Journal of Radiation Research, Vol. 58, No. 3, 2017, pp. 378–385 doi: 10.1093/jrr/rrw103 Advance Access Publication: 3 November 2016

A robust measurement point for dose verification in delivery quality assurance for a robotic radiosurgery system Keita Kurosu1,2, Iori Sumida1*, Hiroya Shiomi1, Hirokazu Mizuno1, Hiroko Yamaguchi1, Hirofumi Okubo1, Keisuke Tamari1, Yuji Seo1, Osamu Suzuki1, Seiichi Ota2, Shinichi Inoue2 and Kazuhiko Ogawa1 1

Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan 2 Department of Radiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan *Corresponding author. Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. Tel: +81-6-6879-3482; Fax: +81-6-6879-3489; Email: [email protected] Received May 5, 2016; Revised June 30, 2016; Accepted September 28, 2016

ABSTRACT In this CyberKnife® dose verification study, we investigated the effectiveness of the novel potential error (PE) concept when applied to the determination of a robust measurement point for targeting errors. PE was calculated by dividing the differences between the maximum increases and decreases in dose distributions by the original distribution after obtaining the former by shifting the source-to-axis and off-axis distances of each beam by ±1.0 mm. Thus, PE values and measurement point dose heterogeneity were analyzed in 48 patients who underwent CyberKnife radiotherapy. Sixteen patients who received isocentric dose delivery were set as the control group, whereas 32 who received non-isocentric dose delivery were divided into two groups of smaller PE (SPE) and larger PE (LPE) by using their median PE value. The mean dose differences (± standard deviations) were 1.0 ± 0.9%, 0.5 ± 1.4% and 4.1 ± 2.8% in the control, SPE and LPE groups, respectively. We observed significant correlations of the dose difference with the PE value (r = 0.582, P < 0.001) and dose heterogeneity (r = 0.471, P < 0.001). We concluded that when determining a robust measurement point for CyberKnife point dose verification, PE evaluation was more effective than the conventional dose heterogeneity-based method that introduced optimal measurement point dose heterogeneity of

A robust measurement point for dose verification in delivery quality assurance for a robotic radiosurgery system.

In this CyberKnife® dose verification study, we investigated the effectiveness of the novel potential error (PE) concept when applied to the determina...
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