CANCER CARE
From large academic medical centres to community hospitals, Elekta stereotactic body radiation therapy (SBRT) is finding a niche.
S BRT encompasses a complete spectrum of treatments from basic
to advanced, enabling a diverse range of clinical environments to offer SBRT to their patients.
“Elekta can address the unique require- ments of individual centres – regardless of their expertise and resources – and help them to begin using SBRT safely and effec- tively,” says Patrick Greally, Elekta’s direc- tor of oncology sales in the UK.
Representing the academic medical centre end of the SBRT user field is St James’s University Hospital in Leeds, which recent- ly treated its 100th patient with lung SBRT. For many of these patients, St James’s doc- tors have used Symmetry motion manage- ment software: new imaging technology from Elekta that enables clear visualisation of moving targets.
John Lilley, a physicist at St James’s, part of Leeds Teaching Hospitals NHS Trust, said: “For patients with lung tumours that move a large amount during breathing, Symmetry has been incredibly useful.
“The standard 3D volume imaging system on our Elekta Synergy system can image stationary targets, but moving objects be- come blurred,” he explains.
“However, by taking the 4DCT planning scan – which shows the ‘envelope’ of space within which the tumour is moving – and matching that to Symmetry reconstruc- tions, which show the tumour’s position during the breathing cycle, we can easily localise moving tumours.”
Recently, St James’s clinicians have incor- porated Symmetry for all lung cancer cases two days before the patient officially begins treatment (‘Day zero’), according to Dr Kevin Franks, consultant in clinical oncol- ogy at St James’s.
He said: “We’re doing it for all patients now to verify that the 4D planning CT scan truly represents the tumour’s motion and to assess whether 4D CBCT is superior for matches for any patient.”
For many patients, the Day zero scan will
be their last Symmetry scan – if doctors determine tumour motion is insufficient to justify the use of Symmetry for every treat- ment session. However, for patients with mobile tumours, typically those close to the diaphragm, Symmetry scans are repeated three times for each of the five SBRT treat- ment sessions. The first scan is to localise the tumour, the second to verify needed patient position corrections and a third to ensure proper patient immobilisation. The treatments are delivered while the patient is breathing freely.
“For tumours with significant motion – particularly small tumours – when using 3D CBCT on the treatment system it had been very difficult to match up the 4D plan- ning CT target volume,” Dr Franks recalls. “Symmetry has been invaluable for this group of patients.”
St James’s clinicians also have been using Intuity, another Elekta imaging tool. Intu- ity ensures that not only is the tumour’s
position accounted for, but also the posi- tion of nearby healthy critical structures, such as the airway and other mediastinal structures.
“The dual registration capability of Intuity enables us to set tolerances for organs-at- risk to avoid the radiation dose going be- yond that organ’s tolerance,” Dr Franks says. “We had been using it in an offline way, but we plan to incorporate Intuity dual registration in a prospective, online way with Symmetry. In this way, we can work out tolerances so that when we go to the treatment it will be safer, quicker and more streamlined.”
Symmetry and Intuity are feature sets of version 4.5 of Elekta’s X-ray Volume Imag- ing (XVI) package of software solutions for Image Guided Radiation Therapy (IGRT).
FOR MORE INFORMATION
Visit
www.elekta.com/symmetry and
www.elekta.com/intuity
national health executive May/Jun 11 | 35
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