A Markovian approach to prostate cell survival under fractionated radiotherapy

Response to Hamilton and Kendall Regarding Possible Stochastic Effects

“…The joint AAPM/ACR/HPS statement in question is simply stating that the incremental risk associated with any given additional dose due to a future radiological procedure is independent of previous history. In other words, the process is Markovian in nature, such that the probability function has no "memory" of previous cumulative exposure or risk, as argued, for example, by Castelino and collaborators (Castelino et al 2011). The critique and recommendation of the authors is based on an incorrect interpretation of the joint AAPM/ACR/HPS statement and should therefore be rejected.…”

“…The authors then go on to recommend that “…a revised guidance statement not include this problematic sentence” on the grounds that the statement “…is out of character in that it claims full knowledge of independence and ignores frequency as factors potentially influencing patient health.” The joint AAPM/ACR/HPS statement in question is simply stating that the incremental risk associated with any given additional dose due to a future radiological procedure is independent of previous history. In other words, the process is Markovian in nature, such that the probability function has no “memory” of previous cumulative exposure or risk, as argued, for example, by Castelino and collaborators (Castelino et al 2011). The critique and recommendation of the authors is based on an incorrect interpretation of the joint AAPM/ACR/HPS statement and should therefore be rejected.…”