A simple and efficient methodology to improve geometric accuracy in gamma knife radiation surgery: implementation in multiple brain metastases.
Title | A simple and efficient methodology to improve geometric accuracy in gamma knife radiation surgery: implementation in multiple brain metastases. |
Publication Type | Journal Article |
Year of Publication | 2014 |
Authors | Karaiskos, P., Moutsatsos A., Pappas E., Georgiou E., Roussakis A., Torrens M., & Seimenis I. |
Journal | Int J Radiat Oncol Biol Phys |
Volume | 90 |
Issue | 5 |
Pagination | 1234-41 |
Date Published | 2014 Dec 1 |
ISSN | 1879-355X |
Keywords | Brain Neoplasms, Humans, Magnetic Resonance Imaging, Phantoms, Imaging, Radiosurgery, Radiotherapy Dosage, Uncertainty |
Abstract | PURPOSE: To propose, verify, and implement a simple and efficient methodology for the improvement of total geometric accuracy in multiple brain metastases gamma knife (GK) radiation surgery.METHODS AND MATERIALS: The proposed methodology exploits the directional dependence of magnetic resonance imaging (MRI)-related spatial distortions stemming from background field inhomogeneities, also known as sequence-dependent distortions, with respect to the read-gradient polarity during MRI acquisition. First, an extra MRI pulse sequence is acquired with the same imaging parameters as those used for routine patient imaging, aside from a reversal in the read-gradient polarity. Then, "average" image data are compounded from data acquired from the 2 MRI sequences and are used for treatment planning purposes. The method was applied and verified in a polymer gel phantom irradiated with multiple shots in an extended region of the GK stereotactic space. Its clinical impact in dose delivery accuracy was assessed in 15 patients with a total of 96 relatively small (<2 cm) metastases treated with GK radiation surgery.RESULTS: Phantom study results showed that use of average MR images eliminates the effect of sequence-dependent distortions, leading to a total spatial uncertainty of less than 0.3 mm, attributed mainly to gradient nonlinearities. In brain metastases patients, non-eliminated sequence-dependent distortions lead to target localization uncertainties of up to 1.3 mm (mean: 0.51 ± 0.37 mm) with respect to the corresponding target locations in the "average" MRI series. Due to these uncertainties, a considerable underdosage (5%-32% of the prescription dose) was found in 33% of the studied targets.CONCLUSIONS: The proposed methodology is simple and straightforward in its implementation. Regarding multiple brain metastases applications, the suggested approach may substantially improve total GK dose delivery accuracy in smaller, outlying targets. |
DOI | 10.1016/j.ijrobp.2014.08.349 |
Alternate Journal | Int. J. Radiat. Oncol. Biol. Phys. |
PubMed ID | 25442348 |