What is the Useful Life of a Linear Accelerator?

The Question of the Linac Lifespan

Some linear accelerators are removed from clinical use after five years.  Others go on to treat patients for 45 years.  At ROS, a global provider of refurbished medical linear accelerators, we have seen the whole spectrum of lifespans.

So what constitutes the recommended lifespan of a linear accelerator?  What drives the replacement cycle?  Why are some replaced sooner vs. later, while others are used for decades?

This is a question that comes up time and again, so we broke this down into a few key areas.

 

Reliability and Performance

Most linear accelerators are built of strong, durable materials, and can last reliably, with proper care and maintenance, for decades.  In the United States, we see linacs being routinely replaced after 15 to 20 years of use.  By the time they reach this age, there is very little value left, and facilities have to pay to have the machines removed or have to include the removal in the purchase of a new machine.

It’s less often we see equipment in use longer, such as a 1997 Siemens Mev77 linear accelerator that was in clinical use for 41 years in Los Angeles.  This is fairly uncommon in the U.S., but this particular machine was housed in such a small vault, that no other machine manufactured today could replace it.  Over its decades of use, the waveguide had been replaced several times, and an aftermarket MLC and portal imaging device had been added to it.

Even today, an older Varian Clinac 6X linear accelerator originally manufactured in 1976 is still treating patients in Paraguay, safely and reliably.  This 44-year old wonder continues to break linear accelerator lifespan records.

 

Care and Usage

The way a linear accelerator is cared for, and how often its used, can also determine its useful life.  Proper maintenance, like adhering to scheduled PMI’s or Preventative Maintenance Inspections, can uncover small problems before they become bigger.  And a good engineering team to look over the equipment can also add years to a linear accelerator’s lifespan, whether your own in-house staff, or those outsourced to an independent service company or to the manufacturer.

Another chief consideration is the linear accelerators usage, often measured in beam hours or filament hours.  Similar to mileage on a car, beam hours indicate the amount of time the beam of the linear accelerator has been activated.  Newer technologies like VMAT (volumetric arc therapy) require much more use of “beam on” time and can reduce the lifespan of a linear accelerator.  Before VMAT became widely used in the United States, a typical linear accelerator, treating 30 patients per day, consumed approximately 250 beam hours.  Today, that number is higher.

Many of the high-use parts of a linear accelerator have a lifespan of 5-7 years.  This does not mean, however, that the entire machine has to be replaced.

 

Technological Advancements and Competition

In the U.S., the typical lifespan of a linear accelerator is 10-12 years.  This isn’t because the machines stop working or can no longer produce accurate and reliable radiation beams, but rather due to technological change.

A new technology may end the life of an older linear accelerator prematurely since the facility/owner may require the new technology for its patients, for its reputation, or to stave off competition.

Some of the major technological advancements that have generated replacement needs have been:  (1) the computerization of linear accelerators in the late 1980’s ; (2) the development of multi-leaf collimators (MLC’s) and portal imaging devices in the 1990’s; (3) the development of KV-Imaging systems for linear accelerators, in the 2000’s; and VMAT, SRS and hypo-fractionation technologies in the 2010’s.

Competition is not to be overlooked.  When a competitor acquires newer technology and starts to pull patients from your center, its generally time for an upgrade or a replacement.

Today, competing technologies like MRI/Linacs, PET/CT Linacs, and even proton therapy machines may also drive shorter lifespans for conventional linear accelerators.

 

 

Software Updates

Whereas in the past, major advancements in linear accelerator hardware drove the demand for replacing a machine, today, it’s more software-related.

In fact, most of the innovation over the last 10 years had more to do with software than with hardware.   The Varian iX/Trilogy, the Varian TrueBeam, and the Elekta Synergy/Infinity linear accelerator systems have been around for 10-15 years, and are still the main workhorse systems being used in the U.S.  What has mostly changed are the computers and software systems, with only some minor hardware upgrades.

But software advancements do not necessarily mean it’s time to replace a machine.  It’s quite possible for a hospital to continually update its existing linear accelerator software and avoid having to change out the entire machine’s hardware.  This may explain why even though manufacturers make annual software upgrades, the lifespan of linear accelerators remains 10-12 years.

 

Conclusion

The recommended lifespan of a linear accelerator is a variable that can differ from facility to facility, country to country, and clinician to clinician.  Much of the need to replace equipment has to do more with the need to keep up with technological advancements than with the loss of reliability and functionality.  In the U.S., typical replacement times are 10-12 years, although some major university hospitals and research centers may replace even more often.  In other parts of the world, 15-20 years may be more typical.  And in some emerging and developing markets, you’ll see lifespans even longer.