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SU‐G‐TeP4‐04: An Automated Monte Carlo Based QA Framework for Pencil Beam Scanning Treatments
Author(s) -
Shin J,
Jee K,
Clasie B,
Depauw N,
Madden T,
Sharp G,
Paganetti H,
Kooy H
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4957129
Subject(s) - monte carlo method , imaging phantom , nuclear medicine , range (aeronautics) , fluence , radiation treatment planning , pencil beam scanning , computer science , optics , beam (structure) , medical physics , materials science , physics , proton therapy , mathematics , medicine , statistics , radiation therapy , radiology , laser , composite material
Purpose: Prior to treating new PBS field, multiple (three) patient‐field‐specific QA measurements are performed: two 2D dose distributions at shallow depth (M1) and at the tumor depth (M2) with treatment hardware at zero gantry angle; one 2D dose distribution at iso‐center (M3) without patient specific devices at the planned gantry angle. This patient‐specific QA could be simplified by the use of MC model. The results of MC model commissioning for a spot‐scanning system and the fully automated TOPAS/MC‐based QA framework will be presented. Methods: We have developed in‐house MC interface to access a TPS (Astroid) database from a computer cluster remotely. Once a plan is identified, the interface downloads information for the MC simulations, such as patient images, apertures points, and fluence maps and initiates calculations in both the patient and QA geometries. The resulting calculations are further analyzed to evaluate the TPS dose accuracy and the PBS delivery. Results: The Monte Carlo model of our system was validated within 2.0 % accuracy over the whole range of the dose distribution (proximal/shallow part, as well as target dose part) due to the location of the measurements. The averaged range difference after commissioning was 0.25 mm over entire treatment ranges, e.g., 6.5 cm to 31.6 cm. Conclusion: As M1 depths range typically from 1 cm to 4 cm from the phantom surface, The Monte Carlo model of our system was validated within +− 2.0 % in absolute dose level over a whole treatment range. The averaged range difference after commissioning was 0.25 mm over entire treatment ranges, e.g., 6.5 cm to 31.6 cm. This work was supported by NIH/NCI under CA U19 21239