Commissioning of the Leksell Gamma Knife(®) Icon™.

Details

Serval ID
serval:BIB_B05F3B565B79
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Commissioning of the Leksell Gamma Knife(®) Icon™.
Journal
Medical physics
Author(s)
Zeverino M., Jaccard M., Patin D., Ryckx N., Marguet M., Tuleasca C., Schiappacasse L., Bourhis J., Levivier M., Bochud F.O., Moeckli R.
ISSN
2473-4209 (Electronic)
ISSN-L
0094-2405
Publication state
Published
Issued date
04/2017
Peer-reviewed
Oui
Volume
44
Number
2
Pages
355-363
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
The Leksell Gamma Knife (LGK) Icon has been recently introduced to provide Gamma Knife technology with frameless stereotactic treatments which use an additional cone-beam CT (CBCT) imaging system and a motion tracking system (IFMM, Intra-Fraction Motion Management). The system was commissioned for the treatment unit itself as well as the imaging system.
The LGK Icon was calibrated using an A1SL ionization chamber. EBT3 radiochromic films were employed to independently check the machine calibration, to measure the relative output factors (ROFs) and to collect dose distributions. Coincidence between CBCT isocenter and radiological focus was evaluated by means of EBT3 films. CBCT image quality was investigated in terms of spatial resolution, contrast-to-noise ratio (CNR), and uniformity for the two presets available (low dose and high dose). Computed Tomography Dose Index (CTDI) was also measured for both presets.
The absolute dose rate of the LGK Icon was 3.86 ± 0.09 Gy/min. This result was confirmed by EBT3 readings. ROF were found to be 0.887 ± 0.035 and 0.797 ± 0.032 for the 8 mm and 4 mm collimators, respectively, which are within 2% of the Monte Carlo-derived ROF values. Excellent agreement was found between calculated and measured dose distribution with the gamma pass rate >95% of points for the nine dose distributions analyzed with 3%/1 mm criteria. CBCT isocenter was found to be within 0.2 mm with respect to radiological focus. Image quality parameters were found to be well within the manufacturer's specifications with the high-dose preset being superior in terms of CNR and uniformity. CTDI values were 2.41 mGy and 6.32 mGy, i.e. -3.6% and 0.3% different from the nominal values for the low-dose and high-dose presets, respectively.
The LGK Icon was successfully commissioned for clinical use. The use of the EBT3 to characterize the treatment unit was demonstrated to be feasible. The CBCT imaging system operates well within the manufacturer's specifications and provides good geometrical accuracy.

Keywords
Calibration, Cone-Beam Computed Tomography/instrumentation, Cone-Beam Computed Tomography/methods, Film Dosimetry, Head/diagnostic imaging, Head/surgery, Humans, Models, Anatomic, Monte Carlo Method, Phantoms, Imaging, Radiosurgery/instrumentation, Radiosurgery/methods, Radiotherapy Dosage, Water
Pubmed
Web of science
Create date
07/02/2017 19:21
Last modification date
20/08/2019 16:19
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