Individual radiation response of parotid glands investigated by dynamic 11C-methionine PET.
OBJECTIVE
Previously, we showed that the net metabolic clearance of 11C-methionine of the parotid gland, K, calculated from dynamic 11C-methionine PET, can be used as a measure of parotid gland function. The aim of this study was to investigate by dynamic 11C-methionine PET the individual radiation dose response relationship of parotid glands in head and neck cancer patients.


METHODS
Twelve head and neck cancer patients were examined by dynamic 11C-methionine PET after radiotherapy. Parametric images of K were generated, co-registered and compared voxel-by-voxel with the 3D radiation dose plan within the parotid gland to assess the individual radiation dose-function relationship.


RESULTS
In each patient, voxel-values of K decreased with increasing radiation dose. Population based analysis showed a sigmoid dose response relationship of parotid gland, from which we estimated a threshold radiation dose of 16 Gy and a mean TD50 of 30 Gy. TD50 ranged from 7 to 50 Gy in the group of patients.


CONCLUSIONS
Individual radiation dose response of parotid glands can be measured by dynamic 11C-methionine PET. The dose response analysis revealed a sigmoid relationship, a threshold radiation dose of 16 Gy, and a mean TD50 of 30 Gy.
PET Centre, Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. simonbuus@dadlnet.dk
Simon
S
Buus
Cai
C
Grau
Ole Lajord
OL
Munk
Anders
A
Rodell
Kenneth
K
Jensen
Kim
K
Mouridsen
Susanne
S
Keiding
D000368:Aged; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008715:Methionine / Q000493:pharmacokinetics; D008875:Middle Aged; D010306:Parotid Gland / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000528:radiation effects*; D049268:Positron-Emission Tomography / Q000379:methods*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D019275:Radiopharmaceuticals; C086242:carbon-11 methionine; D008715:Methionine