Functions of the Linear Accelerator
Target Audience: Customers
Jessica Merrick
What is it?
Figure 1: LINACS
Source:https://www.ecri.org/PatientSafety/Pages/Linear
_Accelerators_Radiotherapy_Units_Cobalt.aspx
A linear accelerator (LINACS) is used for
radiotherapy. It shoots beams of radiation to
tumors to kill cancer cells without affecting the
rest of the body. LINACS emit a beam radiation
of different energies, depending on the
accelerator, and some can even emit beams of
electrons. LINACS are used primarily to treat
bone cancer and tumors of the head, neck, and
breast. High-energy linear accelerators
can treat tumors of the pelvis and thorax. Any hospital
that specializes in radiotherapy will benefit greatly
from this product.
Major Parts
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Wave guide: a metal tube, or other
device, that guides the radiation to the
site it is needed.
Modulator: amplifies power supply so
that it produces high-voltage pulses. It
is then used to power the electron gun
and the RF power source. This
controls the amount of radiation that
hits the tumor. There should never be
too much or too little radiation hitting
the cancer cells.
Electron gun: electron-emitting
cathode. Also directs and focuses the
electrons. Making sure that the
radiation does not hit any cells other
than the cancer cells is very important.
Figure 2: Components of LINACS
Source:https://www.ecri.org/PatientSafety/Pages/Linear_Ac
celerators_Radiotherapy_Units_Cobalt.aspx
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Radio frequency (RF) power source: supplies high-frequency electromagnetic
waves that amplify the power of a low-energy source. The RF power source
supplies the correct power of radiation.
Accelerator guide: speeds up the reaction of the radiation.
Electron beam: can be used for treatment or can be directed toward a metallic
target to produce x-rays.
Gantry: a moveable framework. The gantry has the ability to move 360 degrees
around the patient’s body so that the wave guide has easier access to the
infected site.
Operation of the Linear Accelerator
Radiation therapy has become a primary treatment for cancer, along with chemotherapy
and surgery. Radiation is used to treat 50% of all cancer cases, and many patients
receive a combination of all three modalities. For successful treatment, the radiation
field must be very carefully calibrated and well defined to avoid irradiating healthy
tissue. Radiation oncologists prescribe the right dosage of radiation, the medical
radiation physicist determines how to deliver the dosage and the time needed, and the
radiation therapist operates the linear accelerator. The dosage of radiation is prescribed
based on the size of the tumor. If the patient has a tennis ball-sized tumor, they will be
prescribed a large amount of radiation. If the patient has a golf ball-sized tumor, they will
be prescribed a smaller amount of radiation than would be prescribed for a tennis ballsized tumor.
How does it work?
The linear accelerator uses microwave technology to accelerate electrons in the wave
guide, the electrons then collide with a metal target. High-energy x-rays are produced
from the collision; these x-rays are shaped to conform to the tumor as the exit the
machine. The beam of x-rays comes from the electron gun. The gantry can be rotated
around the patient so that the radiation can get to a tumor in any part of the body.
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Works Cited
"Linear Accelerator: Radiotherapy Units, Cobalt." ECRI Institute . N.p., n.d. Web. 25 Feb. 2013.
"Linear Accelerator (LINAC)." Mobile Radiology Info. N.p., n.d. Web. 28 Feb. 2013.
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