1. A Web interface to cloud-based Monte Carlo simulations for TrueBeam and C-linac
Good morning. I will be introduce the ‘ cloud-based Monte Carlo simulations for TrueBeam and C-linac’.
Jong In Park
M.S. student

2. Contents What is the Virtual Linac Application of Virtual Linac
How can we use (register) ?
In this presentation, first I’m gonna talk about the backgroud of virtual linac, then I will briefly introduce the application of virtual linac
Finally, I will talk about how can we use or register virtual linac

3. Background
Let me refresh your memory on the montecarlo package provided by varian medical system.
They provides phase space files for Truebeam simulation, but it has limited geometry in field-independent components
Varian provides ‘just’ phase space file for TrueBeam simulation
Field-independent components were not open to the public
- Target, ion chamber, carousel

4. Purpose of Virtual Linac
Varian has developed a cloud based web application, called “Virtual Linac”
Linac Monte Carlo simulation as service
- Enable the research community
- Validated geometry (by Varian)
- Fast computing is available w/o server
Now updating ..
Varian has developed a cloud base web application, it is called Virual Linac
Aim of virtual linac is Monte Carlo simulation as service for resarch community which is insufficient computing environment
And.. Important thing that the Virtual linac has validated geometry by Varian.
version 84 (open to the public)
~ version 94

5. Simulation Mechanics Amazon Web Service User Elastic compute cloud 2
Input file
Dose distribution
Amazon Web service provides a various service, EC2 is a application for cloud computing.
Varian design the application for run MC simulation to derive dose distribution
User should type input file to EC2 application, then EC2 application return dose distribution.
Run MC simulation

6. Use Case 1 – General case Virtual Linac Check a plan DOSXYZnrc
First, Monte Carlo expert wants to second check a plan, (research purpose)
Dose distribution

7. Virtual Linac Graphic User Interface
This figure shows the graphic user interface in virtual Linac,
Geometry of TrueBeam and Clinac was embedded in the virtual linac
Can simulate the electron beam and photon beam included with fff beam
After finishing type input file, click the run button, then simulation will perform and download to local computer

8. Validation of Simulation Results
Presented in ‘AAPM’ meeting
This data was presented in AAPM annual meeting
As shown in this figure, simulation results of virtual linac were well matched with measurement with ion chamber.
- Simulation results were well matched with measurement

9. Use Case 2 – What can we change ?
Treatment head
One of the use is changing the geometry and, then obtain the results.
Like as General Monte Carlo simulation, we can investigate changes to the treatment head – all of the target, and limited custom target is also available
Investigate changes to the treatment head
Low energy, medium energy, high energy, imaging,
Custom is also available

10. Use Case 2 – What can we change ?
Originally, in TrueBeam simulation
Virtual Linac
Can define “Target”
When we simulate the TrueBeam
Field independent components can not modified, because of varian confidential.
However, In virtual linac
We can define and change the geomtery of Target component
Therefore, Varian medical system published varlidation article by replacing the carbon target for FFF beam
Using carbon target

11. Use Case 2 – Treatment head
Flattening filter
- Open port (FFF), 4X, 6X, 8X, 10X, 15X, 18X, 20X
Location of writing phase space file
- above the jaw
- below the mylar
- isocenter
- 95 cm from source
- 150 cm from source
Virtual linac has advantage for well-defined treatment head geometry.
Especially, flattening filter for all photon energies and scattering foil for all electron energies
So, we can change only source parameters for benchmarking
When we extract the phase space file, limited locations were available such as above the jaw, below the mylar, isocenter, 95 cm and 150 cm

12. Use Case 3 – TrueBeam Developer mode
Dose distributions from TrueBeam Developer Mode XML file
- non-Monte Carlo expert
What exactly is Developer Mode?
- A method to control all motion axes and imaging through
customized XML scripts
Final Interesting use is Truebeam developer mode
Dose distributions from xml file can be calculated
Developer mode can simulate the all motion axes and imaging by modifying the customized XML scripts !
Current motions supported
Dynamic jaw resizing
Collimator rotation
MLC articulation
Gantry rotation
4-D couch ‘kicks’
Image by Varian

13. Use Case 3 – TrueBeam Developer mode
Still to come !
When we load xml file, virtual linac properly parsing data for simulation
However, this mode is not available in current version.
After the upate the developer mode, we can research a various topic changing the xml file.
TrueBeam
Developer mode ‘xml’

14. How can we use (register) ?
Requirements
① Send an to – Daren Sawkey (Varian Medical Systems) - expression of register
So, how can we register as user to virtual linac application
First, we send an to Daren sawkey, he is representative of monte carlo service in Varian
When we receive the answer to .

15. How can we use (register) ?
Requirements
② IP address as seen by the outside world (google “what’s my ip”)
We investigate the ip, because of virtual linac is private application.
So access right is limited to permitted user

16. How can we use (register) ?
Requirements
③ Amazon Web services account number
You can sign up for the Amazon Web Services (AWS) at
aws.amazon.com.
After the sign up, click my account
Cloud service MC is based on the Amazon web service
So, we need the account number, after the sign up account number, we should mail the this number and ip address
Finally, we can get right access to the virtual linac!
The AWS documentation is great, and available at
aws.amazon.com/documentation/ec2 for EC2.

17. How can we use (register) ?
Requirements
④ A completed license agreement
And then we must sign license agreement
Eligible person who has the power and authority to execute this agreement on behalf of institution.
And..in documents,
When we publishing the results for publication or presentation, we need to review the draft copy by Varian at least 45 days prior to presentation or publication date
He or she has the power and authority
Varian the opportunity to review a draft copy of the proposed publication or presentation for review and approval at least 45 days prior to..

18. How can we use (register) ?
Once the register, you can get started
- Log in to AWS
After the obtaining the right access, we can use Virtual linac and research

19. How much is it? Payment ! When ? Between Amazon web service and users
- Running the instance (Table)
- Data transfer
On-demand instance
However, it is not a cost-free tools
When the running the instance, data trasfer and storage on the instance cause to cost !
If we use On-demand instance – cost is burdensome..
Cost-effective instance is.. Linux based is more appropriate in point of cost, and we can more save cost by using ‘spot request’
It defines the maximum cost per hour, then instance is selected by bid. It’s calculation speed isn’t stable.
But, never happened loss of information.
It is fairy good choice for using virtual linac
Unit: $
“Linux” is cheaper than “window”
Can save cost reduced to 1/10 by using ‘spot request’ (highly recommend)

20. Summary Varian validated geometry of component
- Full TrueBeam simulation is available
Fast parallel computing
TrueBeam developer mode will be soon
Reasonable cost with ‘spot request’
More detail information

21. Thank you for your attention !