Fiber background rejection and crystal over-response compensation for GaN based in vivo dosimetry.
Phys Med
; 29(5): 487-92, 2013 Sep.
Article
em En
| MEDLINE
| ID: mdl-23317814
ABSTRACT
For dosimetric measurements using an implantable optical fiber probe with GaN (Gallium Nitride) scintillator as radioluminescence (RL) transducer, a bi-channel method is proposed to reject the background contribution of the irradiated fiber segment. It is based on spectral differences between the narrow-band light emission from GaN and the large-band background from the irradiated optical fiber. Experimental validation of this method using 6 MV photon beam has shown that the remaining background contribution after subtraction is below 1.2% for square field sizes ranging from 3 cm to 20 cm. Furthermore, a compensation method for the over-response of GaN is also proposed, since GaN is not tissue equivalent. The over-response factor of GaN exhibits a linear increase with square field aperture and depends on depth from phantom surface. This behaviour is modelled to allow compensation in specific conditions. The proposed method has been evaluated and has shown a maximum deviation of 3% for a 6 MV photon beam and 1% for an 18 MV photon beam at a depth beyond the build-up region.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Radiometria
/
Fibras Ópticas
/
Gálio
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Phys Med
Assunto da revista:
BIOFISICA
/
BIOLOGIA
/
MEDICINA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
França