Dosimetric Analysis of Intra-Fraction Motion Detected by Surface-Guided Radiation Therapy During Linac Stereotactic Radiosurgery.

Autor: Foster RD; Levine Cancer Institute, Atrium Health, Concord, North Carolina., Moeller BJ; Levine Cancer Institute, Atrium Health and Southeast Radiation Oncology Group, Charlotte, North Carolina., Robinson M; Levine Cancer Institute, Atrium Health, Charlotte, North Carolina., Bright M; Levine Cancer Institute, Atrium Health, Concord, North Carolina., Ruiz JL; Levine Cancer Institute, Atrium Health, Concord, North Carolina., Hampton CJ; Levine Cancer Institute, Atrium Health, Charlotte, North Carolina., Heinzerling JH; Levine Cancer Institute, Atrium Health and Southeast Radiation Oncology Group, Charlotte, North Carolina.
Jazyk: angličtina
Zdroj: Advances in radiation oncology [Adv Radiat Oncol] 2022 Dec 27; Vol. 8 (3), pp. 101151. Date of Electronic Publication: 2022 Dec 27 (Print Publication: 2023).
DOI: 10.1016/j.adro.2022.101151
Abstrakt: Purpose: Stereotactic radiosurgery (SRS) immobilization with an open face mask is more comfortable and less invasive than frame based, but concerns about intrafraction motion must be addressed. Surface-guided radiation therapy (SGRT) is an attractive option for intrafraction patient monitoring because it is continuous, has submillimeter accuracy, and uses no ionizing radiation. The purpose of this study was to investigate the dosimetric consequences of uncorrected intrafraction patient motion detected during frameless linac-based SRS.
Methods and Materials: Fifty-five SRS patients were monitored during treatment using SGRT between January 1, 2017, and September 30, 2020. If SGRT detected motion >1 mm, imaging was repeated and the necessary shifts were made before continuing treatment. For the 25 patients with intrafraction 3-dimensional vector shifts of ≥1 mm, we moved the isocenter in the planning system using the translational shifts from the repeat imaging and recalculated the plans to determine the dosimetric effect of the shifts. Planning target volume (PTV) coverage, minimum gross tumor volume (GTV) dose (relative and absolute), and normal brain V12 were evaluated. Wilcoxon signed rank tests were used to compare planned and simulated dosimetric parameters and median 2 sample tests were used to investigate these differences between cone and multileaf collimator (MLC) plans.
Results: For simulated plans, V12 increased by a median of 0.01 cc ( P  = .006) and relative GTV minimum dose and PTV coverage decreased by a median of 15.8% ( P < .001) and 10.2 % ( P < .001), respectively. Absolute minimum GTV dose was found to be significantly lower in the simulated plans ( P < .001). PTV coverage decreased more for simulated cone plans than for simulated MLC plans (11.6% vs 4.7%, P  = .011) but median V12 differences were found to be significantly larger for MLC plans (-0.34 cc vs -0.01 cc, P  = .011). Differences in GTV minimum dose between cone and MLC plans were not statistically significant.
Conclusions: SGRT detected clinically meaningful intrafraction motion during frameless SRS, which could lead to large underdoses and increased normal brain dose if uncorrected.
(© 2023 The Authors.)
Databáze: MEDLINE