MCX Studio - A graphical user interface for MCX, MMC and MCX-CL

1. Introduction
2. Installation
3. Using MCX Studio GUI
4. Remote Execution
5. Acknowledgement
6. Reference

  • Author: Qianqian Fang <q.fang at>
  • License: GNU General Public License version 3 (GPLv3)
  • Version: 1.2 (v2024.2)
  • Website:

1. Introduction

MCXStudio is a light-weight graphical user interface (GUI) for MCX, MMC and MCX-CL. It gives user an intuitive environment to browse and set parameters for a wide range of simulations. It also provides functionalities to save, edit and reopen a set of pre-defined simulations and share among users.

MCXStudio is written in Object Pascal using the open-source Lazarus ( rapid application development (RAD) environment and LCL (Lazarus component library). The OpenGL rendering of the GUI is provided by the GLScene Library (

MCXStudio is cross-platform and can run on Windows, Linux and Mac OS. The GUI itself does not contain any Monte Carlo (MC) modeling capability. Instead, it serves as a shell within which one can launch MC simulations by calling externally compiled mcx, mmc and mcxcl binaries.

MCXStudio contains many features that are designed to ease the pre-processing, simulation and post-processing for MC simulations. It is compatible with mcx (NVIDIA GPU), mmc (CPU) and mcxcl (cross-vendor CPUs/GPUs). It has a built-in domain designer, source designer with a convenient panel for media/detector settings. It also supports visualization of simulation output data (mc2, nii, hdr/img) using the built-in 3D volumetric data renderer. One can also launch remote MCX/MMC simulations using the Remote Execution panel.

2. Installation

MCXStudio is portable and can be directly executed without installation. However, in order for MCXStudio to find mcx/mmc/mcxcl binaries, you should use one of the following methods

  1. place mcx/mmc/mcxcl executables side-by-side with the mcxstudio executable
  2. modify system environment variable and add the full paths to mcx/mmc/mcxcl to the PATH variable
  3. create a MCXSuite/ subfolder in the same directory storing mcxstudio, and extract mcx/mmc/mcxcl binary packags inside MCXSuite/ folder, so that one has the following folder structure

  |-  MCXSuite/
  |      |- mcx/bin/mcx
  |      |- mcxcl/bin/mcxcl
  |      |- mmc/bin/mmc
  |-  mcxstudio
  |-  mcxshow
  |-  mcxviewer

If you download and unzip the released MCXStudio package, the above folder structure already exists, and you can simply double click on the mcxstudio executable to start the program.

For windows users, the first time to start MCXStudio, you may see a popup window asking you that your system registry needs to be modified in order for MCX/MCXCL to run more than 5 seconds. You must click "yes" and then reboot the computer in order for this setting to be effective.

If you click yes and receive a permission error, you have to first quit MCXStudio, and then right-click on the mcxstudio executable and select "Run as administrator", then accept the prompt.

Alternatively, one should open file browser, navigate into mcx/setup/win64 folder, and right-click on the "apply_timeout_registry_fix.bat" file and select "Run as Administrator".

You must reboot your computer for this change to be effective!

For Mac users, when double-clicking on the mcxstudio application icon, if you see a popup window warning "This application 'mcxstudio' can't be opened", you must first remove the quarantine attribute from the unzipped files before you can run it. To remove the quarantine attributes from all mcx files, you should open a Terminal, and run the below commands

  cd /path/to/MCXStudio
  xattr -dr .

After applying the above command, you should be able to start mcxstudio (and mcxshow, mcxviewer applications) by double-clicking on their icons.

3. Using MCX Studio GUI

Once MCXStudio is launched, it first checks if the mcx binary presents in the system search paths; if yes, the "GPU" button on the toolbar becomes enabled. If you do not have an NVIDIA GPU and intend to use mcxcl for your simulations, you may click on the "New" button in the toolbar, and select the 3rd option (NVIDIA/AMD/Inte CPUs/GPUs MCX-CL). After selecting "OK", and if mcxcl binary presents in your folders, the GPU button will also become active.

It is recommended to click on the GPU button once, and verify if you have compatible GPUs or processors suitables to run MCX or MCXCL simulations. If you are able to see printed information in a message window, your system is ready to run MCX (or mcxcl). If you get an error message or not able to see any usable GPU, please check the drivers and the binary files.

If your system is verified to support MCX/MCXCL, you can now create new simulations by clicking on the "New" button. MCX Studio will ask you to provide a session name for this new simulation. After a valid session name is provide, MCXStudio creates the simulation and set all parameters to a ready-to-run default configuration (containing a 60x60x60 mm^3 homogeneous domain). You should modify the settings based on your needs. Once you finish the adjustment, you should click the "Verify" button to see if there are missing/conflicting settings. If everything looks ok, the "Run" button will become activated. Clicking on it once will start your simulation. If you want to abort the current simulation, you can click the "Stop" button.

