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Title: Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis

Abstract

Introduction: Patients with vertebral metastasis that receive radiation therapy are typically treated to the spinal cord tolerance dose. As such, it is difficult to successfully deliver a second course of radiation therapy for patients with overlapping treatment volumes. In this study, an image-guided helical tomotherapy system was evaluated for the retreatment of previously irradiated vertebral metastasis. Methods and Materials: Helical tomotherapy dose gradients and maximum cord doses were measured in a cylindrical phantom for geometric test cases with separations between the planning target volume (PTV) and the spinal cord organ at risk (OAR) of 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm. Megavoltage computed tomography (CT) images were examined for their ability to localize spinal anatomy for positioning purposes by repeat imaging of the cervical spine in an anthropomorphic phantom. In addition to the phantom studies, 8 patients with cord compressions that had received previous radiation therapy were retreated to a mean dose of 28 Gy using conventional fractionation. Results and Discussion: Megavoltage CT images were capable of positioning an anthropomorphic phantom to within {+-}1.2 mm (2{sigma}) superior-inferiorly and within {+-}0.6 mm (2{sigma}) anterior-posteriorly and laterally. Dose gradients of 10% per mm were measured in phantom whilemore » PTV uniformity indices of less than 11% were maintained. The calculated maximum cord dose was 25% of the prescribed dose for a 10-mm PTV-to-OAR separation and 71% of the prescribed dose for a PTV-to-OAR separation of 2 mm. Eight patients total have been treated without radiation-induced myelopathy or any other adverse effects from treatment. Conclusions: A technique has been evaluated for the retreatment of vertebral metastasis using image-guided helical tomotherapy. Phantom and patient studies indicated that a tomotherapy system is capable of delivering dose gradients of 10% per mm and positioning the patient within 1.2 mm without the use of special stereotactic immobilization.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Department of Radiation Oncology, Thompson Cancer Survival Center, Knoxville, TN (United States)
Publication Date:
OSTI Identifier:
20788256
Resource Type:
Journal Article
Journal Name:
International Journal of Radiation Oncology, Biology and Physics
Additional Journal Information:
Journal Volume: 63; Journal Issue: 5; Other Information: DOI: 10.1016/j.ijrobp.2005.05.015; PII: S0360-3016(05)00833-3; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0360-3016
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ANATOMY; CAT SCANNING; FRACTIONATED IRRADIATION; IMAGES; METASTASES; MODULATION; PATIENTS; PHANTOMS; PLANNING; RADIATION DOSES; RADIOTHERAPY; SPINAL CORD; VERTEBRAE

Citation Formats

Mahan, Stephen L, Ramsey, Chester R, Scaperoth, Daniel D, Chase, Daniel J, and Byrne, Thomas E. Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis. United States: N. p., 2005. Web. doi:10.1016/J.IJROBP.2005.0.
Mahan, Stephen L, Ramsey, Chester R, Scaperoth, Daniel D, Chase, Daniel J, & Byrne, Thomas E. Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis. United States. https://doi.org/10.1016/J.IJROBP.2005.0
Mahan, Stephen L, Ramsey, Chester R, Scaperoth, Daniel D, Chase, Daniel J, and Byrne, Thomas E. 2005. "Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis". United States. https://doi.org/10.1016/J.IJROBP.2005.0.
@article{osti_20788256,
title = {Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis},
author = {Mahan, Stephen L and Ramsey, Chester R and Scaperoth, Daniel D and Chase, Daniel J and Byrne, Thomas E},
abstractNote = {Introduction: Patients with vertebral metastasis that receive radiation therapy are typically treated to the spinal cord tolerance dose. As such, it is difficult to successfully deliver a second course of radiation therapy for patients with overlapping treatment volumes. In this study, an image-guided helical tomotherapy system was evaluated for the retreatment of previously irradiated vertebral metastasis. Methods and Materials: Helical tomotherapy dose gradients and maximum cord doses were measured in a cylindrical phantom for geometric test cases with separations between the planning target volume (PTV) and the spinal cord organ at risk (OAR) of 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm. Megavoltage computed tomography (CT) images were examined for their ability to localize spinal anatomy for positioning purposes by repeat imaging of the cervical spine in an anthropomorphic phantom. In addition to the phantom studies, 8 patients with cord compressions that had received previous radiation therapy were retreated to a mean dose of 28 Gy using conventional fractionation. Results and Discussion: Megavoltage CT images were capable of positioning an anthropomorphic phantom to within {+-}1.2 mm (2{sigma}) superior-inferiorly and within {+-}0.6 mm (2{sigma}) anterior-posteriorly and laterally. Dose gradients of 10% per mm were measured in phantom while PTV uniformity indices of less than 11% were maintained. The calculated maximum cord dose was 25% of the prescribed dose for a 10-mm PTV-to-OAR separation and 71% of the prescribed dose for a PTV-to-OAR separation of 2 mm. Eight patients total have been treated without radiation-induced myelopathy or any other adverse effects from treatment. Conclusions: A technique has been evaluated for the retreatment of vertebral metastasis using image-guided helical tomotherapy. Phantom and patient studies indicated that a tomotherapy system is capable of delivering dose gradients of 10% per mm and positioning the patient within 1.2 mm without the use of special stereotactic immobilization.},
doi = {10.1016/J.IJROBP.2005.0},
url = {https://www.osti.gov/biblio/20788256}, journal = {International Journal of Radiation Oncology, Biology and Physics},
issn = {0360-3016},
number = 5,
volume = 63,
place = {United States},
year = {Thu Dec 01 00:00:00 EST 2005},
month = {Thu Dec 01 00:00:00 EST 2005}
}