A graphical user interface for an electron monitor unit calculator using a sector‐integration algorithm and exponential curve‐fitting method

A new electron monitor unit (MU) calculator program called ?eMUc? was developed to provide a convenient electron MU calculation platform for the physics and radiotherapy staff in electron radiotherapy. The program was written using the Microsoft Visual Basic.net framework, and has a user-friendly front-end window with the following features: (1) Apart from using the well known polynomial curve fitting method for the interpolation and extrapolation of relative output factors (ROFs), an exponential curve fitting method was used to obtain better results; (2) A new algorithm was used to acquire the radius in each angular segment in the irregular electron field during the sector-integration; (3) A comprehensive graphical user interface running on the Microsoft Windows operating system was used; (4) Importing irregular electron cutout field images to the calculator program was simplified by using only a commercial optical scanner; (5) Interlocks were provided when the input patient treatment parameters could not be handled by the calculator database accurately; and (6) A patient treatment record could be printed out as an electronic file or hardcopy and transferred to the patient database. The data acquisition mainly required ROF measurements using various circular cutouts for all the available electron energies and applicators for our Varian 21 EX linear accelerator. To verify and implement the calculator, the measured results using our specific designed irregular and clinical cutouts were compared to those predicted by the calculator. Both agreed well with an error of ± 2 %.