You can create multiple tasks with MCX Studio by hitting the "New" button again. The information for all session configurations can be saved as a project file (with a ".mcxp" file extension) by clicking the "Save" button. You can load a previously saved project, containing multiple simulation sessions, back to MCX Studio by clicking the "Load" button.

In both the unzipped binary packags of mcx and mcxcl, under the folder named "examples", one can find a pre-created project file (*_examples.mcxp) for MCXStudio. Loading these files using the "Load" button allows you to see these preconfigured simulation.

On Windows, once you start MCXStudio once, the .mcxp suffix becomes automatically associated with mcxstudio executable. To load a .mcxp file, you can simply double-click on the file, mcxstudio will be started automatically.

4. Remote Execution

MCXStudio not only supports running mmc/mmc/mcxcl simulations on your local computer, but also running those remotely on a more powerful server/cluster. Additional information and video tutorial regarding remote execution can be found at

To use the remote execution feature, one must download and install the needed MC simulator (mcx/mmc/mcxcl) in the remote server first, and make sure those executables can be found by your PATH environment variable. On the client side, no need to change any software structure. Only the remote copy of mcx/mmc or mcxcl will be used. They are not restricted by the processors present on your local computer.

The remote execution is performed using the "ssh" command. One must enable the ssh sever on the remote server in order to run commands remotely, and install ssh/scp client on the local computer (your laptop, for example).

On the server side (where mcx/mmc/mcxcl simulations are executed), if it is a Linux computer, you can install ssh server by using

 sudo apt-get install openssh-server


 sudo dnf install openssh-server

If your server is a Mac machine, you should enable SSH access by clicking on System Preference\Sharing\Remote Login and add your username.

If your remote server is a Windows machine, you can install and enable the builtin ssh sever using the instructions below

On the client-side (where mcxstudio is executed, like your laptop), you should have ssh/scp client software ready. If you use Linux or MacOS, ssh and scp commands are typically included by default. If you use Windows, you may download pscp.exe and plink.exe from the following link

and place the two executables in the same folder as mcxstudio.exe (or add to system PATH).

Key-based SSH authentication

Running mcx/mmc/mcxcl simulations remotely requires one to login a remote server using ssh. Typically, one must type password to login. This is the default process when using MCXStudio. However, if one wants to avoid typing password every time making a connection, one can setup ssh key-based authentication by following the steps in the below link

Clusters with shared file system

If your client computer and server computer have a shared file path (i.e., the folder storing mcxstudio can be both accessed from both computers with the same path, typical for an NFS-based Linux cluster), then, you should check the "Shared file system" in the Remote Execution section of MCXStudio window.

If the simulation is launched on a shared file system, your simulation can involve local files (.bin, meshes etc), and all outputs are stored under MCXStudio/Output/ folder. You may directly call the menus under the Plot button in MCXStudio to plot the volume data.

Remote servers without shared file system

If your client and sever do not have shared file folders, you should uncheck the "Shared file system". This way, MCXStudio will send all needed setting info via ssh command and create the output in the ~/Output directory of the server.

In order for a user to plot the output data, one must click on the Plot button in MCXStudio toolboar, and select one of the Download ... menus to retrieve the file back to your client drive in order to visualize the results. You must have scp commands available for the file transfer to work.

5. Acknowledgement

The icon set was created by Qianqian Fang, with a style inspired by the "Uniform" icon-set URL:

The JSON shape editor uses an function "ShowJSONData" adapted from the "jsonviewer" example in Lazarus. URL:

The MCX volume renderer (mcxviewer) was adapted based on the Texture3D Example provided by the GLScene Project ( The original author of this example is Jurgen Abel. The license for GLScene is

GLScene is distributed under Mozilla Public Licence (MPL 2.0), which means, in short, that it is free for both freeware and commercial use. The code is still copyrighted (in that it isn't public domain), but you can use it in products with closed or open-source freely. The only requirements are: Acknowledge GLScene is used somewhere in your application (in an about box, credits page or printed manual, etc. with at least a link to Modifications made to GLScene units must be made public (no need to publish the full code, only to state which parts were altered, and how), but feel welcome to open-source your code if you so wish. Some Delphi units, API headers and DLLs are included in the GLScene package for convenience but are not part of GLScene, may use different licensing scheme and have different copyright owners, such files have an explicit notice attached to them or placed in their directory.

6. Reference

[1] Qianqian Fang and David A. Boas, "Monte Carlo Simulation of Photon Migration in 3D Turbid Media Accelerated by Graphics Processing Units," Optics Express, vol. 17, issue 22, pp. 20178-20190 (2009).

[2] Leiming Yu, Fanny Nina-Paravecino, David Kaeli, Qianqian Fang, "Scalable and massively parallel Monte Carlo photon transport simulations for heterogeneous computing platforms," J. Biomed. Opt. 23(1), 010504 (2018).

If you use MCX in your research, the author of this software would like you to cite the above papers in your related publications.

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