In vivo dose verification of IMRT treated head and neck cancer patients.
An independent in vivo dose verification procedure for IMRT treatments of head and neck cancers was developed. Results of 177 intracavitary TLD measurements from 10 patients are presented. The study includes data from 10 patients with cancer of the rhinopharynx or the thyroid treated with dynamic IMRT. Dose verification was performed by insertion of a flexible naso-oesophageal tube containing TLD rods and markers for EPID and simulator image detection. Part of the study focussed on investigating the accuracy of the TPS calculations in the presence of inhomogeneities. Phantom measurements and Monte Carlo simulations were performed for a number of geometries involving lateral electronic disequilibrium and steep density shifts. The in vivo TLD measurements correlated well with the predictions of the treatment planning system with a measured/calculated dose ratio of 1.002+/-0.051 (1 SD, N=177). The measurements were easily performed and well tolerated by the patients. We conclude that in vivo intracavitary dosimetry with TLD is suitable and accurate for dose determination in intensity-modulated beams.
Engström
Per E
PE
Department of Radiation Oncology, The Finsen Center, Copenhagen University Hospital, Copenhagen, Denmark. engstrom@rh.dk
Haraldsson
Pia
P
Landberg
Torsten
T
Sand Hansen
Hanne
H
Aage Engelholm
Svend
S
Nyström
Håkan
H
D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D015203:Reproducibility of Results; D013819:Thermoluminescent Dosimetry; D013964:Thyroid Neoplasms / Q000532:radiotherapy