Background/aim: Patient immobilization systems are used to establish a reproducible patient position relative to the couch. In this study, the impact of conventional lok-bars for CT-simulation (CIVCO-bar) and treatment (iBEAM-bar) were compared with a novel lok-bar (mHM-bar) in tomotherapy.
Materials and methods: Verification was obtained as follows: i. artifacts in CT images; ii. dose attenuation rate of lok-bar, compared to without lok-bar; and iii. dose differences between the calculated and measured absorbed doses.
Results: With the CIVCO-bar, there were obvious metal artifacts, while there were nearly no artifacts with the mHM-bar. The mean dose attenuation rates with the mHM-bar and iBEAM-bar were 1.31% and 2.28%, and the mean dose difference was 1.55% and 1.66% for mHM-bar and iBEAM-bar.
Conclusion: Using the mHM-bar reduced artifacts on the CT image and improved dose attenuation are obtained. The lok-bar needs to be inserted as a structure set in treatment planning with tomotherapy.
Keywords: Artifacts; immobilizer; lok-bar; tomotherapy.
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