Linear-quadratic model isoeffect relations for proliferating tumor cells for treatment with multiple fractions per day.
A modified linear-quadratic model isoeffect relation that includes the effect of proliferation is proposed. As for a planned course of therapy, the treatment time T and the number of fractions N are not independent variables; the new isoeffect relation involves only the fraction size d and the total dose D, but differs from the unmodified linear-quadratic model isoeffect relation and predicts higher isoeffect doses for small dose fractions. Using the new isoeffect relation it is explicitly shown, for a simple model, that decreasing the fraction size will improve the therapeutic ratio only if multiple fractions per day are given.
Yaes
R J
RJ
Department of Radiation Medicine, University of Kentucky Medical Center, Lexington 40536-0084.
D002455:Cell Division / Q000528:radiation effects*; D006801:Humans; D008433:Mathematics; D011879:Radiotherapy Dosage; D013116:Spinal Cord / Q000528:radiation effects*; D013120:Spinal Cord Neoplasms / Q000532:radiotherapy*