CT image-guided intensity-modulated therapy for paraspinal tumors using stereotactic immobilization

Yenice, Kamil M.; Lovelock, D.Michael; Hunt, Margie A.; Lutz, Wendell R.; Fournier-Bidoz, Nathalie; Hua, Chia-Ho; Yamada, Josh; Bilsky, Mark; Lee, Henry; Pfaff, Karl; Spirou, Spiridon V.; Amols, Howard I.

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Volume 55, Issue 3 , Pages 583-593, 1 March 2003

CT image-guided intensity-modulated therapy for paraspinal tumors using stereotactic immobilization☆

Presented in part at the 19th Annual ESTRO Meeting, Istanbul, Turkey, 2000.

Kamil M. Yenice, Ph.D.
- Reprint requests to: Kamil M. Yenice, Ph.D., Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, Box 84, 1275 York Avenue, New York, NY 10021, USA. Tel: (212) 639-5145, Fax: (212) 717-3010
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
D.Michael Lovelock, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Margie A. Hunt, M.S.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Wendell R. Lutz, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Nathalie Fournier-Bidoz, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Chia-Ho Hua, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Josh Yamada, M.D.
- Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Mark Bilsky, M.D.
- Department of Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Henry Lee, M.D.
- Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Karl Pfaff
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Spiridon V. Spirou, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Howard I. Amols, Ph.D.
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA

Received 3 July 2002; received in revised form 23 August 2002; accepted 28 August 2002.

Abstract

Purpose: To design and implement a noninvasive stereotactic immobilization technique with daily CT image-guided positioning to treat patients with paraspinal lesions accurately and to quantify the systematic and random patient setup errors occurring with this method.

Methods and Materials: A stereotactic body frame (SBF) was developed for “rigid” immobilization of paraspinal patients. The inherent accuracy of this system for stereotactic CT-guided treatment was evaluated with phantom studies. Seven patients with thoracic and lumbar spine lesions were immobilized with the SBF and positioned for 33 treatment fractions using daily CT scans. For all 7 patients, the daily setup errors, as assessed from the daily CT scans, were corrected at each treatment fraction. A retrospective analysis was also performed to assess what the impact on patient treatment would have been without the CT-based corrections (i.e., if patient setup had been performed only with the SBF).

Results: The average magnitude of systematic and random errors from uncorrected patient setups using the SBF was approximately 2 mm and 1.5 mm (1 SD), respectively. For fixed phantom targets, the system accuracy for the SBF localization and treatment was shown to be within 1 mm (1 SD) in any direction. Dose-volume histograms incorporating these uncertainties for an intensity-modulated radiotherapy plan for lumbar spine lesions were generated, and the effects on the dose-volume histograms were studied.

Conclusion: We demonstrated a very accurate and precise method of patient immobilization and treatment delivery based on a noninvasive SBF and daily image guidance for paraspinal lesions. The SBF provides excellent immobilization for paraspinal targets, with setup accuracy better than 2 mm (1 SD). However, for highly conformal paraspinal treatments, uncorrected systematic and random errors of 2 mm in magnitude can result in a significantly greater (>100%) dose to the spinal cord than planned, even though the planned target coverage may not change substantially. With daily CT guidance using the SBF, we showed that the maximal spinal cord dose is ensured to be within 10–15% of the planned value.

Keywords: Paraspinal tumors, CT image guidance, Stereotactic, Intensity modulation