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KMID : 1164220110230010051
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Journal of Korean Society for Radiotherapeutic Technology
2011 Volume.23 No. 1 p.51 ~ p.58
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The Usefulness Assessment of Verifying Daily Output by Using CHECKMATE™
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Cho Han-Sang
Nam Sang-Soo
Park Hae-Jin
Kim Mi-Hwa
Park An-Tae
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Abstract
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Purpose: In this study, we tried to check the usefulness of two Linear Accelerators, Clinac IX and 21EX (Varian, Palo Alto, CA), which are equipped in Ajou Medical Center. From 2008 to 2010, we evaluated the error range of Absolute Dose based on the daily output, which was measured by CHECKMATE™ (Sun Nuclear, Melbourne, FL).
Materials and Methods: For Daily Q.A, photon beams of two linear accelerators, 21EX and IX (6 MV and 10 MV, respectively) were measured daily by using CHECKMATE™ just before the treatment began, while the absolute dose was measured biweekly by using water phantom. We analyzed the data of measured values from the daily Q.A and the absolute dose from 2008 to 2010 for 21EX, and from 2009 to 2010 for IX. We utilized Excel 2007 (Microsoft, USA) to evaluate Average, Standard deviation and Confidence level of the data. Furthermore, in order to check the measured values of CHECKMATE™ and the significance of absolute dose, each error value was compared and analyzed.
Results: During the observation period, the output of two equipment’s absolute dose increased in process of time and in both 6 MV and 10 MV, there was a similar increasing trend. In addition, the error rate of the measured value of CHECKMATE™ and the value of absolute dose were under 0.34, which means that there is a similarity relationship between the two measured values. After checking that the measured value of CHECKMATE™ increased, We measured the absolute dose to adjust that. When the error range was close to 2~3%, the number of changing the output was four for 21EX and three for IX.
Conclusion: As a result of measuring and analyzing the daily output changes for two years by using CHECKMATE™, we could find that there is a significance between the output which we should obey during Q.A, and the measured value of absolute dose within the error tolerance of 2~3%. Thus, the use of CHECKMATE™ can be positively considered for more efficient and reliable daily output verification of linear accelerator. It can also be a good standard for other medical centers to understand the trends of linear accelerator and to refer to for the correction of each output.
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KEYWORD
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CHECKMATE™, daily Q.A., absolute dose
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