Posts Tagged ‘high’

Showcase of latest advances in medical imaging for revolutionary proton therapy cancer treatment

The University of Lincoln’s Professor Nigel Allinson MBE will deliver the keynote talk at the tenth International Conference on Position Sensitive Detectors. The conference, which takes place from 7th to 12th September 2014, features the latest developments in this field from leading researchers around the world.

Professor Allinson leads the pioneering PRaVDA (Proton Radiotherapy Verification and Dosimetry Applications) project. He and his multinational team are developing one of the most complex medical instruments ever imagined to improve the delivery of proton beam therapy in the treatment of cancer.

Proton beam therapy is a type of particle therapy that uses a beam of protons to irradiate diseased tissue. Proton beam therapy has the ability to deliver high doses of radiation directly to a tumour site with very little radiation being absorbed into healthy tissue.

PRaVDA, funded by a £1.6 million grant from the Wellcome Trust, will provide a unique instrument capable of producing real-time 3D images — a proton CT — of a patient, drawing data from the same protons used in the treatment itself.

The patent-pending technology, which uses detectors at the heart of the Large Hadron Collider at CERN alongside world-first radiation-hard CMOS imagers, will reduce dose uncertainties from several centimetres to just a few millimetres.

This promises to make proton therapy an option for thousands more cancer patients by reducing the risks of healthy tissue being damaged during treatment, particularly in vulnerable parts of the body such as the brain, eye and spinal cord.

Professor Allinson, who will also be talking about his research to prospective students at the University of Lincoln open day on Saturday, 20th September, said: “PRaVDA will ensure more difficult tumours will become treatable and more patients overall will be able to receive this revolutionary treatment.”

Other members of the PRaVDA team will also present their work at the conference, describing in more detail the high-speed tracking technology that can record the paths of individual protons as they enter and leave a patient. The team will also outline how they make and test the new detectors in PRaVDA to ensure they are resistant to the high levels of radiation present in proton therapy.

The researchers have just taken delivery of some of the technology which will lie at the heart of the system: two state-of-the-art custom integrated circuits (chips) which will underpin PRaVDA’s imaging capabilities.

One device is a radiation-hard CMOS imager, measuring 10cm x 6.5cm, and producing more than 1,500 images per second. The camera chip in a mainstream smartphone is a CMOS imager but PRaVDA’s chip is over 300 times larger and operates 50 times faster — the fastest large-area CMOS imager ever made. The completed PRaVDA instrument will contain 48 of these imagers, giving a total imaging area of nearly two-and-a-half square metres.

The second device is the read-out chip for the very high-speed strip detectors that track the passage of individual protons as they enter and exit a patient. This chip, called Rhea, converts the electric charge created by a passing proton into a digital signal with additional logic to provide accurate timing (to one hundredth of one millionth of a second) while preventing erroneous signals being recorded.

The strip detectors were designed at the University of Liverpool by the same team that developed detectors for the Large Hadron Collider at CERN, which led to the discovery of the Higgs Boson in 2013. Nearly 200 Rheas are used in the complete PRaVDA system.

PRaVDA’s industrial partner, ISDI LTD, designed both devices. Their testing was undertaken by the project’s second industrial partner, aSpect Systems GmbH, in Dresden, Germany.

source : http://www.sciencedaily.com/releases/2014/09/140904121147.htm

Informed consent: False positives not a worry in lung cancer study

“Most people anticipated that participants who were told that they had a positive screen result would experience increased anxiety and reduced quality of life. However, we did not find this to be the case,” said Ilana Gareen, assistant professor (research) of epidemiology in the Brown University School of Public Health and lead author of the study published in the journal Cancer.

The NLST’s central finding, announced in 2010, was that screening with helical CT scans reduced lung cancer deaths by 20 percent compared to screening with chest X-rays. The huge trial spanned more than a decade, enrolling more than 53,000 smokers at 33 sites.

In the new study, Gareen and co-authors, including Brown faculty and staff members Fenghei Duan, Constantine Gatsonis, Erin Greco, and Bradley Snyder, followed up with a subset of participants at 16 sites to assess the psychological effects of the CT and X-ray screenings compared in the trial.

“In the context of our study, with the consent process that we used, we found no increased anxiety or decreased quality of life at one or six months after screening for participants having a false positive,” Gareen said. “What we expected was that there would be increased anxiety and decreased quality of life at one month and that these symptoms would subside by six months, which is why we measured at both time points, but we didn’t find any changes at either time point.”

The unexpected similarity between the participants with a negative and a false positive screen result is not because getting a false positive diagnosis is at all pleasant, Gareen said, but presumably because study participants understood that there was a high likelihood of a false positive screen result.

“We think that the staff at each of the NLST sites did a very good job of providing informed consent to our participants,” she said. “In advance of any screening, participants were advised that 20 to 50 percent of those screened would receive false positive results, and that the participants might require additional work-up to confirm that they were cancer free.”

Reassuring results

To make its assessments, Gareen’s team surveyed 2,812 NLST participants for the study. Patients responded well, with 2,317 returning the survey at one month after screening and 1,990 returning the survey at six months. The survey included two standardized questionnaires: the 36-question Short Form SF-36, which elicits self-reports of general physical and mental health quality, and the 20-question Spielberger State Trait Anxiety Inventory.

Maryann Duggan and her staff from the Outcomes and Economics Assessment Unit at Brown administered the questionnaires by mail with telephone follow-up as required.

In the study analysis, the researchers divided people into groups based on their ultimate accurate diagnoses: 1,024 participants were “false positive,” 63 were “true positive,” 1,381 were “true negative” and 344 had a “significant incidental finding,” meaning they didn’t have cancer but instead had another possible problem of medical importance.

The results were clear after statistical adjustment for factors that could have had a confounding influence. Whether participants received X-rays or the helical CT scans, the questionnaire scores of those with false positive diagnoses remained similar to those who were given true negative diagnoses.

Meanwhile, the scores of the true positive participants who were diagnosed with lung cancer markedly worsened over time as their battle with the disease took a physical and psychological toll.

Because participants received the questionnaires at one and six months, it is possible that study participants receiving a false positive screen result experienced anxiety and reduced quality of life for a short time after receiving their screen result, Gareen said. But by one month after their screening, there was no evidence of a difference between the screen result groups.

Gareen said the results should encourage physicians to recommend appropriate screenings, despite their high false positive rates, so long as patients are properly informed of the likelihood of a positive screen result and its implications. The data provide evidence that the NLST consent process provided a good model for advising those undergoing screening, she said.

source : http://www.sciencedaily.com/releases/2014/07/140725080404.htm