A margin-based analysis of the dosimetric impact of motion on step-and-shoot IMRT lung plans.
Radiat Oncol
; 9: 46, 2014 Feb 05.
Article
en En
| MEDLINE
| ID: mdl-24499602
PURPOSE: Intrafraction motion during step-and-shoot (SNS) IMRT is known to affect the target dosimetry by a combination of dose blurring and interplay effects. These effects are typically managed by adding a margin around the target. A quantitative analysis was performed, assessing the relationship between target motion, margin size, and target dosimetry with the goal of introducing new margin recipes. METHODS: A computational algorithm was used to calculate 1,174 motion-encoded dose distributions and DVHs within the patient's CT dataset. Sinusoidal motion tracks were used simulating intrafraction motion for nine lung tumor patients, each with multiple margin sizes. RESULTS: D95% decreased by less than 3% when the maximum target displacement beyond the margin experienced motion less than 5 mm in the superior-inferior direction and 15 mm in the anterior-posterior direction. For target displacements greater than this, D95% decreased rapidly. CONCLUSIONS: Targets moving in excess of 5 mm outside the margin can cause significant changes to the target. D95% decreased by up to 20% with target motion 10 mm outside the margin, with underdosing primarily limited to the target periphery. Multi-fractionated treatments were found to exacerbate target under-coverage. Margins several millimeters smaller than the maximum target displacement provided acceptable motion protection, while also allowing for reduced normal tissue morbidity.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Algoritmos
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Planificación de la Radioterapia Asistida por Computador
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Radioterapia de Intensidad Modulada
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Neoplasias Pulmonares
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Movimiento (Física)
Límite:
Humans
Idioma:
En
Revista:
Radiat Oncol
Asunto de la revista:
NEOPLASIAS
/
RADIOTERAPIA
Año:
2014
Tipo del documento:
Article
Pais de publicación:
Reino Unido