Generation of dose calculation data tables using cubic spline interpolation

In order to calculate treatment machine settings for a teletherapy machine (e.g., time or monitor units), tables are usually used for variables such as output factor, TMR, percent depth dose. The tables are often generated from data collected at a few points. A linear interpolation is usually used to generate values between the measured points. This can introduce errors as great as 2% between the calculated and actual data points. Using a mathematical software package a computer can generate smooth, accurate curves that agree with measured values to within a few tenths of a percent. This method is not an averaging type of procedure by which a certain function is chosen and parameters are adjusted to force the function to fit the data as closely as possible, but rather is a procedure that fits curves exactly through the measured data points.