Incorporating heterogeneity correction and 4DCT in lung stereotactic body radiation therapy (SBRT): The effect on target coverage, organ-at-risk doses, and dose conformity.
Med Dosim
; 35(2): 101-7, 2010.
Article
em En
| MEDLINE
| ID: mdl-19931021
ABSTRACT
This study evaluates the dosimetric impact of 4-dimensional computed tomography (4DCT) target volumes and heterogeneity correction (HC) on target coverage, organ-at-risk (OAR) doses, and dose conformity in lung stereotactic body radiation therapy (SBRT). Twelve patients with lung cancer, scanned using both helical CT and 4DCT, were treated with SBRT (60 Gy in 3 fractions). The clinical plans were calculated without HC and based on targets from the free-breathing helical CT scan (PTV(HEL)). Retrospectively, the clinical plans were recalculated with HC and were evaluated based on targets from 4DCT datasets (PTV(4D)) accounting for patient-specific target motion. The PTV(4D) was greater than PTV(HEL) when tumor motion exceeded 7.5 mm (vector). There were significant decreases in target coverage (V100) for the recalculated vs. clinical plans (0.84 vs. 0.94, p < 0.02) for the same monitor units. When the recalculated plans were optimized for equivalent V100 of the clinical plans, there were significant increases in the 60-Gy dose spillage (1.27 vs. 1.13, p < 0.001) and 30-Gy dose spillage (5.20 vs. 3.73, p < 0.001) vs. the clinical plans. There was a significant increase (p < 0.04) in the mean OAR doses between the optimized re-calculated and the clinical plan. Tumor motion is an important consideration for target volumes defined using helical CT. Lower prescription doses may be required when prospectively planning with HC to achieve a similar level of toxicity and dose spillage as expected when planning based on homogeneous dose calculations.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Planejamento da Radioterapia Assistida por Computador
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Radiocirurgia
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Carcinoma Pulmonar de Células não Pequenas
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Tomografia Computadorizada Quadridimensional
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Neoplasias Pulmonares
Tipo de estudo:
Etiology_studies
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Incidence_studies
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Observational_studies
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Risk_factors_studies
Limite:
Humans
Idioma:
En
Revista:
Med Dosim
Ano de publicação:
2010
Tipo de documento:
Article