TITLE:
Verification of Dosimetric and Positional Accuracy of Dynamic Tumor Tracking Intensity Modulated Radiation Therapy
AUTHORS:
Masaki Sueoka, Akira Sawada, Hiroaki Tanabe, Yuki Okada, Sho Taniuchi, Noboru Okuuchi, Masao Tanooka, Masaki Kokubo, Koichiro Yamakado
KEYWORDS:
Dynamic Tumor Tracking (DTT), Intensity Modulated Radiation Therapy (IMRT), Point Dose Verification, Dose Distribution Verification, Log File Analysis
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.8 No.4,
October
11,
2019
ABSTRACT: Purpose: We performed both, dosimetric and positional accuracy verification of
dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with
the Vero4DRT system using a moving phantom (QUASAR respiratory motion platform;
QUASAR phantom) and system log files. Methods: The QUASAR phantom was placed on a treatment couch. Measurement of the
point dose and dose distribution was performed for conventional IMRT, with the
QUASAR phantom static and moving; for DTT IMRT, this was performed with the
phantom moving for pyramid shaped, prostate, paranasal sinus, and pancreas
targets. The QUASAR phantom was driven by a sinusoidal signal in the
superior-inferior direction. Furthermore, predicted positional errors induced
by the Vero4DRT system and mechanical positional errors of the gimbal head,
were calculated using the system log files. Results and Conclusion: For DTT IMRT, the dose at the evaluation point was within 3% compared
with the verification plan, and the dose distribution in the passing rates of γ
was 97.9%, with the criteria of 3% dose and 3 mm distance to agreement. The
position error calculated from the log files was within 2 mm, suggesting the
feasibility of employing DTT IMRT with high accuracy using the Vero4DRT system.