Reirradiation at long time intervals in mouse kidney: a comparison between experimental results and the predictions of the F-type tissue model.
The tolerance of a late-responding tissue to reirradiation after long time intervals has been analysed using the F-type tissue model. In this model the tissue is composed of identical cells, each of which is capable of extensive proliferation and of tissue-specific function. The model was adapted to calculate the response to two fractions of radiation given in a variable overall time. For two equal doses of radiation the repair of tissue damage after the first fraction could be detected theoretically by a change in the rate of cell depletion after retreatment and by an increase in the minimum cell number attained. For an 'experimental set-up', in which a constant first dose was followed by a range of retreatment doses in a variable overall time, the repair of tissue damage theoretically could be detected most sensitively by a shift of the dose-response curves to higher retreatment doses as the time interval between the two doses was increased. A prerequisite for a proper comparison of these dose-response curves was that the responses were evaluated at times after the first dose determined by the minimal latency times after high retreatment doses. From a comparison of these theoretical results with experimental findings for mouse kidneys it was concluded that no recovery of tissue function took place over a 6-month period. Instead it appeared that the kidneys had become more sensitive to irradiation over this period.
Lebesque
J V
JV
Department of Radiotherapy, Netherlands Cancer Institute (Antoni van Leeuwenhoek Huis), Amsterdam.
Hart
A A
AA
Stewart
F A
FA
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects; D007668:Kidney / Q000503:physiopathology / Q000528:radiation effects*; D008433:Mathematics; D051379:Mice; D008954:Models, Biological; D011833:Radiation Injuries, Experimental / Q000503:physiopathology*; D011836:Radiation Tolerance; D013997:Time Factors