Abstract
Recently, the number of patients undergoing intensity-modulated radiation therapy and volumetric modulated arc therapy has increased with the expansion of the adaptation site. However, it is necessary to improve the efficiency of time-consuming dose verification. Therefore, patient-specific quality assurance is expected to shift from dose verification using a conventional ionization chamber dosimeter and film to a three-dimensional dose verification system. However, caution is required when using a three-dimensional dose verification system, especially when it comes to the calibration of the detector. Calibration is performed regularly, but not all necessary verifications are done routinely. There are many uncertainties on how the sensitivity of the three-dimensional dose verification system changes over time. In this study, on the same day, when dose verification using a three-dimensional system for one head and neck case was performed, dose verification using a conventional ionization chamber dosimeter and film was also performed once every two months, for 2 years. From the results of the absolute dose and dose distribution verification using the ionization chamber dosimeter and Gafchromic film, the output of the linear accelerator, mechanical accuracy and precision were secured. From the results of the three-dimensional dose verification system, when the distance to agreement was evaluated at 2 mm and 3 mm, and gamma analysis was performed at 2 mm/2% and 3 mm/3%, the passing rate was almost 100%, and a sensitivity change in 2 years was not observed.
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Acknowledgements
The authors would like to thank Kenji Takimoto (Euro-meditech, Tokyo, Japan), Kanako Sakuragawa (Department of Radiological Technology, Tokushima University Hospital), and Michihiro Yokoishi (Department of Radiological Technology, Tokushima University Hospital) for their help and discussions during this work. This manuscript was partly supported by Akiyoshi Ohtsuka Fellowship of the Japanese Society of Radiological Technology for improvement in English expression of a draft version of the manuscript.
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All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. This study does not involve any kind of animal experimentation.
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Sasaki, M., Ikushima, H., Sugimoto, W. et al. Long-term stability of a three-dimensional dose verification system. Radiol Phys Technol 13, 83–91 (2020). https://doi.org/10.1007/s12194-020-00554-7
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DOI: https://doi.org/10.1007/s12194-020-00554-7