Improving organs-at-risk sparing for choroidal melanoma patients: A CT-based two-beam strategy in ocular proton therapy with a dedicated eyeline.
Radiother Oncol
; 171: 173-181, 2022 06.
Article
en En
| MEDLINE
| ID: mdl-35487435
ABSTRACT
PURPOSE:
To investigate the potential clinical benefit of a two-beam arrangement technique using three-dimensional (3D) imaging of uveal melanoma (UM) patients treated with proton therapy and a dedicated eyeline. MATERIAL/METHODS:
Retrospective CT-based treatment plans of 39 UM patients performed using a single beam (SB) were compared to plans with two beams (TB) optimized for better trade-offs in organs-at-risk sparing. The RBE-weighted prescribed dose was 60 Gy (DRBE, GTV = 60 Gy) in four fractions, assuming an RBE of 1.1. Dosimetric findings were analyzed for three patient groups based on tumor-optic nerve distance and UM staging (group GrA ≤3 mm, T1 T2 UM; GrB ≤3 mm, T3 UM; GrC >3 mm, T1 T2 T3 UM). Finally, two schedules were compared on biologically effective dose (BED) both beams being delivered either the same day (TB), or on alternate days (TBalter).RESULTS:
All strategies resulted in dosimetrically acceptable plans. A dose reduction to the anterior structures was achieved in 23/39 cases with the two-beam plans. D25% was significantly lowered compared to SB plans by 12.4 and 15.4 Gy RBE-weighted median dose in GrA and GrB, respectively. D2% was reduced by 18.6 and 6.0 Gy RBE-weighted median dose in GrA and GrB, respectively. A cost to the optic nerve was observed with a median difference up to 3.8 Gy RBE-weighted dose in GrB. BED differences were statistically significant for all considered parameters in favor of two beams delivered the same day.CONCLUSION:
A two-beam strategy appears beneficial for posterior tumors abutting the optic nerve. This strategy might have a positive impact on the risk of ocular complications.Palabras clave
Texto completo:
1
Colección:
01-internacional
Asunto principal:
Neoplasias de la Coroides
/
Terapia de Protones
/
Melanoma
Tipo de estudio:
Etiology_studies
/
Observational_studies
/
Risk_factors_studies
Límite:
Humans
Idioma:
En
Revista:
Radiother Oncol
Año:
2022
Tipo del documento:
Article