The practical application of scintillation dosimetry in small-field photon-beam radiotherapy.
Plastic scintillation detectors are a new instrument of stereotactic photon-beam dosimetry. The clinical application of the plastic scintillation detector Exradin W1 at the Siemens Artiste and Elekta Synergy accelerators is a matter of current interest. In order to reduce the measurement uncertainty, precautions have to be taken with regard to the geometrical arrangement of the scintillator, the light-guide fiber and the photodiode in the radiation field. To determine the "Cerenkov light ratio" CLR with a type A uncertainty below 1%, the Cerenkov calibration procedure for small-field measurements based on the two-channel spectral method was used. Output factors were correctly measured with the W1 for field sizes down to 0.5×0.5cm2with a type A uncertainty of 1.8%. Measurements of small field dose profiles and percentage depth dose curves were carried out with the W1 using automated water phantom profile scans, and a type A uncertainty for dose maxima of 1.4% was achieved. The agreement with a synthetic diamond detector (microDiamond, PTW Freiburg) and a plane parallel ionization chamber (Roos chamber, PTW Freiburg) in relative dose measurements was excellent. In oversight of all results, the suitability of the plastic scintillation detector Exradin W1 for clinical dosimetry under stereotactic conditions, in particular the tried and tested procedures for CLR determination, output factor measurement and automated dose profile scans in water phantoms, have been confirmed.
University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany. Electronic address: elisa.burke@uni-oldenburg.de.
Elisa
E
Burke
University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany.
Daniela
D
Poppinga
University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany.
Andreas A
AA
Schönfeld
Prof. em., Medical Physics and Biophysics, Georg-August University, Göttingen, Germany.
Dietrich
D
Harder
University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany.
Björn
B
Poppe
University Clinic for Medical Radiation Physics, Medical Campus Pius-Hospital, Carl von Ossietzky University, Oldenburg, Germany.
Hui Khee
HK
Looe
D002138:Calibration; D018130:Diamond; D006801:Humans; D017785:Photons; D010969:Plastics / Q000592:standards; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D012588:Scintillation Counting / Q000295:instrumentation / Q000592:standards
D010969:Plastics; D018130:Diamond
Cerenkov light correction; Cerenkovlichtkorrektion; Dosisprofil-Scans in Wasserphantomen; Plastic scintillators; Plastikszintillatoren; dose profile scans in water phantoms; im Phantom gemessene feldgrößenabhängige Outputfaktoren; in-phantom field output factors