When Is a 'BED' not a 'BED'?-When it is an EQD2: In regard to Buyyounouski et al. (Int J Radiat Oncol Biol Phys 2010;76:1297-1304).

摘要

We are sorry to criticize anything in the Red Journal, especially a well-balanced account of prostate cancer stereotactic body radiotherapy by an efficient task group set up by the Emerging Technology Committee of the American Society for Therapeutic Radiology and Oncology (1).However, all the biologically effective doses (BEDs) reported by Buyyou-nouski et al. (1), helpfully quoted alongside the treatment schedules mentioned, are not BEDs at all. They are all total biologically equivalent doses in 2-Gy fractions (EQD2s) (2)—that NTD (Normalized Total Dose [3]) or LQED (Linear Quadratic Equivalent Dose [Dr. R. Yaes ca 1989]), until the present century. As printed in the report by Buyyounouski et al. (1), they are all biologically equivalent doses (in 2-Gy fraction total equivalent doses), instead of biologically effective doses, as specifically defined by Fowler (4) and used by Jones et al. (5) and many others (6, 7). The printed "non-BEDs" (1) are smaller than the correct BEDs by a factor of 1.67 for most late complications (with a/8 = 3 Gy), and by a factor of 1.2 for rapidly proliferating tissues, including many tumors and acutely reacting normal tissues (with a/8 = 10 Gy). The real BED (4,7) is a simple number to compute, but the "BEDs" as printed (1) require an extra step. A simple step (dividing by the relative effectiveness for 2-Gy fractions (relative effectiveness = 1+2/ [a/8]), using the same a/8 ratio) but tedious and easy to omit.