文档介绍：The British Journal of Radiology, 83 (2010), 554–568
REVIEW ARTICLE
21 years of Biologically Effective Dose
J F FOWLER, DSc, PhD, FInsTP
Emeritus Professor of Human Oncology & Medical Physics, University of Wisconsin Medical School, Madison, WI 53792,
USA
ABSTRACT. In 1989 the British Journal of Radiology published a review proposing the
term biologically effective dose (BED), based on linear quadratic cell survival in
radiobiology. It aimed to indicate quantitatively the biological effect of any
radiotherapy treatment, taking account of changes in dose-per-fraction or dose rate,
total dose and (the new factor) overall time. How has it done so far? Acceptable clinical
results have been generally reported using BED, and it is in increasing use, although
sometimes mistaken for ‘‘biologically equivalent dose’’, from which it differs by large
factors, as explained here. The continuously bending nature of the linear quadratic
curve has been questioned but BED has worked well paring treatments in many
modalities, including some with large fractions. Two important improvements occurred
in the BED formula. First, in 1999, high linear energy transfer (LET) radiation was
included; second, in 2003, when time parameters for acute mucosal tolerance were
proposed, optimum overall times could then be ‘‘triangulated’’ to optimise tumour BED
and cell kill. This occurs only when both early and late BEDs meet their full constraints
simultaneously. New methods of dose delivery (intensity modulated radiation therapy,
stereotactic body radiation therapy, protons, tomotherapy, rapid arc and cyberknife) Received 3 February 2010
use a few large fractions and obviously oppose well-known fractionation schedules. Revised 15 March 2010
Careful biological modelling is required to balance the differing trends of fraction size Accepted 23 March 2010
and local dose gradient, as explained in the discussion ‘‘How Fractionation Really
Works’’. BED is now used for dose escalati