Linac is charged particle accelerator, used for the generation of Xrays and to extract the accelerated charges beam. Linac ranges in size, Its geometry depends upon the working principle. In LINAC at its early ages potential plates were used to accelerate charges which is the basic principle to accelerate the charges. For high acceleration then it is required to have many number of plates with in the LINAC. At SLAC the LINAC is 3.2 Km.

Medical Linacs

1    Introduction

 

                                           During  the  past  50 years,  medical  linacs  have  gone through five distinct generations, each one increasingly more sophisticated:

1. Low energy x rays (4-6 MV).\
2. Medium energy x rays (10-15 MV) and electrons.
3. High energy x rays (18-25 MV) and electrons.
4. Computer controlled dual energy linac with electrons.
5. 4 + combined with intensity modulation.
6. 5 + image guidance + motion tracking.

2    Schematic Diagrams of Medical LINAC

2.2    Simple

2.3    Detailed

3    Components of Linac

 

                                                                     Linacs are usually mounted isocentrically and their operational systems are distributed over five major and distinct sections of the machine:

 

1. Gantry
2. Gantry stand and support
3. Modulator cabinet
4. Patient support assembly
5. Control console

3.1    Gantry

                            Gantry contains the Cathode the electron gun, wave-guide, beam transport system, metal target etc. So the there is more weight in the upper portion which makes it difficult for the electric motor to rotate the gantry easily. So, counter weight is placed in the lower portion of the gantry.

3.2    Gantry Stand and Support

                                                                       It provides the support to the gantry. It contains the electronics system, the motor to rotate the gantry, evacuation system, modulator unit etc.

3.3    Modulator Unit

                                             Modulator unit gives the voltage pulses to the electron gun and to the microwave power source (klystron or magnetron).

3.4    Patient Support Assembly

                                                                      Patient support assembly is mainly the couch on which the patient to be irradiated lies down. It has the control panel with which gantry rotation, couch movement are done. 

3.5    Control Console

                                                As its name suggest it controls the medical LINAC. We give commands and linac executes it.

4    Linac Configurations

                                                                    Medical Linac can be mounted in two configurations. Horizontal configuration has advantages of vertical configuration.

to be continued..................................