January 9, 2012 – Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) delivery techniques have dramatically reduced treatment times for thousands of patients. An obstacle to offering this technique to more patients is the time it takes to create a VMAT plan. Physicians at St. James's University Hospital – the first in the United Kingdom to use the Monaco treatment planning system clinically – have been able to significantly reduce VMAT planning times, increasing the potential to offer this advanced therapy to greater numbers of patients.
Elekta VMAT is an advanced radiation therapy technique that delivers treatment in one or more continuous high-speed arcs around the patient, enabling the radiation dose to precisely conform to a tumor by modulating the radiation beam's intensity in multiple small volumes. The key to rapidly developing Elekta VMAT plans lies in understanding the principles of efficiently producing traditional IMRT plans with step-and-shoot (i.e., non-dynamic) delivery. Medical physics staff at St. James's have used Monaco since January 2011 to plan head-and-neck IMRT cases.
"Our referral rate for radiation therapy is expanding by over seven percent annually," says St. James's head of radiotherapy physics Vivian Cosgrove, Ph.D. "We see VMAT as a key way to manage that growth. If we can plan complex radiotherapy quickly and deliver treatment more efficiently with VMAT, then we can treat more patients and derive more benefit from our existing fleet of treatment machines."
"Monaco has transformed our IMRT service," Cosgrove notes. "After contouring, we can complete a complex head-and-neck plan in two to three hours. This is two to three times quicker than other planning systems we have used. Since we introduced Monaco clinically, we have been able to significantly increase the number of patients receiving intensity modulated treatment: over 260 patients in 2011 and a target to increase this further in 2012."
That number includes many patients who have received VMAT planned with Monaco, which St. James's clinicians began performing in August 2011 on one of its 12 Elekta digital accelerators. VMAT delivery of head-and-neck cases takes 6.5 minutes, half the time of a seven-field step-and-shoot delivery.
Monaco VMAT for lung SBRT
St. James's physicians are eager to begin using Monaco to plan Elekta VMAT for lung stereotactic body radiotherapy (SBRT) cases, in which the shorter delivery time will minimize the risk of patient movement.
"Typically, we set aside a treatment slot of about 30 minutes, which includes two x-ray volume imaging (XVI) scans with the patient in the treatment position," Cosgrove explains. "If the patient moves or treatment delivery is prolonged, we repeat the XVI to ensure there has been no change in the patient set-up. With VMAT, we not only can reduce the patient's time on the table, but also – by decreasing the likelihood of patient movement –can avoid having to take further XVI scans. This is a very important consideration for treatment to this site."
For more information: www.elekta.com