· Exploring Clinical Indications of PET System
· Investigators Call for Standardized IMRT Delivery
· Next Generation of Brachytherapy Treatment!

Exploring Clinical Indications of PET System

The University of Texas MD Anderson Cancer Center, Houston, recently announced an agreement with Naviscan PET Systems, San Diego, to install the company’s PEM Flex Solo II system later this month in its facility. The specialized, high-resolution PET scanner utilizes gentle compression to isolate and immobilize small parts of the body.

Paul Mirabella, chairman and CEO

According to Naviscan, MD Anderson intends to examine the scanner’s current clinical indications as well as explore possible further uses. The center also looks to monitor response to neoadjuvant therapies in breast cancer patients.

“The studies that are proposed right now internally are more or less just to validate the device within the current indications that already exist,” said Gary Seelhorst, senior director, marketing and business development, Naviscan. “The intended use was to have this PEM scanner as a biomarker to determine between the different responders or nonresponders in a chemotherapy trial.”

As the second-generation version, the PEM unit, or positron emission mammography unit, is a device that was cleared in a general PET category and optimized for small parts imaging, said Paul Mirabella, chairman and CEO of Naviscan. With its high spatial resolution of 1.5 to 2.0 mm, the scanner has the ability to characterize the scope of disease at the metabolic level. Additionally, the technology, which has both anatomical imaging and molecular imaging capabilities, generates a 4- to 10-minute scan time per breast per view, is compact and portable, and produces a true 3D telegraphic image of the breast, Mirabella said.

While other PET technologies rely on supplemental x-ray modalities for anatomic imaging, images from Naviscan’s unit do not need to be fused with an anatomic CT.

“We are so close to what it is that we are imaging, and thus so close to the radioactive sugar that is being absorbed by the cancer cells, that we get exquisite anatomical imaging, spatial resolution, and fantastic molecular imaging information as well,” Mirabella said.

Naviscan’s PEM Flex Solo II is a highresolution PET scanner that utilizes gentle compression to isolate and immobilize small body parts.

The agreement with MD Anderson is an 18-month testing and evaluation contract, Seelhorst said, adding that the arrangement allows the center’s physicians to become comfortable with a new technology. During that time period, studies are proposed both internally and externally. Extensions can easily be added to the contract, he added.

Mirabella admitted that with the contacts he has made during his 32 years in the industry, Naviscan could have chosen to develop individual and unique relationships with each of the biomarker pharmaceutical companies. Instead, he decided to call a former colleague, Don Podoloff, MD, head of the division of diagnostic imaging at M.D. Anderson. Physicians of the renowned institution would then have the opportunity to validate the PEM Flex Solo II as a molecular imaging technology and see, in a relatively short period of time, whether their cancer therapy drugs will work.

“It’s going to become very evident to the manufacturers of those therapies that this is exactly the type of device they need to have that feedback early on,” Mirabella said. “That’s our hope. It’s really up to M.D. Anderson now. We’re putting our trust and faith in them to determine which drugs and which trials, and we’ll be along with them as a partner for the next couple of years.”

—Elaine Sanchez

Research Alert

Investigators Call for Standardized IMRT Delivery

A lack of necessary standardization exists in the prescription and delivery of doses during intensity-modulated radiation therapy (IMRT), according to a report published in the March 5 issue of the Journal of the National Cancer Institute.

“With present IMRT practices, cancer patients do not receive radiation doses that are as prescribed by the clinicians,” Indra J. Das, MD, lead investigator, told Reuters Health News.

Das, who works at the University of Pennsylvania Medical Center in Philadelphia, and a team of researchers noted that IMRT treatment planning software, in addition to the particular machine used, influences dosage.

After reviewing the cases of 803 patients who underwent IMRT for cancers of the brain, head and neck, or prostate at five separate facilities, the investigators discovered that 46% of patients received a maximum dose more than 10% higher than the prescribed dose, and 63% received a dose more than 10% lower.

