A feasibility study using TomoDirect for craniospinal irradiation

Ulrich W Langner,John F Gleason,Janelle A Molloy,Jonathan M Feddock

doi:10.1120/jacmp.v14i5.4304

Ulrich W Langner, John F Gleason + Show 2 more

Open Access

https://doi.org/10.1120/jacmp.v14i5.4304

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Abstract

The feasibility of delivering craniospinal irradiation (CSI) with TomoDirect is investigated. A method is proposed to generate TomoDirect plans using standard three‐dimensional (3D) beam arrangements on Tomotherapy with junctioning of these fields to minimize hot or cold spots at the cranial/spinal junction. These plans are evaluated and compared to a helical Tomotherapy and a three‐dimensional conformal therapy (3D CRT) plan delivered on a conventional linear accelerator (linac) for CSI. The comparison shows that a TomoDirect plan with an overlap between the cranial and spinal fields might be preferable over Tomotherapy plans because of decreased low dose to large volumes of normal tissues outside of the planning target volume (PTV). Although the TomoDirect plans were not dosimetrically superior to a 3D CRT linac plan, the patient can be easily treated in the supine position, which is often more comfortable and efficient from an anesthesia standpoint. TomoDirect plans also have only one setup position which obviates the need for matching of fields and feathering of junctions, two issues encountered with conventional 3D CRT plans. TomoDirect plans can be delivered with comparable treatment times to conventional 3D plans and in shorter times than a Tomotherapy plan. In this paper, a method is proposed for creating TomoDirect craniospinal plans, and the dosimetric consequences for choosing different planning parameters are discussed.PACS number: 87.55.D‐

Highlights

IntroductionThe goal of craniospinal irradiation (CSI) is to give a homogeneous radiation dose to the entire neuraxis
105 Langner et al.: TomoDirect craniospinal irradiation (CSI) results are not yet mature, patterns of care data suggest that a further reduction of dose to less than 23.4 Gy may be associated with higher failure rates.The goal of CSI is to give a homogeneous radiation dose to the entire neuraxis
We investigate the feasibility of TomoDirect treatments for CSI, using standard 3D CRT beam arrangements

Summary

Introduction

The goal of CSI is to give a homogeneous radiation dose to the entire neuraxis. This is a technically challenging problem in radiotherapy planning and delivery because of the need to irradiate a large and complex target volume uniformly, while still reducing dose to organs at risk (OARs). The majority of the previously mentioned late effects are dose and volume related; more complex radiation delivery techniques, such as intensity-modulated radiation therapy (IMRT), could be utilized to reduce OAR dose and improve the already narrow therapeutic ratio.[2,6,7,8,9,10,11] separate isocenters for cranial and spinal fields remain an unavoidable problem for CSI treatments on conventional linear accelerators (both for threedimensional conformal treatment (3D CRT) techniques, as well as IMRT techniques), such that matching of these fields and junction changes continue to be necessary. Two posterior spine fields are frequently required, necessitating additional junctions and planning complexity

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