Quality assurance for Varian 21EX linear accelerator

1. Physics Quality Assurance Varian 21EX Linear Accelerator (LINAC)

2. Linear Accelerator Gantry Electrons are accelerated to energies of several million electron volts.

3. Linear Accelerator Block Diagram

4. Linear Accelerator Treatment Head The electrons strike a target to produce x-rays or they strike a scattering foil to treat directly with electrons.

6. Fields can be shaped by using custom made blocks or multileaf collimators attached to the treatment head l

8. This shows the ionization chamber in the water tank. It is connected to the electrometer located outside the room at the control console with a long cable. The TG51 protocol specifies the depth at which the calibration is performed.

17. This device is used each day to check the calibration, energy, symmetry and flatness of each beam energy. If any of these parameters fall outside of limits set by the physicist, the reason must be determined and corrected before patient treatments can be performed.

18. Lasers on the walls and ceiling are used to set up the patient on the treatment couch. This device is used to check the accuracy of the laser positions.