Linear Accelerator

What is a Linear Accelerator?

A linear accelerator is also named as a linear particle accelerator. In radiation therapy, this linear particle acceleration is used for medicinal purposes because it produces the x-rays and electrons that have high energy. Hence the linear particle accelerator is used for many therapeutic applications. Also, they are useful in particle physics because they can produce the highest kinetic energy that can be achieved directly by the linear accelerator. Furthermore, a linear accelerator is suitable for electrons and protons in particle physics to get high kinetic energy. 


The linear accelerator sometimes called linac is a kind of particle accelerator that has the capability to increase the charged subatomic particles or we can say ions where charged particles are subjected to a series of electric potentials that ate oscillating along with the linear beamline. Well, such a method of charged particle acceleration was the first experimented by Leo Szilard. Cancer cells can be cured with medicine in which ionizing radiation damages the DNA of cells.


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Linear Accelerator Construction And Working

A linear accelerator is a machine that can accelerate electrons close to the speed of light with an electromagnetic field. Electrons or protons with more than 18 MeV are bombarding to the target, and higher kinetic energy is produced. In a tungsten target, the particles produce the bremsstrahlung radiation like in the convectional tube of X-ray. Well, the design of the LINAC machine is different from the x-ray tube because of higher energy. 


Components of a Linear Accelerator

Here are the steps and essential components to generate high energy photons. 


Electron Generation Component: Guide and generate electrons into the accelerating waveguide.


Electron Acceleration Component: Accelerate the electrons nearly to the light speed. 


Beam Transport: Transport the electrons to the target.


Ionization Chambers, Collimation and Flattering Filters: Modify the beam before use 


Several Accessories For Linear Acceleration Working:

Radiofrequency Generator: Generates electromagnetic waves in the component.


Pulse Modulator: Produces timed energy pulses to the RF generator and electron gun. 


Control Panel: operational panel to control the function of the linear accelerator. 


Linear Accelerator Working Principle: How Does a Linear Accelerator Work?

In a linear particle accelerator, drift tube has positive potential while electrons have a negative potential. A bunch of electrons are accelerated to the drift tube because of this potential difference. RF source changes its polarity as soon as the particles enter the first drift tube. Hence, the first drift tube becomes negatively charged, but the second drift tube is positively charged. The inertia of electrons makes them come out from the drift tube. So, electrons are pushed into the first tube, and at the same time, they are attracted to the second tube in the same direction. 


Electrons’ velocity turns bigger because of their acceleration. So, this is the reason why drift tubes are longer. Speed of electrons increases as soon as electrons come closer to the target. LINAC is long because of longer drift tubes, and the number of tubes is also higher. 


Who Operates this Equipment?

Mostly the radiation oncologists prescribe the treatment dosage and volume to the patients. Furthermore, dosimetrist and medical physicist will decide the amount and time of dosage, calculating the time for acceleration. Radiation therapy also includes linear acceleration, and therapists may give radiation medication on regular bases to the patients. 


Application of Linear Accelerator

Different industries, researches and medicines include the various usage of this highly efficient accelerator for a different purpose. 


LINAC Synchrotron Injector: It is the first stage for any high energy accelerator. 

Semiconductor Processing: To process various semiconductors.


Boron Neutron Capture Therapy (BNCT): In this therapy, nuclear reactors are used conventionally as a neutron source. LINAC-based source of the neutron can provide a better-controlled energy spectrum of the neutron. It is a low -cost machine that produces less reactor associated radioactive waste  


Isotope Production: Linear particle accelerators are ideal for producing isotopes like PET isotopes. 


Linear Accelerator Safety

LINAC machines are used for cancer treatment, and it produces higher radioactive energy. So, this machine may harm patients in many ways, but it is essential to ensure linear accelerator safety for cancer patients. 


Radio oncologist will first plan the proper treatment according to the patient’s medical reports. So, before the treatment, the plan is made with the help of dosimetrist and radiation physicist. 


Quality procedures are there that ensures the quality treatment, and before the surgery, the plan is checked thoroughly. Also, the process includes the surety of therapy to deliver in a planned manner. LINAC is designed for controlled radiation, and doctors can set according to the treatment. 


Tracker is a particular machine to check the proper functioning of the machine, and a radiation therapist will check the device before the treatment every morning. The tracker monitors the radiation velocity and intensity to ensure the uniform functioning of beams. 


In this process, a radiation physicist also does monthly and weekly checking of the device.

FAQ (Frequently Asked Questions)

1. Who Invented the Linear Accelerator or LINAC?

A linear accelerator is the best example of the outcome of translation researches that help to treat the cancer patients successfully. In 1924, Gustav Icing had purposed the principle of the linear particle accelerator. After four years, in 1928, Rolf Wideroe had invented the actual machine that achieves the noticeable higher energy of electrons. He had developed this machine at RWTH Aachen University. Mainly this machine delivers the highest kinetic energy for medical purpose.

2.  What is a Linear Accelerator Used for?

LINAC or a linear particle accelerator device is used in cancer treatment to provide radiation of external beam to the cancer patients. In radiation therapy, radiation oncologists team up with medical physicists and dosimetrist to prepare the personalized radiation treatment for different cancer patients for effective results. Radiation therapist also includes the delivery method of radiation, time of the medication and dosage. Well, cancer in the organ of the body can be treated with a linear accelerator. Different ways are used for the different body parts depending on the cancer type and organ of cancer tumour. Various techniques for radiation delivery are as follows:

  1. Conventional external beam radiation therapy

  2. Intensity-modulated radiation therapy

  3. Image-guided radiation therapy

  4. Stereotactic body radiation therapy