Practical aspects of the application of helical tomotherapy for craniospinal irradiation

• Published in: Scientific reports Vol. 11; no. 1; p. 6120
• Main Authors: Lee, Joongyo, Kim, Euidam, Kim, Nalee, Byun, Hwa Kyung, Suh, Chang-Ok, Chung, Yoonsun, Yoon, Hong In
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 17.03.2021; Nature Publishing Group UK; Nature Portfolio
• Subjects: Computed tomography; Irradiation; Patients; Pediatrics; Radiation; Risk factors; Spine; Zygomatic arch
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-85574-y

We investigated the practical aspects of the application of craniospinal irradiation using helical tomotherapy (HT-CSI) by evaluating interfractional setup errors and intrafractional movement during each treatment in 83 patients undergoing HT-CSI between January 2014 and December 2018. Interfractional setup errors in each axis (mediolateral; ML, craniocaudal; CC, and anteroposterior; AP) were assessed as differences between pre-treatment megavoltage computed tomography (MVCT) images scanned (zygomatic arch to the C4 spine) and planning CT images. Intrafractional movements were evaluated as the difference between pre-treatment and post-treatment MVCT (T12-L4 spine) images at each fraction. Median interfractional setup error was acceptable in every axis (ML: 1.6 mm, CC: 1.9 mm, AP: 3.1 mm). Seven patients (8.4%) experienced significant intrafractional displacement from 1 to 10 fractions (0.34% for ML, 0.74% for CC, 1.21% for AP). Weight loss grade 1+ during treatment (p = 0.016) was an independent risk factor for significant intrafractional displacement. The risk factor for significant intrafractional movement in pediatric patients was weight loss grade 1+ (p = 0.020), while there was no factor in adults. HT-CSI could be a feasible treatment modality with acceptable setup verification. Inter- and intrafractional errors were acceptable; paying attention to weight loss during treatment is necessary, especially in pediatric patients.