Whitepaper on the science behind RadCalc EPID
Exit-Transit Dose Reconstruction Option first developed with Dosimetry Check
The paper outlines the methodology involving the use of Electronic Portal Imaging Device (EPID) and Monte Carlo simulations to model the point spread response of EPID. The authors propose a deconvolution process to transform EPID images back to in-air x-ray intensity fluence, considering factors like transmission through the patient, scatter from the patient, and limitations associated with large fields and thicknesses. The paper addresses details of the involved physics to provide understanding of corrections for air gap variations, attenuation by the patient, and scatter effects, providing insights into the computational challenges and strategies first used for practical implementation.
With the end of support for Dosimetry Check, we have incorporated Dosimetry Check’s 3D EPID dose calculation technology into RadCalc and improved a variety of correction factors and curve fitting methods. This expanded QA platform will provide all RadCalc’s core dose verification and 3D dose volume functionality while adding support for conventional linac EPID-based patient pre-treatment and exit-transit dosimetry using a collapsed cone convolution superposition algorithm. This makes RadCalc to a single platform for all patient QA needs.