Program Information
Development of Independent Dose Verification Program Considering Respiratory Movement in Spot Scanning Proton Therapy
Y Ueshima1*, N Hayashi2 , K Yasui3 , (1) Graduate School of Health Scienses, Fujita Health University, Toyoake, Aichi, Japan, (2) School of Health Scienses, Fujita Health University, Toyoake, Aichi, Japan, (3) Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya, Aichi, Japan
Presentations
MO-RAM-GePD-T-2 (Monday, July 31, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Lounge
Purpose: To develop an independent dose verification program that allows for routine simply dose verification of spot scanning proton therapy plans and considers the impact of respiratory movement.
Methods: The independent dose verification program was developed by MATLAB (MathWorks) in house using pencil beam algorithm. In the algorithm, PDD calculated by Geant4 (Monte Carlo code) and bivariate normal distribution approximated by H. Szymanowski's sigma in water and measured sigma in air were utilized. To validate the accuracy of this program, we generated a simple treatment plan for a phantom of water with/without respiratory movement by using VQA (Hitachi). Along the obtained treatment plan parameters, this program generated dose distributions for X-Y and X-Z planes. OCRs and PDD from these distributions were compared with VQA and the maximum differences were evaluated. On the other hand, how respiratory movement affects dose distributions was investigated by focusing on dose difference between dose distributions with no respiratory movement and those with respiratory movement. Respiratory conditions could be selected at any respiration waveforms (sinθ, cos⁴θ, patient), amplitudes (0 to 24.6 mm) and cycles (9 to 22 bpm).
Results: The OCRs in this program agreed with those in VQA within ±1.82%. Especially, penumbra agreed well with less than ±0.45%. Within spread-out Bragg peak, PDD was reproducible within ±4.98%. In the impact of respiratory movement, the maximum dose differences were -46.08% in X-Y plane and +21.98% in X-Z plane in a respiratory condition: sinθ, (LR, SI, AP) = (1.8, 24.6, 1.9) mm, 15 bpm.
Conclusion: We have developed the verification program considering respiratory movement in spot scanning proton therapy. This program has high-accuracy of dose verification and could be useful for simply dose verification of spot scanning proton therapy plans with respiratory movement.
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