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  1. Article ; Online: Helium radiography with a digital tracking calorimeter-a Monte Carlo study for secondary track rejection.

    Pettersen, Helge Egil Seime / Volz, Lennart / Sølie, Jarle Rambo / Alme, Johan / Barnaföldi, Gergely Gábor / Barthel, Rene / van den Brink, Anthony / Borshchov, Vyacheslav / Chaar, Mamdouh / Eikeland, Viljar / Genov, Georgi / Grøttvik, Ola / Helstrup, Håvard / Keidel, Ralf / Kobdaj, Chinorat / van der Kolk, Naomi / Mehendale, Shruti / Meric, Ilker / Harald Odland, Odd /
    Papp, Gábor / Peitzmann, Thomas / Piersimoni, Pierluigi / Protsenko, Maksym / Ur Rehman, Attiq / Richter, Matthias / Tefre Samnøy, Andreas / Seco, Joao / Shafiee, Hesam / Songmoolnak, Arnon / Tambave, Ganesh / Tymchuk, Ihor / Ullaland, Kjetil / Varga-Kofarago, Monika / Wagner, Boris / Xiao, RenZheng / Yang, Shiming / Yokoyama, Hiroki / Röhrich, Dieter

    Physics in medicine and biology

    2021  Volume 66, Issue 3, Page(s) 35004

    Abstract: Radiation therapy using protons and heavier ions is a fast-growing therapeutic option for cancer patients. A clinical system for particle imaging in particle therapy would enable online patient position verification, estimation of the dose deposition ... ...

    Abstract Radiation therapy using protons and heavier ions is a fast-growing therapeutic option for cancer patients. A clinical system for particle imaging in particle therapy would enable online patient position verification, estimation of the dose deposition through range monitoring and a reduction of uncertainties in the calculation of the relative stopping power of the patient. Several prototype imaging modalities offer radiography and computed tomography using protons and heavy ions. A Digital Tracking Calorimeter (DTC), currently under development, has been proposed as one such detector. In the DTC 43 longitudinal layers of laterally stacked ALPIDE CMOS monolithic active pixel sensor chips are able to reconstruct a large number of simultaneously recorded proton tracks. In this study, we explored the capability of the DTC for helium imaging which offers favorable spatial resolution over proton imaging. Helium ions exhibit a larger cross section for inelastic nuclear interactions, increasing the number of produced secondaries in the imaged object and in the detector itself. To that end, a filtering process able to remove a large fraction of the secondaries was identified, and the track reconstruction process was adapted for helium ions. By filtering on the energy loss along the tracks, on the incoming angle and on the particle ranges, 97.5% of the secondaries were removed. After passing through 16 cm water, 50.0% of the primary helium ions survived; after the proposed filtering 42.4% of the primaries remained; finally after subsequent image reconstruction 31% of the primaries remained. Helium track reconstruction leads to more track matching errors compared to protons due to the increased available focus strength of the helium beam. In a head phantom radiograph, the Water Equivalent Path Length error envelope was 1.0 mm for helium and 1.1 mm for protons. This accuracy is expected to be sufficient for helium imaging for pre-treatment verification purposes.
    MeSH term(s) Calorimetry/instrumentation ; Helium ; Humans ; Monte Carlo Method ; Phantoms, Imaging ; Protons ; Radiography
    Chemical Substances Protons ; Helium (206GF3GB41)
    Language English
    Publishing date 2021-01-26
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 208857-5
    ISSN 1361-6560 ; 0031-9155
    ISSN (online) 1361-6560
    ISSN 0031-9155
    DOI 10.1088/1361-6560/abca03
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Design optimization of a pixel-based range telescope for proton computed tomography.

    Pettersen, Helge Egil Seime / Alme, Johan / Barnaföldi, Gergely Gábor / Barthel, Rene / van den Brink, Anthony / Chaar, Mamdouh / Eikeland, Viljar / García-Santos, Alba / Genov, Georgi / Grimstad, Silje / Grøttvik, Ola / Helstrup, Håvard / Hetland, Kristin Fanebust / Mehendale, Shruti / Meric, Ilker / Odland, Odd Harald / Papp, Gábor / Peitzmann, Thomas / Piersimoni, Pierluigi /
    Ur Rehman, Attiq / Richter, Matthias / Samnøy, Andreas Tefre / Seco, Joao / Shafiee, Hesam / Skjæveland, Eivind Vågslid / Sølie, Jarle Rambo / Tambave, Ganesh / Ullaland, Kjetil / Varga-Kofarago, Monika / Volz, Lennart / Wagner, Boris / Yang, Shiming / Röhrich, Dieter

    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)

    2019  Volume 63, Page(s) 87–97

    Abstract: Purpose: A pixel-based range telescope for tracking particles during proton imaging is described. The detector applies a 3D matrix of stacked Monolithic Active Pixel Sensors with fast readout speeds. This study evaluates different design alternatives of ...

    Abstract Purpose: A pixel-based range telescope for tracking particles during proton imaging is described. The detector applies a 3D matrix of stacked Monolithic Active Pixel Sensors with fast readout speeds. This study evaluates different design alternatives of the range telescope on basis of the protons' range accuracy and the track reconstruction efficiency.
    Method: Detector designs with different thicknesses of the energy-absorbing plates between each sensor layer are simulated using the GATE/Geant4 Monte Carlo software. Proton tracks traversing the detector layers are individually reconstructed, and a Bragg curve fitting procedure is applied for the calculation of each proton's range.
    Results: Simulations show that the setups with 4 mm and thinner absorber layers of aluminum have a low range uncertainty compared to the physical range straggling, systematic errors below 0.3 mm water equivalent thickness and a track reconstruction capability exceeding ten million protons per second.
    Conclusions: In order to restrict the total number of layers and to yield the required tracking and range resolution properties, a design recommendation is reached where the proposed range telescope applies 3.5 mm thick aluminum absorber slabs between each sensor layer.
    MeSH term(s) Equipment Design ; Image Processing, Computer-Assisted ; Monte Carlo Method ; Phantoms, Imaging ; Protons ; Scattering, Radiation ; Software ; Telescopes ; Tomography, X-Ray Computed/instrumentation
    Chemical Substances Protons
    Language English
    Publishing date 2019-06-06
    Publishing country Italy
    Document type Journal Article
    ZDB-ID 1122650-x
    ISSN 1724-191X ; 1120-1797
    ISSN (online) 1724-191X
    ISSN 1120-1797
    DOI 10.1016/j.ejmp.2019.05.026
    Database MEDical Literature Analysis and Retrieval System OnLINE

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