An in vitro study of the radiobiological effects of flattening filter free radiotherapy treatments.
Phys Med Biol
; 58(5): N83-94, 2013 Mar 07.
Article
em En
| MEDLINE
| ID: mdl-23399781
ABSTRACT
Flattening filter free (FFF) linear accelerators allow for an increase in instantaneous dose-rate of the x-ray pulses by a factor of 2-6 over the conventional flattened output. As a result, radiobiological investigations are being carried out to determine the effect of these higher dose-rates on cell response. The studies reported thus far have presented conflicting results, highlighting the need for further investigation. To determine the radiobiological impact of the increased dose-rates from FFF exposures a Varian Truebeam medical linear accelerator was used to irradiate two human cancer cell lines in vitro, DU-145 prostate and H460 non-small cell lung, with both flattened and FFF 6 MV beams. The fluence profile of the FFF beam was modified using a custom-designed Nylon compensator to produce a similar dose profile to the flattened beam (6X) at the cell surface but at a higher instantaneous dose-rate. For both cell lines there appeared to be no significant change in cell survival. Curve fitting coefficients for DU145 cells irradiated with constant average dose-rates were 6X α = 0.09 ± 0.03, ß = 0.03 ± 0.01 and 6FFF α = 0.14 ± 0.13, ß = 0.03 ± 0.02 with a significance of p = 0.75. For H460 cells irradiated with the same instantaneous dose-rate but different average dose-rate the fit coefficients were 6FFF (low dose-rate) α = 0.21 ± 0.11, 0.07 ± 0.02 and 6FFF (high dose-rate) α = 0.21 ± 0.16, 0.07 ± 0.03, with p = 0.79. The results indicate that collective damage behaviour does not occur at the instantaneous dose-rates investigated here and that the use of either modality should result in the same clinical outcome, however this will require further validation in vivo.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Radiobiologia
/
Radioterapia Assistida por Computador
Limite:
Humans
/
Male
Idioma:
En
Revista:
Phys Med Biol
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Reino Unido