Program Information
Validation of Monte-Carlo Proton Dose Calculation for Real Tissue Samples
H Wang1*, J Wu2 , R Zhang3 , E Baer4 , C Geng5 , K Jee6 , G Sharp7 , H Paganetti8 , J Tang9 , H Lu10 , (1) Massachusetts General Hospital, Boston, MA, (2) Massachusetts General Hospital, Boston, MA, (3) Massachusetts General Hospital, Quincy, MA, (4) UCL, London, UK, (5) Massachusetts General Hospital and Harvard Medical School, Boston, MA, (6) Massachusetts General Hospital, Boston, MA, (7) Massachusetts General Hospital, Boston, MA, (8) Massachusetts General Hospital, Boston, MA, (9) Tsinghua University, Haidian, Beijing, (10) Massachusetts General Hospital, Boston, MA
Presentations
SU-I-GPD-T-119 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: Monte-Carlo simulation has been commissioned for multiple proton therapy systems, but most of the validation work involved only dose data acquired in water tanks or simple plastic phantoms. In this work, we perform TOPAS simulations for actual measurements of water equivalent path length (WEPL) through a variety of fresh real tissue samples including animal muscle, bone, liver, kidney, etc.
Methods: A large number of animal tissue samples in separate boxes (5x5x15 cm) were used for the measurements. The WEPL values were obtained by the technique of dose extinction, where a passively scattered broad beam in the vertical direction with the beam range of 25 cm and modulation width of 20 cm went first through a water tank and then the tissue samples. A Matrixx detector was placed below the sample boxes to record the dose while the water level in the water tank was gradually increased until the dose becomes zero at the Matrixx, thus the term, “dose extinction”. The passive scattering system was previously commissioned in TOPAZ. A simple dose extinction measurement was first simulated and then validated by an actual measurement for the WEPL of a 10 cm solid water block. The simulation for the actual real tissue sample measurements were then carried out for a large number of configurations, each corresponding to a particular water level of the water tank. The WEPL values were extracted and compared to experiment.
Results: The WEPL obtained by the simulation for the 10 cm solid water block was within 0.5 mm. For the real tissue samples, the values by simulation were within 1% from the measured ones, with smallest difference for pig blood (0.03%) and largest for pig leg bone (0.68%).
Conclusion: Monte-Carlo simulation accurately reproduced results by measurements for real tissues samples.
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