Dose equivalents of tumour repopulation during radiotherapy: the potential for confusion.

When employing linear quadratic equations to calculate compensation for changes in overall treatment time, a potential confusion exists regarding use of the parameter commonly described as the dose equivalent of tumour repopulation. The more correct term for this factor is the biologically effective dose equivalent of tumour repopulation. The distinction between the two concepts is discussed and the potential errors arising from their confusion are illustrated by means of an example.