Linac-MR obtains first images during irradiation
The Linac-MR project at the Cross Cancer Institute in Edmonton, Canada, has published the first images produced by its prototype integrated linac-MR system. The device - a 6 MV linac mounted on the open end of a biplanar 0.2 T MR system - is designed such that the magnetic field does not interfere with the electron trajectory in the linac waveguide, and the radiofrequency signals from each system do not interfere with operation of the other. Shielding calculations, confirmed with appropriate measurements, showed that the magnetic shielding was effective enough to allow the linac to produce X-rays (Med. Phys. 36 2084).

Imaging a phantom with conventional gradient echo sequences revealed that MRI was fully operational during linac operation. The MR images produced during irradiation were visually and quantitatively similar to those taken without the beam on, the only difference being a change in signal-to-noise ratio (from 80 to 16) when the beam was on. "This prototype system provides proof of concept that the design has decreased the mutual interferences sufficiently to allow the development of real-time MR-guided radiotherapy," the authors write.

Fluorescence-guidance improves brain tumour resection
Gliomas, the most prevalent of malignant adult brain tumours, can present a challenge for surgical resection as they invade normal brain tissue. In work presented at the 77th Annual Meeting of the American Association of Neurological Surgeons, held in San Diego, CA, earlier this month, researchers at Dartmouth-Hitchcock Medical Center (Lebanon, NH) described the use of florescence guidance during glioma resection. Such guidance should enable more complete resection of a tumour while preserving surrounding normal tissue and critical brain functions.

The study, involving 20 patients undergoing tumour resection, compared the tumour tissue's intraoperative appearance with that of pre-operative imaging studies such as MRI. Study participants were given the fluorescence agent 5-aminolevulinic acid prior to surgery and the surgical site was illuminated with blue light during the operation. The researchers demonstrated high correlation between tumour aggressiveness, MRI-enhancement and intraoperative fluorescence. No normal brain tissue fluoresced.

SBRS proves effective for treating spinal metastases
The spinal column is the most common site for bone metastasis, with 30-70% of cancer patients experiencing spread to their spine. A study at the MD Anderson Cancer Center (Houston, TX) has investigated the use of stereotactic body radiosurgery (SBRS) for treating patients with such metastases. The researchers used SBRS to treat 136 spinal metastases in 121 patients. The six-month and one-year survival rates for spinal metastasis progression-free survival (PFS) were 90% and 84%, respectively. Patient survival was 65% at one year and 42% at two years. The number of patients who were completely pain-free at three and six months post-SBRS doubled compared to baseline.

"SBRS in patients with spinal metastases is a safe and effective treatment modality, yielding high six-month and one-year PFS rates and dramatic reductions in pain and symptoms related to the metastatic cancer," said Eric Chang, who presented this work at the 77th Annual Meeting of the American Association of Neurological Surgeons, held in San Diego, CA, earlier this month.

Synchrotron source enhances soft-tissue imaging
Lyncean Technologies (Palo Alto, CA) has bagged a grant of almost $1.3 million from the National Center for Research Resources to develop differential phase-contrast imaging using its Compact Light Source (CLS), a miniature synchrotron source that delivers a monochromatic pencil-beam of tunable X-rays. Differential phase-contrast imaging uses a pair of micron-scale gratings to create three images: an absorption image, a phase-sensitive image and scattering contrast image. The combination of these images enables superior soft-tissue visualization.

The technique relies on the use of a point-like monochromatic X-ray source, such as produced by the CLS, to achieve the coherence necessary for the fringes. The grant will enable development of an X-ray imaging system called "The Clinical High Resolution Imaging System" or CHRIS. Potential uses include mammography, osteoarthritis imaging, small-animal imaging and other clinical radiological applications that require detection of fine structure within soft tissue.

Prototyping tools aid adaptive radiotherapy planning
Researchers at the University of Houston (Houston, TX) are employing technologies originating in the automobile industry to develop improved radiotherapy planning tools. The idea is to use visualization and rapid prototyping methods to develop predictive models of tumours, enabling treatment plans to be adjusted as the tumour shrinks in response to therapy. "We aim to better understand tumour deformations using geometric and statistical models - rather than repetitive CT scans," explained Ali Kamrani, founding director of the University of Houston's Design and Free Form Fabrication Laboratory.

The researchers hope that, by using initial CT scan readings to classify tumours and predict through radiation models the various stages of their demise, the scheme will reduce the number of CT scans that patients undergo. According to Kamrani's collaborator Lei Dong, from the MD Anderson Cancer Center (Houston, TX), applying auto prototyping tools to tumour modelling could help solve workflow issues. "If we do replanning every day and re-CT every day, that's lot of effort," he said. "We're thinking there is a better, smarter way."

PET/CT bone-imaging trial enrols first patients
The Academy of Molecular Imaging (AMI) has enrolled the first ten patients to its multicentre trial investigating the use of 18F-sodium fluoride (18F-NaF) PET/CT to detect bony metastases. The randomized study compares conventional planar 99mTc-MDP bone imaging with 18F-NaF PET/CT in patients with breast, prostate and non-small cell lung cancers. 18F-NaF PET/CT bone scanning may prove advantageous as it is able to find smaller metastases and differentiate more accurately between cancerous and non-cancerous conditions.

"This exciting development is the culmination of many months' work and an extraordinary level of collaboration," said principal investigator Johannes Czernin. "This important research is a result of cooperative efforts between thirteen clinical sites, AMI and the molecular imaging industry. Siemens/PETNET Solutions furnished these initial 18F-NaF doses and GE Healthcare and IBA Molecular will also provide doses in the future."

Software tool keeps track of radiation exposure
Canadian software developer Tidal Pool Software has released Radiation Passport 1.0, a tool that monitors a person's cumulative radiation dose. Designed for the Apple iPhone and iPod Touch, Radiation Passport logs all radiology and imaging-related exams and procedures, including details of the exam type, date, dosage and related notes. It then calculates the total radiation exposure, estimates the associated cancer risks and displays other common risks for comparison. The program includes average dosage values for over 140 exams and procedures. The tool also estimates background radiation exposure, taking into account location and lifestyle. Other features include: an extensive background section with links to relevant studies and reports; graphs showing radiation exposure, cancer risks and the sources of exposure and risk; and emailing of exposure/risk reports.