MRI-based treatment planning and dose delivery verification for intraocular melanoma brachytherapy.
Brachytherapy
; 17(1): 31-39, 2018.
Article
en En
| MEDLINE
| ID: mdl-28818442
PURPOSE: Episcleral plaque brachytherapy (EPB) planning is conventionally based on approximations of the implant geometry with no volumetric imaging following plaque implantation. We have developed an MRI-based technique for EPB treatment planning and dose delivery verification based on the actual patient-specific geometry. METHODS AND MATERIALS: MR images of 6 patients, prescribed 85 Gy over 96 hours from Collaborative Ocular Melanoma Study-based EPB, were acquired before and after implantation. Preimplant and postimplant scans were used to generate "preplans" and "postplans", respectively. In the preplans, a digital plaque model was positioned relative to the tumor, sclera, and nerve. In the postplans, the same plaque model was positioned based on the imaged plaque. Plaque position, point doses, percentage of tumor volume receiving 85 Gy (V100), and dose to 100% of tumor volume (Dmin) were compared between preplans and postplans. All isodose plans were computed using TG-43 formalism with no heterogeneity corrections. RESULTS: Shifts and tilts of the plaque ranged from 1.4 to 8.6 mm and 1.0 to 3.8 mm, respectively. V100 was ≥97% for 4 patients. Dmin for preplans and postplans ranged from 83 to 118 Gy and 45 to 110 Gy, respectively. Point doses for tumor apex and base were all found to decrease from the preimplant to the postimplant plan, with mean differences of 16.7 ± 8.6% and 30.5 ± 11.3%, respectively. CONCLUSIONS: By implementing MRI for EPB, we eliminate reliance on approximations of the eye and tumor shape and the assumption of idealized plaque placement. With MRI, one can perform preimplant as well as postimplant imaging, facilitating EPB treatment planning based on the actual patient-specific geometry and dose-delivery verification based on the imaged plaque position.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Neoplasias de la Úvea
/
Planificación de la Radioterapia Asistida por Computador
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Braquiterapia
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Imagen por Resonancia Magnética
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Melanoma
Límite:
Humans
Idioma:
En
Revista:
Brachytherapy
Asunto de la revista:
RADIOTERAPIA
Año:
2018
Tipo del documento:
Article
Pais de publicación:
Estados Unidos