The median dose to the target was found to be 2% higher or lower than the prescribed dose in 68% of patients, 5% higher or lower in 88% of the patients, and 10% higher or lower in 96% of patients.

All in all, the smallest dosimetric variations were in prostate cancer patients and the largest were in head and neck cancer patients.

“Patients treated in different centers do not get a standard and uniform dose in IMRT, which used to be the case in the era of conformal therapy,” Das said. “The variability in radiation dose is huge and creates ambiguity in outcome from the clinical trials using IMRT.”

Agreeing on the need for IMRT planning standards, John Willins, MD, and Lisa Kachnic, MD, wrote an accompanying editorial that said widespread use of such standards “would not only facilitate multicenter clinical trials, but would also provide clinicians with solid guidance in their everyday practice on the question of what constitutes a ?good’ IMRT plan.”

—E. Sanchez

Product Launch

Next Generation of Brachytherapy Treatment!

Spring brought more than rain showers; it brought with it a comprehensive volume-based treatment planning system promising to optimize cancer treatment planning. The Oncentra Brachy Treatment Planning Solution from Nucletron provides clinicians with faster and easier creation of treatment plans, ranging from simple to complex, in user-defined workspaces allowing for adaptation to specific clinical workflows.

The Oncentra Brachy Treatment Planning Solution recently received FDA approval.

“Historically, we have used two-dimensional imaging; in 2D, we are dealing with a much lower volume of information. When we move to 3D, we have a lot more data process,” said

I-Chow Hsu, MD, associate professor of Radiation Oncology at the University of California, San Francisco. He and his team have been testing the Oncentra Brachy system for about a year. “The Oncentra is to be able to control, to manipulate, and to navigate through these three-dimensional data sets.”

Mastering this functionality is of particular importance in image-guided brachytherapy, which relies on 3D images for accurate planning and placement.

“This [capability] is critical for brachytherapy, because of the complexity of the anatomy and the dose distribution, it’s a lot more complicated than external-beam radiation,” he said. “With the typical implant there could be hundreds of different source positions, each of which produces different dose distributions, so it’s very important for the brachytherapist to have a picture of exactly where all of the implants are, where the hot spots are located, and how those doses are conforming to the area you are trying to treat.”

Oncentra Brachy is the first fully DICOM-compatible treatment planning system, according to its manufacturer. It provides excellent 3D contouring and margining tools to identify regions of interest either with CT or in a multimodality imaging environment.

Because FDA regulations prohibit the use of a system for treatment while it is being tested, the team at UCSF used it for specific parts of the procedure, such as contouring or catheter digitization, with the final dose calculation and planning being completed by the PLATO Brachytherapy system (also manufactured by Nucletron) that the hospital has used for nearly a decade. Still, Hsu found the Oncentra Brachy to be a benefit to the department.

“As one of the original gamma testing sites for Oncentra Brachy, I am very pleased with the efficient and flexible tools of this new treatment planning system from Nucletron,” said Hsu, who notes that the hospital plans on using Oncentra Brachy exclusively in his center once it receives regulatory approval for use in North America. “It actually sped up our process, in part because you use a tablet and pen and you draw, rather than click, the areas you want to treat.”

While he admits that using a computerized table and stylus took a little getting used to, he said the learning curve is very short. The same is true of the system’s display, according to Hsu.

“The design of the interface is very user friendly. There are a lot of planning systems that have 3D information capable of handling the data that aren’t as easy to use,” he said. “With the Oncentra, you can simultaneously get a correlation of where you’re drawing on the axial view, the coronal, or the sagittal.” Not only are they available, but they’re provided in real time, a feature that facilitates remote evaluations and treatments.

“The release of Oncentra Brachy marks the first of some new and exciting treatment planning innovations forthcoming from Nucletron,” said Jeroen Cammeraat, COO of Nucletron. “We have set a new benchmark in technological achievement with Oncentra Brachy that represents the future of brachytherapy treatment planning. We have worked with our clinical partners to develop a state-of-the art solution that includes many sophisticated and powerful new tools to improve patient care.”

—Dana Hinesly