TrueBeam Linear Accelerator
How it works
The TrueBeam is the newest model of medical linear accelerator, the
mechanism that transforms electrons into photons by shooting them at a
metal target at nearly the speed of light. The energy from that impact
is measured in millions of volts. When the photons, or X-rays, contact
cancer cells, the result is meant to be so lethal that the cancer
cells will lose their ability to reproduce and will then die.
An important part of the new machine's radiation delivery precision
is its built-in imaging capabilities. TrueBeam's on-board imaging
system captures CT scans and fluoroscopy, or movie-like X-ray images
to help doctors ensure that the patient's tumor and normal organs are
positioned with millimeter accuracy, and that motion is properly controlled.
The respiratory gating feature is especially good for tumors in the
chest and belly because it adjusts for movements in tumors, which are
nudged in various directions with each breath. With respiratory
gating, the TrueBeam sends out radiation only when the tumor is within
the beam's line of delivery. In combination with the TrueBeam's
on-board imaging, the effect is a much higher degree of protection for
healthy tissue adjacent to the cancer.
Types of treatments
TrueBeam is used for stereotactic ablative radiotherapy. SABR, also
known as radiosurgery or stereotactic body radiation therapy (SBRT),
is a type of cancer therapy in which very precisely focused beams of
radiation target the tumor. The beams are as exact as a scalpel, but
accomplish tumor destruction without any incisions. The TrueBeam
requires almost the same amount of space as an operating room. It
stands 9 feet tall and 15 feet long, and including all its components,
weighs more than 9 tons. Its curvilinear arm, called a gantry, rotates
in a complete circle to enable treatment from any direction. The level
of control is remarkable considering the weight of the gantry.
Advantages
The TrueBeam linear accelerator is capable of delivering radiation
at a faster dose rate than most conventional linear accelerators. This
advance translates into shorter treatment times for patients. The time
for a typical radiation treatment could be cut in half with the
TrueBeam. Other special features improve the accuracy of treatment so
the overall duration of a course of treatment may also be shortened
from several weeks to just a few days.
More information