Three discipline collaborative radiation therapy special debate: All head and neck cancer patients with intact tumors/nodes should have scheduled adaptive replanning performed at least once during the course of radiotherapy

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149241/1/acm212587_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149241/2/acm212587.pd

Quality assurance of an image guided intracranial stereotactic positioning system for radiosurgery treatment with helical tomotherapy

The aim of this work was to determine the accuracy and precision of stereotactic localization and treatment delivery using a helical tomotherapy based stereotactic radiosurgery (SRS) system. A tomotherapy specific radiosurgery workflow was designed that exploits the system’s on board megavotage CT (MVCT) imaging system so that it not only provides a pre-treatment volumetric verification image that can be used for stereotactic localization, eliminating the need for a patient-frame based coordinate system, but also supplies the treatment planning image. Using an imaging guidance based intracranial stereotactic positioning system, a head ring and tabletop docking device are used only for fixation, while image guidance is used for localization. Due to the unconventional workflow, a methodology for determining the localization accuracy was developed and results were compared to other linear accelerator based radiosurgery systems. In this work, the localization error using volumetric localization was found to be 0.45 mm ± 0.17 mm, indicating a localization precision of 0.3 mm within a 95% confidence interval. In addition, procedures for testing the delivery accuracy of the Tomotherapy system are described. Results show that the accuracy of the delivery can be verified to within ±1 voxel dimension. These results are well within conventional SRS tolerances and compare favorably to other linear accelerator based techniques

The helical tomotherapy thread effect

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder

Dosimetric verification of helical tomotherapy for total scalp irradiation

Total scalp irradiation is a treatment technique used for a variety of supercial malignancies.Helical tomotherapy is an effective technique used for total scalp irradiation. Recent publishedwork has shown the TomoTherapy planning system to overestimate the supercial dose. In thisstudy, the supercial doses for a helical tomotherapy total scalp irradiation have been measured onan anthropomorphic phantom using radiochromic and radiographic lm as well as a new skindosimeter, the MOSkin. The supercial dose was found to be accurately calculated by the Tomo-Therapy planning system. This is in contrast to recent reports, probably due to a combination of thesmaller dose grid resolution used in planning and this particular treatment primarily consisting ofbeamlets tangential to the scalp. The supercial dose was found to increase from 33.6 to 41.2 Gyand 36.0 to 42.0 Gy over the rst 2 mm depth in the phantom in selected regions of the PTV,measured with radiochromic lm. The prescription dose was 40 Gy. The supercial dose was at theprescription dose or higher in some regions due to the bolus effect of the thermoplastic head maskand the head rest used to aid treatment setup. It is suggested that to achieve the prescription dose atthe surface 2 mm depth bolus or a custom thermoplastic helmet is use