Which electron beam's diameter (field size)is most likely to have an effect on a 20-MeV beam's surface dose and percent depth dose?

Question

Quizplus · Accepted Answer

There is little effect of field size on both surface dose and percent depth dose of electron beams,provided the fields are of sufficient size.The rule is that the electron beam's diameter (field size)in centimeters should not be less than the practical range.

Which Electron Beam's Diameter (Field Size)is Most Likely to Have