Comments on 'The influence of dose heterogeneity on tumor control probability in fractionated radiation therapy'.

By analyzing the radiobiological model, and the equations derived from the model, it is shown that the main results of the article 'The influence of dose heterogeneity on tumor control probability in fractionated radiation therapy' by Wiklund et al (2011 Phys. Med. Biol. 56 7585-600) are valid only under the condition that the dose to any cell is statistically independent of the dose to any other cell in the same fraction. This condition is in practice not fulfilled for radiotherapy. Hence the main results and most of the discussion are not applicable to fractionated radiation therapy.