Practical aspects of the application of helical tomotherapy for craniospinal irradiation

Joongyo Lee,Euidam Kim,Hong In Yoon,Yoonsun Chung,Hwa Kyung Byun,Chang-Ok Suh,Nalee Kim

doi:10.1038/s41598-021-85574-y

Abstract

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.

Highlights

We investigated the practical aspects of the application of craniospinal irradiation using helical tomotherapy (HT-Craniospinal irradiation (CSI)) by evaluating interfractional setup errors and intrafractional movement during each treatment in 83 patients undergoing HT-CSI between January 2014 and December 2018
With a median body mass index (BMI) of 20.4 kg/m2, 26 patients were categorized as underweight (BMI < 18.5 kg/m2), 50 were categorized to have normal weight (BMI 18.5–25 kg/m2), and 7 were categorized to have overweight (BMI 25–30 kg/m2) according to the World Health Organization c riteria[31]
To demonstrate the feasibility of CSI using HT, we evaluated the accuracy of setup in interfractional and intrafractional movements based on setup errors and patient movement during treatment, respectively

Summary

Introduction

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. Three-dimensional conformal RT (3D-CRT) has been the most common and useful technique for CSI, CSI using 3D-CRT still has many limitations such as problems related to multiple isocenters, need for junction movement during treatment, and dose inhomogeneity at the beam junctions[5,6,7]. Large areas of the organs at risk (OARs) near the target can be irradiated due to the low conformity of 3D-CRT compared to those of the latest RT techniques[6,8,9,10] These drawbacks of the 3D-CRT technique are highlighted by the fact that CSI is generally used for pediatric patients because they are known to have more severe side effects such as endocrine and fertility dysfunction, growth and musculoskeletal abnormalities, neurobehavioral deficits, and secondary malignancies due to unnecessary irradiation to O ARs4,11–14. Characteristic Age (years, median [range]) < 20 years (pediatric) ≥ 20 years (adult) Histology–Pediatric Germ cell tumor Medulloblastoma Miscellaneous Histology–Adult Glioblastoma Leptomeningeal carcinomatosis Germ cell tumor Miscellaneous Sex Male Female Height (cm, median [range]) Body-mass index (kg/m2, median [range]) Weight loss grade ≥ 1* Nausea grade ≥ 2* Total CSI dose (Gy, median [range]) Total CSI fraction number (fractions, median [range]) Fractional CSI dose (Gy, median [range]) CSI field Brain-Sacrum Posterior fossa-Sacrum C1 spine-Sacrum Beam on time (seconds, median [range]) Sedation during treatment Concurrent chemotherapy Overall CSI treatment time (days, median [range]) Medically-indicated treatment interruptions Days (median [range]) Adaptive during CSI

Methods

Results

Conclusion