OHSU

Elekta's Monaco System Used for First Time to Create VMAT Plan for Delivery on Varian Treatment System

11/09/12  Portland, Ore.

The Department of Radiation Medicine at Oregon Health & Science University's (OHSU) Knight Cancer Institute was first to treat a cancer patient using Elekta's Monaco® software to create a Volumetric Modulated Arc Therapy (VMAT) treatment plan and then deliver it on a Varian Trilogy® treatment machine. Prior to this first clinical use combining Monaco VMAT and Trilogy, OHSU physicists had produced Monaco test plans using prior treatment data from 15 patients, the plans for which had been generated using their customary planning system.

The Monaco test plans compared favorably to the clinical plans in three crucial aspects, said Wolfram Laub, Ph.D., M.B.A., chief physicist for the OHSU Knight Cancer Institute's radiation medicine department and clinical associate professor at OHSU.

"First, Monaco uses the XVMC Monte Carlo dose engine, which is considered the gold standard for dose calculation," he said. "Comparing the Monaco plans to those produced by our usual planning system, I noticed higher volumes of normal tissues exposed to low radiation dose levels, which I attribute to the fact that Monte Carlo can more accurately account for photon scatter."

Dr. Laub, who serves as a consultant for Elekta, believes that the Monaco treatment plans tend to be less complex in terms of the shape of IMRT segments, when producing the same quality plans. QA passing rates on average have been observed to be higher. "Less complexity is always better as long as it doesn't impact plan quality," he said. 

The third observation regarding the Monaco plans applies to the advantages of using biological constraints. "I believe that biological constraints give a great deal of control over a treatment plan. They allow the use of templates, or what I call a 'class solution,' which is not possible to the same extent when dosimetrists use DVH constraints for optimization - since those really need to be tailored for each patient."
The latest version of Monaco (v.3.20) features the new Segment Shape Optimization(TM) tool, which drives improved dose conformity, plan quality and delivery efficiency, he added.

The OHSU Knight Cancer Institute's radiation oncology team has already begun treating a second cancer patient using the Monaco VMAT/Trilogy combination.

Monaco works seamlessly with ARIA OISDr. Laub also has found that Monaco is compatible with Varian's ARIA® oncology information system (OIS) as well.

The typical workflow entails sending the CT simulation scan to their existing planning system, which is used for contouring. The contours and CT scan are subsequently exported from the planning system into Monaco.

"We then run the optimization in Monaco, import everything back into ARIA for record-and-verify, and that's where the plan gets approved and sent to the treatment machine," he explains. "It's pretty seamless, actually."

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