A Web Interface to Cloud-Based Treatment Head Simulations
D Sawkey*, M Constantin, M Svatos, Varian Medical Systems, Palo Alto, CAWE-F-105-5 Wednesday 3:00PM - 3:50PM Room: 105
Purpose: Monte Carlo simulations of linear accelerator treatment heads have traditionally involved building the simulated treatment head from specifications provided by the manufacturer. Here, we make pre-compiled applications available through a web interface, with processors running in the cloud.
Methods: Simulations are run on computers on Amazon Web Services, a cloud provider. A machine image (AMI) was created from which multiple instances can be used on a pay-as-you-go basis. The instances present a web interface, where input parameters (such as the target and flattening filter, code version, and parameters of the incident electron beam) are entered. The web form is converted to an input file for the simulation code by a php script. Simulations of the Varian TrueBeam accelerator using Geant4 simulation code are currently available. Phase space files can be written either above the jaws, or below the MLC, and then imported into a separate simulation. Alternatively the dose deposited in a phantom can be calculated. Modifications to the treatment head, for example custom targets, are also possible. The AMI is available to researchers through their own Amazon account. We share the AMI without additional cost; the user is responsible for the Amazon charges (typically USD 0.01/hr/core).
Results: The code was verified by matching commissioning data. The web interface was used by collaborators who both matched commissioning data and investigate treatment head modifications. The treatment head was simulated, and modified in the simulation, without disclosure of proprietary information. Input of phase spaces files into EGSnrc was verified.
Conclusion: Geant4-based simulations of the Varian TrueBeam can be run in the cloud, without need for treatment head specifications or a computer cluster. The methods readily generalize to other codes or geometries.
Funding Support, Disclosures, and Conflict of Interest: As noted in the affiliations, the authors are employees of Varian Medical Systems.