Dosimetry Calculation in Human Glioblastoma for Radiotherapy: a Graphical User Interface with Monte Carlo Simulations

We developed a graphical user interface based on GEANT4 and GATE to calculate particle interactions and absorbed dose estimates in phantoms and small animals such as mice. In the present work, we extended the interface to absorbed dose calculation and particle interactions in humans based on 3D CT images and radiation beam definition in a clinical setting. The images of the subject and of the beams were supplied in DICOM format. All the parameters needed to calculate the absorbed dose were obtained from these DICOM images. In this work, images of a human brain with glioblastoma were used together with the parameters of five photon beams defined in the clinic. The DICOM file of the beams contained several parameter values such as beam energy, in this case 6 MV, the dose to be deposited in the tumor as a total of 60 Gy, and the 5 beams orientation. Based on the 3D CT images of the patient brain, the whole patient head was rebuilt from the voxel intensity and size providing the real dimensions and calculated density of the head. The results show how the primary photons and secondary particles interact in the brain, and a 3D dose grid similar in dimensions and spatial resolution to the supplied images of the brain was obtained representing the absorbed dose in Gy. In conclusion, with this new interface, it is simple to enter geometrical objects, animal or human 3D images, to select the appropriate tasks from menus, and to run the simulation without the need to be familiar with computer programming or investigating the many classes of GEANT4 or GATE. The interface can also be used to simulate any type of radiation beams provided by the DICOM-RT set of the subjects.