VMAT Radiotherapy Reduces Patient Treatment Time with More Precise Tumor Targeting

"On Monday 28th of January we treated our first patient with the VMAT technique,” reported Jim Warrington, head of radiotherapy physics at the Royal Marsden. "The patient received a single 340° arc of 6 MV X-rays, with simultaneously variable gantry rotation speed, dose rate and dynamic multi-leaf collimator modulation. The treatment arc delivered a 2-Gray fraction to the target in 93 seconds. The efficiency and flexibility of this technique is impressive, and we hope to be able to expand the use of this advanced new treatment method to become routine practice in the future. We anticipate that when used in conjunction with our Elekta Synergy image guidance systems and employing non-coplanar angles of delivery, VMAT will be a significantly improved treatment modality for the Royal Marsden's radiotherapy patients” he concluded.

The two key benefits of this unique technology promise to be a significant reduction in treatment time (in the case of the Royal Marsden treatment, 50% from the patient's previous conformal plan) combined with a significant improvement in conformance to the target and sparing of dose to adjacent healthy tissues. An additional benefit of reducing treatment times is greater comfort for the patient, which in turn, by making it easier for the patient to keep still, increases the likelihood of delivering radiation beams more accurately as targeted.

During the same week in January 2008, Allgemeines KrankenHaus/Medical University of Vienna (AKH; Austria) delivered the world's first PreciseBeam VMAT treatment. PreciseBeam VMAT is delivered as a combination of optimized treatment planning using Ergo++ and an Elekta Synergy linear accelerator, upgraded with a next-generation digital control system.

The treatment was to an intracranial glioblastoma and consisted of three non-coplanar VMAT arcs with variable gantry speed and simultaneous leaf movement and rotation of the dynamic multileaf collimator. The Elekta accelerators are unique in their ability to deliver this level of movement complexity. The patient had a brain lesion very close to vital structures such as hypophysis, brain stem, optical nerves, and lenses of the eyes, however the treatment was completed within 10 minutes--including set-up, imaging, repositioning, and delivery.

"The new system will revolutionize the practice of tailored intensity modulated radiotherapy during the next decade,” commented Prof. Dr. Richard Pötter, chief medical doctor at AKH. "Very soon, not only head and neck lesions but also tumors in the lung, close to the cervical spine and in the pelvis will be treated with VMAT.”

"For many years AKH has been practicing a technique called IMRT. The new technique VMAT adds the possibility of modulating the radiation intensity during an arc treatment. The advantage is an even better sparring of healthy organs and a more effective and better targeted irradiation of the tumor … At the same time, the total treatment time is significantly reduced from 15 minutes to 6-7 minutes, which is of highest importance for patients with serious diseases,” continued Prof. Dr. Pötter.


Related Links:
Royal Marsden Hospital
Elekta
Allgemeines KrankenHaus/Medical University of Vienna