Comparison of Helical Tomotherapy versus Conventional Radiation to Deliver Craniospinal Radiation

Abstract

The purpose of this study was to investigate whether helical tomotherapy would better dose-limit growing vertebral ring apophyses during craniospinal radiation as compared to conventional techniques. Four pediatric patients with M0 medulloblastoma received tomotherapy craniospinal radiation (23.4 Gy, 1.8 Gy/fx) by continuous helical delivery of 6 MV photons. Weekly blood counts were monitored. For comparison, conventional craniospinal radiation plans were generated. To assist in tomotherapy planning, a cross-sectional growth study of 52 children and young adults was completed to evaluate spine growth and maturation. Vertebral ring apophyses first fused along the posterolateral body-pedicle synostosis, proceeding circumferentially toward the anterior vertebral body such that the cervical and lumbar vertebrae fused early and mid-thoracic vertebrae fused late. For the four pediatric patients, tomotherapy resulted between 2% and 14% vertebral volume exceeding 23 Gy.Conventional craniospinal radiation predicted between 33% and 44% exceeding 23 Gy. Cumulative body radiation doses exceeding 4 Gy were between 50% and 57% for tomotherapy and between 25% and 37% for conventional craniospinal radiation. Tomotherapy radiation reduced neutrophil, platelet, and erythrocyte hemoglobin levels during treatment. Tomotherapy provides improved dose avoidance to growing vertebrae as compared to conventional craniospinal radiation. However, the long-term effects of tomotherapy dose avoidance on spine growth and large volume low dose radiation in children are not yet known.

High-precision radiotherapy for craniospinal irradiation: evaluation of three-dimensional conformal radiotherapy, intensity-modulated radiation therapy and helical TomoTherapy

“…Kunos et al [25] investigated the role of TomoTherapybased CSI in limiting dose to growing vertebral ring apophyses in four paediatric patients with medulloblastoma and compared it with conventional techniques. Helical TomoTherapy provided improved dose avoidance to growing vertebrae (2-14% of the vertebral volume exceeding 23 Gy) when compared with conventional CSI (33-44%).…”

Solitary plasmocytoma: improvement in critical organs sparing by means of helical tomotherapy

“…However, factors contributing to the recently renewed concern about the second cancers include emerging treatment modalities such as IMRT that can potentially elevate secondary exposures to healthy tissues distant from the target volume (33,34). Preliminary findings suggest that HT may significantly improve the therapeutic ratio with respect to a conventional IMRT delivery method (35)(36)(37)(38). HT demonstrated its ability to sculpt in a more efficient way the dose distribution around the PTV, resulting in a significantly better homogeneity, without any cold-hot spot (Figs 1 and 2).…”

Assessment of Three-dimensional Set-up Errors using Megavoltage Computed Tomography (MVCT) during Image-guided Intensity-modulated Radiation Therapy (IMRT) for Craniospinal Irradiation (CSI) on Helical Tomotherapy (HT)

“…This unique feature of HT has been explored for CSI with promising dosimetric and early clinical results (11)(12)(13)(14). However, despite rapid adoption of newer technology in clinical practice, there is a paucity of data on set-up errors during CSI and the appropriate margins required thereof for ensuring adequacy of target volume coverage.…”