Optimization of combined proton-photon treatments.
Radiother Oncol
; 128(1): 133-138, 2018 Jul.
Article
em En
| MEDLINE
| ID: mdl-29370987
ABSTRACT
PURPOSE:
Proton treatment slots are a limited resource. Therefore, we consider combined proton-photon treatments in which most fractions are delivered with photons and only a few with protons. We demonstrate how both modalities can be combined to optimally capitalize on the proton's ability to reduce normal tissue dose.METHODS:
An optimal combined treatment must account for fractionation effects. We therefore perform simultaneous optimization of intensity-modulated proton (IMPT) and photon (IMRT) plans based on their cumulative biologically effective dose (BED). We demonstrate the method for a sacral chordoma patient, in whom the gross tumor volume (GTV) abuts bowel and rectum.RESULTS:
In an optimal combination, proton and photon fractions deliver similar doses to bowel and rectum to protect these dose-limiting normal tissues through fractionation. However, proton fractions deliver, on average, higher doses to the GTV. Thereby, the photon dose bath is reduced. An optimized 30-fraction treatment with 10 IMPT fractions achieved more than 50% of the integral dose reduction in the gastrointestinal tract that is possible with 30 IMPT fractions (compared to 33% for a simple proton-photon combination in which both modalities deliver the same target dose).CONCLUSIONS:
A limited number of proton fractions can best be used if protons hypofractionate parts of the GTV while maintaining near-uniform fractionation in dose-limiting normal tissues.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neoplasias Ósseas
/
Planejamento da Radioterapia Assistida por Computador
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Cordoma
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Fótons
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Radioterapia de Intensidade Modulada
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Terapia com Prótons
/
Neoplasias
Limite:
Humans
Idioma:
En
Revista:
Radiother Oncol
Ano de publicação:
2018
Tipo de documento:
Article