The aim of this study was to determine the shuttle dose for all collimator helmets (4, 8, 14 and 18 mm) of the Gamma. Knife, model B, in Vienna, Austria. The additional dose accumulated during the transport of tile patient in and out of the treatment position should be considered in the dose planning procedure of multicentre treatment regimens and in fractionated stereotactic Gamma Knife radiotherapy. The GafChromic film study was basically used to determine the shuttle dose of all four collimator helmets. In addition, measurements with an ionization chamber (18 and 14 min collimator)--and, for the 18 mm collimator helmet, TLD dosimetry-were performed in order to confirm the GafChromic film data. The shuttle dose ranged between 99.6 and 183.5 mGy, depending mainly on the size of the collimator and the irradiated isocentres at the half-life activity of Co-60 in a brand new Gamma unit. Our film-generated data were in good correlation with the dose levels obtained with the ionization chamber and the TLD dosimetry, showing a dose difference of less than 0.8%. Since it was possible to verify the shuttle dose even for the 4 and 8 min collimator helmets, we consider it a non-negligible factor and would advocate the inclusion of the shuttle dose in radiosurgical dose planning.
|Seiten (von - bis)||1567-1578|
|Fachzeitschrift||Physics in Medicine and Biology|
|Publikationsstatus||Veröffentlicht - 1998|
- Biosensor Technologies