Output factors of ionization chambers and solid state detectors for mobile intraoperative radiotherapy (IORT) accelerator electron beams
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2019-01-10 |
| Journal | Journal of Applied Clinical Medical Physics |
| Authors | Görkem GĂŒngör, Gökhan Aydın, Teuta Zoto Mustafayev, Enis Ăzyar |
| Institutions | Kent Hastanesi, Istanbul Medipol University |
| Citations | 11 |
Abstract
Section titled âAbstractâAbstract Purpose The electron energy characteristics of mobile intraoperative radiotherapy ( IORT ) accelerator LIAC Âź differ from commonly used linear accelerators, thus some of the frequently used detectors can give less accurate results. The aim of this study is to evaluate the output factors ( OF s) of several ionization chambers ( IC ) and solid state detectors ( SS ) for electron beam energies generated by LIAC Âź and compare with the output factor of Monte Carlo model ( MC ) in order to determine the adequate detectors for LIAC Âź . Methods The OF s were measured for 6, 8, 10, and 12 MeV electron energies with PTW 23343 Markus, PTW 34045 Advanced Markus, PTW 34001 Roos, IBA PPC 05, IBA PPC 40, IBA NACP â02, PTW 31010 Semiflex, PTW 31021 Semiflex 3D, PTW 31014 Pinpoint, PTW 60017 Diode E, PTW 60018 Diode SRS , SNC Diode EDGE , and PTW 60019 micro Diamond detectors. Ion recombination factors ( k sat ) of IC were measured for all applicator sizes and OF s were corrected according to k sat . The measured OF s were compared with Monte Carlo output factors (OF MC ). Results The measured OF s of IBA PPC 05, PTW Advanced Markus, PTW Pinpoint, PTW microDiamond, and PTW Diode E detectors are in good agreement with OF MC . The maximum deviations of IBA PPC 05 OF s to OF MC are â1.6%, +1.5%, +1.5%, and +2.0%; for PTW Advanced Markus +1.0%, +1.5%, +2.0%, and +2.0%; for PTW Pinpoint +2.0%, +1.6%, +4.0%, and +2.0%; for PTW microDiamond â1.6%, +2%, +1.1%, and +1.0%; and for PTW Diode E â+1.7%, +1.7%, +1.3%, and +2.5% for 6, 8, 10, and 12 MeV, respectively. PTW Roos, PTW Markus, IBA PPC 40, PTW Semiflex, PTW Semiflex 3D, SNC Diode Edge measured OF s with a maximum deviation of +5.6%, +4.5%, +5.6%, +8.1%, +4.8%, and +9.6% with respect to OF MC , while PTW Diode SRS and IBA NACP â02 were the least accurate (with highest deviations â37.1% and â18.0%, respectively). Conclusion The OF s results of solid state detectors PTW microDiamond and PTW Diode E as well as the IC s with small electrode spacing distance such as IBA PPC 05, PTW Advanced Markus and PTW Pinpoint are in excellent agreement with OF MC . The measurements of the other detectors evaluated in this study are less accurate, thus they should be used with caution. Particularly, PTW Diode SRS and IBA NACP â02 are not suitable and their use should be avoided in relative dosimetry measurements under high dose per pulsed ( DPP ) electron beams.