First use of Symmetry motion management software in Australasia makes 75-year-old’s treatment more preciseSydney Australia — Monday, October 31, 2011
To successfully irradiate a moving lung tumor requires doctors to find a way either to stop the tumor from moving or a means to compensate for its motion. On September 8, clinicians at Prince of Wales Hospital Cancer Centre (Randwick, New South Wales) chose the second option, using Elekta’s Symmetry™ respiratory motion management software for the first time to treat a 75-year-old male patient with a tumor that moved back and forth with his breathing. Symmetry enables physicians to visualize the tumor’s complete range of motion and then ensures that the tumor is always positioned in the treatment beam regardless of its movement.
Accurate treatment of this patient’s tumor, a primary, malignant non-small cell cancer (NSCLC) in the upper lobe of the left lung, was critical due to the therapy approach used. Prince of Wales Hospital clinicians used hypofractionated Stereotactic Body Radiation Therapy (SBRT), which called for precise immobilization of the patient’s body to enable just three treatment sessions (i.e., fractions), each using a highly potent radiation dose.
“The whole concept of hypofractionated stereotactic treatment relies on accurate and precise planning datasets and treatment verification systems,” says Wenchang Wong, M.D., radiation oncologist at Prince of Wales Hospital. “Symmetry afforded us clear visualization of the tumor at the treatment couch and gave me confidence that treatment delivery would be safe and reproducible for this patient.”
Symmetry, a feature set of Elekta’s X-ray Volume Imaging (XVI) software package, enables clear visualization of moving lung tumors by providing a dynamic fourth dimension (4D) of motion to enhance image guidance with the patient in the treatment position.
“Conventional cone beam CT provides only a static, blurred image of a moving lung tumor that cannot tell us in which part of the respiratory cycle it was captured,” Dr. Wong explains. “Conversely, Symmetry provides a dynamic 4D cine/picture of the movement of the tumor mass throughout the entire respiratory cycle. This is especially important in lung cancer treatment given the natural excursion of the tumor with the breathing cycle. Symmetry enables us to see the tumor’s movement in real time.”
Hypofractionated SBRT of lung tumors at Prince of Wales involves several Elekta solutions, encompassing planning through to treatment.
To ensure a consistent patient breathing pattern during treatment, planning CT scans are performed with Active Breathing Coordinator™. This Elekta technology enables acquisition of a breathing trace that shows peak inhalation and exhalation points during normal breathing.
“Patients are instructed to hold their breath for 12 seconds at both peak points so that CT scans can be acquired,” says Simon Downes, Director of Medical Physics. “The images show the tumor’s position at both maximum inhalation and maximum exhalation, and guide treatment planning.”
Clinicians plan lung treatments with XiO® treatment planning system. MOSAIQ® Oncology Information System is used to verify and record the plan. For immobilization, Prince of Wales clinicians use BodyFIX®, and Symmetry provides the needed data on tumor position – with Symmetry CBCT scans acquired just before treatment. Patients are treated on the center’s Elekta Axesse™ system.
“All of these different systems come together seamlessly to allow us to perform these lung treatments,” Downes observes. “In particular, it’s remarkable how well Symmetry maps the tumor’s position. In a second Symmetry CBCT scan after treatment, we found that we had achieved less than a two millimeter positional error, meaning that the clinical target volume was still enclosed in the treatment field for the entire therapy session. It was a great result.”
As lung cancer represents about nine percent of New South Wales’ cancer cases, Prince of Wales clinicians anticipate a rapid increase in the number of cases for which Symmetry is employed, he says.
*Approval of indications may vary between different countries. Additional regulatory clearances may be required in some markets
Today, Elekta solutions in oncology and neurosurgery are used in over 6,000 hospitals worldwide. Elekta employs around 3,300 employees globally. The corporate headquarters is located in Stockholm, Sweden, and the company is listed on the Nordic Exchange under the ticker EKTAb. Website: www.elekta.com.
Stina Thorman, Vice President Corporate Communications, Elekta AB
Tel: +46 8 587 254 37
Time zone: CET: Central European Time
Michelle Lee Joiner, Director, Global Public Relations and Brand Management, Elekta
Tel: +1 770-670-2447
Time zone: ET: Eastern Time