Cumulative Lung Dose for Several Motion Management Strategies as a Function of Pretreatment Patient Parameters
- Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)
Purpose: To evaluate patient parameters that may predict for relative differences in cumulative four-dimensional (4D) lung dose among several motion management strategies. Methods and Materials: Deformable image registration and dose accumulation were used to generate 4D treatment plans for 18 patients with 4D computed tomography scans. Three plans were generated to simulate breath hold at normal inspiration, target tracking with the beam aperture, and mid-ventilation aperture (control of the target at the mean daily position and application of an iteratively computed margin to compensate for respiration). The relative reduction in mean lung dose (MLD) between breath hold and mid-ventilation aperture ({delta}MLD{sub BH}) and between target tracking and mid-ventilation aperture ({delta}MLD{sub TT}) was calculated. Associations between these two variables and parameters of the lesion (excursion, size, location, and deformation) and dose distribution (local dose gradient near the target) were also calculated. Results: The largest absolute and percentage differences in MLD were 1.0 Gy and 21.5% between breath hold and mid-ventilation aperture. {delta}MLD{sub BH} was significantly associated (p < 0.05) with tumor excursion. The {delta}MLD{sub TT} was significantly associated with excursion, deformation, and local dose gradient. A linear model was constructed to represent {delta}MLD vs. excursion. For each 5 mm of excursion, target tracking reduced the MLD by 4% compared with the results of a mid-ventilation aperture plan. For breath hold, the reduction was 5% per 5 mm of excursion. Conclusions: The relative difference in MLD among different motion management strategies varied with patient and tumor characteristics for a given dosimetric target coverage. Tumor excursion is useful to aid in stratifying patients according to appropriate motion management strategies.
- OSTI ID:
- 21276842
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 74, Issue 2; Other Information: DOI: 10.1016/j.ijrobp.2008.12.069; PII: S0360-3016(09)00043-1; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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