test was used to compare the effect between two plans. The mean CI was 0.860±0.007 and 0.864±0.008 (p