Dose, dose-rate and field size effects on cell survival following exposure to non-uniform radiation fields
- 1 May 2012
- journal article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 57 (10), 3197-3206
- https://doi.org/10.1088/0031-9155/57/10/3197
Abstract
For the delivery of intensity-modulated radiation therapy (IMRT), highly modulated fields are used to achieve dose conformity across a target tumour volume. Recent in vitro evidence has demonstrated significant alterations in cell survival occurring out-of-field which cannot be accounted for on the basis of scattered dose. The radiobiological effect of area, dose and dose-rate on out-of-field cell survival responses following exposure to intensity-modulated radiation fields is presented in this study. Cell survival was determined by clonogenic assay in human prostate cancer (DU-145) and primary fibroblast (AG0-1522) cells following exposure to different modulated field configurations delivered using a X-Rad 225 kVp x-ray source. Uniform survival responses were compared to in- and out-of-field responses in which 25-99% of the cell population was shielded. Dose delivered to the out-of-field region was varied from 1.6-37.2% of that delivered to the in-field region using different levels of brass shielding. Dose rate effects were determined for 0.2-4 Gy min⁻¹ for uniform and modulated exposures with no effect seen in- or out-of-field. Survival responses showed little dependence on dose rate and area in- and out-of-field with a trend towards increased survival with decreased in-field area. Out-of-field survival responses were shown to scale in proportion to dose delivered to the in-field region and also local dose delivered out-of-field. Mathematical modelling of these findings has shown survival response to be highly dependent on dose delivered in- and out-of-field but not on area or dose rate. These data provide further insight into the radiobiological parameters impacting on cell survival following exposure to modulated irradiation fields highlighting the need for refinement of existing radiobiological models to incorporate non-targeted effects and modulated dose distributions.Keywords
This publication has 13 references indexed in Scilit:
- Out-of-Field Cell Survival Following Exposure to Intensity-Modulated Radiation FieldsInternational Journal of Radiation Oncology*Biology*Physics, 2011
- Temporal characterization andin vitrocomparison of cell survival following the delivery of 3D-conformal, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT)Physics in Medicine & Biology, 2011
- A study of the biological effects of modulated 6 MV radiation fieldsPhysics in Medicine & Biology, 2010
- Radiation-induced bystander signalling in cancer therapyNature Reviews Cancer, 2009
- Cellular response to modulated radiation fieldsPhysics in Medicine & Biology, 2007
- A Monte Carlo study of the variation of electron fluence in water from a 6 MV photon beam outside of the fieldPhysics in Medicine & Biology, 2007
- An investigation of energy spectrum and lineal energy variations in mega-voltage photon beams used for radiotherapy.Radiation Protection Dosimetry, 2002
- Medium from irradiated human epithelial cells but not human fibroblasts reduces the clonogenic survival of unirradiated cellsInternational Journal of Radiation Biology, 1997
- Code of Practice for high-energy photon therapy dosimetry based on the NPL absorbed dose calibration servicePhysics in Medicine & Biology, 1990
- ACTION OF X-RAYS ON MAMMALIAN CELLSThe Journal of Experimental Medicine, 1956