What Is RapidArc®?

RapidArc® is a type of radiotherapy technology developed for the treatment of cancer. Cedric X. Yu, the director of medical physics and professor in the department of radiation oncology at the University of Maryland in College Park, is credited with the invention of RapidArc® in 1995. RapidArc® is manufactured by California-based Varian Medical Systems, a medical devices and software manufacturer that specializes in cancers and other deadly diseases by using methods such as radiation therapy, as well as brachytherapy, proton therapy and radiosurgery. In some circles, it is hailed as a highly advanced step in radiation oncology, the study of using radiation to battle cancer.

The machine using RapidArc® technology has a linear accelerator gantry, which is a device used for administering the radiation therapy. This is accomplished by rotating it in a single continuous 360-degree motion for a three-dimensional distribution. During therapy, the machine changes three parameters. They are the gentry’s rotation speed, the shape of the beam used for radiation by employing a dynamic multileaf collimator (MLC), and the rate of the dose delivery.

Altogether, the RapidArc® administration lasts no more than two minutes. The three-parameter algorithm is for ensuring the precision of the radiation, consequently sparing the surrounding normal healthy tissue around the tumor that would otherwise be destroyed. Regulating gantry speed in particular establishes a single optimized dosage.

Some oncologists promote RapidArc® as a more advanced cancer treatment technique than intensity-modulated radiotherapy (IMRT). This is the most common form of radiation therapy. Many physicians or medical researchers draw comparisons between RapidArc® and IMRT in that both methods involve the ability to change the radiation’s intensity during treatment so that as much healthy tissue as possible can be spared.

Unlike RapidArc®, treatment with IMRT usually takes longer, about 15 to 20 minutes. This is because the machine has to make several rotations around the patient to administer the dose. Moreover, during these rotations, the machine must be stopped to adjust the beam’s intensity, then started again to resume treatment.

Supporters of RapidArc® also contend that IMRT is less effective. In a plan comparison that Varian Medical Systems has posted on its website, IMRT required 1,685 monitor units (MU) to target tumors at the head and neck. The RapidArc® machine only needed 496 MU. The latter plan also took less than a minute and 20 seconds to administer.