Line Plot from Scientific Research

Beam size at the isocentre for different energy beams (with an uncertainty of ±3%). In general, the treatment planning system defines the beam using a 1 σ value ( σ is the standard deviation of the distribution of sizes of the beam). Consequently, we utilize the 1 σ value as the definition at the isocentre. In a and b , the lines connecting two data points represent the approximate transmission values.

DOI