Klinisk strålebiologi - normalvev

1. Klinisk strålebiologi - normalvev

3. Tidlig reaksjon

4. Sen reaksjon teleangiectasi

7. Basis for dose-respons-kurver

8. Stigetallet for dose-responskurven

10. Gaussian distribution of radiation sensitivity Gaussian distribution of technical and dosimetrical factors Uniquely described by two parameters: - gradient at 50% response level D50% - dose to achieve 50% response biolo > clin Dose response curve Clinical dose response curve Pettersen M et al Radiotherapy and Oncology 2008

11.  Uniquely described by two parameters: - gradient at 50% response level D50% - dose to achieve 50% response   is linked to the standard deviation, , of the Gaussian distribution by:  and Pettersen M et al Radiotherapy and Oncology 2008

12. Steepness of clinical dose-response curve is depending of the dose variation Pettersen M et al Radiotherapy and Oncology 2008 Roué et al 2004 ESTRO-Equal external audit 102 centres, 235 beams in France 3% beams had deviations >  5% 24 centres had deviations >  5%

13. Design of a randomised clinical study • The null hypothesis is that the two treatment options produce no different outcome • To prove a difference, the null hypothesis has to be rejected • The numberof patients needed is linked to , the difference in response (R), the level of significance () and the power ()  = 0.2  = 0.05 Pettersen M et al Radiotherapy and Oncology 2008

14. The number of patients required Conclusions: To keep the number of patients required for RCT as low as possible, the standard deviation of the dosimetry should be kept below 5%.

20. Volumeffet for rektumblødning

21. Strandqvist plot

24. a-kill b-kill LQ-formelverket