TrueBeam Linear Accelerator

The TrueBeam Linear Accelerator is one of the world’s leading inventions for administering radiotherapy and surgery to those with cancer. The information below covers all you need to know about the TrueBeam, including what it is, how it works, and what sets it apart from other radiotherapy devices.

What is the TrueBeam Linear Accelerator?

A linear accelerator (LINAC) is a machine that is used to generate high-energy particle beams for external beam radiation therapy^[1]. Linear accelerators are used standalone or as auxiliary particle accelerators that are used to power other external beam devices, such as proton therapy machines.

The TrueBeam Linear Accelerator is a LINAC product developed by Varian, a company that specializes in the invention of cutting-edge medical systems. Unlike auxiliary LINAC systems, TrueBeam generates an energy beam of much higher intensity. It is considered one of the best LINAC systems available to date due to its increased precision and faster dose rate compared to other standard LINACs.^[2]

How It Works

Particle Acceleration and Emission. LINAC systems can accelerate any subatomic particles, with photons being the most common of applications. Either photons or electrons can be used to create LINAC energy beams. Photons are usually generated as a by-product of electron acceleration.^[3] Photons are most often used for internal tumors in compartments of the body that are difficult to reach through standard surgery or other radiotherapy techniques. Electrons are considered harsher and may be used to treat external tumors on or near the skin’s surface. Proton therapy machines may use a LINAC system, yet usually use a microtron (type of smaller cyclotron), which is a similar variant that accelerates protons through a circular motion.

Heat Induction and Particle Generation. To accelerate particles, LINAC generates electrons from a heated metal filament (usually tungsten or tantalum) from a high-voltage source inside a vacuum chamber. The flow of electrons is controlled and accelerated through alternating electrical potentials, which serve to produce a linear (not curved) high-intensity beam of energy that can be controlled like a laser beam.

Multileaf Collimator. The exit point of the LINAC beam is often fitted with a device that moderates the beam’s intensity, known as a multileaf collimator. This device consists of multiple “leaves” or sheets of tungsten or another similar metal. Each of the leaves can be adjusted, moving in or out of the beam’s path, which serves to dampen or heighten the energy level of the emission. Multileaf collimators can also be used to shape the beam to a certain degree and are a requirement in medical settings for precision targeting.

TrueBeam LINAC works on the same principles as a standard LINAC system, yet with higher speed, more power and better precision. The TrueBeam multileaf collimator comprises 120 computer-controlled sheets (more than double the 52-leaf standard) that enable extreme control over beam intensity and a much higher degree of precision^[4]. The device is able to rotate around the patient using a gantry that can target the destination tissue from multiple angles.

Medical Applications and Therapeutic Benefits

Like the majority of radiotherapy devices, the TrueBeam Linear Accelerator is mainly used to administer radiotherapy and to treat and obliterate tumors that are difficult to reach. In a medical setting, a LINAC is operated by a medical physicist and dosimetrist who ensure that the oncologist’s radiation prescription is met.^[5] The TrueBeam’s features allow it to offer several types of external beam radiation therapy, including image-guided radiation therapy, volumetric modulated arc therapy and intensity modulated radiation therapy.

In addition to offering above-average radiotherapy, the TrueBeam can administer total skin electron therapy (a specific technique used to treat those with cutaneous lymphoma^[6]) and low-dose total body irradiation (used for complete immunosuppression).

TrueBeam LINAC systems have been used to treat many types of cancer with a high degree of success. Preliminary trials reveal that it may serve as a promising treatment for those with trigeminal neuralgia^[7].

Top Features of the TrueBeam Linear Accelerator

Integrative CBCT Imaging. The TrueBeam Linear Accelerator does its own in-depth 3D imaging to assess the location of the tumor, making use of some of the most advanced cone beam CT scan technology available. The TrueBeam imaging system is known to be one of the most sophisticated of its kind, being able to accurately survey over 100,000 points of data. It updates the image every 10 milliseconds, which is a faster visual refresh rate than the brain is capable of decoding, allowing for seamless integration of the computer interface with the patient and the beam’s focal point.

Precision Targeting. The TrueBeam system makes use of a technique known as respiratory gating, where the machine is programmed to send out the beam only when the target is in alignment. The base that holds the patient, known as the platform couch, also adjusts the patient’s position down to sub-millimeters of precision. Thanks to these latest innovations, the patient’s involuntary movements, such as breathing or blinking, will not affect the accuracy of the procedure and allow for a continuous stream of high-energy particles to remain on target. As a result, the TrueBeam has solved one of the most difficult challenges that previously faced external beam manufacturers.

More Accurate Than Standard LINAC Systems. When adjusting the beam for higher accuracy, the industry standard accepts an error rate of roughly 2%. The accuracy of the TrueBeam linear accelerator falls far beneath this standard, incurring an error rate of 1.2% for photons and 1% for electrons. Error rates can be further reduced through calibration of the device, down to 0.5% for both particle emissions.^[8] While these results are possible, the degree of calibration and its success depends on the operator and technique used.

Saves Time. According to a Varian press release, TrueBeam Linear Accelerators are capable of delivering radiation doses of up to 2400MU per minute, which is twice the rate of most standard radiotherapy machines on the market. The improved imaging technology that follows the patient’s movements is also noted to reduce the treatment time by up to 60%. Even years after its release, the TrueBeam has proven to be faster than other new radiotherapy systems at precision imaging.^[9]

How TrueBeam Linear Accelerators Differ from Other Radiotherapy Devices

The TrueBeam Linear Accelerator is truly ahead of other LINAC systems of its time. It incorporates many features of other radiotherapy systems, including CT scanning, providing a comprehensive, all-in-one medical system that can be used for all oncological needs. Most of the TrueBeam’s features surpass other radiotherapy systems from a technological perspective.

TrueBeam vs CyberKnife. Studies show that TrueBeam technology delivers comparable levels of high-intensity energy to that of the CyberKnife, making it as suitable for radiosurgery^[10]. Other findings suggest it may be superior to the CyberKnife in various surgical applications from the perspective that it can administer less radiation to the patient in a shorter space of time. The CyberKnife is better suited to minimizing relative radiation to nearby structures yet may deliver more overall body radiation than linear accelerators.^[11]

TrueBeam vs Proton Therapy. The TrueBeam linear accelerator may be able to radiate the body less than the CyberKnife, however, according to preliminary studies, proton therapy may still offer less intense radiation and adverse effects than the TrueBeam^[12].

Conclusion

The TrueBeam Linear Accelerator is a cutting-edge medical invention by Varian that can be used for the vast majority of radiotherapy and surgery applications. Unlike other LINAC systems, it can deliver twice as much energy at twice the velocity. The TrueBeam has one of the most comprehensive built-in 3D imaging systems that keep track of the target every 10 milliseconds. Coupled with its incredible selectivity and beam sensitivity, the TrueBeam is expected to remain at the forefront of radiation treatments for years to come.

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