The importance of the conformality, heterogeneity, and gradient indices in evaluating Gamma Knife radiosurgery treatment plans for intracranial meningiomas.
Int J Radiat Oncol Biol Phys
; 83(5): 1406-13, 2012 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-22209151
ABSTRACT
PURPOSE:
To investigate the relationship between the conformality index (CIn), heterogeneity index (HIn), and gradient index (GIn) and the development of toxicity in patients treated with Gamma Knife radiosurgery (GKRS) for intracranial meningiomas. METHODS AND MATERIALS Treatment records of patients treated from 1997 to 2009 with at least 6 months of follow-up were reviewed. The following parameters were collected CIn, HIn, GIn (ratio of the volume receiving half the prescription isodose to the volume receiving the full prescription isodose), brainstem (BS) maximum dose (MD), BS volume receiving ≥ 12 Gy (V12), optic apparatus (OA) MD, OA V8 Gy, OA V10, number of isocenters, number of isocenters outside target volume, and the occurrence of six toxicities. Univariate and multivariate logistic regression modeling were used for analysis.RESULTS:
This study included 145 patients (148 meningiomas) with a median follow-up time of 27 months (range, 6-113.9 months). The majority of meningiomas were located in the skull base (53%). The median prescription dose was 13 Gy (range, 10-24 Gy) to the 51.50% (range, 50-92%) isodose. A lower HIn was correlated with a higher GIn (p = 0.007). CIn was not associated with any toxicity. Higher HIn was associated with the development of dizziness (odds ratio [OR] 1.9; p = 0.02), whereas a lower GIn was associated with motor deficits (OR 0.38; p = 0.04) and auditory changes (OR 0.59; p = 0.04). The OA MD, V8, and V12 were not associated with visual changes, but visual changes were associated with a higher number of isocenters outside the target volume (OR 1.93; p = 0.07). BS V12 was correlated with the development of auditory changes (OR 1.05; p = 0.05), whereas patients with higher BS MD tended to have increased toxicity.CONCLUSIONS:
Close attention must be paid to all three indices (CIn, HIn, GIn) when optimal treatment plans are determined. We recommend that the target CIn should be ≤ 2.0, the HIn ≤ 2.0, and the GIn ≥ 3.0 for intracranial meningiomas.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Radiocirurgia
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Neoplasias Meníngeas
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Meningioma
Tipo de estudo:
Diagnostic_studies
/
Etiology_studies
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Observational_studies
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Prognostic_studies
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Risk_factors_studies
Limite:
Adult
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Aged
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Aged80
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Female
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Humans
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Male
/
Middle aged
País/Região como assunto:
America do norte
Idioma:
En
Revista:
Int J Radiat Oncol Biol Phys
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos