Technology | February 14, 2012

Sixth Generation Elekta Control System Boosts Radiation Therapy System Speed, Performance

February 14, 2012 — The advanced functionality of Elekta's family of digital linear accelerators demands a high degree of intelligent coordination. Elekta's latest control system, Integrity R1.1, provides this with three tiers of safety, command of MLC interdigitation for exceptional field shaping, and support of virtually limitless options to adjust the radiation dose.

Integrity R1.1 has undergone rigorous tests in eight international centers, demonstrating safe reductions in treatment delivery times of as high as 30 percent. The receipt of 510(k) clearance for Integrity R1.1 enables United States medical centers to realize these treatment speed and safety benefits when Elekta begins delivery of the control systems.

"I appreciate the use of multiple measures to ensure correct treatment delivery," said Jonas Fontenot, Ph.D., physicist at Mary Bird Perkins Cancer Center, Baton Rouge, La., which has been evaluating a previous release of Integrity since February 2011. "In addition, during volumetric modulated radiation therapy [VMAT], Integrity constantly captures delivery parameters and sends them back to our Mosaiq oncology information system, where they become part of the patient's electronic record."

With interdigitation of MLCi2 enabled by Integrity R1.1, MLC capabilities have caught up with the ability of the treatment planning system to create fields with complex geometry. Because MLC leaves can move past one another – or interdigitate – clinicians can employ island fields in difficult cases, such as those involving multiple targets.

"Interdigitation is important for treating multiple targets – such as multiple brain mets – and also when there is a target geometry that consists of different dose objectives," said Fontenot. "For example, we may want to treat a primary target to 70 Gy and a nodal region to 57 Gy."

Integrity R1.1 supports continuously variable dose rate (CVDR), which allows the dose rate to be adjusted to its ideal value during delivery of both dynamic and VMAT prescriptions. This makes prescription delivery smoother and faster when compared to previous discrete dose rates.

"The additional dose rate options permit the control system to easily navigate complex dose modulation paths," explained Fontenot. "Less variability in gantry speed smoothes VMAT arc motion, which also translates to reduced delivery times."

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