klinisk strålebiologi - normalvev
DESCRIPTION
Klinisk strålebiologi - normalvev. Tidlig reaksjon. Sen reaksjon. teleangiectasi. Basis for dose-respons-kurver. Stigetallet for dose-responskurven. Gaussian distribution of radiation sensitivity. Gaussian distribution of technical and dosimetrical factors. - PowerPoint PPT PresentationTRANSCRIPT
Klinisk strålebiologi - normalvev
Tidlig reaksjon
teleangiectasi
Sen reaksjon
Basis for dose-respons-kurver
Stigetallet for dose-responskurven
Gaussian distribution of radiation sensitivity
Dose response curve
Uniquely described by two parameters: - gradient at 50% response
levelD50% - dose to achieve 50%
response
Gaussian distribution of technical and dosimetrical
factors
biolo > clin Pettersen M et al Radiotherapy and Oncology 2008
Clinical 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:
21
Pettersen M et al Radiotherapy and Oncology 2008
22bioldoseclin ),( bioldoseclin f and ),( bioldoseclin f
Steepness of clinical dose-response curve is depending of the dose variation
Pettersen M et al Radiotherapy and Oncology 2008
Roué 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 = 0.05
Pettersen M et al Radiotherapy and Oncology 2008
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%.
Volumeffet for rektumblødning
Strandqvist plot
-kill
-kill
LQ-formelverket