Commissioning of a motion system to investigate dosimetric consequences due to variability of respiratory waveforms
| Autor: | B. Wang, Ashley J. Cetnar, J James |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Respiratory-Gated Imaging Techniques
HexaMotion Movement Acoustics ITV Gating Radiotherapy Setup Errors Patient Positioning Standard deviation 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine motion management Neoplasms Humans Radiation Oncology Physics Waveform Radiology Nuclear Medicine and imaging Instrumentation Mathematics Reproducibility Radiation Phantoms Imaging Radiotherapy Planning Computer-Assisted Reproducibility of Results Radiotherapy Dosage Amplitude respiratory gating 030220 oncology & carcinogenesis Radiotherapy Intensity-Modulated Rotation (mathematics) Algorithms Software Motion system |
| Zdroj: | Journal of Applied Clinical Medical Physics |
| ISSN: | 1526-9914 |
| Popis: | A commercially available six‐dimensional (6D) motion system was assessed for accuracy and clinical use in our department. Positional accuracy and respiratory waveform reproducibility were evaluated for the motion system. The system was then used to investigate the dosimetric consequences of respiratory waveform variation when an internal target volume (ITV) approach is used for motion management. The maximum deviations are 0.3 mm and 0.22° for translation and rotation accuracy, respectively, for the tested clinical ranges. The origin reproducibility is less than ±0.1 mm. The average differences are less than 0.1 mm with a maximum standard deviation of 0.8 mm between waveforms of actual patients and replication of those waveforms by HexaMotion for three breath‐hold and one free‐breathing waveform. A modified gamma analysis shows greater than 98% agreement with a 0.5 mm and 100 ms threshold. The motion system was used to investigate respiratory waveform variation and showed that, as the amplitude of the treatment waveform increases above that of the simulation waveform, the periphery of the target volume receives less dose than expected. However, by using gating limits to terminate the beam outside of the simulation amplitude, the results are as expected dosimetrically. Specifically, the average dose difference in the periphery between treating with the simulation waveform and the larger amplitude waveform could be up to 12% less without gating limits, but only differed 2% or less with the gating limits in place. The general functionality of the system performs within the manufacturer's specifications and can accurately replicate patient specific waveforms. When an ITV approach is used for motion management, we found the use of gating limits that coincide with the amplitude of the patient waveform at simulation helpful to prevent the potential underdosing of the target due to changes in patient respiration. PACS numbers: 87.55.Kh, 87.55.Qr, 87.56.Fc |
| Databáze: | OpenAIRE |
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