- gradually replaces the cobalt-60
- produces gamma rays, x-rays and electrons; more energetic than cobalt-60.
- operates at 4 MeV to 20 MeV
- the charged particles travel in a straight line as they gain energy from alternating EM field.
- higher energy beams can be generated with greater skin sparing.
- field edges are more abruptly design with less penumbra and personnel receive less exposure to radiation leakage.
- provides better isodose distribution (greater dose to the tumor and less dose to normal tissues)
- fastest dose rate and more manageable radiation protection concerns.
• LINACS producing electrons- for shallow lesions and superficial lesions
Major Components:
1. Drive Stand- contains the apparatus that drives the LINACS like gauges, tanks an buttons.
a. Klystron/ Magnetron- most important part of LINAC; provides the source of microwave power that is used to accelerate electrons.
b. Waveguide- hallow tubular structures.
c. Circulator- directs the RF energy into the waveguide and prevents any reflected microwaves from returning to klystron/magnetron.
d. Cooling System- allows many components or assemblies in the gantry drive stand to operate the constant temperature.
- absorbs the heat generated by the machine.
2. Gantry- most important; contains the source.
- responsible for directing the x-ray photon or the electron beam at the patient’s tumor.
a. Electron Gun- responsible for producing electrons and injecting them into the accelerator structure.
b. Accelerator Structure or Guide- It is where the microwave power is transported on which corrugations are used to slow up the waves.
c. Treatment head- contains the source; most important in the gantry.
d. Beam Stopper or Counterweight- optional; balances the lead shielding.
-made of lead and helps the machine rotate smoothly and provides additional shielding.
3. Control Console- monitors and controls the LINAC.
4. Treatment Couch or Patient Support Assembly (PSA)
- area on which the patients are positioned to receive their radiation treatment.
- looks like a table.
LINACs facility should be securely installed in steel buildings to protect both the workers and the patients.
