The Radiotherapy Workhorse | Radical Radiation Remedy
A linear accelerator is a machine that uses high frequency electromagnetic waves to accelerate electrons. This acceleration is done along a straight acceleration waveguide, hence the word linear. They then smash these electrons into a target to generate x-rays. Linacs come in all shapes and sizes and the x-rays they produce are used in many areas, like research, container x-ray machines, and as we know in Radiotherapy.
Linacs have become the workhorse in radiotherapy after the decline of the cobalt-60 machine. They have many advantageous that make them so versatile, if you’re interested in reading more about Linacs there is a great book called “Engines of Discovery: A Century of particle accelerates” which describes the history of particle accelerator and discusses the revolutionary developments in accelerator design and technology.
In radiotherapy, the accelerated electron beam can either itself be used for treatment. This is called electron beam therapy (EBT). Or, a tungsten target can be placed in the path of the beam causing violent deceleration of the electrons and creates bremsstrahlung or x-rays. This process is like the x-rays created in x-ray tubes.
Linacs have had several advancements over the years to improve patient treatments. They can now modulate and shape the radiation field to shape it to the tumor being treated using Multileaf Collimators. This destroys the cancer cells while sparing the healthy surrounding tissues. They have on board CT imaging to guide the radiotherapy (IGRT). Several internal checking systems to ensure it delivers the dose prescribed by your doctor.
How does a LINAC Work? The Radiotherapy Workhorse
A Linac uses microwave technology, developed in world war 2 radar systems, to accelerate electron in what is called a wave guide. The electrons travel down the waveguide and gain kinetic energy. These electrons are then collided into tungsten target to produce x-rays. These x-rays are then shaped using collimators or MLCs to the patient’s tumor.
The Patient lies on a treatment table and the Linac can rotate around the patient. This allows multiple beams of radiation to target a tumor from different directions. The patient is lighted up to the machine using a laser system to ensure that the patient is in the right position at every treatment. The treatment table can move in many directions. Up, down, left, right, in, and out are the standard directions, but more expensive treatment tables can also rotate
Who operates a Linac?
Radiation therapists operate the Linac when a patient receives their daily treatment. Medical Physicist also operate the machines when checking patient treatment plans or performing machine quality control and calibrations.
How much does a Linac cost?
Linacs are highly complex medical systems with many components that have to work together in order to deliver the correct dose. On top of this are many safety systems to ensure nothing goes wrong. All this means Linacs are expensive devices. The average price of a Linac ranges from 2 to 4 million US, depending on the model, features, and deals offered by the vendors.
Why does everyone leave the room?
Linacs are normally housed in bunkers. A Linac bunker is a room with thick concrete walls so that the high energy x-rays are contained within the rooms to ensure no-one outside the room is exposed to radiation. It is safe to walk around a Linac because unlike a cobalt-60 machine the radiation is only present when the machine is turned on.
When the radiation therapists are ready to give patients their treatment they leave the treatment room. The then continuously monitor the patient using cameras and microphones. Once the treatment is over the radiation therapists will come back inside the room to assist the patient in getting off the treatment couch. The patient does not become radioactive after their treatment either, this is just a myth.
Can you show me a video or a pictures of Linac?
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Originally published at www.radicalradiationremedy.com on January 4, 2017.
