News Column

Researchers from Ryerson University Report Details of New Studies and Findings in the Area of Medical Physics

May 28, 2014

By a News Reporter-Staff News Editor at Biotech Week -- Research findings on Health and Medicine are discussed in a new report. According to news reporting from Toronto, Canada, by NewsRx journalists, research stated, "Electronic Portal Imaging Devices (EPIDs) have been widely used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Our aim is to develop a new high quantum efficiency (QE) Cerenkov Portal Imaging Device (CPID) that is quantum noise limited at dose levels corresponding to a single Linac pulse."

The news correspondents obtained a quote from the research from Ryerson University, "Recently a new concept of CPID for MV x-ray imaging in radiation therapy was introduced. It relies on Cerenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibers aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few Cerenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required in order to overcome the readout noise for portal imaging application. In this work the authors propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index (similar to 1 versus 1.38 in a typical cladding layer), a much superior light collection efficiency is achieved. A Monte Carlo simulation of the new design has been conducted to investigate its feasibility. Detector quantities such as quantum efficiency (QE), spatial resolution (MTF), and frequency dependent detective quantum efficiency (DQE) have been evaluated. The detector signal and the quantum noise have been compared to the readout noise. Our studies show that the modified new CPID has a QE and DQE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current low-QE flat-panel based EPIDs."

According to the news reporters, the research concluded: "Furthermore it was demonstrated that the new CPID does not require an avalanche gain in the AMFPI and is quantum noise limited at dose levels corresponding to a single Linac pulse."

For more information on this research see: Monte Carlo simulation of a quantum noise limited Cerenkov detector based on air-spaced light guiding taper for megavoltage x-ray imaging. Medical Physics, 2014;41(4):221-233. Medical Physics can be contacted at: Amer Assoc Physicists Medicine Amer Inst Physics, Ste 1 No 1, 2 Huntington Quadrangle, Melville, NY 11747-4502, USA. (American Association of Physicists in Medicine -; Medical Physics -

Our news journalists report that additional information may be obtained by contacting A. Teymurazyan, Ryerson Univ, Dept. of Phys, Toronto, ON M5B 2K3, Canada. Additional authors for this research include J.A. Rowlands and G. Pang (see also Health and Medicine).

Keywords for this news article include: Canada, Toronto, Ontario, Radiation Therapy, Health and Medicine, North and Central America

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC

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Source: Biotech Week

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