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A Python Application for Calculating the Output Factors of Electron Cutouts

L Kofman1,2*, J Chang2,3, (1) Tufts University, Medford, MA, (2) Northwell Health, Lake Success, NY, (3) Hofstra University, Hempstead, NY


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: To develop a Python application and graphic user interface for calculating the output factors of electron cutouts of arbitrary shape from available measurement data and compare the accuracy of interpolation by field size and area to determine the optimal expedient of yielding output factors corresponding to field sizes in range.

Methods: This Python application takes the user’s input parameters, including cone size, electron beam energy, and estimated equivalent square field size. It interpolates the output factor of user’s cutout accordingly. The output factor is computed by the square root method and interpolation is performed using the measured output factors of square fields (e.g., 10×10 cm², 6×6 cm², 3×3 cm², etc.), stored in an on-line database and accessed using Python’s indexing methods. Two methods of interpolation – by field size and by area – were tested for 21 electron cutouts, the output factors of which were already measured for clinical use.

Results: Calculation of output factor by interpolated field size values versus interpolated area values evidenced that of the 21 various output factor values computed, 15 of the values yielded a smaller percent error using interpolation by field size. The average percent error was 0.8% for interpolation by field size, and 1.0% for interpolation by area.

Conclusion: We have developed a Python application allowing physicists to calculate the output factor of electron cutout more efficiently, relative to the alternative of human calculations that pose a more prolonged, vexatious task. Preliminary test of this application indicates that interpolation by field size is a viable and accurate method.


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