Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements.

Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements.
Phys Med Biol. 2017 Aug 10;:
Authors: Zoros E, Moutsatsos AS, Pappas EP, Georgiou E, Kollias G, Karaiskos P, Pantelis E
Abstract
Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the Solid Water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry. MC calculations for OF-measurements correction factors in SW were compared against corresponding experimental results for a subset of ionization chambers and diode detectors. Reference experimental OF data were obtained through the weighted average of corresponding measurements using TLDs, EBT-2 films and alanine pellets. Reference dosimetry correction factor values close to unity (within 1%) were calculated for most of ionization chambers in water. Greater corrections of up to 6.0% were observed for chambers with relatively large air-cavity dimensions and steel central electrode. A phantom correction of 1.006 and 1.024 (bre...

Source: Physics in Medicine and Biology - August 10, 2017 Category: Physics Authors: Zoros E, Moutsatsos AS, Pappas EP, Georgiou E, Kollias G, Karaiskos P, Pantelis E Tags: Phys Med Biol Source Type: research