Klinisk strlebiologi - normalvev

Tidlig reaksjon

Sen reaksjonteleangiectasi

Basis for dose-respons-kurver

Stigetallet for dose-responskurven

Gaussian distribution of radiation sensitivityDose response curve

Uniquely described by two parameters: - gradient at 50% response levelD50% - dose to achieve 50% response

Gaussian distribution of technical and dosimetrical factorsbiolo > clin Pettersen M et al Radiotherapy and Oncology 2008Clinical dose response curve

Uniquely described by two parameters: - gradient at 50% response levelD50% - dose to achieve 50% response

is linked to the standard deviation, , of the Gaussian distribution by: Pettersen M et al Radiotherapy and Oncology 2008and

Steepness of clinical dose-response curve is depending of the dose variationPettersen M et al Radiotherapy and Oncology 2008Rou et al 2004ESTRO-Equal external audit102 centres, 235 beams in France3% beams had deviations > 5%24 centres had deviations > 5%

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 number of patients needed is linked to , the difference in response (R), the level of significance () and the power () = 0.2 = 0.05Pettersen M et al Radiotherapy and Oncology 2008

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

Volumeffet for rektumbldning

Strandqvist plot

LQ-formelverket