Program Information
Dosimetric Evaluation of Amplitude-Based Gating in Volumetric Modulated Arc Therapy (VMAT)
Chang Yeol Lee1, Hyun Do Huh1, Woo Chul Kim1, Hun Jeong Kim1, Chul Kee Min2, Young Hoon Ji3, Kum Bae Kim3, (1) Department of Radiation Oncology, College of Medicine, Inha University, Incheon, Korea, (2) Department of Radiation Oncology, College of Medicine, Soonchunhyang University, Asan, Korea, (3) Department of Radiation Oncology, Korea Institute of Radiological and Medical Science, Seoul, Korea
Presentations
SU-E-J-54 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose:
The purpose of this work is to evaluate the dosimetric influence in the gated volumetric modulated arc therapy.
Methods:
This study is performed in three liver cancer patients. Execution of 4D CT simulation and plan deliveries on one-dimensional respiratory motion phantom were based on patient's respiratory trace data sets. We chose the regular and irregular respiratory amplitude patterns among the patient respiratory-gated treatment log file. Dose distributions were evaluated using EBT3 film by comparing the gated delivery with static delivery.
Results:
The presented results of static measured and calculated dose distributions showed good agreement with gamma-index passing rates above 97% for 3%/3 m dose accuracy/distance-to-agreement criteria. In regular respiratory amplitude pattern, the results of two in three patients evaluated gamma-index passing rates above 92% except for another patient who was evaluated of 87.16%. Patients whose plans had the largest percentage failing the gamma statistics exhibited irregular respiratory amplitude pattern that evaluated less than 70%. Minimum passing rate was 37.40%. This results showed that the correlation of between sorted 4D CT phase and irregular patient respiratory amplitude pattern may results in considerable dosimetric difference.
Conclusion:
The effort to maintain regular patient respiratory amplitude pattern between 4D CT simulation and treatment is the most important in gated volumetric modulated arc therapy.
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