Program Information
A Multi-Institutional Study of Independent Dose Verification Software Program for Lung SBRT
D Kawai1*, R Takahashi2 , T Kamima3 , H Baba4 , T Yamamoto5 , Y Kubo6 , S Ishibashi7 , Y Higuchi8 , H Takahashi9 , H Tachibana10 , (1) Kanagawa Cancer Center, Yokohama, Kanagawa-prefecture, (2) The Cancer Institute Hospital of JFCR, Koutou-ku, Tokyo, (3) The Cancer Institute Hospital of JFCR, Koutou-ku, Tokyo, (4) The National Cancer Center Hospital East, Kashiwa-city, Chiba prefecture, (5) Otemae Hospital, Chuou-ku, Osaka-city, (6) Otemae Hospital, Chuou-ku, Osaka-city, (7) Sasebo City General Hospital, Sasebo, Nagasaki, (8) Sasebo City General Hospital, Sasebo, Nagasaki, (9) St Lukes International Hospital, Chuou-ku, Tokyo, (10) National Cancer Center Hospital East, Kashiwa, Chiba
Presentations
SU-E-T-50 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:
The accuracy of dose distribution depends on treatment planning system especially in heterogeneity-region. The tolerance level (TL) of the secondary check using the independent dose verification may be variable in lung SBRT plans. We conducted a multi-institutional study to evaluate the tolerance level of lung SBRT plans shown in the AAPM TG114.
Methods:
Five institutes in Japan participated in this study. All of the institutes used a same independent dose verification software program (Simple MU Analysis: SMU, Triangle Product, Ishikawa, Japan), which is Clarkson-based and CT images were used to compute radiological path length. Analytical Anisotropic Algorithm (AAA), Pencil Beam Convolution with modified Batho-method (PBC-B) and Adaptive Convolve (AC) were used for lung SBRT planning. A measurement using an ion-chamber was performed in a heterogeneous phantom to compare doses from the three different algorithms and the SMU to the measured dose. In addition to it, a retrospective analysis using clinical lung SBRT plans (547 beams from 77 patients) was conducted to evaluate the confidence limit (CL, Average±2SD) in dose between the three algorithms and the SMU.
Results:
Compared to the measurement, the AAA showed the larger systematic dose error of 2.9±3.2% than PBC-B and AC. The Clarkson-based SMU showed larger error of 5.8±3.8%. The CLs for clinical plans were 7.7±6.0 % (AAA), 5.3±3.3 % (AC), 5.7±3.4 % (PBC-B), respectively.
Conclusion:
The TLs from the CLs were evaluated. A Clarkson-based system shows a large systematic variation because of inhomogeneous correction. The AAA showed a significant variation. Thus, we must consider the difference of inhomogeneous correction as well as the dependence of dose calculation engine.
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