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Implementation and validation of a new fixation system for stereotactic radiation therapy: An analysis of patient immobilization


Lang, Stephanie; Linsenmeier, Claudia; Brown, Michelle L; Cavelaars, Frederique; Tini, Alessandra; Winter, Christopher; Krayenbuehl, Jerome (2015). Implementation and validation of a new fixation system for stereotactic radiation therapy: An analysis of patient immobilization. Practical Radiation Oncology, 5(6):e689-e695.

Abstract

PURPOSE: Stereotactic radiation therapy is an established treatment technique for intracranial malignancies. We evaluated a new intracranial immobilization system with an emphasis on determining the intrafraction motion and the correlation of this motion with treatment time.
METHODS AND MATERIALS: Patients were immobilized using the trUpoint ARCH fixation system (CIVCO Medical Solutions). We collected data from 85 lesions in 73 patients treated between November 2011 and December 2013. Sixty-nine of 73 patients (95%) used the complete mask system; for the remaining 4 patients, the system had to be adapted. Patients were treated using volumetric modulated arc therapy stereotactic radiation therapy on a TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA). Fraction doses of 2-8 Gy were applied in 4-30 fractions. Daily cone beam computed tomography imaging was performed before the treatment and was matched to the reference computed tomography using a 6-degrees-of-freedom automatching procedure. Additionally, posttreatment cone beam computed tomography scans were performed to assess intrafraction motion for 67 patients (375 fractions).
RESULTS: The average 3-dimensional setup error was 2.1 ± 2.9 mm. The mean pitch and roll was -0.1 ± 0.7° and 0.2 ± 0.7°. A total of 98.0% of the pitch values and 98.9% of the roll values were <1.5°. Mean intrafractional motion was 0.51 mm (±0.27) and mean treatment time was 10.1 minutes (±1.4). The maximum intrafractional motion was 2.0 mm in the longitudinal direction; 95% of the total shifts were <1.4 mm. The linear regression showed a weak but significant influence (R(2) = 0.26, P = .01) of the treatment time on the total intrafractional shift.
CONCLUSIONS: The new intracranial immobilization system appears to be robust in terms of setup accuracy, intrafraction motion, and repositioning of the mask system.

Abstract

PURPOSE: Stereotactic radiation therapy is an established treatment technique for intracranial malignancies. We evaluated a new intracranial immobilization system with an emphasis on determining the intrafraction motion and the correlation of this motion with treatment time.
METHODS AND MATERIALS: Patients were immobilized using the trUpoint ARCH fixation system (CIVCO Medical Solutions). We collected data from 85 lesions in 73 patients treated between November 2011 and December 2013. Sixty-nine of 73 patients (95%) used the complete mask system; for the remaining 4 patients, the system had to be adapted. Patients were treated using volumetric modulated arc therapy stereotactic radiation therapy on a TrueBeam linear accelerator (Varian Medical Systems, Palo Alto, CA). Fraction doses of 2-8 Gy were applied in 4-30 fractions. Daily cone beam computed tomography imaging was performed before the treatment and was matched to the reference computed tomography using a 6-degrees-of-freedom automatching procedure. Additionally, posttreatment cone beam computed tomography scans were performed to assess intrafraction motion for 67 patients (375 fractions).
RESULTS: The average 3-dimensional setup error was 2.1 ± 2.9 mm. The mean pitch and roll was -0.1 ± 0.7° and 0.2 ± 0.7°. A total of 98.0% of the pitch values and 98.9% of the roll values were <1.5°. Mean intrafractional motion was 0.51 mm (±0.27) and mean treatment time was 10.1 minutes (±1.4). The maximum intrafractional motion was 2.0 mm in the longitudinal direction; 95% of the total shifts were <1.4 mm. The linear regression showed a weak but significant influence (R(2) = 0.26, P = .01) of the treatment time on the total intrafractional shift.
CONCLUSIONS: The new intracranial immobilization system appears to be robust in terms of setup accuracy, intrafraction motion, and repositioning of the mask system.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Radiation Oncology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2015
Deposited On:09 Dec 2015 16:55
Last Modified:11 Jan 2017 09:06
Publisher:Elsevier
ISSN:1879-8500
Publisher DOI:https://doi.org/10.1016/j.prro.2015.03.007
PubMed ID:26209122

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