6D image guidance for spinal non-invasive stereotactic body radiation therapy: Comparison between ExacTrac X-ray 6D with kilo-voltage cone-beam CT

Chang, Zheng; Wang, Zhiheng; Ma, Jinli; O’Daniel, Jennifer C.; Kirkpatrick, John; Yin, Fang-Fang

doi:10.1016/j.radonc.2009.12.036

« Previous Next »Radiotherapy & Oncology
Volume 95, Issue 1 , Pages 116-121, April 2010

6D image guidance for spinal non-invasive stereotactic body radiation therapy: Comparison between ExacTrac X-ray 6D with kilo-voltage cone-beam CT

Zheng Chang
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
- Corresponding author. Address: Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Zhiheng Wang
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
Jinli Ma
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
- Department of Radiation Oncology, Fudan University Cancer Hospital, Shanghai, China
Jennifer C. O’Daniel
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
John Kirkpatrick
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA

Received 16 September 2009; received in revised form 4 December 2009; accepted 29 December 2009. published online 01 February 2010.

Abstract

Purpose

To investigate setup discrepancies measured with ExacTrac X-ray 6 degree-of-freedom (6D) and cone-beam computed tomography (CBCT) for patients under treatments of stereotactic body radiation therapy (SBRT).

Materials and methods

In this work, phantom and patient studies were performed. In the phantom studies, an anthropomorphic phantom was placed with pre-defined positions, and imaged with ExacTrac X-ray 6D and CBCT to test the accuracy of the imaging systems. In the patient studies, 16 spinal SBRT patient cases were retrospectively analyzed. The patients were initially positioned in customized immobilization cradles and then aligned with ExacTrac X-ray 6D and CBCT. The setup discrepancies were computed and quantitatively analyzed.

Results

This study indicates modest discrepancies between ExacTrac X-ray 6D and CBCT with spinal SBRT. The phantom experiments showed that translational and rotational discrepancies in root-mean-square (RMS) between ExacTrac X-ray 6D and CBCT were, respectively, <1.0mm and <1°. In the retrospective patient studies, translational and rotational discrepancies in RMS between ExacTrac X-ray 6D and CBCT were <2.0mm and <1.5°.

Conclusions

ExacTrac X-ray 6D represents a potential alternative to CBCT; however, pre-caution should be taken when only ExacTrac X-ray 6D is used to guide SBRT with small setup margins.

Keywords: Extra-cranial non-invasive stereotactic body radiation therapy, IGRT, ExacTrac X-ray 6D, Cone-beam CT