Single center study of clinical dosimetry data characteristics and quality assurance of VSI CyberKnife(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2018年第12期
- Page:
- 1392-1398
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Single center study of clinical dosimetry data characteristics and quality assurance of VSI CyberKnife
- Author(s):
- WANG Lin1; ZHANG Jianping1; XU Benhua1; LI Xiaobo1; 2
- 1. Department of Radiation Oncology, Fujian Medical University Union Hospital, Fuzhou 350001, China; 2. College of Medical Technology and Engineering, Fujian Medical University, Fuzhou 350001, China
- Keywords:
- ; Keywords: VSI CyberKnife; dosimetry; data characteristics; quality assurance; clinical commissioning
- PACS:
- R318；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2018.12.005
- Abstract:
- Abstract: Objective To study and summarize the clinical dosimetry data characteristics and quality assurance commissioning procedure of VSI CyberKnife. Methods Combining the practical operating experience, a comparative analysis was carried out retrospectively on clinical commissioning data and reference data from VSI CyberKnife which installed in Fujian Medical University Union Hospital in June 2017. Except for off-center ratios, the clinical dosimetry data were obtained by PTW 60019 detector. Results Three factors, namely eccentricity, three-dimensional error and the total error, were comprehensively considered in automatic quality assurance and end-to-end test. Both radiochromic film and equivalently high spatial resolution detector were available for the quality assurance of Iris collimator, but the use of radiochromic film was strongly recommended when the baseline set of measurement was done. At source-axis distance of 650, 800 and 1 000 mm, the average deviation between measurements and reference values for output factors across all apertures in Fixed collimator were -1.27%, -0.21% and 0.70%, respectively. And for 5.0 mm/7.5 mm collimator, the deviations were -5.10%/-2.67%, -2.08%/-1.41% and -1.12%/0.06%, respectively. For Iris apertures, the corresponding deviations were -1.88%, -0.74%, 0.09%; -8.61%/-3.53%, -4.38%/-1.97% and -1.34%/-0.33%, respectively. At the surface of water, the mean values of tissue phantom ratios of two types of collimators were -6.22% (Fixed) and -4.81% (Iris), respectively, both less than reference values. Except for 5.0 mm and 7.5 mm Iris collimators, the measurement values of off-center ratios for those two types of collimators had a tendency that the shoulder and bottom of curves toward positive deviation, and that the deviation was more obvious with the increase of collimator sizes. The output of dose calibration of TRS 277 was about 2% smaller than that of TRS 398. Conclusion In commissioning and acceptance procedures of CyberKnife, the user should fully understand the characteristics of two types of collimators especially for smaller collimators, and then select the appropriate commissioning procedures and tools.
Last Update: 2018-12-24