When buying a used or refurbished linear accelerator, how important are the HV hours, also known as “beam hours?”
Beam hours for linear accelerator are like the mileage on a car. They reflect the amount of time that beam has been on, and therefore are a good indication of the “wear and tear” on a particular machine.
Generally speaking, machines with higher beam hours will sell for less than those with lower beam hours, all other things being equal. Of course, there are dozens of other variables that influence the price of a linear accelerator, like the age, technologies and upgrades.
The chart below reflects our opinion of the maximum number of beam hours for a pre-owned machine that will be re-installed without a major refurbishment. The axis on the left reflects the intended level of use of the machine at its new location. The scale is relative, and we use “number of patients/day” being treated as a general measure. This axis indicates, in a general sense, how many beam hours are expected to be consumed at the new installation site. The more patients per day, the more beam hours. It is important to note that using IMRT and VMAT consumes more beam hours.
Maximum Beam Hours Recommended for a Pre-Owned LINAC
The horizontal axis reflects the age, in years, that the pre-owned machine is expected to be in place at the new installation site. Some facilities purchase a pre-owned machine only as a temporary need. Others intend to keep it longer. The three boxes in the top row reflect sites that intend to keep a pre-owned linac for four years, for eight years, and for 12 years.
The box on the lower left (3000 beam hours) reflects a site that intends to keep its pre-owned linear accelerator in operation for approximately five years. Most likely, the pre-owned linear accelerator is a temporary solution until the site builds up a revenue base to afford a brand new machine. Because the expected patient volume will be low at the new site, it won’t consume many beam hours. And because the machine will be replaced in the next five years, it’s not important for the machine to have very low beam hours. So we recommend that for a site like this, it’s okay to install a machine with higher beam hours.
On the opposite side, in the upper right box (1000 beam hours), the site intends to keep the pre-owned machine for the next 15 years, and has no need to replace it with a new machine. Sites like this are typical in Latin America, where the need for the “latest and greatest” technologies is outweighed by the need for reliable, effective, practical radiation therapy. This machine will also be treating a great many patients per day, and hence the expected beam hour consumption will be high. For such a site, the maximum beam hours on the machine to be installed should be low, or closer to 1,000.
These figures are general guidelines, since with proper maintenance and parts-replacements, many pre-owned machines can last for decades, even when purchased with higher beam hours. In general, however, we see machines that reach 3,500 to 4,500 beam hours, and higher, to require ongoing repairs, and are therefore good candidates for replacement.
See Tips for Buying a Linear Accelerator for more information.
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