Question

In proton-beam therapy, a high-energy beam of protons is fired at a tumor. The protons come to rest in the tumor, depositing their kinetic energy and breaking apart the tumor’s DNA, thus killing its cells. For one patient, it is desired that 0.10 J of proton energy be deposited in a tumor. To create the proton beam, the protons are accelerated from rest through a 19MV potential difference.

What is the total charge of the protons that must be fired at the tumor to deposit the required energy?

Answer 1

q =E/U =0.1/19•10⁶ =5.26•10⁻⁹ C