-Dear Madam
>I prefer to use the term cellular radiosensitivity. (Also called
>inherent or intrinsic radiosensitivity.) This is because many
>clinicians use the word radiosensitivity (inappropriately?) to
>describe a tumour that shrinks rapidly following radiotherapy (if the
>term must be used I prefer to call this clinical radiosensitivity).
>Cellular radiosensitivity is measured using a clonogenic survival
>curve. The best measures of radiosensitivity are SF2, alpha and Dbar.
>These three survival curve parameters were shown to give the best
>discrimination between cell lines derived from different tumour types.
>They measure the initial part of cell survival curves. In Fertil and
>Malaise (1981) they looked at cell survival following 2 and 8 Gy.
>Significant differences in radiosensitivity between tumour cell lines
>could not be detected at 8Gy. SF2 was not chosen because it is a
>commonly used dose per fraction in radiotherapy. In Malaise et al
>(1987) survival following 1-6 Gy was studied. In the Malaise et al
>(1987) paper the capacity of survival levels to identify significant
>differences between radioresponse groups showed a maximum at 1.5 Gy
>for tumour cell lines and 3 Gy for fibroblasts.
>
>Therefore my definition of radiosensitivity is: Cellular
>radiosensitivity as measured using a clonogenic survival curves using
>parameters that describe the initial portion of a curve such as SF2,
>alpha and Dbar.
>
>Catharine West
>
>
>
>
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